# NiMh batteries overheating causing Dinotte battery holder to melt



## RainRider (Jul 10, 2008)

I have a 2500 mAh NiMH Energizer batteries. I charge them using an Energizer charger. Couple of days ago I left batteries in charger unattended and after I removed them from charger they were kind of hot to the touch. Even though I still put them in the Dinotte AA battery holder and left over night. Next morning, to my surprise, they were still hot and melted the holder to the point I can't use it anymore. Springs lost their tension and the body of the holder melted around places where springs were attached. 
My second try with spare holder was better. I put recharged cold batteries in the holder a minute before connecting to the light. After installing them, however, I felt instant temperature increase and removed them from the holder. Some of the springs lost part of their tension, but are still usable. There is slight signs of melt on the holder body around springs, but nothing important. Assuming, that batteries are overcharged, I put them back into the holder and connected to the light running high mode to quickly draw overcharge. 
My question is: can somebody with electrical background explain to me what happened and how to avoid this situation in future? 
Thank you.


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## Cat-man-do (May 16, 2004)

RainRider said:


> I have a 2500 mAh NiMH Energizer batteries. I charge them using an Energizer charger. Couple of days ago I left batteries in charger unattended and after I removed them from charger they were kind of hot to the touch. Even though I still put them in the Dinotte AA battery holder and left over night. Next morning, to my surprise, they were still hot and melted the holder to the point I can't use it anymore....
> ...My question is: can somebody with electrical background explain to me what happened and how to avoid this situation in future?
> Thank you.


My theory: Your batteries are toast. I too have an old Energizer charger for AA cells. Unfortunately, it is not a "Smart Charger". That means it keeps charging even after the cells are charged to their full recommended voltage. At that point the cells begin to over-heat. Eventually, this will cook the batteries and possibly short out the internal resistance if they are not taken out of the charger at the right time. Worst case scenario is the battery(s) could reverse polarity and cause all kinds of problems including stuff like melting or getting real hot. You will need new batteries. If you don't have the AA charger that Dinotte supplies with the 200L's you can get the same one from BatterySpace.>
> http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1351 This is a "Smart" charger and will work with any brand AA rechargeable NiMh battery. It will automatically stop charging when the batteries are fully charged. If it was me I would buy this one > http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1126 ..Same as the other only it includes a plug for car charging and 4 new batteries....Can we say, Win, Win. ....P.S....you can get extra battery holders from Dinotte...probably for free if you explain and ask nicely.


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## itsdoable (Jan 6, 2004)

RainRider said:


> ... I put recharged cold batteries in the holder a minute before connecting to the light. After installing them, however, I felt instant temperature increase and removed them from the holder...


Sounds like a short circuit of some kind, either in the battery holder or in the connector (if the DiNotte was connected to the battery holder).

Hot batteries in the charger is another issue - either the charger did not sense the battery was full, or you don't have a smart charger.


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## denmikseb (Aug 27, 2007)

Toss those batteries, toss that cheap charger, and toss the battery holder and get a good smartcharger. I have a LaCrosse BC-900 smart charger that also occassionally doesn't stop charging when the batteries are full, causing one of the four to overheat. It is a piece of crap and I no longer use it. I have replaced it with a Maha MH-C401FS that does an excellent job, though it is expensive. I always charge my batteries at the lowest adjustable rate to keep them cooler and give them a longer life. You can get a new battery holder from Dinotte or Radio Shack. I think your problem was caused by your charger overcharging and damaging your batteries, that is why I say toss those batteries, they are damaged. I saw those references to other really cheap smart chargers by another poster and at those low prices I wouldn't trust those chargers any further than I could throw them.


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## RainRider (Jul 10, 2008)

Thanks for the replies, guys. I thought, that Energizer charger will be good for Energizer battery. I got CH1HR charger. Here is the link to pdf document with data about it, that claims this charger is a "smart charger" that monitors cell condition and terminates charging when battery is full. Maha charger is too expencive for me, but if you are saying Powerizer does a good job, I will take a look at it.


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## RainRider (Jul 10, 2008)

I forgot to mention: the problem is with the Energizer battery/charger and not with the Dinotte light system - it works perfectly and without any flaws even with toast batteries. Actually, plugging the light and turning it on solves the problem.


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## denmikseb (Aug 27, 2007)

RainRider said:


> Thanks for the replies, guys. I thought, that Energizer charger will be good for Energizer battery. I got CH1HR charger. Here is the link to pdf document with data about it, that claims this charger is a "smart charger" that monitors cell condition and terminates charging when battery is full. Maha charger is too expencive for me, but if you are saying Powerizer does a good job, I will take a look at it.


 I have found that with battery chargers you generally get what you pay for. The exception is the La Crosse BC-900, which is expensive, but still a piece of crap!


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