hello, does anyone know how to check if a battery charger is working correctly? the reason I ask is I have one with led's and it shows full charge but the little inspection hole on the maint free batt shows white "needs charging" the electrolyte is topped up and the batt will start the car,but goes flat after about a week (short trips) is the charger buggered? mark.w
More likely the battery is failing - the indicator on the battery is a simple hydrometer, showing that the specific gravity of the electrolyte is low. Probably the battery is badly suphated, and needs replacing. Check the voltage across the battery when it's charging, it should be around 14-15 volts, if this is so then your car charging system or battery charger are fine.
More likely the batterys dead, you could check it with a meter but that sounds like a battery on the way out
A simple test for the charger is to just stick a multimeter (set to DC volts) on the crocodile clips and power the charger on. You should get a reading of 11-12 volts.
A word of warning - don't allow the crocodile clips to touch eath other when the charger is switched on though, or the charger certainly won't be working after that!
Dan
But from your symptoms it will be the battery! Might also be worth popping a multimeter on the battery terminals with the engine running, just to make sure it's charging OK. You should get in the region of
13.5-14.5 volts. If this is OK, swap the battery out.Dan
This won't work on many modern chargers - as part of the protection against wrong connection they use a relay which is pulled in by battery volts via a diode. So unless it's connected across a battery, you get no output. I suppose this might also stop them charging a *totally* flat battery, but one this flat is probably scrap anyway.
thanks for the advice. I checked the battery on the car, alternator working fine so I went to the local car shop tested batt with heavy discharger, yup its a duffer so got a new one (exide heavy duty £35 all in) seems charger is ok after all! cheers again for the replies,mark.w
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