Hi Everyone,

I've had a recent problem with my battery and am wondering
what the consensus is on how many volts a battery will
(should) drop when engaging the starter.

I did a parasitic draw reading to see if there was a
drainage problem while at rest, however the reading averaged
0.45 amps at rest, and did this reading several times during
the day. My understanding is this is normal draw at rest.

I metered the volts yesterday and here are the results : (I
had to jump start it and let if run for 30 minutes)

Sunday (engine off)
5:47pm - 12.57v
6:48pm - 12.35v
7:50pm - 12.30v
Monday
7:10am - 12.15v
12:15pm - 12.12v

At the last reading I opened/closed the door and the reading
fell to 11.88v, then returned to 12.09v, I think that's
within reasonable expectations.

Then I went to start the vehicle:
Position 1 dropped to 11.96v
Position 2 dropped to 9.5v

and......it wouldn't even crank over ... had to jump start
it.

Question: am I having an excessive draw on the battery to
crank the engine over, or does it sound like my battery is
shot?

I went to Advanced Auto where I purchased it (Aug, 2010) and
had them test, they said all is good. I have not been
driving the vehicle much since I bought the battery. I
probably start the car about once a week on average for the
past two years.

Here's some more numbers: (after I jump started it)

First reading
14.26V engine running (dash volt meter reads the same)
12.54V engine off, at rest

Second reading (hour later)(car started without jump)
14.11v engine running, ditto on the dash reading
12.55V engine off, at rest

I bought the high-end battery and IIRC the cold crack starts was rated at 588. Considering how little it's been utilized since purchase, do
you think it's seen it's better days?

Look forward to your responses, Thank you in advance.

 

Rob,
Not sure what the starter draw should be but my first thought is do you have a trickle or regular battery charger? If you are only starting and or driving it once a week the battery may not be getting fully recharged. Just jumping and running the engine for a while will not fully charge a battery unless you drive it for an extended period. I would use a battery charger and fully charge the battery and then periodically charge it for a couple of hours. I would hope that top line battery would last more than three years. I know during the winter with the car sitting in the garage I will put the charger on once a week to keep it fully charged otherwise it does drain down to where it won't crank. Cary