Charging at lower but above 0C temperatures...

[MrMatt]

Greetings...

I have 4 eve 280 AH 3.2V bounded to make 12v in VW camper
I left a small draw appliance running unknowingly which brought my batteries down to 2.8V argh!
Found this out when went to set my batteries 50% charge for the winter.
Engaged my solar panels - battery cells now 3.2V
EVE Specifications show an allowed 0.5C charge at 25C

I have a 45 amp charger.
Batteries temp in vehicle reading =9C
Can I charge the batteries using this charger at this temperature?


Is there a general rule for this e.g. amp charging vs temp above 0C?

Optional request..
If one cares to elaborate what happens to batteries being charged to cold, I would be interested.

Thanks so much

 

[RCinFLA]

This is EVE's recommendation. Personally, I would cut all the numbers in half.

 

[MrMatt]

Thank you so much!!!!....

But as a newbie, not quite sure at the moment.. what the "25C rested OCV" means.
Is this the equilivent cell voltage at 25C? -implying it would it voltage be different at 8C? Would be surprising to me

 

[Symbioquine]

This is EVA's recommendation.

Okay, I have a possibly silly question: what is "EVA" and is it different than the "EVE" cells that OP (and a lot of other folks including myself) have? I would assume a typo, except that its also spelled that way in the table image above...

 

[MrMatt]

Okay, I have a possibly silly question: what is "EVA" and is it different than the "EVE" cells that OP (and a lot of other folks including myself) have? I would assume a typo, except that its also spelled that way in the table image above...

Thanks.. I did not catch that... just focused on the table..

 

[Symbioquine]

Thanks.. I did not catch that... just focused on the table..

Well, don't thank me yet. Like I said it might be a silly question on my part.

 

[Symbioquine]

implying it would it voltage be different at 8C? Would be surprising to me

I don't know if it's a very prominent effect for LFP batteries in normal temperature ranges, but I think we can reason that battery voltage should be a function of temperature using first principles. Presumably at zero kelvin all reactions would stop and the battery would be inert.

 

[MrMatt]

I would think even 0C is so far above 0 kelvin ( = -270C) the difference between 20C and 0C would be negligible comparative re: reactions
but what do I know about this.. I keep reading...

 

[RCinFLA]

The ionic transfer is hindered by cold temps so there is more voltage slump at cold temp with load current on cell. Open circuit, no load voltage does not change too much over these temp ranges.

 

[MrMatt]

Thank you again.. love this learning!

 

[MrMatt]

Also in the table I see OCV, .. should this read VOC?

just saying...

 

[RCinFLA]

Voc is taken for PV panels, OCV is Open Circuit Voltage, unloaded, no cell current, rested to equilibrium.

 

[MrMatt]

Voc is taken for PV panels, OCV is Open Circuit Voltage, unloaded, no cell current, rested to equilibrium.

Thank you

 

[brum]

Here are the recommendations from CATL. A lot more conservative compared to the one from EVE.

 

[MrMatt]

Here are the recommendations from CATL. A lot more conservative compared to the one from EVE.

View attachment 132132

Thanks!.. are these guidelines for LiFeP.. heard CATL has switched their cathode from LiFeP to Li manganese iron phosphate.. not sure if this change only applies for their batteries designated for electric cars or not..

 

[brum]

Yep. This is from the datasheet of a pretty new cell - the CB310.