Charging a discharged battery - never done this before!

EdGasketTheSecond

MinuteNoodles said:

kittykat500 said:

Hi
I've got a Toyota Verso 1300 cc that had the boot left open for a number of days and now there is not a peep out of the engine/lights, etc. so I am surmising that the battery is dead.  I've found a battery charger in my shed that was used on my previous car (I think), a Focus, but it says 'over 1800 cc and Diesel' charger but suitable for all 12v lead acid batteries.  The Toyota has a 12V battery installed.  Is it OK to use this charger?

Don't waste your time. The battery is duff. Once a car battery drops below 11.6V sulphation occurs on the plates inside the battery, meaning crystals form on them which kills it. It may appear to be OK if you charge it and use it regularly but you'll find if you leave it stood for a few days or a week or when we get the first cold nights in winter that you come out to a flat battery again.

I've had a flat battery due to light left on for days. When I measured the battery voltage is was only 1.8v, way below your 11.6v. However I charged it up and its been fine ever since, even with not being used for a week or more; car starts first time, every time. I conclude you know a bit of theory but have not tried the practice.

AdrianC

EdGasketTheSecond said:
I conclude you know a bit of theory but have not tried the practice.

Or you've dodged a bullet so far, and haven't really had to stress that battery too much.

"A week". Woo.
Quiescent draw is, what, 100mA absolute tops? So a week would be <17Ah. What nominal capacity's your battery? 80Ah? More?

EdGasketTheSecond

Its a type 363 battery so capacity is not much 44Ah claimed; its a Drivetec. Its still got 2 years left of a 3 yr warranty so how does that work then if batteries are ruined by going flat? Do you just take it in and they give you another new battery ??

molerat

EdGasketTheSecond said:

Its a type 363 battery so capacity is not much 44Ah claimed; its a Drivetec. Its still got 2 years left of a 3 yr warranty so how does that work then if batteries are ruined by going flat? Do you just take it in and they give you another new battery ??

Pretty much.  I expect the number of batteries damaged by neglect within the warranty period is pretty small.

EdGasketTheSecond

Well it wasn't wilful neglect, it was just the tailgate not closed properly leaving a light on. I imagine its quite common for batteries to go flat due to a light somewhere accidentally being left on.