Quote:
Originally Posted by Veloc
If I missed anyone discussing this, it's probably because my duck-fu failed. But... has anyone considered using an EV battery pack for their bus's house power? Wondering, because it looks like it would make for a simpler install. One could pick up, for example, a used Chevy Volt in the 7000 dollar range, scavenge the battery pack and ICE engine, and have a compact 57KWH battery pack and an on-board generator designed specifically to that battery pack. The rest of the car could be parted out to recoup some of the money spent to buy it. Just a quick check shows that a typical full size house only requires half of this to operate for a couple of days, so this would likely allow a bus to boondock for a week, or let a bus run HVAC for a couple of days without needing the generator. The main disadvantage would be requiring gasoline for the generator if your bus is diesel, but it wouldn't be any great thing to add a tank, or use a diesel generator and sell the engine.
And, I did look into buying just the battery, looks like it would cost more to just buy a used battery pack from a wreck, and a lot more from a refurbishing center, and I wouldn't trust a lithium battery from a wrecked car. Those things can catch fire weeks after the accident happens.
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Most EV battery packs are made with Lithium Ion chemistry, because it is light and energy dense. This is wonderful for getting a lot of energy in a small space. But there is a very serious drawback to consider. Lithium ion batteries are volatile.
If the anode and cathode contact each other there will be a very violent thermal runaway. That word I never want to have to use in the same sentence with, "my skoolie..." is FIRE. You may think that since so many EV manufactures are using Lithium ion batteries they must have solved this concern. Not by a long shot. They package the batteries in heavy metal boxes and integrate cooling systems into the box, they develop complex battery management systems to prevent overcharging and under charging, but the fact remains. Lithium ion chemistry is unstable.
You mentioned buying a used Chevy Volt. Had you considered the problems they have been plagued with?
Chevy Volt recalls.
Here are a couple links to youtube videos about thermal runaway with Lithium batteries:
https://youtu.be/VZSMEBzG_2k
This one goes into detail about what causes thermal runaway and examples.
https://youtu.be/VWMfeseybt4
On top of that what most DIYers do when they take an EV battery fir their power wall is remove the packs from their shielding and remove the battery management to build their own pack suitable for their power wall.
Personally I would never use a massive bank of lithium Ion batteries in my stationary setup, where they are not subject to the vibration and bumping around that a skoolie produces. One note in that direction is that every manufacturer of EV school busses that are currently in production or development are using Lithium Iron batteries. School bus design always errs on the side of safety.
Lithium Iron batteries, LiFeP04, are a little less energy dense than Li Ion batteries, thus are a bit larger and heavier, but still far more energy dense than lead acid batteries. If you are into DIY as you would be tearing a Chevy Volt apart for used Li Ion batteries, $7000.00 will build you about 25KW of LiFeP04 battery bank out of brand new cells.
Our battery bank is made out of 220AH 24V BYD commercial LiFeP04 batteries reclaimed from a solar farm. Used when we got them, but still testing out to nominal capacity. We have 6 of them in a 6P 24V configuration for about 31KW. We have less than three thousand bucks in the batteries.
I was just wondering why you would choose generator over solar? We lived that way back when gasoline was a buck seventy nine a gallon. Since we are full timers that ran us about $650.00/month in fuel. we got tired of that and built our solar system.
We have 12 329W Sunpower E series panels that allow us to live like we are grid tied, no matter where we are. It is currently 100 degrees here in the SW New Mexico desert, and the air conditioning is running day and night. Yet not a drop of gas is being burned.
You've got a lot of real estate on a bus roof and solar panels are getting cheaper by the minute. We have less than 2K sunk in about 4KW of solar panels and those are low yield compared to what is available today.
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