Charging up a LifePo4 battery from a state of deep discharge

[Creamytash]

My solar panel died, it's winter, it's been quite cold and I took my eye of the ball allowing my LifePo4 battery to decend in to a state of deep discharge. I put my charger on with it set to lithium setting but it would not put any chage in. What I had to do was to use a charged up 12v battery (of any kind) as a jumper battery and hook it up to the LifePo4 with a set of jump leads, leave it for 10mins, then put the charger onto the LifePo4 battery posts - straight away I could see that the charger was working and the battery was accepting charge. I left it like that for 15mins then removed the jump leads thus disconecting the 12v jumper battery. The charger continued to charge the LifePo4. I left it on charge and within 4hrs the LifePo4 battery was fully charged. I hope this helps anyone that finds themself in the same situation as me. I have received some great help and support from this group since I jouned, it's nice to be able to give something back.
Creamytash.

 

[Salty Spuds]

My solar panel died, it's winter, it's been quite cold and I took my eye of the ball allowing my LifePo4 battery to decend in to a state of deep discharge. I put my charger on with it set to lithium setting but it would not put any chage in. What I had to do was to use a charged up 12v battery (of any kind) as a jumper battery and hook it up to the LifePo4 with a set of jump leads, leave it for 10mins, then put the charger onto the LifePo4 battery posts - straight away I could see that the charger was working and the battery was accepting charge. I left it like that for 15mins then removed the jump leads thus disconecting the 12v jumper battery. The charger continued to charge the LifePo4. I left it on charge and within 4hrs the LifePo4 battery was fully charged. I hope this helps anyone that finds themself in the same situation as me. I have received some great help and support from this group since I jouned, it's nice to be able to give something back.
Creamytash.

This could be more about your charger than your battery. Depending on the BMS sophisticatoryness of your battery this is what normally happens:-
The battery discharges to a point where it risks damage, but the BMS physically disconnects the battery from the outside world, thus protecting your battery. And here’s the tricky part. Most “smart” chargers need to see a battery and do a SOC test before they will start charging, but when you connect it to the disconnected (via BMS) battery and the charger sees an open circuit, I.e. nothing, nada, zero battery, so doesn’t start to charge.
What you need to do is wake up the BMS by applying a charge voltage, the BMS sees this incoming charge and reconnects the battery and voila charger sees battery, charger charges battery. By putting on your jump leads, you woke up the BMS.
Victron chargers have a BMS wake-up function
From the IP22 blue smart manual:-
Fully discharged battery recovery function

Will initiate charging even if the battery has been discharged to zero volts.

Will reconnect to a fully discharged Li-ion battery with internal disconnect function

You can also use an old school non-smart charger that just outputs 13.8V or thereabouts, regardless of what it’s connected to.

 

[JDC]

I done something similar with my caravan lesuire battery that went dead the week before we were going away over New Year. It had dropped to 4vdc. Looked around and was struggling to get a replacement battery or solar mppt for the caravan. Luckily enough I removed it and put my charger on it and and it came back upto 14v. I'm yet to check it since we came back though!!!