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Left my in progress van build for 2 weeks and came to find that my 12v lithium house batteries had dipped all the way down to 0.50 volts… I killed the power to everything while I was away (in hindsight I should have left everything live so the solar could top off the batteries but I’m new to this and assumed they’d be okay for a 2 weeks..)

Is there any glimmer of hope that they will still function normally if I charge them back up?

I feel like they shouldn’t have died that quickly as well.. is that normal for the heat of being in the van to drain them that fast? I’m in NC where the temps were about 80-90s over the last 2 weeks, internally I don’t know what the temperature of the van would reach..

Any insight would be greatly appreciated.

🙏🏼🙏🏼🙏🏼
 

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I think they’re dead, that’s incredibly low. Even 10V would be iffy. What batteries are these? Most systems should have over discharge protection I’d think. @harryn might have some insight.
 

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2017 350 XL HD passenger
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Left my in progress van build for 2 weeks and came to find that my 12v lithium house batteries had dipped all the way down to 0.50 volts… I killed the power to everything while I was away (in hindsight I should have left everything live so the solar could top off the batteries but I’m new to this and assumed they’d be okay for a 2 weeks..)

Is there any glimmer of hope that they will still function normally if I charge them back up?

I feel like they shouldn’t have died that quickly as well.. is that normal for the heat of being in the van to drain them that fast? I’m in NC where the temps were about 80-90s over the last 2 weeks, internally I don’t know what the temperature of the van would reach..

Any insight would be greatly appreciated.

🙏🏼🙏🏼🙏🏼
Saw your post on reddit. I think you mentioned they were Renogy batteries? Pretty sure they have over discharge protection. Sounds strange to me. Maybe they just completely failed?
 

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I feel like they shouldn’t have died that quickly as well.. is that normal for the heat of being in the van to drain them that fast? I’m in NC where the temps were about 80-90s over the last 2 weeks, internally I don’t know what the temperature of the van would reach.
I have not used my van in at least two weeks under similar ambient temperature conditions and my 12V, 380Ah lithium battery pack's voltage barely dropped. Note: the master electrical switch was turned off and there was no charging. LiFePO4 batteries should have a verrrrrrry slow discharge rate if there is no draw on them.....at least that has been my experience.
 

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2017 Ford Transit 350 Passenger Wagon
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Slightly hijacking this thread.

Why would my 2 100ah LiFEPO4 batteries read 100% at the shunt but 'only' 199ah available?

No draw. On a 12v charger.

Where'd my 1ah go?

Thanks!
 

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Left my in progress van build for 2 weeks and came to find that my 12v lithium house batteries had dipped all the way down to 0.50 volts… I killed the power to everything while I was away (in hindsight I should have left everything live so the solar could top off the batteries but I’m new to this and assumed they’d be okay for a 2 weeks..)

Is there any glimmer of hope that they will still function normally if I charge them back up?

I feel like they shouldn’t have died that quickly as well.. is that normal for the heat of being in the van to drain them that fast? I’m in NC where the temps were about 80-90s over the last 2 weeks, internally I don’t know what the temperature of the van would reach..

Any insight would be greatly appreciated.

🙏🏼🙏🏼🙏🏼
I can confirm a failed/dead bms will do this exact thing, 0.5V. It's possible a bms in normal cutoff state will also do this but I've never had one cutoff, only die.

It can happen by connecting an inductive load (motor) or capacitive load (decent sized inverter or even a large mmpt) without pre-charge. It could even be delayed since the damage of an inrush current may be just shy of what it takes to fail completely, and then high ambient heat finished the job.

My giant inverter blew one bms, and then I intentionally blew dozens more working with the bms vendor to try to overcome it through improvements the vendor was making to the hardware. None were ultimately successful, so I finally installed an REC pre-charge device and some custom circuitry.

The good news is the cells are almost certainly fine. The bad news is that if you disconnect all loads and ensure appropriate temperature and still get 0.5V after a few hours, you most likely need to replace the bms.

Cheers.
 

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2021 Cargo 130" MR AWD Ecoboost
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I suspect that your BMS has shut down the batteries. Follow the start up procedure and I bet you will be happy.
What is the start up procedure?

I received two large LiFePo 4 24V batteries in December and have not touched them yet (because we bought another house and are busy with that). They are in a computer server-like housing (eg pizza box) and each have a breaker on the front panel. My understanding is that I will have to bring the voltages very close to each other before I connect them in parallel but am not aware of a startup procedure.
 
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