Cold Temp LiFePO4 Charging Test

SherylinRM

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So the question in my mind is how much of the loss from 176 Ah to 155 Ah is just the reduced capacity of using the batteries at a low temperature and how much is permanent degradation from the damaging effects of charging at low temperature.

This will be interesting.
That is on my mind as well.
As I use mine when outside on my mobility scooter.
 

Will Prowse

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So the question in my mind is how much of the loss from 176 Ah to 155 Ah is just the reduced capacity of using the batteries at a low temperature and how much is permanent degradation from the damaging effects of charging at low temperature.

This will be interesting.
Yes exactly. I need temp probe and capacity test at room temperature to know. Will repeat test with new cells.
 

Will Prowse

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Best price for loop tester was 12k$ so I'm doing it manually. I have inverter and charger in parallel so it takes seconds to switch over, but I need something better
 

Ulmo

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Can I see that video? I would like to know the genesis of this thread, since I don't understand the discussion without the context. I cannot view the video. I posted another thread about something that might be similar:

 

upnorthandpersonal

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Ok, so I did a first test charging at -17C. I had the battery hooked up (after it being outside for a few hours) for about an hour, but could only get 2 to 3A of current into the battery. In other words, the internal resistance got so high it was impossible to get power into the battery. After about an hour, I let the battery warm up for a few hours and then charged it fully at 0.5C. I did a 0.2C capacity test an hour after the battery was full and managed full capacity. My guess is that the time I kept the battery on the charger combined with the low power I was able to put in at this temperature prevented any significant damage.

My next step would be to leave the charger on the battery for a longer period of time, however the power supply does not like -17C either and starts acting up. Which brings up an important point: even if you could charge at -17C, would you trust the charge controller, BMS, etc. at those temperatures?
 

DJSmiley

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Keep the charger inside, and run slightly longer wires to the battery outside?
 
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