car battery dud or not?

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Couple of questions really. My car battery charges up to normal voltage but over a period of a week or so, it drops to about 12.3, is that normal?
Originally I thought there was a parasitic current draw that was discharging the battery and when I tested it with doors closed, it read .30amps for about 30 secs, then dropped to .02. So I imagine that once the battery is connected there is some current draw for maybe electronics, then it goes to minimum.
 
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mine has a slight drain from the immobiliser and alarm package, it also has a clock and the ICE and other settings in the on-board computer are maintained by the battery. With a good battery, it takes about a month to six weeks to lose enough to be an unreliable starter. Seems to be longer in summer. I do have a 100AH battery, though.

12.4v is considered to be "charged" when open circuit (disconnected from any load) so you need a pretty accurate meter if yours is marginally below.
 
The important measurement to check is a voltage drop when cranking the engine....not much below 11v is what you are looking for.
A motor factor can put a heavy discharge meter across the battery which may reinforce any measurements you take.
A reduction to 12.3 volts shouldn't be any big deal here, I think.
John :)
 
I haven't checked the volts on cranking or running, so I'll do that next. It's an old Scudo, so very little electronics that could be a drain and as I said, on checking amps from neg terminal to ground, initially it draws .3amps, but then you can hear some relays click and it drops to .01 or .02.
 
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That will be the immobiliser system if the clicks are within a minute or so of stopping the engine.
A 2mA drain is easily coped within your battery - that leakage is likely to be through the rectifier inside the alternator and its within tolerance.
John :)
 
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