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How to hack a dead battery of a cordless vacuum cleaner?

Hi Everybody,

I've got an old cordless vacuum cleaner with an old short lasting battery, so I decided to hack it in order to use it on the plug directly ( I'll be using the output of  its charger).

The cordless vacuum cleaner has a battery of 3.7 V and a 9V DC- 150mA as an output for its charger.
Note: I was not able to see the motor characteristic because it's covered and it was difficult the remove it.
So I disassembled everything and try to plug the output of the charger directly to the motor, the motor didn't work.
I plug the motor directly to its battery = it works
I plugged a 15V - 150mA (from an old printer transformer) => the motor it barely turns (about 1 rpm)
I plugged a 32V - 150mA (from an old printer transformer) => the motor turns very slow but faster than the previous experiment (about 2 rpm)

Can anyone explain what's going on. Why the motor cannot accept DC from chargers?
Thanks in advance

Picture of How to hack a dead battery of a cordless vacuum cleaner?
The motor needs a LOT more current than your little supplies can provide. Think nearer 2-4 Amps, than a few mA.

Remember, the battery would probably be charged pretty gently - I'd guess at a 10 hour rate, making the battery capacity roughly 1200maHr. Bitter experience suggests you wouldn't have had more than 15 minutes of vacuuming from a charged battery - which would mean all the energy is gone in 1/4 of the time, 1200*60/15= 4.8 A
wdarwish (author)  steveastrouk4 years ago
Thx dude, but what do u mean by 1200*60/15= 4.8 A
Thanks (for steve) I looked it up!

1200mA x 60 seconds / 15 minuets - 4.8 Amps. To give some idea of what the motor may draw from the battery.

If the nbattery is a lead acid battery or Nicd they are fairly easy to get and replace.
We don't charge for extra letters. What does "Thx" mean ?

4.8A looks the likely kind of current you need from your supply