BLUEMOMENT

hmmm ... I needed a 12v battery to test the £50 B&Q generator I'd slung into the bottom of a locker 2 years ago (it laid under the dinghy which was a source of continuous friction wi hersel who claimed she got a wet bum every time she got in it so a new dinghy wus purchased and .. erm .. oops whit's this at the bottom of the locker?). So I "lifted" a scrapped lead acid 110AH battery from the marina dead battery dump and plugged it into Halford's cheapest charger and the generator.

The generator refused to start - fair enough, I suppose given where its been efter twa years. The spark plug got a seeing to but the chinese put it together on the p1ss; it was squint. Replaced it and it purred into life ... but clearly the mucky sine/square wave coming out of it wasn't doing the charger nor battery much good ... hmmm .. plugged the charger direct into the mains and 4 days later the battery's holding 12.7 volts.

jings .. some people are made of money .. there might be some bits of an ebesplutter doon there ...

I've travelled that same road with batteries. It might hold 12.7v but if you give it a decent sook with something like a wire coat hanger across the terminals (warning - it should get hot enough to glow bright red, so watch your fingers!) it might not be well enough to recover back to a decent voltage. The other way is to hang a bulb on it - something like a car headlamp yin - and see how long it lasts before going dim.

The last battery I threw away (read - recycled in a carbon-neutral tree hugging way) would hold the voltage as long as you didn't want to do anything like start the donk or keep the nav lights going all night.

Para
I still can't believe that you managed to get your car out of one...