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Apr 28, 2001, 12:42 AM
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battery charger as 12v power supply

Is there anything wrong with using a automotive-type battery charger as a 12v power supply for my nicad charger? It seems like I heard not to do this. What are the dangers?
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Apr 28, 2001, 01:33 AM
Single-task at best...
tim hooper's Avatar

I did this for quite a while, with no problems except that the car-battery charger would cut out at 3amps draw, so everything had to be charged at below this rate.

I believe there are technical reasons why this practice is frowned on by some, but I'm no expert.

What I do now is charge my field battery from the domestic AC supply, at the same time as charging flight packs from the field battery, daisy-chain fashion.

Apr 28, 2001, 02:36 AM
Registered User
its possible to do this but you need to modify it some. if you can solder and have access to electronic parts its no problem. you will need one of the larger chargers, 20 amps at least. if you dont allready have one then and you have a voltmeter dont buy one untill you contact me if you want to take this further. as usuall the cheap ones are the ones you have to modify the most.
Apr 28, 2001, 03:04 AM
Registered User
The problem with those chargers is that they do not provide pure DC. They have no smoothing or regulation and just provide a crude pulsed DC current. Fine for connecting to a lead-acid battery which does it's own smoothing but no so good for connecting to the complex electronics which is a modern NiCd/NiMH charger. Some will work. Some will die.

The best way to use one is to connect it to a 12V charging battery then connect the 12V battery to the NiCd charger.

May 08, 2001, 10:54 PM
Registered User
Been using a SEARS 10/2 AMP charger
for 12 years now , no problem ! Works
fine on my ASTRO , LEISURE , & HITEC
May 09, 2001, 01:30 AM
Registered User
Agreed with the 12V lead battery as "stabilizing capacitor".

Steve, what capacity would you suggest? Do you think a 7Ah sealed cheap battery is enough?
May 09, 2001, 03:15 AM
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plinse's Avatar
Originally posted by Giacomo:
Agreed with the 12V lead battery as "stabilizing capacitor".

Steve, what capacity would you suggest? Do you think a 7Ah sealed cheap battery is enough?

As a big capacitor is already enough a 7Ah baterie will do as well.


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