Question for cheap guys: Volts/Amps & Battery Chargers

[Anonymous]

Will an ac adaptor with an output of a 9.0 volts at 300 mA recharge a cordless drill's 9.6 volt battery whose charger is designed for an output of 9.6 volts at 250mA?

Here's the deal ... I need my DeWalt cordless power drill to to do some minor work on by bike. The drill's battery charger is dead. I can rig an obsolete adaptor to the charging receptacle for the battery. I'd rather try that than use a 12 volt trickle charger and end up frying the DeWalt battery.

So, if the rigged job actually will recharge that battery, I'll either save $50.00 (not having to buy another battery for the drill) or more (doing the work myself).

Yes, Hap, I know I ought to use the right tool for the right job!

[Anonymous]

Is the random power supply a charger? Or is it just a DC power supply? If it is a charger it might work, although your battery has a charge memory and only charging 9.0 volts may cause it to not fully charge. Also a charger is constantly measuring voltage and current to know when to shut off when battery is full, so if it never reaches 9.6 it may never turn off and overheat (ruin) the battery. You could only let it charge for 1 hour or some specific amount of time to help prevent this.


If it is a DC power supply it will not work. A Power Supply gives a constant voltage while a charger pulses at a specific frequency. The higher the frequency the faster the charge, that is why cellphones and some other rechargable batteries have a quick or rapid charger available, they just crank up the frequency.

So unless you REALLLLLY need to do it before buying a new charger, I wouldn't. Of course the worst that could happen is you need to buy a new battery with the new charger.

Just some useless information: A trickle charger for most cell phones charges at 1hz and a quick charger at 32hz.

[Anonymous]

being cheap

It's a charger. The cost of a new DeWalt charger is as much as a new battery 9.6 volt. The battery is a couple of years old, so it probably is going to die on me in the next year or so anyway. I'd let it charge for only an hour or so at a time. I was just trying to rig something to last me until Santa could give me a new and heavier duty cordless drill set.

[Anonymous]

Ok well then just refer to paragraph 1 in my first reply.

[SqDancerLynn1]

I wouldn't make a habit of it, but it should give enough charge to use the drill. MAKE sure the polarity is the same