cold eneloop or flashlight prob?

mdixon

Newly Enlightened
Joined
Nov 21, 2013
Messages
12
for temp reference I live in the boston area. I have a little 3-aaa coleman metallic flashlight in my jeep that I put new eneloops in. I got the batts from amazon and while the wrapper says utga the eneloop rep I phoned said they were mismarked gen3. date stamps are all mid-2013 and from everything I can tell they're genuine eneloops which was all I cared about. I posted about this in the eneloop sticky and mention here in case it's a factor.

I charged them full on my bc700 and put the light in the jeep in november-ish before it got really cold. once day/night temps stayed below 35-ish degrees there was 0 light when I turned it on. I then read some threads here and found this is probably to be expected. every once in awhile I'd try it again and it never worked. took batts out once, reinserted, still nothing so the issue was definitely just the cold. one time I brought the light indoors, sat it on the counter and once it warmed up a bit it worked fine. I topped up the batts then put it back in the jeep figuring I'd only be able to use it during non-winter times.

weather has been mild/warm since late march/early april. I clicked on the light yesterday (65 degrees) and while it came on it was very very faint, all but unusable. I brought the batts into the house, plopped in the charger and it said 1.4v initially. @500ma setting (what I always use on aaa) within < 10 minutes voltage went to 1.55/"full". bc700 says all 3 took less than 90mah. I put them back in the light and it was super bright and looked normal again.

so what I'm wondering is, given the batts were essentially totally full already, why was the light so faint when I first tried it? would a crappy flashlight lead to something like this? or maybe my eneloops aren't really genuine after all? w/eneloops that have always been indoors I'd never seen one shoot from 1.4v to full in 10 minutes, usually it would be more than an hour to do that.
 

StarHalo

Flashaholic
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Dec 4, 2007
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10,927
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California Republic
Unusually short charge times mean your batteries have lost capacity and are damaged/defective. Decent NiMHs are good down to about 0F.
 

HKJ

Flashaholic
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Mar 26, 2008
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9,715
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Copenhagen, Denmark
Chemical processes slows down when it is cold, batteries are based on chemical processes and will have less performance when it is cold.
How much the cold affect batteries, depends on the actual chemistry. Primary lithium batteries are the best in cold weather.
Eneloop are supposed to work down to -20C, but with greatly reduced performance.
Cold weather will not discharge the battery, only reduce performance, until it gets warm again.

You case sounds more like a problem with the light, not the battery.
 

mcnair55

Flashlight Enthusiast
Joined
Oct 27, 2009
Messages
4,448
Location
North Wales UK
Best bet for you is the Lithium route.My car edc is powered up that way,pain really as i run Eneloop type and Alkies.
 

Etsu

Enlightened
Joined
Jul 1, 2013
Messages
783
I agree with the above. I regularly use Eneloops down to -20C/0F, and they're fine. Either the flashlight won't work in cold temps, or the batteries died for some reason. Your short charge time doesn't indicate the batteries are dead, it may just be that they were used very little since the last charge. Eneloops don't self-discharge much.

I suspect your flashlight.
 

reppans

Flashlight Enthusiast
Joined
Mar 25, 2007
Messages
4,873
The 1.4V reading on your charger was probably input voltage - my C9000 starts charging there. You need a multimeter to test batt voltage. Your charger probably has a discharge function/capacity test - run the Eneloops through that to rule out batt issues. I'd bet your light/driver is voltage sensitive and doesn't like sub 3x1.3v where Eneloops typically run. My ET D25As moonlight modes run like crap on Eneloops - fresh off charger 1.4+ V it runs great and with full spec output, but when V drops <1.3 (most of an Eneloops discharge curve), moonlight falls to half output or less and with PWM-like effects.
 

oKtosiTe

Enlightened
Joined
Jan 7, 2012
Messages
974
Location
Sweden
Does the light have an electronic switch or a true clicky/switch? Electronic switches will slowly drain cells with a standby current, which could explain the behavior you described.
 
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