Battery Chargers.

On or around Tue, 23 Nov 2004 05:17:47 +0000, Rory Manton enlightened us thusly:

charge it up by doing a long journey or by using a charger :-)

personally, I think fairly well of the Absaar chargers. I've had various cheap plastic ones, and the absaar one I have now has outlasted all of 'em. This one does "normal" or "fast" charge rates. If you have the money, a starter/charger is handy for the occasions when you find the battery's flat in the morning.

is something like mine, although it doesn't do the faster charge rate, but then mine doesn't do 6V... same make, to all appearances - badge engineering, no doubt.

looks reasonable value for a small booster. Obviously, these come in many sizes and prices; it has a bigger brother, for example:

Machine Mart/Clarke do a good range as well.

What do you expect this battery charger to do? Occasional trickle charge after vehicle has been stood for a while. Bung in enough charge to start the engine in an hour or so when you've left the lights on over night. Have enough grunt to be connected for 15 mins and also augment the battery for starting.

Doesn't show up a battery that is knackered for starting but OK otherwise. Take it to a garage and ask them to test it. Basicaly they pull 30 or 40A from it and measure the voltage. If it drops more than

2 or 3v it's knackered as far as starting is concerned.

Correction - basically they will pull 300 or 400A from it.

Dave is (as ususal) correct.

I've just replaced the battery on Marge as it was almost new but faulty. Fault Symptoms: flattening over a 3-5 day period of standing. Confusing data: 1. All cells of correct specific gravity & electrolyte level. 2. Charging to correct voltage. 3. Discharge current when fully charged in excess of 200A, recovering normally.

Several people who should know looked at it and proffered opinions. We tested it with a heavy current shunt (one of those concertina things with big spikes) and a high-current clamp ammeter. This did NOT show the fault. I even changed the alternator, to no avail.

Eventually, I took it back to the (specialist) battery dealer, where they tested it exactly as Dave says, on a meter that had an adjustable shunt. The process was to test it at a current of approx 1/2 the rated A/H capacity, so for a 90A/H battery that meant 45A. The meter had current and voltage indication. On that test it obviously failed, and you could see the voltage dropping off over a minute or so. I still don't know exactly what he physical fault was, but hte dealer had seen this before.

Regards,

Simonm.