What is the lowest/highest tempeature that you've exposed NIMH batteries to?

[Frijid]

I just installed some eneloops for my transmitter for my outdoor wireless weather unit. Lowest it gets here is maybe like 15 F in the winter, and the hottest may be like 100 F in the summer, so i'm just waiting to see how they hold up

So, what's the highest/lowest you've used them at, and how was your results?

 

[oKtosiTe]

I've used my Eneloops in -18°C (0°F), but the high drain application probably kept them a fair bit warmer than that. Not sure how they would have fared in a low-drain application...

 

[Milan]

Alkalines are going to last longer and you don't have to worry about temperatures.

 

[wertzius]

Alkalines are nearly useless below 0°C. I would use Energizer Lithium AA.

 

[oKtosiTe]

Alkalines are going to last longer and you don't have to worry about temperatures.

The only reason you wouldn't need to worry about temperature would be that they are terrible batteries to begin with and that they are disposable.
In reality Alkaline cells are more sensitive to low temperatures than almost every other chemistry on the market today.

 

[zespectre]

Disclaimer: The following information is several years old and may not apply to the chemistry in newer batteries.

Having said that, I have intentionally taken Alkaline, NiMH, and several types of Lithium batteries out winter camping and left them sitting, exposed, in weather that has been as cold as -7 Fahrenheit.

Below about 20 degrees (F) the Alkaline batteries showed a significant drop in performance and at somewhere around 2 degrees (F) they were essentially useless, I believe that they had actually frozen at that point. Interestingly with the NiMH batteries I was using, their output actually seemed to -improve- just slightly from roughly 35 degrees (F) down to about 25 degrees. Once they got below about 5 degrees then things seemed to taper off pretty fast.

The lithium chemistry batteries...just kept going.

Because of that testing, all of my automobile flashlights/led "flares" and so forth have lithium batteries in them and so do the outdoor sensors for the wife's "weather station".

 

[Lou Minescence]

I used Eneloops in my weather station. Worked fine. They probably saw -10f for a short period of time and still worked. Once in a while the weather station would search for the transmitter. I don't know if it was because of the batteries being weak from cold or what. But you should be fine using them.
My GPS is almost useless after an hour using Eneloops because of the higher draw off the battery and the cold battery can't keep up. The weather station transmitter doesn't need to draw much power.
I don't know about high heat. Your probably going to put your transmitter in the shade anyway.

 

[DrafterDan]

I use AA eneloops in my Canon flash (430EXii), and it is often in my truck. Here in Phoenix it stays above 100° for several months straight, and for about 30 days it is over 110°. In my truck, even with the windows cracked it hits 120° pretty easy. I'm still on my first batch I purchased a couple years ago. I'm using them today in fact.

 

[RetroTechie]

Personal experience mostly with NiMH AA's and AAA's in various bicycle lights. Take away knowledge: don't expect much from either alkalines or NiMH when temps go significantly below freezing (0 o​C). Sometimes no problem, sometimes lights go near-dead in short order. Alkalines better for low-drain (rear lights), NiMH better for high-drain (front lights) - same as in higher temps.

Maybe it's just the particular NiMH's I have used. Regardless, I'd expect lithium batteries to do (at least somewhat, possibly a lot) better in cold temps, especially primaries. So far my CR123-based light showed no sign of being affected by the cold when used as a bicycle light. But then again, I haven't used it in freezing weather yet...

High temps? Get some shade / improve cooling. :sweat:

 

[jtr1962]

My Eneloops seem to suffer from some voltage depression in colder weather. The low battery indicator on my bike light goes on in cold weather when the batteries still have about 20 to 25% left. This is when it's right around freezing, or slightly below. I generally don't ride when it's more than a few degrees below freezing. At that point battery performance is moot because my performance goes down the tubes. I have a set of two Eneloops running a temperature transmitter in the freezer and they seem to cope with temperatures in the -10° to 0°F range just fine. The receiver gets the signal from the transmitter with no issues.

As for hot weather, the highest we'll generally see here in NYC is about 120°F and that doesn't seem to affect the performance of NiMH.