I am hoping this question isnt too basic for this forum but I amtrying to replace some rechargeable batteries (in a Roomba: Iunderstand that generally only one or two start malfunctioning overtime and that it is usually the same one). It MUST be easier than I amfinding it.I can just about solder on a connection but these rechargeable C cells(nickel metal hydride? I am pretty sure they aren't lithium!) alwaysseem to have some sort of electro-welded rectangular plate connectingthe batteries which wont come off with a normal soldering gun? Or doI just have to apply an inordinate amount of heat at exactly theposition where the ;nick' seems to be in the plate? Given the amountof heat I seem to have applied to it already with no effectwhatsoever, to me it seems that this might damage the cell?Is there some trick to doing this please or am i supposed to use adremel wheel to cut the plates off, leaving just the electro-weld towhich I solder the wire for the new cell?

The connections are welded. Maybe several thousand degrees willtake it off. Normally you bend them off.Soldering to batteries can be risky both safety and damage.To solder, Dremel scratches in the metal. Use a very hot ironat about 750 degrees F. Time is the important part. You want toheat it up quickly and solder so it has time to cool. Metal strips can bereplaced with ordinarywire. greg

What is the trick to replacing rechargeable batteries please?

Feb 19, 2010 62 Replies

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GregS 16 years ago

It all depends on the charger. NOT all fast chargers work properly. I see some make too many charge cycles, and some keep the battery warm even when done. My old Panasonic cell phone made the lithium battery expand to twice as thick. My Maha C7800 charger does NiMh is one hour and they barely get warm.

greg

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William Sommerwerck 16 years ago

That is not my understanding. Rather, the harder the charge, the greater the voltage drop.

Which is my understanding, as well.

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mike 16 years ago

That works because waste and pollution leads to greater corporate profits.

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