Lister CS direct drive
generator - a DC Battery
Charging Set.
record of proceedings.
Sorry for lack of photos - see earlier pages for pictures of the system components.
Having assembled the system, there was now the task of getting the it to work reliably and conveniently, and to
interface efficiently with the household electrical and heating systems, so making an appreciable contribution
to offsetting my grid power and natural gas usage.
Some questions were:
1. How much power is available and at what overall efficiency?
2. How long will the fully charged battery bank keep the office and other light loads running?
3. How much fuel is needed to recharge the batteries after a typical overnight battery run?
4. How much heat can usefully be extracted from the system?
5. How best to integrate this heat content into the central heating and DHW requirements of the house?
6. How to assess the overall performance of the system, in terms of electricity and gas saved?
7. A documentation of any operational problems.
Some System Objectives.
The Lister CHP system should be able to do the following:
1. Provide 4 to 5kW of heating for the radiators, underfloor heating loop and heat the 120 litre domestic hot
water cylinder.
2. Supply 1700W of electrical power for a 12kWh electric storage heater for office heating.
3. Provide up to 2500W of electrical power for powering the office, washing machine, dishwasher etc.
4. Provide up to 8kWh per day to offset grid electricity usage, and provide overnight battery back-up.
Following some recent installation work of plumbing and cables, renewable heat and power has now been
brought into my household.
I am using my office area as a guinea-pig, mainly because it is under my control, more often than not occupied, I
use between 2 to 4 kWh of electricity each day, and I have a fairly constant need for background heat during the
winter months.
The Lister recharges a battery bank to a nominal 125V dc and this is used to power a large inverter consisting of
two 2500W units. They can be used in isolation or ganged together to make a 5kW inverter.
The output of one inverter is brought up to my office via a 25m length of 2.5mm2 cable. This terminates in a
double switched 13A socket, one half is used for the 1700W storage heater and the other feeds the rest of the
office equipment, which may be up to a 400W load.
Further cables will be brought in to supply selected loads such as the dishwasher, washing machine and
probably the kettle - as these represent most of our high wattage appliances.
The inverter is consuming 121.8V at 18.9A from the batteries = 2290W
The storage heater, office equipment and engine room light amount to 1645+ 215 +60 = 1920W
So the inverter is operating at about 83.85% efficiency.
The current flowing into the batteries is measured on an oscilloscope and is pictured below.
Generator current = 19.8A x 121.8V = 2412W
The hot water output is 50 litres per hour at 24.2 C temperature rise - so about 1.4 kW. Improved pipework and
better insulation would improve this considerably.
13:00 Engine started
13:04 Storage Heater turned on
14:52 Office supply switched over to inverter
16:29 Storage Heater Turned off
On Time 3 hours 25 minutes
KWh used 5.62
Mean Power 1645 W
The current here is measured by the millivolt reading so +19.8mV is equal to 19.8A flowing into the battery
from the dc generator.
The frequency reading 5.411Hz should be multiplied by 120 to give rpm - in this case 649.32rpm.
Note the distinct peak in the waveform for the power stroke and the lesser peaks for the exhaust and induction
strokes. The trough in the waveform is of course the compression stroke in which kinetic energy from the
flywheel is being used to compress the air charge. With heavier flywheels, such as on a Startomatic, the peaks
and troughs would be less pronounced.
Friday Sept 21st 2007.
Outside temperature 17.7 C
After 3 hours running
Top of Local Store 92.6 C
Engine coolant inlet 64C
Engine Coolant Out 94 C
Top of DHW Tank 62.2 C
Bottom of DHW Tank 45.9C
Tank start temperature Top 35C, base 22.8C
Energy in DHW tank
Exhaust Heat exchanger inlet 39.5 C
Exhaust Heat Exchanger Outlet 75.5
Flow Rate 50.4 litres per hour
Heat exchanger power = 2.108 kW
Heat exchanger and exhaust need properly insulating.
Energy into storage heater in 3hrs 25 mins = 5.62kWh = 1.645kW power
Energy into office in 2hrs 54 minutes = 0.78kWh = 200W power
Engine room fluorescent light = 60W
Total power = 1905W
Fuel Burn Rate (at 9.4kWh/litre) =10.575kW
Conversion Efficiency from veg oil to ac power = (1.905/10.575) = 18.01%
Fuel Used: 3 litres in 2hrs 40 minutes. = 1125cc per hour
circuit and the exhaust. For best overall system efficiency, the CHP system needs to capture as much of this
heat as possible and make it available in a form that is directly useful for the property to be heated.
Because of system pipework temperature limitations, the heated water should not exceed 90 centigrade. The
coolant in the engine should also be limited to around 90C.
My first approach was to plumb in a local gravity feed store to provide engine cooling, and to moderate the
peak system temperatures. Sizing of this store, and the rate at which heat is extracted appear to be critical to
the efficiency and heat-up time of the system.
Following the initial 3.5 hour run, the local tank had reached 92.6C and the DHW cylinder was receiving
water at 65 centigrade.
To get a better idea of the thermal performance, we can consider the engine coolant circuit to approximate a
2kW heater, and the exhaust heat exchanger also a 2kW heater.
Weather sunny spells warm
Overnight the battery terminal voltage has dropped to 106.0V powering the office.
Decided to run the engine on just 3 litres of fuel as a typical battery recharge cycle.
10:00 The empty fuel tank had 3.0 litres of filtered WVO added
10:00 Engine started on high compression 116V at 27.4 A battery charge current 3178W
10:10 Compression setting lowered
10:40 Engine stopped due to defective pipe joint flooding workshop! 1hr 50 minute shut down.
12:30 Engine restarted - high compression
12:40 Compression setting lowered
13:07 Battery Voltage 121.9V, charge current 17.7A 2157.6W
13:30 Battery Voltage 122.6V, charge current 14.3A 1753W
14:00 Battery Voltage 122.4V, charge current 10.3A 1260W
14:00 Water from house 27.7C, return to house 56.6 C (washing machine drawing from hot)
14:30 Rapid drop in battery charge current 124.6V @ 8.0A 996.8W
14:30 Engine shut down. Fuel used 2.8litres Fuel remaining <200ml
Run time 2 hrs 40 minutes, fuel used 2.8 litres.
Average fuel consumption 1050ml per hour
As can be seen, the charge current on the batteries is rapidly decreasing as they charge up. This was most
notable in the last half hour of the recharge. The load on the engine decreases and this is why it may be
beneficial to use the storage heater or other domestic loads to help maintain a more constant load on the
engine.
Weather Warm, Sunny spells 21 C
The Lister CHP system produced enough hot water last night for us both to enjoy hot baths - I much
needed one having been splattered with engine oil and prematurely showered with water earlier in the
day.
The engine was shut down at 2:30pm and the office continued to run from the batteries and inverter.
Overnight the office was semi-powered so continued to draw about 100W.
At 8am this morning the energy meter showed that I had used 6.73kWh of power in the office in the last
42 hours since 3pm on Friday afternoon, plus 5.62kWh were used in the electric storage heater on Friday.
Checking my daily energy figures, my gas consumption showed a significant drop for the last 3 days, and
the electricity was also down by about 2.5 KWh per day.
By 9am the battery bank voltage had dropped to 99.0V, and with a recommended minimum of 10.8V per
battery (97.2V), it was decided to restart the engine and give the batteries their daily charge.
Batteries follow a very distinct charging curve. They start off drawing a high current and this then tapers
off until the battery is fully charged and drawing very little current. I took voltage and current readings
every half hour to illustrate this charging behaviour.
This means that the engine begins the recharge cycle on a high load of about 3.2kW which tapers down to
900W when the batteries are near charged.
11:00 am Office active at about 330W consumption - 2 x PC, router etc.
11:00 7.4kWh consumed in 44 hours - mean office consumption of 168W
11:30 Engine shut down - run time 2.5 hours - fuel used 2.6 litres
Average fuel usage 1.04 litres per hour.
System Efficiency
During the 2.5 hour battery charging cycle, the generator was producing an average of 2.25kW.
So the approximate total electrical energy into the batteries = (2.5 x 2.25) = 5.625kWh
The energy content of the fuel burned = (2.6 litres x 9.4kWh) = 24.44kWh
So the average conversion efficiency of veg oil to dc into the battery = (5.625/24.44) =23.01%
The heat recovered into the 120 litre DHW tank can be estimated from the tank start temperature and the
end temperature. Note that the top of the hot water cylinder may well be 20C hotter than the base.
From the temperature measurements taken, the heat captured into the cylinder is about 2.9kWh.
This is a fairly poor result, and reflects the low flow rates, the heat losses and the inefficiency of the
existing pipework.
Battery voltage was down to 96V at 8am this morning suggesting that a full recharge was in order.
08:00 Engine started with 3.4 litres in tank
10:00 3 litres of WVO added
10:00 Dishwasher started
10:20 Dishwasher commences heat cycle
10:25 Generator 109.7V @ 20.6A Inverter 109.7V @28.5A
11:45 Dishwasher stops after 1.43kWh consumed
11:52 Washing machine started
12:10 1.75l of fuel remaining
12:45 Engine shut down
14:00 Washing machine started for second wash - 1.19kWh consumed
18:00 Office consumption 8am to 6pm = 1.7kWh
Running the dishwasher and then the washing machine (twice) from the inverter had proven successful.
As of 6pm the rest of the house had only consumed 2.0kWh in 10hrs since 8am and with 4.32kWh offset
from the grid onto the veg oil generator.
Chilly, bright start, with clear skies last night. Central heating fired about twice in the night.
Purchased 6 way split RCD protected consumer unit and MCBs to be installed on the inverter output.
Engine started at 09:15 with 3 litres of fuel added to tank.
Batteries had got low, although terminal voltage still showed good state of charge. Tripped out the
Battery Low volts at 93V when trying to boil a kettle at 2.7kW.
Inverter restarted at 09:30
Batteries will need an equalisation charge about 2 times per week in order to keep them up to full
capacity.
Now pressing need to plumb the output of the Lister into the DCH, in order to allow longer runs and
shift some of the waste heat.
New Fuel tank with Burette level indicator planned.
11:45 Generator shut down because of suspected bearing failure in dc starter/generator or ST alt.
Fuel remaining 1.5 litres
Motor casing feels very hot, and there is a general graunchiness about the belt drive.
Fortunately I have a spare motor which could quite easily be swapped in but - this will give me
something to fix!
Evening Update.
Stripped out the PM dc motor/generator to find that it was almost entirely seized. Either a bearing has
failed, or the rotor is now touching the stator and putting a whole lot of extra friction on the shaft.
Got the new motor into place, aligned the shafts correctly and ensured that the belt was not over
tightened.
20:15. With remaining fuel - about a litre, ran the engine for 45 minutes in order togive the battery a
much needed charge.
With these home built systems, there is a fair degree of flexability on what can be done, with improved
system components available from time to time.
Added 3.0 litres to the now empty fuel tank.
17:25 Engine started for battery charging.
18:25 Engine working hard, 30.5A at 119.5V into batteries. (3645W). 1.5 litres fuel remaining
18:25 DC motor warming up - but not critical. Belt tension OK
19:25 End of charge period, 125V at 25A (3125W). Engine shutdown. Engine almost out of fuel.
19:30 3 litres of fuel added for tomorrow.
This was a fairly high powered run, with the engine working at full load, into quite exhausted batteries
(93.5V the inverter cuts out on low battery volts). 3 litres of fuel consumed in just 2 hours.
The engine maintained an average of about 3500W into the batteries for 2 hours - so about 6 or 7kWh
returned.
Lots of hot water too.
I am going to re-instate the 3kW ST alternator as an alternative means of extracting power from the
system. After a 2 hour battery charging run, the alternator can be energised by turning on its field coils
and contribute say 1700W of power to the upstairs storage heater. This will take some of the load of
the dc generator and give it a chance to cool down. No more seized bearings I hope.
Rebuilt the motor mount this evening to correct the problems of shaft alignment and belt tension.
The 3 motor mount bolts that hold the mounting plate down onto the original Startomatic slotted rails
were turning. Replaced these bolts with M12 x 40mm, bolting down into a rectangular captive nut,
that fitted nicely into the slotted rail. Motor alignment corrected to make it parallel to the ST
alternator and belt correctly tensioned.
3 litres of fuel in tank
18:15 Engine started for battery recharge.
20:00 Additional 3 litres added to tank
21:00 Dish washer started using the feed from the ST alternator
22:45 Dishwasher cycle stopped. 1.50 kWh consumed. Engine shut down -almost out of fuel.
Fuel Used - 6 litres
Time of engine run : 4 hours 30 minutes
Office consumption at 11pm: 3.40kWh
Hot water from engine reached 78 C.
Tickling an ST alternator into Life.
The ST alternator relies on residual field remaining in the soft iron rotor core to allow it to self
excite. Unfortunately this might not happen, even though the alternator is spinning at 1500rpm with
the Lister at it's rated speed of 650rpm. Only an engine overspeed can coax the ST into self exciting.
The solution to this is to apply an external dc supply to the field winding - by connecting across the
slip-ring brush holders. Note the polarity of this connection, by first testing the voltage across the
slip-rings with a DVM.
I clipped a couple of small croc-clip leads onto the brush holders and applied 12V dc from a battery
charger. Immediately the ST comes to life.
The next time this happened, the battery charge was not to hand, so I reached for a somewhat dead PP3
battery and used this. Even the 6V remaining in the PP3 was enough to excite the field sufficiently to
get the ST to "fire-up".
I am going to build a small rechargeable battery into the ST, and a switch circuit which will allow me
to manually excite the field.
With the ST running at rated speed, there is about 24 to 25V measured across the brushes. The
resistance of the rotor is in the order of 2 ohms, so the field current is about 1.25A.
This source of low voltage dc could be used to trickle charge a rechargeable battery - not only for field
excitation, but possibly for powering the engine monitoring system.
Notes about heat output
The generator set is providing considerable waste heat, particularly when run for longer than a couple
of hours.
Part of the improvements planned will be to get efficient utilisation of this waste heat.
At the moment it is contributing to my domestic hot water supply, with 3 litres of oil supplying
sufficient waste heat to heat the 120 litre hot water cylinder to 55C, and heat up the engine "local
store" to around 95C.
After the recent 4.5 hour run, the water returned to the house was at 78C, in spite of the uninsulated
heat exchanger and poorly lagged local store tank.
Clearly there is a considerable amount of waste heat available, and it just needs to be captured and
used more effectively.
My existing heating system has the circulating pump fitted in the boiler flow, where it then is split via
the 2-port electric valves into separate flows for the radiators and the domestic hot water.
The intention is to T the flow from the Lister circulation pump, into this pumped flow, using non
return valves to prevent the heated water from one source, back-flowing through the idle pump of the
other source - i.e. either shorting through the boiler, or back feeding hot water through the Lister
system.
Always make a point of turning on the circulation pump BEFORE you start the engine!
5 minutes of heavy load running, without circulating water will boil the water in the exhaust gas
heat exchanger!
10:00 3 litres of WVO fuel added into nearly empty tank.
10:05 Engine started and ST alternator tickled into action.
10:10 Circulation pump turned on! Engine set to low compression
10:15 Washing machine plugged into output from ST and put on pre-wash cycle
10:30 Battery voltage 127.5 V charge current = 20A
10:45 Washing machine appears to be working normally.
11:00 Batteries charging at 128.6V at 18.7A
12:35 Engine shut down, 100ml fuel left. Battery Voltage 132V at 13.5A
12:35 Washing machine and office continue to run on battery/inverter supply.
The dc output from the generator appears to be able to charge the batteries at fairly high currents -
right up to the float voltage and above.
Whilst the dc generator might be a good way to get a lot of charge into the battery bank in a short
time, it may be overcharging the batteries at the end of their charge cycle.
A mosfet speed/charge controller will be needed for the dc starter generator, so that it can keep the
batteries floated at a smaller current. As there are 4 parallel stings - even 20A is divided into 5
amps per string.
Enersys recommends that batteries are given a freshening charge of 2.27 to 2.4 volts per cell, and at a
current of 10% of C10, for 24 hours.
http://www.enersysreservepower.com/documents/PS-SBS-CL-IS-UN-v2.pdf
So for my 54 cell string, a charge voltage of 129.6V is acceptable.
The SBS 40 battery has a quoted C10 capacity of 37Ah to a voltage of 1.8V per cell. This suggests that
3.7A per string is acceptable for a refresher charge - therefore 14.8A for the combined current of the
4 parallel strings.
Weekly Summary.
31 Litres of WVO consumed
32 kWh of power utilised in the house. *
* This is an estimate because I had 3 energy meters plugged into various circuits, and a couple of
them reset losing their current total KWh reading.
New electricity meter to be installed at the weekend - should solve this problem.
An early start and drove down to Devon to visit some renewable energy colleagues.
Nigel has a large house in Devon, where he has installed a 1kW solar pV array and a 2kW
Navitron wind generator. Although sunny, the wind turbine failed to produce any power.
He charges up a 48V battery bank - salvaged from an old fork lift truck battery.
When the wind don't blow and the sun don't shine, he has a little 2 cylinder Kubota engine
generator that he runs on solid vegetable oil - often commonly referred to as lard. The waste heat
from the Kubota engine supplies the heat needed to melt the lard. The excess will be used to help
heat the house and the hot water tank.
A 7kW Studer inverter converts the dc from the fork-lift battery bank to ac to power the house.
We spent the afternoon welding up a new frame to accept the engine and twin truck alternators.
Saturday was spent in Somerset and Devon, so today I got home early and decided to have a day spent
working on the wiring and fuse board in the workshop.
07:00 Left Taunton
09:15 Arrived Redhill, Surrey.
Spent the morning making the enclosure for the workshop wiring and engine control system out of an old
packing case that once held a 5kW ST alternator - perfect size for the job.
Made up "Fuse board" from spare kitchen unit back panel, and fitted the 6-way "Contactum" consumer
unit and the Iskra digital electricity meter that has a 1 Wh pulse output. I now have 6 circuits with
individual MCBs and RCD protection for the workshop power.
Dishwasher 16A
Washing machine 16A
Living room double socket 16A
Office double socket 16A
Workshop sockets 10A
Workshop lights 6A
18:30 3 litres of fuel added to Lister fuel tank and engine started
21:00 Engine shutdown after 150 minutes runtime - about 0.5 litre fuel remaining.
22:00 Circulation pump turned off.
Runtime 150 minutes - fuel use - about 2.5 litres.
cabinet, so I cut down a 5kW ST alternator
packing case, which was a perfect fit, to
make a custom enclosure for the fuse board
and the electric meter and associated wiring.
Eventually this will be expanded to house
the engine monitoring and control system
and the grid change-over switch.
Just above the white uPVC window, is the
40mm white trunking that carries the 4
circuits back to the house - washing
machine, dishwasher, office and living room
- all are terminated in double sockets.
This was the back panel of a kitchen unit
that was surplus after the kitchen
installation. 700 wide x 500 high.
I took advantage of the mid-day sunshine to
wire up the 6-way consumer unit and the
Iskra import-export electricity meter.
The meter tails are 6mm2. My inverter is
only rated at 5kW, so 6mm2 is perfectly
adequate for short runs.
populated with the MCBs was put into place
above the inverter cabinet.
It hinges forwards on the bottom screws to
allow the wiring to be accessed from behind.
The blue panel below is a digital meter
showing the inverter battery volts and amps
as well as a load of warning LEDs that I
usually try to ignore.
the front panel was screwed into position
and the system tested.
Perhaps the lack of smoke and sparks
suggested all was well with my
installation.
I have been wiring plugs since the age of
5, and all electrical installation work is
done at my own risk.
Part P - Eat your heart out!
for £35 on Ebay.
This is an import export meter, and gives
one flash of the LED for every watt-hour
consumed. It also has volts-free pulse
outputs for both the import and export -
which will be very easy to interface with
my data logging unit. One flash per Wh
consumed.
4 of the circuits are protected by 16A
MCBs whilst the lighting circuit and ring
main in the workshop have RCD
protection.
08:30 3 litres of fuel added - engine started
08:35 Low compression, dishwasher started
10:30 Dishwasher cycle ends, 1.43kWh. Engine stopped.
Fuel Usage Approx 2.5 litres
Run time 120 minutes.
The new meter on the inverter output shows that 2.0kWh have been consumed by the dishwasher and the
office since 08:00.
The household continued to run off the inverter for the remainder of the day, and I arranged that the water
circulation pump (54W) and the TV/Video stack was also benefiting from Lister power.
The inverter battery voltage had fallen to 100.0V by 8:00am this morning. Whilst this is not critical, it is
a good point to re-start the generator and recharge the batteries.
This was now becoming fairly routine, start the engine first thing in the morning to recharge the losses in
the batteries incurred during the last 22 hours. Once the batteries have picked up a little charge, make use
of the power available to run the high wattage appliances such as the dishwasher or washing machine.
The new electricity meter showed that a total of 7.8kW had been supplied to the house in the last 2 days
from the inverter, 6kWh of it used on Monday alone.
An Electrisave power meter has been fitted to the output tail of the inverter.
It has a wireless link up to a display in the office, so I can glance over and see how much power is being
drawn from the inverter.
With just the office, it hovers about 380 to 400W, rising to 2520W when the dishwasher is heating its water.
08:00 3 litres of fuel was added to the tank and the engine restarted.
08:45 Dishwasher cycle started
09:00 Dishwater heater comes on. Lister gen working hard. Vols and amps readings follow:
Generator output = 33.3A at 112.6V = 3750W.
Inverter input power = 26.6A at 112.6V = 2995.6W
Power to house =2.52 kW
Inverter efficiency = 84.1%
Overall efficiency (generator to ac outlet) = 67.2%
10:30 Engine shut down
18:10 3 litres fuel added. Engine started
18:40 Engine shutdown.
23:50 Battery Volts 105.5V. Total kWh used from inverter =12.8
Total run time today 180 minutes
Wednesday 3rd October 2007.
Inverter meter reading = 12.9 kWh . So 5.1kWh used on Tuesday
08:00 Battery Volts 102.4V.
08:05 About 2 litres fuel remaining. Engine started for battery charging
09:15 Batteries up to 123.0V, still charging at 26.5A. Engine shut down.
Run time 70 minutes
The short 30 minute run yesterday evening and the run this morning are not efficient use of fuel, with the 3
litres of fuel consumed in just 100 minutes. Longer runs will be preferable particularly when the heat can
be better utilised.
Overnight inverter power is very inefficient use of the inverter which draws a fixed load of 200W, so a
total 1.6kWh drawn from the battery for the 8 hour period, just to supply 0.1kWh. What's needed is a more
efficient low power inverter that can run in sync with the big one, and supply perhaps a maximum of
1500W, but at a much higher efficiency.
As it would happen, my mate Simon had found a 1500W computer UPS system in a scrapyard with two
external battery packs. £ 30 secured the deal.
With a 96V battery voltage, it was close to compatibility with my 108V system and used much less standing
current than the old lighting inverter. During a 10 hour recharge period overnight it consumed 0.7kWh.
By 11pm battery voltage was getting dangerously close to the low voltage cut off point of the inverter. The
inverter was switched to standby mode where it draws about 30 to 40 W from the battery.
The inverter will not boot-up until it sees a health battery voltage of at least 117V, but will continue
running down to 93.5V. It can be switched back to idle any where between these two voltages (or >117V)
and then be re-enabled. This gives the option of turning the big inverter to idle at say 100V overnight and
then running the night time load from the small inverter.
The battery pack had got very low overnight. I decided to run the engine for at least 2 hours to recharge
the batteries, and then keep it running whilst the dishwasher went through its wash cycle.
09:00 3 litres fuel added. Generator started
10:00 Battery volts = 117V, inverter started. Office load switched over to inverter power.
11:00 Fuel nearly finished. Another 3 litres added. Dishwasher started
13:30 Engine shut down. 400ml fuel remaining.
Run time 270 minutes. Fuel used approx, 5.6 litres.
The 1500W inverter has been powered up for 33 hours and drawn 3.08kWh from the mains input. This
suggests that it has a quiescent power consumption of about 93W.
I am considering the best approach to using it within the system. Because of its low quiescent
consumption, it could be argued that it is wired directly to the grid and powers the essential circuits
in UPS mode up to a maximum of 1500W.
If Lister power is available from the ST alternator, then this could be fed to the ac input of the UPS, via
a change over switch. ST power could also be used directly for running the storage heater in the office
and any other resistive heating devices.
The UPS inverter will happily handle the interruption to supply during change over, and if a white
meter were available, recharging the UPS could be arranged to occur at night so as to benefit from the
lower rate tariff.
The UPS would ensure that essential loads such as the fridge/freezer, VCR clock, lights and office
supply were maintained and supplied predominately from the Lister generated power.
The Best Power 610 Inverter claims an ac to ac efficiency of 83%.
Fridge & Freezer 0.75kWh
Lighting 0.5kWh
Office 3.0kWh
TV/Video stack 0.5kWh
Total 4.75kWh per day
The battery back-up is about 3.5kWh so with a little experimentation the UPS should be able run these
systems for about 18 hours.
The workshop project is making good progress. Most of the electrical wiring is in place and on
Friday afternoon, I moved the door frame for the engine shed door, into its final position, and reversed
the door in the frame, so it makes it impossible to accidently walk into the Lister when its running.
My nephew Adam came up from Southampton to stay this weekend, and together we cleared out the
engine shed and got ready for the concreting of the Startomatic mounting base and the foundations for
the forge area, expected for next Saturday. Behind the engine shed will be a substantial concreted
apron for storage of the 1000 litre veg oil IBC and the fire wood for the wood-burning boiler.
The Startomatic engine will sit on a block of concrete, 1200 x 900 x 450mm isolated from the rest of
the shed.
With the work proceeding, it was 4pm before we got a chance to run the engine.
16:00 Added 3 litres fuel.
17:00 Started up dishwasher
17:50 Out of fuel - added 3 more litres
19:00 Shut down engine. 180 minutes runtime, estimated 5 litres fuel used.
Continued to work on workshop with Adam. Extra shelves were added to the benches in the workshop and a set
of 5 substantial shelves made from some old chipboard panels.
Dug the trench across to the "garden office" so that heating pipes and power cables etc can be routed across.
Continued to work on the groundwork that has to be done prior to laying the concrete out at the back.
The engine shed will be extended at the back with a 1200mm x 3000mm lean to which will provide storage for
the vegetable oil IBC tank and the supply of firewood.
Below are some of the pictures showing progress over the weekend.
situated behind the
partition wall between
the engine shed and the
workshop.
Next to the Lister is the
salmon pink coloured
"Plint" dynamometer.
On Saturday, we will be
laying some more
concrete to complete the
engine shed floor, and to
lay a 120 sq ft apron of
concrete between the
engine shed and the
"garden office".
intended to house the two Lister engines,
the dynamometer and the metal working
forge area.
With the doorframe repositioned on
Friday, he remaining plywood wall panels
were fitted with the 75mm of thermal
insulation installed in the gap.
The Lister is run on a daily basis for a
couple of hours to recharge the large
battery bank situated in the workshop next
door.
into the 10' wide engine shed
from the open end. In order to
move some of the large
equipment out of the shed it was
easier to remove the wooden
panels from the back wall, than
manoeuvre them through the
door.
Here the engine crane is shown
supporting he spare Startomatic
baseplate, ready for the
installation of the Startomatic
when we get the mounting block
of concrete laid.
tidied out to allow access for
concreting next weekend.
The floor will be extended by
910mm to allow the forge
area to be constructed.
The forge is a 1200mm wide
brick built fireplace and
chimney allowing space to
install the woodstove and the
experimental gasifier.
This shot shows the start of
the digging for the
substantial concrete block to
take the Startomatic
generator engine, a block of
concrete 1200 x 900 x
450mm, about 1100kgs of
concrete.
I have taken to shutting down the large inverter at night in order to maintain battery capacity. When idling it
draws 30 to 40W as opposed to the 200W when running. The inverter can be switched from run to idle with a
single pole switch. It is anticipated that this will be done remotely or under microcontroller control using a
relay.
08:00 3 litres of fuel added to 0.5l remaining in tank
08:20 Engine started
08:30 Dishwasher started
09:50 3 litres fuel added
11:30 Engine shut down.
Run time 190 minutes. Fuel used 3.8 litres
The Lister has now consumed 61.3 litres of fuel since Friday 21st September. The total run duration has been
2840 minutes and 61.24kWh of power consumed from the inverter.
Since fitting the electronic meter on the inverter output, 30.2 litres of veg oil burned and 30.6kWh of power
consumed - plus a fully charged battery bank.
This appears to be setting the baseline for consumption.
Allow 1 litre of WVO per kWh electricity consumed and 1 litre will last 45 minutes typical runtime.
With 2 computers active in the office yesterday and the dishwasher, the total consumption from the inverter
was 3.7kWh. I have continued to monitor my grid power usage and have noted that the sum of my grid power
plus the inverter power is greater than what I was using from the grid alone 3 weeks ago. I am actually
becoming wasteful of power - because I have it available from the Lister! This situation will definitely need
further investigation.
I keep a running total of the gas and electricity consumption figures for the last 365 days. This show the long
term trend of whether I am consuming more or less energy. The figures for the last 365 days are:
Gas 12224 kWh
Electricity 2473 kWh
Looking at the latest consumption figures, it would appear that I can generate all my electricity for just short
of 2500 litres of filtered WVO per year. This corresponds to 2 1/2 IBC containers over the course of the year.
The other point to note, is that the gas usage to electricity usage is in the ratio of 4.94:1 - approximately 5:1.
I am currently spending £768 per year on electricity and gas, so in theory this could be reallocated to
purchasing filtered waste vegetable oil in 1000 litre IBCs.
The big question is can I get the balance between heat and power such that I can use the Lister generator set
throughout the year.
With about 5kWh of recoverable heat, for every unit of electricity consumed, and roughly 7 units of electricity
used each day, there will be the problem of what do I do with 35kWh of waste heat in the summer - perhaps I
should be buying a hot-tub?
In Spring and Autumn, that waste heat will help keep the house comfortable, and in mid-winter, I will be
producing extra electricity to run a couple of storage heaters.
It is starting to become quite a complex problem of energy management, to utilise efficiently what is available
without creating an excess or unnecessary burning of fuel.
It might be worthwhile investing in some additional batteries so that the 1500W inverter has its own large
96V battery bank. A 300 litre thermal store is also in the planning stage.
The following readings show how the generator becomes more lightly loaded as the battery voltage rises.
08:00 3 litres fuel added. Engine started, Power into batteries = 120V at 30A = 3600W
08:30 Generator producing 124.0V dc at 25A (3100W)
09:00 Generator producing 127.5V dc at 20A (2550W)
09:30 Generator producing 130.0V dc at 16A (2080W) Washing machine started on 90 minute cycle.
10:00 Generator producing 132.2V dc at 16A (2112W). Battery refresher charge.
10:15 Dishwasher started on 90 minute 65C wash cycle. This should improve the load balancing!
10:30 910W being consumed from inverter - measured on Electrisave
10:35 Dishwasher heating element kicks in - 3.05 kW from inverter.
11:50 Dishwasher finishes
12:00 Engine shut down
Run time 240 minutes. Estimated fuel used 5 litres.
In the last 20 days, I have used 71kWh from the inverter and 96kWh from the grid.
The average daily runtime, on days that the engine is run, is 181 minutes.
With the weather cooling, it is now time to step things up a gear, and run the engine longer. Rather than the
typical 3 hour run, it will soon be time to aim for an 7 or 8 hour run, and consume about 9 litres of fuel per day.
This should allow a complete move away from grid power, and a large percentage of the gas consumption offset
to CHP heating.
To achieve this, the plumbing will have to be altered to allow for a greater heat dissipation within the house,
by utilising the central heating loop and the underfloor heating as well as the domestic hot water.
From an electrical point of view, either additional battery storage capacity will be needed, to absorb the
additional power, or it will be consumed in water heating or storage heaters.
19:00 3 litres fuel added. Engine started.
21:30 Engine shut down
Run time 150 minutes.
I have been preparing the area behind the engine shed for concrete which is arriving on Saturday morning
about 10am.
Behind the shed will be a concrete area about 4.5m x 2m, suitable hard standing for all the heavy items not
needed in the shed. The hard standing will be roofed over to form a lean-to shelter.
Tomorrow I hope to install the pipes and cable ducts in a trench under this area, which convey the heat and
power from the engine shed to the garden office. There will also be a drain and soak-away for the salvaged
stainless steel sink unit which will be installed in this lean-to. The sink unit will allow oily and dirty hands
to be washed outdoors next to the workshop, with hot water without having to return to the kitchen.
18:30 3 Litres fuel added. Engine Started. Dishwasher started
20:30 Engine shutdown.
Runtime 120 minutes.
Much of today was spent digging the pit for the new Startomatic mounting block. Concrete is due tomorrow
morning. See this page for details.
Concrete arrived about 9:45am, and the morning was spent laying it.
In the afternoon, Paul, my Startomatic friend turned up with a couple of very large steel expansion vessels,
that had been salvaged from a commercial buildings heating system. One was 200 litres and the other is 300
litres, they will make excellent thermal stores or the smaller as an oil tank for the Lister.
18:30 Lister started for quick battery top-up charge.
19:00 Lister shut down
Today the Startomatic engine was installed on its base. See this page for details.
This evening the Startomatic was
rigged up with a temporary
exhaust and fuel tank and given a
first test run.
The massive flywheels make
hand-cranking much easier than
on the standard 6/1 engine and
withing a few turns it had fired
and was rapidly gaining speed.
The temporary exhaust was very
loud and there was a great deal of
sooty black smoke, suggesting
excess fuel or a dripping injector.
I will get the proper exhaust and
water cooling arranged and then
she can be given a proper test run.
Using my digital voltmeter I confirmed that the Startomatic alternator was indeed producing ac power. The
regulator will need adjusting because I was measuring 280Vac at 60Hz and the engine was still accelerating. The
engine fuel rack was quickly shut down to bring the speed down from a scary 780rpm, and took about a minute
to come to a complete stop.
The colder weather is finally upon us. Last night was probably the coldest so far this Autumn. At 8am the outside
temperature was a chilly 4.5 degrees C. In side the engine shed, which currently has no back panel, it was 5.5C
and in the insulated workshop it was 9.2C.
With the Startomatic installation taking up much of the spare time over the last few days, the other Lister
generator had not been run since Saturday evening and the inverter batteries were getting very low - about 92V.
It was decided to run the generator and give the batteries a good refresh charge.
08:30 3 litres fuel added. Engine started
08:45 Engine producing 115V dc at 30A (3450W)
09:00 Inverter enabled, office supply switched to inverter power, dishwasher started.
09:30 Generator producing 31.5A at 108.6V. (3420W) Inverter drawing 26.7A - dishwasher on heater cycle.
10:40 Dishwasher ends cycle
11:00 Engine shut down. Washing machine started on inverter. Inverter power meter 49.4kWh
Run time 150 minutes
18:00 3 litres fuel added. Engine started.
20:00 Engine shut down.
19:00 4 litres fuel added. Engine started.
19:20 1.7kW storage heater turned on as test load.
21:00 Engine shut down.
Today was the big plumbing day. A 4 port manifold was constructed from copper pipe fittings, which would
allow the Lister and the boiler to work together and supply heat to the radiators, hot water cylinder and
underfloor heating loop.
By 7pm the manifold had been installed and it was time to fire up the Lister. Earlier we had had some
circulation problems because of air in the circuit. Once this was bled, the system worked fine.
At 8pm the temperature of the water into the house was 50 degrees, at 9pm it was 80 degrees.
There is sufficient heat available to run another radiator and the hot water tank from the Lister heat. These
connections will be added to the manifold later. Hence the 4 isolating valves on the outputs - the unused ones are
easily shut off.
Next year we are planning to build a 16 m2 conservatory. The underfloor heating loop will be connected in
series with the return heat pipe that runs back to the Lister. This will ensure that the last dregs of useful heat
are extracted from the hot water, and that the return water temperature to the Lister is as cool as possible -
probably around 30 degrees C.
plumber's solder applied to the
end-feed fittings.
There is a skill required to make
successful, neat end feed joints,
and even on the bench with a big
blowtorch, I found it difficult to
keep things neat.
However with plenty of flux and
a little patience it soon came
together and most importantly, it
was leak-free.
The worst of the flux staining
was removed with a pan scrub.
Boiler feeds in from left hand
side via a non-return valve. The
pumped Lister circuit feeds in
from the right hand side through
an isolation valve and a
non-return valve.
Behind the manifold is the
modified pipe to feed the flow
into the living room radiator
which required an angle fitting
to be soldered to it.
The 15mm isolating valves can be
bough in packs of 10 from
Wickes for about £1.30 each. I fit
them everywhere, it makes later
servicing and alterations so
much easier to do if you can
isolate a section.
outlets having cleaned off all the
soldering flux and
discolouration. These will feed 2
radiators, the coil in the hot
water cylinder and the
underfloor heating loop.
Lister was plumbed in, and a 180
degree "loop" arranged to get
over some of the awkwardness of
dealing with 22mm flexible
plastic piping.
Isolation valves fitted as
standard, but the pump really
needs an air bleed screw on its
right hand outlet so that the air
can be released more easily.
Enamelled dish was to catch the
drips when it was bled by
slackening off the right hand
union.
Small bore pipes on left of photo
were the original pump feeds to
the shed. They are redundant now
and will be removed.
the floorboards in the heating
access space. The four branches
can just be seen in the foreground.
Flexible hoses were ised becaus
of the problems of making rigid
connections reliably in such a
tight space.
wide by 600mm high double
convector. It produces about
1500W of heat when at 50C.
This photo is just to the right of
the fireplace in the living room.
It has seen at least 3 generations
of heating added, from a
primitive back boiler in the
1920s to a modern condensing
gas boiler in 2005. All the pipes
pass horizontally beneath this
access hatch and then vertically
up the side of the chimney breast.
heating circuits.
Both the boiler and the Lister are pumped systems, and so at the left and right arm of the manifold is a
non-return valve, to stop the water from the Lister shorting through the boiler heat exchanger and vice versa.
The 4 outlets from the manifold feed separate circuits, namely lounge radiator, underfloor heating loop, coil in
the hot water cylinder and one spare for connecting to additional radiators. I wanted to check that the Lister
could run the existing heat load before adding more.
In the shed, the Lister thermosyphons into a 120 litre storage tank. It also has an exhaust gas heat exchanger, that
feeds into a heating coil in the storage tank. The tank moderates the water temperature from the exhaust heat
exchanger and also allows the Lister to run for about 2 hours without any overheating problem.
After 1 hour, the water back to the house was coming at 50C. After 2 hours it was 80C. I then shut down the
engine and 90 minutes later the water is still returning at 50C - using up the heat from the local store.
I'd been planning this job for a long time but finally got around to doing it.
I ran the Lister tonight with a 1.7kW storage heater as the load. That heater heats my office whilst the loung is
heated by a 1.5kW double convector radiator. The underfloor heating also got nice and warm - it's about 15
square meters in the tiled kitchen and bathroom.
It's now 95 minutes since I shut down the engine, and the water from the shed is still coming in at 47.5C. That
small store certainly seems to be doing it's job. Boiler hasn't fired since 7pm.
I will now probably adapt a solar controller to turn the pump on and off automatically when it senses the exhaust
gas heat exchanger getting hot.
I still have lots of insulation to do on the ex-gas-H.E., and some improved pipe runs - but basically the system is
functional.
I will finish the plumbing of the hot water cylinder coil tomorrow and possibly use the spare output of the
manifold to drive another radiator or possibly a 200 litre thermal store located in the understairs cupboard..
As I have been busy, I have not been running the engine as much as I would like this week, about every other day.
Here is a summary:
Saturday 20th October. 4 Litres of fuel added. Engine run time 120 minutes
Sunday 20th October. 3 Litres of fuel added. Engine run time 120 minutes
Tuesday 22nd October. 3 Litres of fuel added. Engine run time 90 minutes
Thursday 24th October. 3 Litres of fuel added. Engine run time 90 minutes
Saturday 27th October. 3 Litres of fuel added. Engine run time 230 minutes
On Thursday I made a heating element for the high pressure fuel line. It appears to be working well and heating
the injected oil up to about 75 degrees C. This has helped reduce the black soot and improved the fuel economy.
Saturday was spent erecting the framework for the extension to the engine shed. This will add approximately
2.25m x 3m to the engine shed and give a load more undercover, insulated dry storage space.
Unfortunately my PMDC starter/generator failed today during the 4 hour run. It overheated and unfortunately
the permanent magnets have been cooked beyond their Curie temperature and lost their permanence. This
means that there will be a pause in proceedings until I can get the Startomatic engine fully commissioned with
exhaust and cooling systems and up and running.
The Lister generator set was reconfigured so as to allow the ST alternator to provide battery charging of the
main battery bank and a 1500W UPS used to supply clean power to the office.
By the middle of November, another electricity meter had been installed to monitor the power suppled bu the
ST alternator and it was time again for a test run and system shakedown.
Thursday 15th November
19:30 3 litres of fuel added and engine started. 3kW Furnace used as load
21:00 Engine shut down
Runtime 90 minutes
Energy supplied 2.79kWh
Friday 16th November
18:30 3 litres of fuel added and engine started. 3kW Furnace used as load
21:30 Engine shut down
Runtime 180 minutes
Energy supplied 5.07 kWh
18:35 3 litres of fuel added and engine started to charge batteries
22:00 Engine shutdown
205 minutes runtime
Friday 23rd November
11:45 3 litres of fuel added and engine started
14:30 3 more litres added
15:30 4 litres added
20:00 Engine shutdown
Total of 8 hours 15 minutes. Approximately 10 litres of fuel used.
17.1 kWh recorded on new electricity meter.
New watt meter running at 37 pulse per minute (1000 = 1kWh) - about 2.22kW
Over the next few days the Lister was run regularly
22/11/2007 3 l oil 205 mins
23/11/2007 10 l oil 495 mins
24/11/2007 6 l oil 330 mins
25/11/2007 9 l oil 275 mins
30/11/2007 3 l oil 230 mins
1/12/2007 9 l oil 466 mins
3/12/2007 7 l oil 332 mins
12/12/2007 6 l oil 105 mins
13/12/2007 30 mins - testing out new pump system
14/12/2007 3l oil 240 mins - further testing of pump in cold return pipe.
Total 56 litres 2708 mins
During this time 83kWh of electricity was produced.
A good friend dropped by with 80 litres of good quality used vegetable oil, so there was now plenty of oil for
some extended run periods.
On 12th and 13th December the plumbing was altered to remove the 120 litre local store in the shed and to
connect the pump immediately before the exhaust gas heat exchanger. The pump managed to push 6 litres per
minute around the system.
The modifications seemed to work OK and the final temperature of the water from the engine reached a
plateau of 65 degrees C after 2 hours of running.
After 4 hours run time the water temperature had plateaued out to 67 C -ideal for the radiator and the plastic
pipe runs.
During this time, the principal loads on the ST alternator were a 1500W PTC room heater and the 1100W
battery charger. The meter on the ST output was running at 35 pulses per minute - so approximately 2.1kW
load.
Now that the pump has been moved to the return pipe to the Lister and the water is being positively pushed
through the system, the circulation is now reliable.
The pump manages almost exactly 6 litres per minute, and this provides adequate cooling of the Lister
without excessive temperatures in the pipework. As measured yesterday, the water entering the house does
not quite reach 70 C.
This could be improved by insulating the exhaust gas heat exchanger which will reduce its losses
significantly - so one of this weekend's jobs is to wrap it in rockwool.
Additionally, there are certain improvements to the pipework, which will reduce losses in the piperuns as
well as making the system neater and more stable.
The primary consideration is adequate cooling of the engine, without over-cooling, and keeping the
temperature of the water flow, well within the temperature specification of the plastic pipework.
After 2 hours on the maximum setting, I tried the middle and the lower settings.
At 14:47 the flow temperature went dangerously into the 90's which sent me running for the shed to shut the
engine down.
Of course, this shut off the circulation pump - so I had to plug that into the maintained supply in order to
allow things to cool down a little.
By 15:02 things were back to normal temperature - so I restarted the engine. I reverted to the original full
speed pump, and things seemed to stabilise again at 65 C.
Time started 07:58
Time Stopped 14:47
Run time 409 minutes
Meter kWh 95.3 kWh
Power used 12.3 kWh
Engine restarted 15:02
3 l fuel added 17:00
3 litres of fuel were added at 07:55, 10:00, 12:00, 14:00, 17:00, 19:00 and 21:00 making 21 litres in total.
Consumption appears to be slightly short of 3 litres every 2 hours - probably 1.35 litres per hour.
Whilst there is the desire to run the Lister as hot as possible, you certainly don't want to run the polypipe at
temperatures approaching 90C for extended periods of time. Polypipe is rated at 90C at 6 bar of pressure -
whilst my system is not pressurised, the 90C is the limiting factor.
At 15:30 the temperature had stabilised to 68C, the thermal output was 4.49kW and the engine was
producing 2.1kW of electricity. The skies had cleared and outside temperatures were down to 1.5C and
dropping fast. Fortunately I had plenty of oil - and the means to keep the house comfortably warm.
By mid- afternoon, I bit the bullet and decided to connect up the coil of the hot water cylinder to the Lister
heat manifold. A length of 10mm barrier pipe was already very nearly in place - left over from the original
solar heating installation. To connect up, I made up an isolating valve on a bit of pipe, and without draining
the system, cut into the 15mm pipe and fitted the isolating valve - with almost no loss of water.
Then I tee'd the 10mm barrier pipe into this feed, so that it would direct hot water from the Lister into the
coil of the cylinder, after the automatic valve, so that the Lister would heat the tank whenever it was
running. After checking all the compression joints for weeps, I then released both isolating valves and the
hot water began to flow through the coil.
I also realised that if I closed the gate valve on the boiler pump, and opened both the automatic valves for the
hot-water and central heating, that I could direct the flow of Lister heated hot water around the rest of the
radiators in the house.
After selectively setting the thermostatic radiator control valves to allow water through, I then went to
monitor the flow and return temperatures and the flow rate.
425 litres per hour at a temperature differen