Stephen Clark

Yes, I understood your meaning, thanks.

I am looking at the charging voltage of 13.88 volts, and thinking that's a
bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that
is about 14 mos. old. But, then I haven't started the car since Thursday,
and today the battery voltage at the jumper post is 12.35. The original
charge was 12.63 after a quick charge at the auto parts store on Thursday.
Is that too much of a drop? I'm trying to determine if maybe there is a
fault in the battery, like an intermittent shorted cell.

Other sources say that 75 ma is the max parasitic draw, so 82 isn't extreme.
It wouldn't have pulled the battery completely down during the 10 minutes I
was in the grocery store.

Is a puzzlement....


"PeterD" <peter2@hipson.net> wrote in message
news:0m5j53d0ul66270mjuu6glo2vkm1kq0hl7@4ax.com...
> On Sat, 26 May 2007 20:35:50 -0400, PeterD <peter2@hipson.net> wrote:
>
>
>>
>>82 MA (I rounded up) is a *bit* high, but totally out of line.
>>Generally you want it below 50 MA if possible. Consider also that some
>>loads may come and go, so a current logging setup may be needed.
>
>
> I should slow down when I type, I meant to say:
>
> "*bit* high, but NOT totally out of line."
>
> IOW, it would be nice to be below 50 (or even better below 30), 80
> isn't the end of the world.
>

Frank

Stephen Clark knastet inn: :
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that
> is about 14 mos. old. But, then I haven't started the car since Thursday,
> and today the battery voltage at the jumper post is 12.35. The original
> charge was 12.63 after a quick charge at the auto parts store on Thursday.
> Is that too much of a drop? I'm trying to determine if maybe there is a
> fault in the battery, like an intermittent shorted cell.

To eliminate battery fault; Recharge, disconnect it, and do the same
test as described above.

If you find no significant voltage drop, it's a leak elsewehere.

Frank

Stephen Clark knastet inn: :
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that
> is about 14 mos. old. But, then I haven't started the car since Thursday,
> and today the battery voltage at the jumper post is 12.35. The original
> charge was 12.63 after a quick charge at the auto parts store on Thursday.
> Is that too much of a drop? I'm trying to determine if maybe there is a
> fault in the battery, like an intermittent shorted cell.

To eliminate battery fault; Recharge, disconnect it, and do the same
test as described above.

If you find no significant voltage drop, it's a leak elsewehere.

Frank

Stephen Clark knastet inn: :
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that
> is about 14 mos. old. But, then I haven't started the car since Thursday,
> and today the battery voltage at the jumper post is 12.35. The original
> charge was 12.63 after a quick charge at the auto parts store on Thursday.
> Is that too much of a drop? I'm trying to determine if maybe there is a
> fault in the battery, like an intermittent shorted cell.

To eliminate battery fault; Recharge, disconnect it, and do the same
test as described above.

If you find no significant voltage drop, it's a leak elsewehere.

Frank

Stephen Clark knastet inn: :
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that
> is about 14 mos. old. But, then I haven't started the car since Thursday,
> and today the battery voltage at the jumper post is 12.35. The original
> charge was 12.63 after a quick charge at the auto parts store on Thursday.
> Is that too much of a drop? I'm trying to determine if maybe there is a
> fault in the battery, like an intermittent shorted cell.

To eliminate battery fault; Recharge, disconnect it, and do the same
test as described above.

If you find no significant voltage drop, it's a leak elsewehere.

DC

"Stephen Clark" <noone@nothing.not> wrote in message
news:135jqg7168at0de@corp.supernews.com...
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch
> that is about 14 mos. old. But, then I haven't started the car since
> Thursday, and today the battery voltage at the jumper post is 12.35. The
> original charge was 12.63 after a quick charge at the auto parts store on
> Thursday. Is that too much of a drop? I'm trying to determine if maybe
> there is a fault in the battery, like an intermittent shorted cell.
>
> Other sources say that 75 ma is the max parasitic draw, so 82 isn't
> extreme. It wouldn't have pulled the battery completely down during the
> 10 minutes I was in the grocery store.
>
> Is a puzzlement....
>
Hi Stephen,
dropping 300mV in "at least" three days seems quite
believable to me. Once charging has ceased (engine off) the terminal voltage
will fall quite quickly to an open circuit value say 12.65V and assuming a
capacity of nominally 40A/Hr a 100mA load would take approximately 14 days
to fully discharge the battery down to say 10.5V My guess would be a week
and the car might be hard to start? - so no obvious anomalies from your
information so far.

14.2V is more suited to short runs than 13.88, depends on your normal trip
duration whether your present voltage is a bit low. 13.65V is a "float" or
continuous charge voltage.

Regards

Dave

DC

"Stephen Clark" <noone@nothing.not> wrote in message
news:135jqg7168at0de@corp.supernews.com...
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch
> that is about 14 mos. old. But, then I haven't started the car since
> Thursday, and today the battery voltage at the jumper post is 12.35. The
> original charge was 12.63 after a quick charge at the auto parts store on
> Thursday. Is that too much of a drop? I'm trying to determine if maybe
> there is a fault in the battery, like an intermittent shorted cell.
>
> Other sources say that 75 ma is the max parasitic draw, so 82 isn't
> extreme. It wouldn't have pulled the battery completely down during the
> 10 minutes I was in the grocery store.
>
> Is a puzzlement....
>
Hi Stephen,
dropping 300mV in "at least" three days seems quite
believable to me. Once charging has ceased (engine off) the terminal voltage
will fall quite quickly to an open circuit value say 12.65V and assuming a
capacity of nominally 40A/Hr a 100mA load would take approximately 14 days
to fully discharge the battery down to say 10.5V My guess would be a week
and the car might be hard to start? - so no obvious anomalies from your
information so far.

14.2V is more suited to short runs than 13.88, depends on your normal trip
duration whether your present voltage is a bit low. 13.65V is a "float" or
continuous charge voltage.

Regards

Dave

DC

"Stephen Clark" <noone@nothing.not> wrote in message
news:135jqg7168at0de@corp.supernews.com...
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch
> that is about 14 mos. old. But, then I haven't started the car since
> Thursday, and today the battery voltage at the jumper post is 12.35. The
> original charge was 12.63 after a quick charge at the auto parts store on
> Thursday. Is that too much of a drop? I'm trying to determine if maybe
> there is a fault in the battery, like an intermittent shorted cell.
>
> Other sources say that 75 ma is the max parasitic draw, so 82 isn't
> extreme. It wouldn't have pulled the battery completely down during the
> 10 minutes I was in the grocery store.
>
> Is a puzzlement....
>
Hi Stephen,
dropping 300mV in "at least" three days seems quite
believable to me. Once charging has ceased (engine off) the terminal voltage
will fall quite quickly to an open circuit value say 12.65V and assuming a
capacity of nominally 40A/Hr a 100mA load would take approximately 14 days
to fully discharge the battery down to say 10.5V My guess would be a week
and the car might be hard to start? - so no obvious anomalies from your
information so far.

14.2V is more suited to short runs than 13.88, depends on your normal trip
duration whether your present voltage is a bit low. 13.65V is a "float" or
continuous charge voltage.

Regards

Dave

DC

"Stephen Clark" <noone@nothing.not> wrote in message
news:135jqg7168at0de@corp.supernews.com...
> Yes, I understood your meaning, thanks.
>
> I am looking at the charging voltage of 13.88 volts, and thinking that's a
> bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch
> that is about 14 mos. old. But, then I haven't started the car since
> Thursday, and today the battery voltage at the jumper post is 12.35. The
> original charge was 12.63 after a quick charge at the auto parts store on
> Thursday. Is that too much of a drop? I'm trying to determine if maybe
> there is a fault in the battery, like an intermittent shorted cell.
>
> Other sources say that 75 ma is the max parasitic draw, so 82 isn't
> extreme. It wouldn't have pulled the battery completely down during the
> 10 minutes I was in the grocery store.
>
> Is a puzzlement....
>
Hi Stephen,
dropping 300mV in "at least" three days seems quite
believable to me. Once charging has ceased (engine off) the terminal voltage
will fall quite quickly to an open circuit value say 12.65V and assuming a
capacity of nominally 40A/Hr a 100mA load would take approximately 14 days
to fully discharge the battery down to say 10.5V My guess would be a week
and the car might be hard to start? - so no obvious anomalies from your
information so far.

14.2V is more suited to short runs than 13.88, depends on your normal trip
duration whether your present voltage is a bit low. 13.65V is a "float" or
continuous charge voltage.

Regards

Dave

Stephen Clark

Thanks to you all for your kind contributions. The battery is holding now at
12.34 volts.

I am beginning to think that what caused the discharge incident was an
intermittent short of some kind in the electrical system somewhere, possibly
the classic problem of the harness in the driver's door jamb. I have had
trouble with the driver's window working intermittently lately, but it is
working ok now.

If I happened to cause a short when I closed the door to go into the store
that day, then that could have caused the battery to go flat very quickly. I
don't know why a fuse did not blow, but perhaps the current draw wasn't
sufficient to blow the fuse, but just enough to drain the battery. I suppose
the battery was just too low to jump, or we had bad connections between the
cars.

Anyway, that is my best theory to date. I'll either take a look at the
harness wires myself, or have my mechanic do it this week. I'll let you all
know what, if anything, we find.

Happy Memorial Day to all!


--
Stephen Clark
89 Audi 100
Houston, Texas USA