Heat and power - Listeroid Inverter Generator

[veggie]

Not quite pure CHP, but heat and power are harvested, just in different locations.
In this system modification, my Listeroid runs full time to power 6 key house circuits, (up to 24 hrs per day if needed) when grid power is out.
The cooling fan on the engine radiator also heats the garage when in operation. It keeps the garage at 70f inside when outside temperatures are -16C.

Earlier this winter we experienced a power outage.
It happened at dinner time and ran for most of the evening during a winter storm with temperatures at -16C.
The house started to cool rapidly.
Wearing my headlamp, I ventured out to the garage, fired up the listeroid, and flipped the transfer switch.
All good, we had power and heat. But one annoying thing was the flickering lights throughout the house.
It also concerned me that damage may occur to sensitive electronics such as the $600 control board in my natural gas furnace.
Here's a short video of the Listeroid running in the dark and powering the house.
Notice the 240 volt AC generator head. (Soon to be changed).
https://www.youtube.com/watch?v=WfS4dqnn4_I

I decided to try a different approach.
Driving a DC alternator -->  battery bank ---> pure sine inverter --> House

I already had a set of batteries left over from a previous solar project, so I though they could act as a load buffer and a voltage clamp for the alternator/inverter system.
I swapped out the AC generator head for a Delco 25Si heavy duty 50A, 24 volt alternator.
Next step was to build a power module consisting of box, batteries, solar charge controller, pure sine inverter, and safety breakers.
This is what I ended up with.
The idea is that during an outage the Listeroid runs constantly.
Sometimes the house pulls from both the batteries and the alternator, and other times the charging is greater than the house draw.
Overall the system can keep up.
The listeroid can achieve 50A alternator output at the reduced speed of 395 rpm which makes the system very quiet.
Here is a video of the first run where the bank is charging at 20 amps.
The yellow cable from the power module plugs into the generator inlet box to the house transfer switch.
https://www.youtube.com/watch?v=MxJo6UqwCi0

When not in use, float charging is accomplished with a small 24 volt, 5amp 3 step battery maintainer.
Once the solar charge controller is connected to the 600 watt panel array, the solar charger can take care of keeping the batteries topped.
The Magnum inverter provides split phase, 240 volt AC to the house, just as my AC alternator did.
I realize this is less efficient, but I don't care. I can justify it by not having to replace expensive electronic components.

cheers,
veggie

[DKMC]

What is the cost and life expectancy of those batteries?
Nice looking setup.

[Tom Reed]

Very nice setup Vegie. I wanted to do something similar with my 48vdc off-grid system, but now that I have LiFePo4 batteries, the generator hardly ever needs to run.

[veggie]

What is the cost and life expectancy of those batteries?
Nice looking setup.

Sorry, I don't know the current cost. These batteries are 10 years old. They were used on a previous solar power system.
They are a 6 volt golf cart battery. The four are wired in series to make 24 volts. I believe they are approximately $110 US each these days.

[mobile_bob]

the story goes that golf cart batteries in a solar setup have a life expectancy of 5-7 years "if" well maintained...

however in your system Veggie, with the listeroid running and the battery bank basically buffering the system,
the lifespan may well be much longer... again if well maintained.

it is likely that there is seldom a time that you need to draw down the batteries with the engine running,
and keeping them cycling up toward the top seems like it would add to the lifespan of the batteries

looks like you have a really well thought out hybrid system, and there ought to be a lot for others to learn from your experience.

i like it.

bob g

[veggie]

thanks Bob,

I wanted to use older (no cost) batteries to build and test the system.
They can be upgraded in the future.
It is surprising how these batteries still perform and hold power.
I spent $30 on a battery pulse desulfator and applied it to the batteries for a week.
Apparently if the batteries aren't too far gone, it can help break down sulfate crystals from that build up from storage.
Lots of debate on that, I can't say if it worked or did any good. But for $30 I thought it was worth it to add a bit more life to the bank.

[RJ]

thanks Bob,

I wanted to use older (no cost) batteries to build and test the system.
They can be upgraded in the future.
It is surprising how these batteries still perform and hold power.
I spent $30 on a battery pulse desulfator and applied it to the batteries for a week.
Apparently if the batteries aren't too far gone, it can help break down sulfate crystals from that build up from storage.
Lots of debate on that, I can't say if it worked or did any good. But for $30 I thought it was worth it to add a bit more life to the bank.

Your system is almost exactly like I plan on doing, except on a slightly larger scale with a CS 12/2. Any lubrication issues running the engine at ~400 rpm?

I have a giant 24v/12v 400a military alternator that I was planning to use, overkill but I have a couple NOS units. The battery bank as in your system will act like a giant flywheel buffering surge loads. I don't have batteries but was thinking of LiFePo batteries in a 24v configuration. Although I'm not sure how the VR on the alternator will handle those as I'm sure it's designed for flooded batteries. I've read that LiFePo batteries aren't ideal for standby loads as keeping them topped off isn't ideal. I live in the SE so I'm not entirely sure it's worth the effort for me to try to harvest heat from the engine. The unit will basically just be a standby unit for long duration power outages.

It would be neat to have the engine ramp up based on load, not sure how that would be accomplished but I'm sure there is something out there that can be rigged up. Future upgrades I suppose.

[veggie]

RJ

No issues running the engine at 475 rpm.
My particular model has a pressure lubricated con-rod bearing fed by a cam operated oil pump inside the crankcase. That is unique to the GM90 "mini-Lister" design. Even without that pump I would not be concerned. At 475 rpm there's a LOT of oil flying around the crankcase.

Having the engine ramp up or down based on electrical demand is not that complicated.
Only works with an alternator system.
It does require some electronics.
1] An inline amperage sensor feeding to a micro-controller (Ardunio ??)
2] A throttle servo controlled by the micro-controller (Ardunio ??)
3] A throttle control algorithm in the controller based on the amperage reading.

Looking forward to seeing you project progress.

veggie