Battery goes flat quickly

My car battery seems to go flat quickly. If I do not use my car
for 2 weeks then it will not start. Also, if I leave it with the
tiny map light on, it goes flat overnight (Not even enough juice
left for one crank). What might be causing this?

I can't think of anything that would drain the battery while
the car is off, except for the alarm. I seem to have noticed that
it goes flat more quickly if I leave the alarm not-armed (but I
haven't scientifically checked this).

I tried measuring some voltages. After charging on the charger,
the battery was 13.25V . When my car is idling, it is 13.92V .
After leaving the car overnight, the voltage was 12.62V .
When idling after that. 13.92V. After a 5-minute idle and turning
the car off, it was back down to 12.65V.
While idling, the map light causes a voltage drop of 0.05V .

I haven't tried checking the voltage immediately after a
long drive, to see if my alternator is working properly
(I was going to but my multimeter battery ran out :/ )

The battery is of the smaller kind physically, although I
don't see why this ought to make it go flat any quicker.
The only devices I have are a 50W stereo, OEM lighting,
and a boost gauge.

The battery has had this go-flat-quickly problem ever since
I bought it.

The battery has a coloured spot on the top that's designed
to indicate whether it needs charging or not (green = charged,
black = flat, clear = needs water). The spot is a faint green
most of the time. It used to go clear as soon as I tilted the
battery in one direction by about 3 degrees, but I filled it
up a few weeks ago and it doesn't do that any more. (I'm not
sure how that works though, because the 6 cells are all separate
so how can it indicate them all?)

When I put the flat battery on the charger, it indicates 'fully
charged' on the charger for about 5 minutes, after which it resumes
normal operation. I haven't seen this effect with any other battery
I've charged. What does this mean?

those indicators on the battery are not necessarily right.
I've had green indicating batteries go to zero under load, so green means
nothing or at least cant be 100% trusted. IMHO


How old is the actual battery. It should have a date code. If its 3 or more
years, replace it or take it to a parts place and have a load test done on
it. I would think about putting an ammeter in the battery line and see
whats drawing out of the battery and when (with the car not running).

my .02

"Old Wolf" > wrote in message
oups.com...
> My car battery seems to go flat quickly. If I do not use my car
> for 2 weeks then it will not start. Also, if I leave it with the
> tiny map light on, it goes flat overnight (Not even enough juice
> left for one crank). What might be causing this?
>
> I can't think of anything that would drain the battery while
> the car is off, except for the alarm. I seem to have noticed that
> it goes flat more quickly if I leave the alarm not-armed (but I
> haven't scientifically checked this).
>
> I tried measuring some voltages. After charging on the charger,
> the battery was 13.25V . When my car is idling, it is 13.92V .
> After leaving the car overnight, the voltage was 12.62V .
> When idling after that. 13.92V. After a 5-minute idle and turning
> the car off, it was back down to 12.65V.
> While idling, the map light causes a voltage drop of 0.05V .
>
> I haven't tried checking the voltage immediately after a
> long drive, to see if my alternator is working properly
> (I was going to but my multimeter battery ran out :/ )
>
> The battery is of the smaller kind physically, although I
> don't see why this ought to make it go flat any quicker.
> The only devices I have are a 50W stereo, OEM lighting,
> and a boost gauge.
>
> The battery has had this go-flat-quickly problem ever since
> I bought it.
>
> The battery has a coloured spot on the top that's designed
> to indicate whether it needs charging or not (green = charged,
> black = flat, clear = needs water). The spot is a faint green
> most of the time. It used to go clear as soon as I tilted the
> battery in one direction by about 3 degrees, but I filled it
> up a few weeks ago and it doesn't do that any more. (I'm not
> sure how that works though, because the 6 cells are all separate
> so how can it indicate them all?)
>
> When I put the flat battery on the charger, it indicates 'fully
> charged' on the charger for about 5 minutes, after which it resumes
> normal operation. I haven't seen this effect with any other battery
> I've charged. What does this mean?
>
>

With most of the newer vehicles the battery drain key off is enough to
kill a battery in 3-4 weeks. The computer/clock/alarm all take power. I
would pull the terminals, clean them REAL good with some baking soda,
then hook the positive cable on and put a test light between the
negative post and the cable. If it lights up more than a DIM amount you
have a problem with current draw. Charge the battery and then check the
voltage with the cable still off. Let it set a day and check it again,
it may drop .25-.5 volts and should settle. But I would bet you have a
bad battery anyway, they really don't like being drained down and
recharged more than once.

--
Steve Williams




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get an auto electrician to hook a meter on the battery with everything
turned off.

If there is a current draw you will need to track it down.

My convertible needs to be either disconnected or trickle charged when
stored over winter. Battery lasts about a week if not run.