Right now i keep my batteries in a corner thats about 10ºC (50ºF) due to being winter outside (and not insulated well), but with warm weather coming i am looking for suggestions. I have tried the fridge, but items end up with condensation even in sealed bags.
A frost free fridge should do the job. It would keep Mrs Bort happy as well.
I dont worry too much about battery life. You are not gonna get them through enough cycles to notice anything.. so I keep them at room temperature. They age faster above 40°C or so.
that depends on how flashaholic i am :bigsmile:
a related question, it it bad for the battery longevity to use directly from 5-10ºC, or should i wait until they warm to room temperature?
Not sure it is flashaholic, more batteriaholic to me. 
It’s OK to use cells above 0C. Once you go below 0C, output capabilities drop off considerably. At –20C, you have about half capacity.
It is not a good idea to charge a Li-Ion cell when it is below 0C.
excellent thanks, i figured keeping them in the fridge when not in use in a sealed container may improve their longevity, hence 5-10º
Ooooh, Bort just hit 1000 posts! :party:
20 C or slightly below is considered optimum li-ion operating temperature from what I know. Its my understanding that the temps relic38 mentioned does not effect the cells life expectancy but does effect the capacity only if operated at those temps.
It can affect the cell life and even damage the cell if you attempt to charge a cold cell.
Yes, I know that is why I said relics38 mentioned temps.
I think you are both right.
A cell can be discharged or stored without damage while below 0C. Capacity is temporarily reduced while below 0C (worse as it gets colder).
A cell should not be charged while below 0C; damage to the cell may result. This is one way to get lithium metal plating on the anode. Capacity is permanently reduced.
but charging at 0-5ºC is fine, or just less bad?
The cell can be discharged at that temp with no loss in life expectancy, was what I was trying to add to your post. It doesn’t really hurt the cell in anyway there’s just a reduction in capacity. The cell will also have a current loss or ability to give current. The internal resistance increase as temp decreases. You had already stated the issue’s with charging.
5 C temp should be OK but 10 C would be better. At 5C temp you might want to reduce the charge current a little to .5C charge rate.
i have a 650ma charger, it aint 0.5 of anything
650mA is 1C for most 14500 cells, and over 2C for 10440 cells.
Most off the web chargers will not be close to 1C charge rate for an 18650 cell.
i meant 0.5C of what i would be buying, 18650, 26650