I’m trying to recover a Victron lithium battery bank that has become deeply discharged, I let it discharge over the winter and haven’t been able to get the system to charge plugging in so I bought a blue smart charger. After connecting that for a few hours not sure I’m doing it right.
System Setup:
3 × Victron batteries, with mppt and battery protect – combined capacity 600Ah (in parallel)
Batteries connected to a Victron BMS and Cerbo GX (currently off due to low voltage)
Trying to get them to take a charge by using Blue Smart IP65 Charger (12V/15A)
Situation:
The batteries were accidentally left deeply discharged. I tried charging by leaving plugged in to house power for 2 days… didn’t work. Now trying the blue smart charger one battery at a time (without disconnecting the others I don’t know how I paid to have it professionally built)
Here’s what happened:
1.Battery #1:
Initial voltage: ~2.96V dropping to 2.93V after 2 hours
Charger shows 0.2A charging current
battery protect gave a “circuit” error when I first connected to the blue smart charger
*Battery are not hot swollen look fine
2.Battery #2:
I finally gave up and thought I should try charging another battery.. The voltage started at 3.9V and dropped to 3.08V within 5 minutes while charging with the blue smart charger and reading said 0.2A
Maybe this voltage likely reflects the whole battery bank and not just the battery I’m connecting the charger too since batteries are still paralleled
Suggestions on what I should do? Am I charging it correctly?
Should I disconnect the parallel connections to isolate and charge each battery individually? (I don’t know how to do that.. but have handy neighbors) Is the issue the BMS and I haven’t overridden it so the batteries are not accepting a charge?
Once lithium batteries are discharged below 2.0V / cell, then they are only good for recycling. Trying to recharge from below this voltage is normally prohibited by the BMS.
so a 12v 4 cell block reading 2.9V you have big problems…
Thank you Mike, brutal news, but helpful. They are only a few years old. Should I assume all 3 are completely wasted? It was just from a few months of snow on the roof but then.. a few more months not taking care of it every time I tried to charge it.. couldn’t figure out what was wrong.
just make sure that if there is an internal BMS disconnect, that you are measuring the cell voltages, not any leakage through the disconnect. Some smart battery chargers also will not turn on if there is no battery on the output - which a lithium battery in LV-disconnect state will not qualify.
Try with a low current 12V source to see if there is any recovery. If there is no charge current after 2 - 3 min, then give up.
Thanks Mike! Its charging now. I turned all the breakers off for all the things that could be draining power, and.. there are two switches on the top of the batteries labled VE bus and DC – both were flipped off. I turned them on and reconnected blue smart charger to the 1st battery and now the battery protect has flipped to on and the blue smart charger app keeps showing the battery voltage going up it went from 2.93, to 2.97 and then 3 and keeps climbing its at 3.03 now - so it seems positive
and its still climbing, ok so many beginner things done wrong, (and I’ve owned it for a few years,..) I think those switches on top of the battery were main disconnects, and either the guy who helped me, or me.. turned one off and then flipped the other one to match - uncertain who did what or why but, flipping both of them appeared to be the trick and might have been the reason the batteries were dead - draining they couldn’t get a charge.