So im recharging my flat car battery and its hooked up to a big car battery charger. Its now been on Slow charge for 4 days. Is there a way to tell if the charger is working? I can hear a definite "humming" from the charging unit. Also when i contact the two clamps I get sparks. There is a Ampere reading gauge on it that is at Zero. The battery was bought new about 18 months ago but never really used. Have it correct Voltage also there is option of 12 and 6. IF I connect a working car battery should it show a change on the ampere meter.
ABSAAR BATTERY CHARGER
20 AMP 6/12 RMS
100 AMP BOOST
NORMAL CHARGE & FAST CHARGE AND START
That could be your problem OP.
If the Battery has been sitting for a year and a half then it could very well be fecked.
Batteries need to be kept fully charged to last their longest.
Have you put a voltage meter across the battery terminals or the charger leads?
If the charger is putting out power than the battery is probably dead.
No, the amp meter measures the electric current passing through the charger. Did you notice what it read when you first started charging?
Normally, when you start charging a non-full battery, you'll get an amp reading as the charger works to charge the battery. As the battery becomes charged, you'll eventually get a zero reading, as there is no more 'work' for the charger to do.
It's the battery voltage you'd be interested in.
Some chargers do have a built in battery tester which can test the battery voltage, but I can't see if your one has. Other than that if you have a voltmeter you can test it.
After 4 days, it's definitely as charged as it's going to get. If you don't have a voltmeter, the easiest way to see if it's good is check if it will start your car.
You can estimate how long it will take to charge by dividing the battery capacity by the charger rating, e.g a 40 ah battery should take approx 10 hours to charge at 4 amps. A properly charged battery should be reading over 12v (with charger disconnected). As said already leaving a battery in a discharged state for long periods will damage it.
The reading was just above zero when i started now its at Zero left it on turbo boost all night reckon shes dead!
Ill get a multi meter. I assume if i get the probes and connect from terminal to terminal if the battery is ok i should get a reading of 12 volts?
12 v min, a healthy battery should be around 13 v as far as I recall.
Yep, as Kev said, 12V at a minimum. 13V would be more like it. If it's below 12V and if it's not a sealed battery ie, it has 6 round 'tops' you can open, you should check the fluid level. If it's low you can use de-ionised water to top up.
If you do open it, make sure you're in a well ventilated area, as sometimes gas can build up due to over charging.
Cheers Kevin Haughey and Buffman.
COnnected my multimeter have 12.5 coming up when i stick the probes on the terminals so its looking good! Ill report back tommorow when i start her
12.4v is what you are looking for. However if you are just using a normal voltmeter, it will be testing it without load. Pop it in the car and that will be the best test.