Empty battery instantly at 14.5v when charging

[masamyyris]

My lifepo4 200ah battery is about 6 months old, charged mainly with solar and has been working fine.

Suddenly my MPPT controller gave me a warning today for too high voltage, when I left my van in the morning the voltage was at 12.5 (nearly empty battery) when I came back it was at 12.6 and showing the error (too high voltage) now when I charge the battery with my generator (via 30a victron lion charger) it instantly spikes the voltage to 14.4 (this has never happened before) and my charger will skip the bulk phase and go straight to absorb. I kept it on for 2 hours and disconnected the charger for a second and the voltage dropped back to 12.5, showing that it didnt charge nearly anything. Any tips?

Living in our van atm so getting this to work is crucial, thanks to anyone replying in advance!

 

[bolhuijo]

Sounds like the BMS is turning off for some reason, either for low temperature or maybe an individual cell hitting a protection limit?
anecdote: I have a cheap battery for a solar light string that got way out of balance due to a weak cell.. I had to bust it open and rebalance the cells myself to get another 6 months of use out of it.

 

[TomC4306]

I am not familiar with the victron charger. Can you adjust the charge voltage? If yes, try 13.8 for an hour and test again.

 

[Q-Dog]

Does the battery power any loads? or does it shut down when a load is applied?

 

[mikefitz]

ifepo4 200ah battery is about 6 months old

What make, model or self built?
Sounds like a fault in the BMS, or a faulty cell , or an interconnection fault within the battery.
As TomC suggested, set the victron charger In power supply mode at a voltage of 13.6 to 13.8 and see if the battery accepts charge, (use the app to monitor charge process).
A previous post discussed issues you had with the solar controller, have these solved and what absorbtion and float values were used?

 

[sunshine_eggo]

Does the battery power any loads? or does it shut down when a load is applied?

This

In some cases, batteries in charge protection mode will report something in the 12.6-13.0V range. If you lightly load the battery, you may observe the voltage jump to something in the 13s.

 

[740GLE]

Adding a shunt will allow you to track SOC to verify if you see 12.7v that you actually have a full battery but a BMS in protection/sleep mode.

 

[masamyyris]

Does the battery power any loads? or does it shut down when a load is applied?

Battery is supporting loads, Ive used it for many hours as long as its plugged into the victron charger at the same time. As soon as I detach it from the charger, the voltage drops to 12.5

 

[sunshine_eggo]

Sounds like the BMS is in permanent charge protection mode.

 

[jeff.lankford]

Battery is supporting loads, Ive used it for many hours as long as its plugged into the victron charger at the same time. As soon as I detach it from the charger, the voltage drops to 12.5

How do you know the battery was providing load current and not just the charger?

 

[Q-Dog]

Low temperature protection?

 

[740GLE]

Battery is supporting loads, Ive used it for many hours as long as its plugged into the victron charger at the same time. As soon as I detach it from the charger, the voltage drops to 12.5

How long did you let it sit at 12.5v with a load on it? And how much load was it?

 

[masamyyris]

How do you know the battery was providing load current and not just the charger?

Well I dont, most likely its the charger now that I think about it

 

[masamyyris]

How long did you let it sit at 12.5v with a load on it? And how much load was it?

Load was next to nothing, maybe 4 hours. During that time the temperature of my van dropped from +13 C to around 0

 

[masamyyris]

Sounds like the BMS is in permanent charge protection mode.

How can I get it off?

 

[masamyyris]

Low temperature protection?

Maybe, but how do I get it off?

 

[Q-Dog]

Maybe, but how do I get it off?

If it is shut down due to cold I would say you need to warm up the battery then apply a constant voltage to it to wake it up. But, it depends on the battery. What does the manufacturer/manual say about it?

 

[740GLE]

Load was next to nothing, maybe 4 hours. During that time the temperature of my van dropped from +13 C to around 0

Did you try and apply a large load to it? Even if the battery is 100% dead a large load saw 500w won’t damage anything, the BMS will protect it.

Low temp protection usually happens before low discharge temp protection.

What make and model battery/bms? Share a link?

 

[masamyyris]

Did you try and apply a large load to it? Even if the battery is 100% dead a large load saw 500w won’t damage anything, the BMS will protect it.

Low temp protection usually happens before low discharge temp protection.

What make and model battery/bms? Share a link?

Core-12V/24V/48V 200Ah Deep Cycle Lithium Iron Phosphate Battery

Core Basic 12V 200Ah Lithium Battery LiFePO4 with 5000 Deep Cycles

The Renogy Smart Lithium Iron Phosphate Battery enables the auto-balancing among parallel connections and provides more flexibility for the battery bank configuration.

eu.renogy.com

I have also contacted renogy support but it doesnt feel like they even read my message.

 

[jeff.lankford]

So back to earlier questions... does the battery power any loads, when the chargers are disconnected?

The battery is either dead and not taking any charge because it's BMS-disconnected. Or, we think the battery might be charged and in a disconnect mode (due to temperature?) where it might read a lower than normal voltage until you wake it up with a small load. Some battery brands behave this way. Not sure about Renogy.

Do you have a shunt monitor on your system to be able to see current flow?

 

[masamyyris]

So back to earlier questions... does the battery power any loads, when the chargers are disconnected?

The battery is either dead and not taking any charge because it's BMS-disconnected. Or, we think the battery might be charged and in a disconnect mode (due to temperature?) where it might read a lower than normal voltage until you wake it up with a small load. Some battery brands behave this way. Not sure about Renogy.

Do you have a shunt monitor on your system to be able to see current flow?

Yes, it does power some loads when chargers are disconnected and no I dont have a shunt monitor

 

[jeff.lankford]

Yes, it does power some loads when chargers are disconnected and no I dont have a shunt monitor

When it's powering a load is the voltage getting pulled down to 12.0 or lower, or holding at the ~12.5? If you turn off the loads does the voltage go up very much?

It sounds like it is operating but in protect mode. You said the temp in your van dropped to 0. Has it ever been warm enough in your van for long enough to warm up this battery's thermal mass? It will not charge below 0 deg and it doesn't have a heater. Also, if the battery has gotten down to 0 and triggered the low temp protection, it probably has to get back up to a higher recover temperature, like 5 deg, before it will take a charge.

 

[ScrotpusGobbleBottom]

I have also contacted renogy support but it doesnt feel like they even read my message

It's because they don't

 

[masamyyris]

When it's powering a load is the voltage getting pulled down to 12.0 or lower, or holding at the ~12.5? If you turn off the loads does the voltage go up very much?

It sounds like it is operating but in protect mode. You said the temp in your van dropped to 0. Has it ever been warm enough in your van for long enough to warm up this battery's thermal mass? It will not charge below 0 deg and it doesn't have a heater. Also, if the battery has gotten down to 0 and triggered the low temp protection, it probably has to get back up to a higher recover temperature, like 5 deg, before it will take a charge.

Yes that is my guess atm aswell, battery is now at friends house near the radiator, we let it sit there for a day and try again. We have been quite a few times in cold weathers with the battery (-10c) and no problems at all, but I guess this was the first time for the battery to have low voltage and cold temperature (-5c) combined.

The voltage drops abit (12.3-12.4) when under some load, but Im abit scared of trying higher loads on the battery atm.

 

[jeff.lankford]

The voltage drops abit (12.3-12.4) when under some load, but Im abit scared of trying higher loads on the battery atm.

I think that tells us the battery is operating and isn't really dead. I agree maybe not good to put a large load on it until you get it warmed up and charged. It probably hasn't taken a good charge for a while. You don't need to exchange low-temperature shutdown for an over-discharge shutdown.

I assume you know this, but I'll state it anyway... whenever the battery is taking in charging current you will never be able to measure the output voltage of the charger. The measured voltage will be pulled down by a lot during charging. The 14.4 V you measured is an indication that no charge current was flowing.