DeWalt flat batteries

[Anonymous]

I have a DeWalt 12v cordless drill and am having problems with the batteries. The charge only lasts about 3mins when charged with the 1 hour charger, but seem fine when charged overnight with a car battery charger. When the output voltage was checked with a volt meter, the DeWalt drill charger is producing 46v DC. Can anyone out there check the DC output on a 12v DeWalt 1 Hour charger to see if there is a fault with my charger.

Thanks
Kelpie

 

[aldel]

Kelpie

Never ever charge NiCad or Ni Mh batteries with a car charger!!!!!
You are very lucky indeed that the cells have not exploded.
Ni cads should be normally be charged with a current regulated charger at 10th. the amp/hour rate for 15 hours. Metal anhydride cells also need their own regulated charger which are not compatable with NiCad chargers.
Fast chargers have chips in them that detect certain characteristics in the temperature/voltage curve that will stop charging the cells at a safe level.
In general car battery chargers are very crude and charge at a high voltage and high current (several amps) and depend on the voltage rise of the charged lead/acid battery to reduce the charging current to a low level.
Chargers for sealed 12volt lead/gel cells are votage regulated to 13.8 volt and should not be used either!!
You are very lucky indeed that you have not been injured and it is very likely that the drill batteries are now damaged.

Regards Aldel

 

[Midnight]

sounds like the NiCads are toast....

 

[Anonymous]

sounds like the NiCads are toast....

they soon will be if charged with a car battery charger - hope you sat in a bunker whilst they were connected to it!!!!