Best rechargeable li-ion cells for use in hot temperatures? Or am I stuck with Ni-mh?

[RedForest UK]

I have done a bit of a search accross the forums, and maybe I wasnt putting in the right keywords but I couldnt find anything specific about which lithium rechargeable cells react and deal best with hot temperatures.

I know that li-ion cells quickly degrade in the heat, and that lifepo4's are generally a lot better, but that comes at a capacity loss.

I am asking because I am lucky enough to have a girlfriend taking me over to Florida in the summer, and I would like to be able to take a good high performance light with rechargeable cells which will not be destroyed or degrade in the hot Florida summer temperatures.. :thinking:

So, could anyone please clarify which rechargeable cells would be best in a cr2/cr123/18650 cell light at a pretty good capacity but with good safety and performance levels in hot temperatures of say up to and around about 60'C?

Thanks for your help and your time.

 

[RedForest UK]

Re: Best rechargeable lithium cells for use in hot temperatures?

I'm sure someone must know about batteries on here..

 

[lumenosity]

well, I live in Florida so I'll attempt an answer for you... It does get pretty hot here in summer, but I haven't had any issues yet with rechargeable batteries yet. My experience has been with lithium ion and NiMh rechargeables. I have used both in cell phones as well as a flashlights for my bike.

generally, you don't want to store the batteries long term in the heat, but if they're just used in the heat (and not stored there permanently) they should be fine. You probably don't want to put them in the sun in a parked car though. I'm sure someone more knowledgeable can chime in, but this has been my experience at least.

 

[RedForest UK]

Thanks for the input, I'm thinking generally to have on my person around and about, but then they might get left out in the car/sun, so I'm hoping to find something which will retain charge without damage to the cell at up to 60 or even 80'C if possible. It's a very good point you make about the phones though, I hadnt even thought about that..

 

[Battery Guy]

When you heat up a lithium-ion cell, degradation first occurs at the negative electrode. Irreversible side reactions start between 60-80 degrees C for a fully charged cell, and since all lithium-ion cells use carbon and/or graphite as the negative electrode, they are all susceptible to this degradation. Therefore, not even LiFePO4 will help you here. Seriously, do not even consider using lithium-ion cells for temperatures above 55 degrees C. At best the cell will degrade relatively fast, and at worst you may find yourself with a burning battery someday.

In the 60-80 degree C range, I recommend going with lithium primary batteries. The Energizer lithium AA and AA hold a charge very well in that temperature range, but have relatively low power capability compared to rechargeables. If you need higher power/current draw, then you might consider looking at NiZn or LSD NiMH cells, although both of these will self discharge faster at the higher temperatures.

Cheers,
Battery Guy

 

[alpg88]

60C is 140F it doesn't get that hot even in Fl.
i,m sure millions of Florida residents use their laptops, cell phones...ect with li ion cells and do just fine.
i think you worry too much you'll be fine with whatever cells you got.

 

[Mr Happy]

The Florida heat is mainly uncomfortable for humans due to the humidity. There is nothing exceptional about the temperature where mechanical devices are concerned -- unless you happen to leave things in a car parked in the sun (don't do that).

It is an irony of working life in America that when temperatures are hottest outside they are coolest inside. If you happen to be working in an office in the summer heat you may find a jacket or sweater comes in handy to avoid freezing to death!

 

[RedForest UK]

Okay thanks for the info. I think li-ions should be okay, but to avoid any risk of damaging the cells themselves I think I'll stick with my eneloops for this trip, it's only 2 weeks but it should be a good work-out for them!

 

[march.brown]

60C is 140F it doesn't get that hot even in Fl.
i,m sure millions of Florida residents use their laptops, cell phones...ect with li ion cells and do just fine.
i think you worry too much you'll be fine with whatever cells you got.

I took some measurements of temperatures in my car on a day when it was only 71.2F (about 22C) in the shade ... My car was left in the sun for a few hours.
The temperature of the dashboard top was 158.0F ... Inside the glovebox was 127.5F ... So bear in mind that the car is an oven even at only 71.2F air temperature.

On a window-cill inside the house , the temperature can be just as drastic.

Coolest place is probably in your pocket.
.

 

[RedForest UK]

I took some measurements of temperatures in my car on a day when it was only 71.2F (about 22C) in the shade ... My car was left in the sun for a few hours.
The temperature of the dashboard top was 158.0F ... Inside the glovebox was 127.5F ... So bear in mind that the car is an oven even at only 71.2F air temperature.

On a window-cill inside the house , the temperature can be just as drastic.

Coolest place is probably in your pocket.
.

Yeah, I read your results and they were what made me think again about taking li-ions. I know I should always keep the lights with me but I can't guarantee that they wont be left in the car at some point, unfortunately I'm not sure if I can with my phone either.. :thinking:

 

[alpg88]

I took some measurements of temperatures in my car on a day when it was only 71.2F (about 22C) in the shade ... My car was left in the sun for a few hours.
The temperature of the dashboard top was 158.0F ... Inside the glovebox was 127.5F ... So bear in mind that the car is an oven even at only 71.2F air temperature.

On a window-cill inside the house , the temperature can be just as drastic.

Coolest place is probably in your pocket.
.

well, i assume op knows better than to leave his li ions on top of dashboard.
someone did the same measurements before, and found out the coolest place in the car was door pocket.