Prostar battery APU shuts down too fast

[Downthehaul]

I got me a 2010 prostar with the battery powered APU. Even after driving all day, the “no idle” A/C shuts off after only a few hours. It’s like the batteries are drained. They aren’t that old, maybe a year or two, and they are the deep cycle ones with 190 cold crank amps. What can be the problem?

[Nilao]

I had a nite system in a freightliner many moons ago. It'd last around 8 hours if the night was in the 70's. Less than 6 if it was 80+. Those systems tend to take them to the bottom as far as charge goes. Like 80% discharged. Lead acid deep cycles can go around 800 cycles at that discharge rate. Of course there is diminishing returns ...meaning as you cycle it it can no longer get back to 100% of its Amp hour rating. It looses a percentage of its rated capacity every cycle. If I had one today I would use 4 lifepo4 batteries in its place with a separate battery charger that charged them off the main bank.

[Nostalgic]

(07-25-2022 )Nilao Wrote:  I had a nite system in a freightliner many moons ago. It'd last around 8 hours if the night was in the 70's. Less than 6 if it was 80+. Those systems tend to take them to the bottom as far as charge goes. Like 80% discharged. Lead acid deep cycles can go around 800 cycles at that discharge rate. Of course there is diminishing returns ...meaning as you cycle it it can no longer get back to 100% of its Amp hour rating. It looses a percentage of its rated capacity every cycle. If I had one today I would use 4 lifepo4 batteries in its place with a separate battery charger that charged them off the main bank.

I bought 4 Lifepo4 batteries for just that, but then found that my charge isolator was bad, and for a change my 2 year old lead acid flooded batteries were fine. Anywho, I made the mistake of buying batteries without a built in heater bms. So... trying to figure out the simplest way to limit charging when below 32F. Also, can't just use a charging isolator since it wouldn't shut off until the lithium were pretty much discharged completely.

So far my 140/160 amp Bosch alternator has kept up with charging 4 AGM starting bank and my 4 marine house bank with just a simple battery charge isolator. Not sure if it would play as well once the lithium are in the house bank side.

[Nilao]

My setup would use 12v lifepo4 batteries as well as the following....

Battery Protect 12/24-Volt, 65 amp
https://amzn.to/3PVpdc8

DC to DC On-Board Battery Charger for Flooded, Gel, AGM, and Lithium, Using Multi-Stage Charging in RVs, Commercial Vehicles, Boats, Yachts, 60A
https://amzn.to/3PJaLV1

[hhow55]

Didn't Mr Waterloo install solar panels on his truck?

[hhow55]

https://rawze.com/forums/showthread.php?tid=6549