24V Panasonic rotary hammer drill - battery and wires got hot (drill didn't) and drill stopped working.

I have a 24V Panasonic rotary hammer drill, model EY6813. It came with two 3.0 amp-hr NiMh batteries, both of which had a problem with one of the contacts almost welding itself to the contact in the drill, and also in the charger. I stopped using those batteries. Now, using an external 7.0 amp-hr NiCd, it's worked fine until recently. The drill began to intermittently shut-off, then quit working altogether. I then noticed that the battery, the wire running to the drill, and the contacts in the drill were hot (battery was very warm, the wires & contacts were VERY hot). Any ideas about the problems with the NiMh or NiCd? Could it be the drill and not the batteries? The hot batteries/wires occurred after minimal runtime, so I don't think its a matter of overdrawing the battery, but I'm just not sure. The vent holes on the drill are not blocked.

appolo8 years ago
I suspect your problem lies with the battery to drill contacts. Any resistance to the high current flow due to poor contacts will cause overheating. If you can dismantle your drill you may find the wires from the battery contacts to the drill control have burnt or charred. Possibly a poor solder or crimp connection may have caused the fault. If this is the case you will need to replace the wire(s) and pay particular attention to the battery contacts, they must be absolutely clean and bright. The drill motor draws a high current in use so any resistance to the current flow of current will result in heat being generated! You'll find this is where your problem lies. Hope this helps. Regards
rickharris8 years ago
Short circuit in the drill somewhere.