how to check a mains charger

[Gonch]

Hi all,
Ive got a battery booster/jump start pack that wont re-charge from the mains. Ive taken the battery out of the pack and that appears to be taking a charge from a car battery charger. Before i take the rest apart, how do you go about checking to see if the mains charger is working?

Cheers

Fraz

[slimy999]

Originally Posted by Gonch

Hi all,
Ive got a battery booster/jump start pack that wont re-charge from the mains. Ive taken the battery out of the pack and that appears to be taking a charge from a car battery charger. Before i take the rest apart, how do you go about checking to see if the mains charger is working?

Cheers

Fraz

I had a similar problem with a laptop charger, and the man that can used a meter at the adapter, placing the probes one inside and one outside..........this should give an output reading if the charger is working...........other ideas maybe a dodgy connection with the adapter socket on the unit.

Hope that helps

Simon

[oglyoodoo]

I assume your Booster/Jump start pack has a couple of attached heavy cables and a socket in which to plug the charger. I also asume you have a reasonably accurate Analogue or Digital DC voltmeter. Not a dash mounted vehicle type Voltmeter!!

Initially just connect the voltmeter to the charger output connector, as has been suggested, and you should see anything from 14 to 20V. The Battery will pull this down when connected.

If this is OK then connect the Voltmeter to the Main battery output Croc Clips and if it has a switch like mine, turn it on. Make sure you keep the leads well separated else you'll see some scary fireworks!! The battery voltage should be around 12 to 13V. Now connect the charger and switch on. After a short while you should see the battery voltage rise ultimately to around 14-15V when charged. If it rises then it is charging. Most low cost Booster packs have pretty crude charging arrangements and don't really charge the battery properly.

If you have no output at all from the charger, apart from a dud fuse, damaged cable/plug etc the most likly cause is an open circuit thermal fuse but as this is usually buried in the transformer windings it is not recommended you try to dig it out to replace it unless you are absolutely confident you can do so without damaging the transformer windings and also being able to replace all the safety insulation. If it is duff, bin it and obtain a new charger is my suggestion!.. Places like CPC sell new 12V chargers for a few Pounds. HTH

Denis.

[Gonch]

Thanks for the replies. It appears that the charger is duff as Im getting nothing from it by using a multimter on the output plug. The unit is a 13.5V 500ma output and a little difficult to find a replacement, found 1 for £25 + postage but the pack was only about £80!