Replacing an AC converter?

Question

Thanks all for reading in advance!

I have a blown AC/DC converter for a power tool charger.

The specs on the busted converter are 15V 200mA.

It's just about impossible to find another converter with the same exact specs, so I was told that to find another converter with the following rules:

* Choose a voltage equal or lower than required

* Choose milliAmps equal or higher than required

First question is... are the above rules accurate?

Second, I have an old converter with the following specs: 12VAc and 1000mA.

Will it hurt to try this converter? I was told the current written on the converter is the MAX allowable current on the converter and the actual current would be dependent on what the device needs....

Thanks all!

Answer 1

The rule is not totally accurate.  

The part about choosing milliAmps equal to or higher that the original is correct.  

The part about equal or lower voltage is incorrect.  The voltage has to be the same.  If the voltage is lower it won't charge the battery to it's full capacity.  You'll be working with only partially charged batteries.  

The 12 volt charger won't charge a 15 volt battery pack.  

Have you tried checking the web site of the brand you have to see if they offer a charger as a replacement part?

Answer 2

Wires is correct, but the milliamp thing is a bit dodgy with smaller power supplies. It's best to choose one with a milliamp rating close to that of the original is the supply is unregulated.

This is because an unregulated supply rated at, say, 12v at 1000ma will output 12v when the device is drawing 1000ma. However, if you only draw 200ma, it will output quite a bit more voltage, which risks damaging your device.