Eneloop Reaching 115-125 Degree on BC1000

crxman2010

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Apr 9, 2015
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I have Eneloops ranging from several years old to only a month or two and some of them are used infrequently so I decided to run a discharge test cycle on all my cells on the La Cross BC-1000 and take some notes. All of the batteries are AA Eneloop in either 2ah or 2.5ah capacity and I am using the 1000 mah charge/500 mah discharge function. What I am finding is that a couple of the cells in random charger slots will get very hot, infrared gun claims 125-128 degrees when I go to remove the cells from the charger after it has been sitting in the trickle charge mode. After noticing the second battery getting that warm, I started sitting a 5v 50 cfm fan on legs facing down at the charger to keep air moving around it which has lowered the temperatures during normal charging quite a bit but trickle charge mode is still heating up at random.

Example, about 6 hours ago my Eneloop Pros would have finished charging and had been sitting on the charger at 60 mah? trickle rate. Three of the cells ranged from 70-75 degrees and the fourth cell was 115 degrees. Ambient air was about 68 degrees with the ran running on the batteries the entire time. I have noted 6 cells out of 24 reaching temperatures over 110 degrees and up to 125 degrees with anywhere from less than 5 cycles on the battery to more than 50 and ranging in age from a month to several years... From what I could find online, they shouldn't be getting that hot after the 1000 ma charge is done and it doesn't seem like sitting on trickle charger for 2-8 hours should heat them up like that. It has happened in charger slot 1 & 3 and I believe 2. I wasn't taking note of which charger slot at first because I thought it was just the cell after it happened the first time or two.

Indication of bad cells? Charger need to be taken out back? or rather normal?
 

SilverFox

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Jan 19, 2003
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Hello Crxman2010,

Welcome to CPF.

My best guess is that it has something to do with the particular cells. I charge mine at 1000 mA and while they do get warm to the touch they don't get hot.

Tom
 

markr6

Flashaholic
Joined
Jul 16, 2012
Messages
9,257
Same with my BC700 @ 700mA. For some reason the Eneloop XX (Pro) got hotter than hell. I started using a Maha 801D charger instead and never have warm cells, even at 1A!
 

LAtraffic

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Oct 6, 2014
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Los Angeles, San Francisco
I just had something like this happen to me yesterday and posted it in a new thread. The eneloop pros were so hot the charger had failed. The other two batteries were warm, and 18650 and rcr123 but not even comparable.
 

lemlux

Flashlight Enthusiast
Joined
Mar 27, 2002
Messages
2,366
Location
San Diego
I have a pair of BC900's I've had for several years. They overheat all cells, including eneloops, at 1000 mA. I've taken to charging at 700 mA or 500 mA on these chargers. I've found that my 2 or 3year old MAHA MH-C808M charger apparently has better termination programming as the eneloop AA's don't overheat.
 
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