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xdorland avatar image
xdorland asked

Lithium Battery low voltage (battery dead or not?)

Good evening.

We live in a camper for 2 years. 18 months ago, we changed our 2 GEL batteries (115 Ah each) for a 1 lithium (110Ah)...without time to really investigate.


After a few months :

- we add a Smartshunt

- we replaced the Cyrix-CT by a Cyrix-Li-CT

(the settings of the MPPT solar charger have been updated much more quicly

(...no change of the charger which charge when we are plug to the grid)


==> Things went pretty well the last 12 monts. BUT, the last days were verry worry

1) the battery shut down in the middle of the night (maybe because our fridge has a problem and run for hours...)

2) during this night, the outdoor temperature was around -6°C...but how much for the battery? (wich is not IN the camper, but in a unheated hold)

(not very concerning for now...we though the battery was just empty because of the crazy fridge)

3) BUT, when I started the charge (starting the engine), the voltage was 14.5V...in a few seconds!!! normally, it takes at least 20 minutes

4) during the day, the voltage stayed too high comparing to what we were used too (13,6V with a very poor sun...)

5) As soon as there were no charge (no sun or the engine was OFF), the voltage was 11,1V, and even 10.6V before we were plugged to the grid!!! (and the sounf of our 12V pump was a proof of this low voltage!!!)

==> This lasted 2 days (the Voltage of the battery was too high and too quicly up when the battery was on charged...and fell to weaks voltage as soon as they were no charge). When I checked the data of the MPPT solar charger, it said me that the "lowest voltage of the day" were around 12,2V (!! this is a lithium battery!!) 4 of the last 6 days

Important : before these 6 days, we were plugged to the grid for 2 weeks and the temperature went under 0°C (-2°C) a few times...but the temperature of the (unheated) hold was may above 0°?


7) since today, the voltage was normal (?!?!) : 13.2V when no charge, 13.7 on charge...

I have check terminals and connections, use a multimeter...everything seems normal

SO :

A) do you have an explanation of these low (and too high) voltage

B) do you think we had broken this lithum battery? (I read tha charging a lithoum battery at temperature above 0°C is deadly for them...)

C) What is the symptome of a dead lithium battery? ...and the fact that today is "normal" is a proof tha the battery is not dead?


Thanks you in advance.

Lithium Batterybattery system voltage
1 comment
2 |3000

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What battery do you have exactly?

I think it is to cold for the battery most lithium batteries with internal BMS stop charging between 0-5°C or lower.

You should move the battery to a heated place.

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1 Answer
Wayne avatar image
Wayne answered ·

Hi there, this is not uncommon with lithium batteries in external lockers, the battery BMS will have almost certainly shut down your ability to charge when the temp dropped below 0degC.

The reason if you are not aware, lithium can discharge below 0degC but can be damaged charging below that temp

For that reason we usually like to install lithium in internal lockers.

Cheers

Wayne

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