Awhile ago I asked if anybody had tried non-OEM NiMh rechargable batteries. Nobody had mentioned any problems. Today I bought some Radio Shack AAs and put them in the Olympus charger. They got EXTREMELY hot after a few hours (initial charge), almost too hot to hold.

Is this normal? My Olympus batteries never get that hot. It's a good thing I checked on them or it could have started a fire.

-- MikeB (airlinestuff@yahoo.com), May 26, 2000

Answers

I purchased a Radio Shack one hour charger and 4 of their batteries. They get extremely hot. I switched to a MAHA (about 2 hours to charge) charger and they don't get as hot. Should increase the life of the batteries. Maybe I should take the Radio Shack back.

Owen

-- Owen R Auer (oauer@aol.com), May 26, 2000.

Funny you should mention that. The batteries cost $17.95 and they tried to sell me a charger for only $2!!! Maybe I should take them up on their offer...

-- MikeB (airlinestuff@yahoo.com), May 26, 2000.

I have an Olympus charger and when I tried charging Kokat batteries the other night the red light began to blink after some time. When I picked the unit up I noticed the batteries were very hot. Reading the Olypus directions I found that the charger will turn off when there is too much heat and the red light will blink until the temperature comes down, which is what it did. It makes you wonder whether the Olypus batteries are rated differently than the rest.

-- bill (this_old_house@pobox.com), May 27, 2000.

I should have mentioned that the reason I have an Olypus (which are too expensive) is because the DigiPower charger I originally bought quit working all together after a week (three sets of batteries). I liked the fact that the DigiPower had a cover on it and don't like the fact that Olypus doesn't. If you pick it up wrong while it's charging the batteries can fall out.

-- bill (this_old_house@pobox.com), May 27, 2000.

I have all of the above and have not had any problems. The batteries do get warm in the oly charger.... no matter what the brand of nimh (NOTE: NiMH)....but the charger always shuts off when the batteries are charged although they take awhile to cool down.

I have left the charger & batteries plugged in for several days with no problems and they are cool to the touch and perform fine.

-- Rick Hoge (hoge@webzone.net), May 27, 2000.

Batteries can get warm when charging - but not hot!
The cooler batteries stay during charging the longer they will last. When batteries are new the hot charge will indeed charge them - but you will experience a much earlier mortality rate with a battery/charger combination that produces a lot of heat. Heat is unnecessary to the charging process - it is, however a natural byproduct of charging. Heat is natures way of dissipating the energy the battery cells cannot absorbe as a charge on the cell. Too much heat means there is too much current being placed against the cells.
Personally, I would avoid charging systems that produce anything other than a slightly warm battery. Batteries that are literally HOT! to the touch will last less than half as long as they should.

Des

-- Dan Desjardins (dan.desjardins@avstarnews.com), May 27, 2000.

In summary, most of what I have read describes my situation. The Radio Shack batteris got very HOT, and the Olympus charger DID start blinking. I had left the Oly batteries in the charger for days too, and they only got mildly warm.

Bottom line, I'll just keep an eye on the Radio Shack batteries when charging them, and won't leave them in for TOO long. Agreed that these won't probably have a long life span. I have learned my lesson.

Thanks for all of your contributions...

-- MikeB (airlinestuff@yahoo.com), May 29, 2000.

Sure they get warm, but not that kind of hot! Sounds dangerous, I'd stop using that charger unless you want a battery acid shower.

-- benoit (foo@bar.com), June 01, 2000.

Basically there are 3 different kinds of charger: 1. "Overnight" which will charge the batt at low rate and generally safe to leave for days. 2. Quick charge which takes 4 to 5 hours (factory standard for most camera). 3. Fast charge takes about 1.5 hours. The later two have higher charge rates but most of them come equipped with the sensors to cut off the power either totally or down to slow rate. The question is the batteries themselves which are of different capacities (for AA size ranging from 1000 Mah to over 1500 Mah). If the batt is "too hot to touch" after a while in the charger, this simply means that that brand of batt is not specifically designed to be charged with that high rate or the charger of that type is not compatible in terms of charging rate and/or full charge sensor circuit. In short, if possible use the batt that was designed for that charger (just to be safe). Also if you read the small prints on the batt case, most likely it will says, something like, "charge at 150 Mah for 12 hrs". One more thing, never mix different kind (type or brand or even the same ones from different time you buy) in the same charger !!!

-- Tanasit Siriluck (tanasit@flashcom.net), June 19, 2000.

Look for the new Rayovac 1 hour charger out now. It will fully charge a 1600 ma AA in one hour max. Yes the cells will get hot but only reach max temp during the final minutes of charge as the IC senses the neg delta V termination. This is normal. Each cell is individually controlled which eliminates issues related to mixing cells of different capacities and state of charge.

Steve C.

-- Steve (sconkey@iccus.com), August 20, 2001.

Rayovac 1hour charger melts battery labels....

I read good reviews about the Rayovac 1hr charger and batteries, so I just bought the charger and a 4-pack of batteries. The charger comes with 2 batteries, but I needed 4 so I bought a seperate pack of 4 batteries (so as to use all from same lot). On the first charging of these batteries, 3 out of the 4 batteries got so hot that the labels melted and shrank, leaving about a 1/4" of the battery exposed from end to end. I'm going to return both the charger and batteries and consider another.

-- Phil Grimm (bigdaddy94583@yahoo.com), October 13, 2002.

I purchased a Rayovac 1 hr charger at the end of August this year (2002). I charge several sets of 1800 / 1850 mAh NiMH batteries on a regular basis. They do get moderately warm to the touch at the end of the charge cycle, but never too warm to handle. If the charger melts or shrinks the plastic cover on the batteries, there's something wrong! I have 3 sets of Digital brand 1800 mHa, 1 set of Energizer 1850 mHa and 1 set of Sanyo 1850 mHa batteries. They all charge fine in my Rayovac PS4 battery charger.

-- Brad W. (bwinterburn@rogers.com), December 20, 2002.

I bought a Daewood DVD, came home & put the new AAA batteries in the remote. (They were supplied by the manufacturer.) They immediately made the end of the remote (where the batteries were located) very hot. I changed to a different pair of batteries (this time they were Radio Shack Enercell), and the same thing happened again. Does anyone have any ideas? Something must be wrong with the remote since it happened with 2 different brands of batteries.

-- Judy (jubykay@aol.com), January 19, 2003.