Testing current draw

[Simon Allcorn]

~ 13.5 Volts charging sounds way to low to me - I would expect about 17
Volts - what RPM was the engine running when you did this ? Should make no
difference but if it's not working correctly (i.e. only charging a full
potential of you'r doing above 2k RPM) then this may be worth checking.

~11 Volts when cranking sound's ok to me

> suspect that the starter will fail even with a battery not
> completely flat.  I wonder what that ampere/hour value is that will not
> quite be
> enough to start the car.
> 
	Amp/Hour is a measure of how much current and for how long it can be
delievered, a battery will also have a maximum Amp delievery at one time,
noticeably this is much lower in winter (hence the engine turning over more
slowly). 
	I think that when the engine cranks it takes about 100 Amps current
(not sure on this though) , and if a battery can't supply enough current
then the voltage will drop.

> Another piece of evidence: I drove for about an hour, parked the car for
> about
> 20 minutes, and when I opened the door to start it again, a buzzer sounded
> off
> and wouldn't quit.  Needless to say, the car wouldn't start, didn't make a
> sound.  I got a boost and went on my way.  I drove for another 2 hours, to
> take
> my wife to the Montreal airport and another 2 hours to drive home without
> shutting off the engine.  When I got home, it started fine for a couple of
> days,
> after which it died again.
> 
> Initially, I had Sears test the battery and they put a load test on it and
> found
> no problem.  They also said they tested the charging circuit and found it
> to be
> working fine.  Later, after it failed again, I charged it overnight and
> put a
> voltmeter on it while I cranked it ten times with the coil wire
> disconnected.
> After the tenth crank, the voltmeter read 11.6, which I assumed was
> probably
> normal.
> 
> Do either of these further symptoms support any of your ideas?
> 
> 
> 
> Simon Allcorn wrote:
> 
> > Huw, Larry,
> >
> >         That (Huw's assumption that the battery / charger may not be
> working
> > correctly) seems quite sensible, lets do some ball park figures:
> >
> > Current draw = 0.017 A (0.204 Watts)
> >
> > Assume the battery is 48Ah (I think this is about the capacity of a
> normal
> > battery - I'm sure it won't be any less)
> >
> > If the battery is fully charged then it should last with a drain of
> 0.017A
> > for:
> >
> > 48 / 0.017 = 2823 hours = 117 days  = 16.8 weeks !
> >
> > Simon
> >
> > > considering how low a draw that is, even if it slightly higher than
> has
> > > been said here is appropriate, I would investigate your charging
> system
> > > integrity as well.  Specifically, I believe the type 44 has, among its
> > > many unique and aggravating traits, a splice in the main battery wire
> > > under the passenger side carpet (?) which is trouble prone.  Check the
> > > battery ground and alternator functions as well, of course.
> > >
> > > The type 44 consumes a *lot* of electricity while running, so a poor
> > > conductor to the battery might result in minimal recharging, and your
> > > small "off use" curent draw could be enough to flatten your battery.
> Do
> > > this over and over again and you shorten the battery life, as well.
> How
> > > old *is* the battery, anyway?
> > >
> > > --
> > > Huw Powell
> > >
> > > http://www.humanspeakers.com/audi/
> > >
> > > http://www.humanthoughts.org/