Battery broken?

[simjoc]

Hello,

I have a problem with my camper, and I hope there are people who can help me think through it.

Currently, I have the following system:
2p4s 12V 560A (8x Eve 280)
Batrium BMS
No heating pads (yet)

This system is still under construction and was used this summer. I haven't used the camper since, and I disconnected all low-voltage systems for the winter. The battery was still 90% charged when I turned everything off. All power was disconnected, except for the Batrium BMS, which I left on. The temperature here has been around 5 degrees Celsius (41 Fahrenheit) in the past few days.

I used a small amount of power briefly, but it was no more than 1 or 2 Ah.

Now, the BMS is in a Critical Battery Fault state, and undervoltage has been detected. I measured, and one series is at 7.6 volts, and the other is at 6.8 volts. When I log into the Batrium BMS, it doesn't display anything, but the last known percentage was still 90% full. Some cells are at 1.2V, and others at 2.0V.

The temperature has not been lower than 5 degrees Celsius.The battery has not been charged, neither by the vehicle nor by solar. What could have happened here? And what is the wise thing to do now? The period during which the batteries did nothing is about a month, and I can't imagine that so much power has leaked away.

Merry Christmas, and I hope people can help me think through this ?

 

[rodrick]

The cells were discharged from some draw they can set for a extremely long time with a charge if there is no draw.
some contactor type bms can have a substantial self consumption over time.
you have likely damaged the cells but you can try to bring them up to normal voltage preferably with a power supply on each cell individually slowly at first then at a higher rate but keep a eye on them

 

[Steve_S]

The BMS is SHUTDOWN and in safety mode, hence why you see that voltage.
Your batteries are NOT damaged if the BMS has shutdown.
Bring your batteries inside and let them warm up thoroughly, 1 day @ 20C+ temps will do fine. Then apply 12V charge and you should be able to wake the BMS' and charge up the battery packs.

If I recall Batrium does use power, even when idle. You actually have to turn off the BMS. This was raised some time back as a quirk. Sorry I don't use Batrium.

IF the cells ARE BELOW 2.500 Volts, you can still recover the cells/batteries.
AS LONG AS They were not charged in a frozen state. They can safely freeze to -30C but cannot be used till thawed out.

Recovery Instructions:
Charge each LOW cell, one at a time, starting at 3.000V and around 10A and let it slowly take the charge till it cuts off. Rinse and repeat for each cell. They should all take it BUT BE GENTLE & POLITE ! Once they all get to 3.000 then parallel the cells and top them in INCREMENTS, I would suggest 0.100V increments. Yes slow, painful, TEDIOUS but if you want to recover them....
-
They technically can recover IF they were not charged when frozen or cooked while in a state of discharge, if they have, then do one cell at a time and in a safe box in case it pops & leaks. IF you are lucky, they will recover and maybe you've only lost a percentage of capacity. IF they recover to at least 3.400Vpc, I would run at least 3 good cycles through them (charge/discharge) and then capacity test each cell to ensure the packs integrity, because even if One Cell goes wonky, it will affect the whole pack, as the lowest common denominator rules.
-
Once you get the cells up to 3.650 (I would stick to 3.600 myself) and fully saturated (meaning taking <2A) and stop charge current. The cells WILL SETTLE which is perfectly normal & expected behaviour. They will likely drop to about 3.500 from 3.600 within 1 hour or so, give or take a bit. They will usually continue to settle till around the 3.400-3.450 mark where it will slow considerably as the LFP Working Voltage range is 3.000-3.400.
-
Once this is done, I would set up the pack temporarily with the BMS and discharge the battery pack to cutoff, then recharge through the BMS till it reaches full at a respectable Amperage. 100AH Cell can typically take a Max of 0.5C or 50A charge rate. 20-40A Charge rate would be as high as I would go "for now" while determining their condition.
-
When charging at a higher amperage the cells heat up (normal & expected) and the higher the amps the warmer they get. With ESS cells @ 0.5C it's never crazy ! EV Grade Cells @ 5C Charge Rate = another matter ok. We are dealing with ESS cells here, so staying "in context". You will want to check the cells during Higher Amp charging feel the sides etc, they should be consistent/constant... a Hot Spot = Warning Flag ! You WILL NOT GET THAT with Lo Amp Charging, it has to be at least 0.25C and the temps should be notable within 1/2 hour or so. Be diligent & watchful !

 

[rodrick]

The BMS is SHUTDOWN and in safety mode, hence why you see that voltage.
Your batteries are NOT damaged if the BMS has shutdown.
Bring your batteries inside and let them warm up thoroughly, 1 day @ 20C+ temps will do fine. Then apply 12V charge and you should be able to wake the BMS' and charge up the battery packs.

If I recall Batrium does use power, even when idle. You actually have to turn off the BMS. This was raised some time back as a quirk. Sorry I don't use Batrium.

IF the cells ARE BELOW 2.500 Volts, you can still recover the cells/batteries.
AS LONG AS They were not charged in a frozen state. They can safely freeze to -30C but cannot be used till thawed out.

Recovery Instructions:
Charge each LOW cell, one at a time, starting at 3.000V and around 10A and let it slowly take the charge till it cuts off. Rinse and repeat for each cell. They should all take it BUT BE GENTLE & POLITE ! Once they all get to 3.000 then parallel the cells and top them in INCREMENTS, I would suggest 0.100V increments. Yes slow, painful, TEDIOUS but if you want to recover them....
-
They technically can recover IF they were not charged when frozen or cooked while in a state of discharge, if they have, then do one cell at a time and in a safe box in case it pops & leaks. IF you are lucky, they will recover and maybe you've only lost a percentage of capacity. IF they recover to at least 3.400Vpc, I would run at least 3 good cycles through them (charge/discharge) and then capacity test each cell to ensure the packs integrity, because even if One Cell goes wonky, it will affect the whole pack, as the lowest common denominator rules.
-
Once you get the cells up to 3.650 (I would stick to 3.600 myself) and fully saturated (meaning taking <2A) and stop charge current. The cells WILL SETTLE which is perfectly normal & expected behaviour. They will likely drop to about 3.500 from 3.600 within 1 hour or so, give or take a bit. They will usually continue to settle till around the 3.400-3.450 mark where it will slow considerably as the LFP Working Voltage range is 3.000-3.400.
-
Once this is done, I would set up the pack temporarily with the BMS and discharge the battery pack to cutoff, then recharge through the BMS till it reaches full at a respectable Amperage. 100AH Cell can typically take a Max of 0.5C or 50A charge rate. 20-40A Charge rate would be as high as I would go "for now" while determining their condition.
-
When charging at a higher amperage the cells heat up (normal & expected) and the higher the amps the warmer they get. With ESS cells @ 0.5C it's never crazy ! EV Grade Cells @ 5C Charge Rate = another matter ok. We are dealing with ESS cells here, so staying "in context". You will want to check the cells during Higher Amp charging feel the sides etc, they should be consistent/constant... a Hot Spot = Warning Flag ! You WILL NOT GET THAT with Lo Amp Charging, it has to be at least 0.25C and the temps should be notable within 1/2 hour or so. Be diligent & watchful !

You should add the recovery method to your signature box very well explained. I copied it to my notes for future reference
thanks alot

 

[Aussieguy]

campers are notorious for hidden parasitic drains... can have hidden fuses etc under the frame etc
for alarms and "user" upgrades

best to store a camper with battery disconnected at terminals ... not just to turn OFF stuff

 

[simjoc]

Thank you for all the responses, especially Steve_S. The batteries are fully integrated, and I plan to remove them in a few days. I will follow your instructions, and I hope to get them working again. I will post the outcome here.

I disconnected everything immediately and now see that all cells are at 2.1V. I have also identified the cause of the drainage. I connected both the Batrium itself and the relay module before the Shunt. As a result, I never saw the consumption, and the batteries completely drained. Stupid mistake, but nothing can be done now. A good lesson for myself :/

Merry Christmas, everyone!

 

[RvNaut]

You drained the batteries.