How to test a car/bike battery charger

Russ

Russ

Club Member
Hello,

Just wondered the best way to test a battery charger. Have a trickle charger for a motorbike that seems pretty useless and not sure what the deal is.

Now my thinking is measure a battery voltage, say 12v, then put charger on it, then measure across the battery terminals again and hope for 14v, then that's about all I can do?

Cautious of testing across the charger terminals when not connected as I imagine that's some big amps and I could knacker my meter?

Any help much appreciated, thanks

Russ
 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
If you don't know if it's working or not just put a 12v lightbulb on it. That's how I test old bulbs :thumbs:

All it will indicate though is that it's giving an output.
 
S

Steve Dodson

Well-Known Forum User
The charger will give the current the battery requires, the flatter the battery the higher the current. But current will be limted by the charger but the voltage should be around 14v, probably dropping to around 12v as the battery reaches full charge. You can put you meter, set to volts, across the battery without issue. Just don't short the battery terminals together, thats when the current becomes an issue, as the battery will supply all of its capacity in an instant.
 
R

RobZ32

Well-Known Forum User
Trickle charger will be giving low amps so you may need to leave it on for a long time to do any good. If the battery is still connected with any parasitic drain then the charger may not work at all. Put an amp meter in series with it and you will see if it’s charging at all.

PS you cannot successfully recharge a sulphated battery its dead. This starts to happen when any battery goes and stays below about 10 volts so you must always store batteries fully charged
 
Russ

Russ

Club Member
Ok well I knew the battery was good and there was no drain, I was just testing my mates charger for him as he didn't think it worked.

Anyway I left my motorbike lights on, few hours later 2v at the battery. Trickle charger on over night, next day 5.32v, cool keep going, next day still 5.3v, day later same. So it has enough to get it so far and beyond that no good so I guess it's knackered? Put my proper charger on it (60amp) and 2 hours later back at 12.5v.

Cheers
 
johnymd

johnymd

Club Member
Sounds like the chargers knackered.

Anyone know if its possible to "repair" a battery that has become sulphated? The ctec chargers seam to claim quite a lot.
 
johnymd

johnymd

Club Member
OK Mike but does it work?

or what about the Ctec chargers that are supposed to be good for your battery but can they fix it with the pulse charging?

Anyone have any joy with either of these?
 
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