I discharged my lifepo4 to 0% (.1 - .2V) and now it won't charge. Is it a paperweight now?

tascern

Is it possible to revive or do anything with a LiFePO4 battery that has a resting voltage of between .1 - .2V and which my charge controller won't charge? Do I have to just get rid of it?

From googling around it seems that the answer is that I need to get rid of it. It's a paperweight. Recycle it. This page, for instance, makes me conclude that. https://community.victronenergy.com/questions/102624/low-voltage-on-a-lifepo4-is-it-dead.html

I ask this obvious question because when I contacted Lossigy customer support she seemed to be saying the battery still has a chance of being revived:

"You can try activating the battery in the following ways:

1. You can use a 14.6V lithium iron phosphate charger with 0V charging function to activate the battery pack.
2. You can use a single 18 or 36V battery pack to directly charge the battery pack (note: do not connect the controller).
3. You can use a DC power source to charge the battery."

Here's some useless info to be more specific. When I connect the multimeter to the battery's terminals, it says .32 V at first for a split second, then quickly, steadily declines for 2 minutes to .13V where it stayed. It kept declining even after 2 minutes but very slowly. At around 3 minutes I disconnected the multimeter. After 2 minutes, the multimeter said it was about .134V and slowly declining by about .001 every 10 seconds.

It's this battery:

Lossigy 12V 20Ah LiFePO4

https://www.amazon.com/gp/aw/d/B0B7DTNZDW?psc=1&ref=ppx_pop_mob_b_asin_title#

tascern

You're supposed to be able to discharge a lifepo4 down to 0% so I'm not sure why mine died. It may've been because for a month I left it disconnected from the solar panel and connected to the charge controller which draws a small amount of power. It went from 50% full to 0% full during that time. I didn't realize the CC would drain it so fast.

I accidentally killed yet another of these Lossigy batteries prior to this. That time, I didn't realize its state of charge was only 7% and then proceeded to leave it disconnected from anything for 5 months. If it self-discharged a little each month, then maybe that's what killed that one.

These two pages say it's possible to kill a lifepo4 by over-discharging it. I don't know if what the second page says applies to lifepo4 though. It's about li-ion batteries but lifepo4 is a type of li-ion, isn't it?

https://ecotreelithium.co.uk/news/lifepo4-battery-depth-of-discharge/

"Can you over-discharge a LiFePO4 battery?

Yes, it is possible to over-discharge a LiFePO4 battery. Over-discharging occurs when the battery power is consumed even after the battery is fully discharged. Therefore, any use of a LiFePO4 battery after 0% charge level will cause it to over-discharge."

https://batteryuniversity.com/article/bu-808a-how-to-awaken-a-sleeping-li-ion

"Slipping into sleep mode can happen when storing a Li-ion pack in a discharged state for any length of time as self-discharge would gradually deplete the remaining charge."

Horsefly

I can't really tell from what you've told me, but I would guess there is a pretty good chance that the cells are not really dead, but the BMS has cut off the terminals from the battery. Since it is an assembled battery, I'm not sure how to get inside to check the cell voltages, but that would be the first thing I would try to do.

SteveK

You need to disconnect all devices from the battery to test this. If you don't the internal BMS will continue to be driven into low voltage disconnect mode. In low voltage disconnect mode you will see those ~0.0V readings. If you disconnect the devices from the terminals and test with only a multimeter the numbers should be more like 9-11V on a BMS/battery that had previously entered low voltage disconnect mode.

Once you have disconnected all devices (charge controllers/inverters/etc) from terminals you can connect a 12V battery or a 12V charger that operates with zero volts present (any old 12v schumacher NOT your charge controller as it will not work)  and the battery will begin to charge or "wake up". You can then attach your charge controller normally.

The battery you have is nothing like the Victron battery you referenced in your link above. The Victron battery has no protection device or BMS internally. It can only balance the cells not disconnect it like yours does.

After all of that get a Victron Battery Protect that is suited to your power requirements and program it properly so you don't have to jumpstart the battery again.

tascern

Horsefly said:

I can't really tell from what you've told me, but I would guThaksess there is a pretty good chance that the cells are not really dead, but the BMS has cut off the terminals from the battery. Since it is an assembled battery, I'm not sure how to get inside to check the cell voltages, but that would be the first thing I would try to do.

Thanks, I'm going to try to hook it up to my 170-Ah 12V battery with a jumper cable. There are no screws so I don't think I can disassemble it. Hopefully any jumper cable off amazon.com will do the trick. I don't think it needs to be a thick gauge. I'll get a 10-gauge, 12-ft jumper cable. 

One of the comments in reply to this video even said you can hook it up directly to a solar panel to wake it up. https://m.youtube.com/watch?v=TJ_Klwp-JyM

 That doesn't sound right to me though. That would be too high a voltage for a 12V battery, I would think.

tascern

SteveK said:

You need to disconnect all devices from the battery to test this. If you don't the internal BMS will continue to be driven into low voltage disconnect mode. In low voltage disconnect mode you will see those ~0.0V readings. If you disconnect the devices from the terminals and test with only a multimeter the numbers should be more like 9-11V on a BMS/battery that had previously entered low voltage disconnect mode.

Once you have disconnected all devices (charge controllers/inverters/etc) from terminals you can connect a 12V battery or a 12V charger that operates with zero volts present (any old 12v schumacher NOT your charge controller as it will not work)  and the battery will begin to charge or "wake up". You can then attach your charge controller normally.

The battery you have is nothing like the Victron battery you referenced in your link above. The Victron battery has no protection device or BMS internally. It can only balance the cells not disconnect it like yours does.

After all of that get a Victron Battery Protect that is suited to your power requirements and program it properly so you don't have to jumpstart the battery again.

Thank you, I'm going to try that. I'll buy this 10-ga, 12-ft jumper cable and connect the sleeping battery to my 12V, 170-Ah lead-acid battery.

https://www.amazon.com/Schumacher-AWG-Foot-Booster-Cable/dp/B079GVH7N3/ref=mp_s_a_1_8?keywords=jumper+cable&qid=1695617725&sr=8-8

Although, I tested the dead-or-asleep battery without the CC connected to it and it still says .25V and then steadily declines to .1V. So, if it's supposed to say about 9-11V when nothing is connected then it might be dead. I searched based on the responses to this thread and found this vid in which someone wakes up a battery that has about 0V (see it at 00:30) when nothing is connected to it. That gives me hope that mine isn't dead.

https://m.youtube.com/watch?v=TJ_Klwp-JyM

BB.

Jumping your Li Ion bank with a decent sized Lead Acid Battery (car size or larger) does run the risk of sending too much current to your Li battery pack... From your Amazon link, the charging current is 4 amps standard and 20 amps maximum. A Car Sized lead acid battery can output 100(s) of amperes into what is very close to a dead short if the Li Ion battery is zero volts, or even less than full charge.

Yes, you can use any solar panel with less than 20 Amps Isc (rated output) to start the process. As the battery charges from 0 volts to 12.xx volts, it will clamp the solar panel output voltage to whatever voltage the battery is accepting at that time.

Once the Li Ion battery approaches 100% SoC, then it has no capability to (safely and reliably) absorb any more current and the voltage will rise above its rated charging voltage of 14.2 to 14.6 volts and ruin the battery from over charging.

So, you could (for example) charge with a 10 amp rated panel for 1 hour (10 AH into a 20 AH battery), and get to 50% state of charge... High enough to continue charging with whatever setup you have... You could also charge for 6 minutes (0.1 hour) with 10 amps, and get 1 AH of charge into the battery--More than enough to either boot a good battery...

Or, you could use your car battery charger (less than 20 Amps) to charge the battery too... Assuming your car battery charger can charge a "dead battery" (some can, some can't, and some will over current into a "dead battery").

A solar panel has no "charge controller" so will charge to the maximum output voltage of the panel (somewhere between Vmp and Voc depending on conditions).

A {real) charging controller will charge to its output rated voltage (a solar charge controller, a Li Ion rated controller).

A "dumb" charge charger designed for Lead Acid batteries can charge to 17 volts--Because Lead Acid batteries can take (relatively low charging currents) at excessive voltages for a period of time (a few hours or less--Again depending on the charger, battery, etc.).

In theory, what you want is the Li Ion battery to hold >9 to 10 volts, then connect your proper charging source to bring the battery to full (if the battery is still working correctly). Most solar charge controllers need a minimum of 9 volts or so before they will boot and charge.

-Bill

SteveK

tascern said:

Although, I tested the dead-or-asleep battery without the CC connected to it and it still says .25V and then steadily declines to .1V. So, if it's supposed to say about 9-11V when nothing is connected then it might be dead. I searched based on the responses to this thread and found this vid in which someone wakes up a battery that has about 0V (see it at 00:30) when nothing is connected to it. That gives me hope that mine isn't dead.

Yes, if the BMS has tripped a long time before the problem was corrected it is possible the cells continued to discharge slowly. Given enough time the cells could get so low that the BMS would not release and present 9-11V to the terminals. There is still the opportunity to "jump start" such a battery/BMS combination.

I left a Battle Born 12v 100ah battery in low voltage disconnect for 10 months once. It "woke up" after "jump starting" to full capacity and is still in service today.