My wife completely flattened the battery in her car by leaving the lights on for 3 days. I've got the battery in the house now and I put it on a 4 amp charge overnight and then it's been on an 8 amp charge for 2 full days now. the LED's show it is recharging but is it taking too long? is this a sign that it's dead?
It's not a big battery, it's from a 2 litre saab.
Regards. Mark.(AKA, Mr.Nice.)
Allowing for inefficiencies, that's around 200Ah, but whether that's excessive does depend on the battery size. I'm used to big ones, and wouldn't worry yet.
When I started using a battery hydrometer I was quite surprised how long it took to get a fully topped-off charge. The battery voltage rises, the current delivered drops, and it can take a long time.
I recommend you get a hydrometer. A charger with an analogue meter can tell you a bit more, but an hydrometer can also check individual cells.
Take the battery to your local decent motor factors. They should have a fancy gadget that will test the battery. Bear in mind that modern batteries often die rather quickly if fully discharged for any significant length of time. Yes 3 days is sufficient to kill one.
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