Best 18650 for long-term exposure to high heat

Looking for the best 18650 cell for storage and use in a hot enviroment. Needs to have the lowest self-discharge over time and lose as few charge cycles as possible due to heat related damage.
MUST be 18650, please don't suggest Eneloops or Lithium primaries - those are not options. Any LiIon chemistry is fine - I can charge them all.
I'm not that worried about cell capacity, anything over 1750mAH is OK. Price is not a concern, though I'd like to find something that's actually available to buy!
Thanks!

Hi Heat an lithium based battery dont really go together, but would lifepo4 be suitable as it is regarded as the safest, but does this apply to heat as well.

EDIT : link below mention`s 300 F

http://www.candlepowerforums.com/vb/showthread.php?312871-LiFePO4-abuse-tolerance-amp-overall-safety

John.

Please define / describe "hot environment" ?

TinderBox (UK) said:

Hi Heat an lithium based battery dont really go together, but would lifepo4 be suitable as it is regarded as the safest, but does this apply to heat as well.

EDIT : link below mention`s 300 F

http://www.candlepowerforums.com/vb/showthread.php?312871-LiFePO4-abuse-tolerance-amp-overall-safety

John.

Click to expand...

From that post:

When you heat a lithium-ion cell, the first thing to degrade is the negative electrode (graphite or hard carbon). The lithium dissolved in the graphite or carbon begins to react with the electrolyte, resulting in a permanent decrease in capacity and a permanent increase in internal resistance. This reaction starts between 70-90 degC (158-176 degF). Since LiFePO4 cells use the same negative electrode as other lithium-ion cells, they also have the same problem with respect to temperature stability.

Click to expand...

My requirements are not for temperatures that high, probably the max. I'll ever expose my cells to is 150 F.
I am just looking for the 18650 type/chemistry that deals with high heat the best, with the lowest amount of negative effects such as self discharge and reduced charge cycles.

RetroTechie said:

Please define / describe "hot environment" ?

Click to expand...

110-150 F continuous - for 14 hours a day, cooling to maybe 90 F. Going on for months.
Basically, car storage in summer weather.

Myself, I'm curious what you find holds up the best, in the heat?

I know you've a hundred or so lights from your posts,
now what have you found that degraded or not held up so well?


Your experience is something too, and
I want to know too 😀

Have a read of the pdf below, it mention medical tools that have built in battery`s that can be autoclaved to 137c

http://www.google.co.uk/url?sa=t&rc...sg=AFQjCNFAa1hRv8EXOe-3lMwkCJPJoPR1Sw&cad=rja

John.

TinderBox (UK) said:

Have a read of the pdf below, it mention medical tools that have built in battery`s that can be autoclaved to 137c

http://www.google.co.uk/url?sa=t&rc...sg=AFQjCNFAa1hRv8EXOe-3lMwkCJPJoPR1Sw&cad=rja

John.

Click to expand...

+1
I like the part about storage at reasonable high temps, but far under 60c. Seems it's not as bad as I figured.

Interesting.

Under optimal storage conditions of 20ºC, a fully charged Li-ion cell has a natural self-discharge of 1 percent per month

The EagleTac 3400 I had in my car for over ONE YEAR hardly lost 3%...that entire time. And that was with crazy temp swings thru summer and winter. I'm sure it depends on the brand, capacity, and some other things.

WarRaven said:

Myself, I'm curious what you find holds up the best, in the heat?

I know you've a hundred or so lights from your posts,
now what have you found that degraded or not held up so well?


Your experience is something too, and
I want to know too 

Click to expand...

I am not a good test subject for this, as almost all of my "user" 18650s are Panasonic NCR18650B (3400mAH) cells, with and without protection circuits. I have 3 Sony VTC5 (high-discharge rate) that I recently received with the TN35vn I bought from a forum member here, but I haven't used them a whole lot yet. I also have a few laptop pulls (Sanyo, Samsung, and Panasonic) that friends have given me, but I only use those around the house in ZL headlamps and SC62 lights. I only take the Panny 3400 cells with me when I head to the outdoors.

Also, my previous "car light" was an AA light, loaded with a Energizer lithium primary, so it's no help. My new car light is a SWM C22C - it's currently loaded with a Panasonic 3400, but it's only been there for a little over a week. Too early to tell yet.

Amelia said:

I am not a good test subject for this, as almost all of my "user" 18650s are Panasonic NCR18650B (3400mAH) cells, with and without protection circuits. I have 3 Sony VTC5 that I recently received with the TN35vn I bought from a forum member here, but I haven't used them a whole lot yet. I also have a few laptop pulls (Sanyo, Samsung, and Panasonic) that friends have given me, but I only use those around the house in ZL headlamps and SC62 lights.

Click to expand...

I figured your hiking lights might have been telling as you gots way too many 😀, on track I was thinking some of yours sitting around in storage cars etc might have been telling of issues.

OK, so you're looking to maximize rechargeable life span around mixed conditions of heat/cold an storage which is enlightening indeed as above.

+1