I have a Bosch PSB 12 VSP-2. It is a 12 Volt hammer drill and the battery pack is as dead as the proverbial dodo. All the cells are short circuit and I have never come across this before.
Was it the battery pack dying or has the charger fried them? I need to know so that I can arrange a new drill or not.
At this point, what battery hammer drill should I buy for economic reasons?
TIA
Dave
Dave explained :
Crystals grow across the poles inside of the cells and short circuit it. This results from leaving the cells uncharged for an extended period.
You can blow them clear with a source of high DC current, such as a large power supply or a car battery. You simply connect the source across the cells briefly, and it will clear the internal shorts enabling them to be charged once again.
Be VERY CAREFUL sparking a car battery or similar high-current source across a dead nicad. There is a large current flow and this may weld your bit of wire to the battery terminal,. If this happens, the electrolyte will boil and the cells can explode - and it only takes a few seconds! I would suggest making up a rig with a 35 or 50A fuse in series, so if the wire welds, then hopefully the fuse will blow before the cells... K.
Yes - a car battery is a bit much. You want something like 10-30A, maybe a car battery with a halogen headlamp bulb in series with it - this will give a high initial current surge but then limit the current as the filament heats up.
Do one cell at a time.
Yes, I know that, but what I wanted to find out, was why all ten of the cells went short circuit :-)
If I can determine that, I can re-battery the pack and convert the charger to 14 hour charge and save the school the cost of a new drill.
73Dave
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