generic 'condition' voltages for a lead acid
car battery
volts specific gravity capacity
12.6-12.8V 1.265 100%
12.4-12.6V 1.225 75-100%
12.2-12.4V 1.190 50-75%
12.0-12.2V 1.155 25-50%
11.7-12.0V 1.120 0%-25%
The specific gravity is of the electrolyte in the battery.
This is directly measurable with one of those
'turkey baster' style 'floater' specific gravity battery testers.
The above numbers (volts) are after letting the battery
settle for approx one hour after a full charger cycle.
Now how do you tell if you have a properly and fully
completed charge cycle? Certainly NOT with the
typical sub-$50 battery charger. Those will usually shut off
when a the battery reaches a certain voltage. The problem is
older (used) batteries will have a higher voltage, while the
s.p. is still lower than it should be. This is a result
of the electrolyte attaching itself to the plates, thus lowering
the current (ie: rate) delivery. You need a good electronic
auto-charger. Even better is a 'pulser' type charger designed
to desuficate older batteries.
Do an internet search. :-).
Paul Tegler
ptegler@cablespeed.com
www.teglerizer.com
----- Original Message -----
From: "Dave Chu" <dave@ece.concordia.ca>
To: <Alan.McEachran@anixter.com>; <spitfires@autox.team.net>
Sent: Tuesday, July 06, 2004 12:30 AM
Subject: Re: Alternator Testing
> In message
<OF3C93391E.9EF166BC-ON85256EC8.004CD1E2-85256EC8.004E0210@anixter.c
> om>you write:
> >I suspect the alternator as my problem. My Haynes says I can do a rough
> >check on it by connecting an Ampmeter in series between the brown wire
from
> >the alternator and the starter. I'm no electrical whiz, but I do have a
> >nice Fluke Digital Multimeter that I'm sure I could fry if I fought the
> >need for advice.
>
> You should first check if your battery is still good. Try to charge the
> battery and see if it will hold a charge. You will have to put it under
> some load such as turning the head lights on and use a multimeter to
> get an voltage reading. It should be above 13V after it is fulling
> charged and it will go down a little but stay about 12V when you turn the
> lights on without the engine running.
>
> The next item to check will be the alternator. With the engine running
> the voltage at the battery should be above 13.5V. Never disconnect the
> battery while the car is running, that could damage the electronics
> inside the alternator. Another quick way to test your alternator is to
> remove it from the car and go to your local Canadain Tire and have them
> test it at the auto parts counter (you can also bring your battery at
> the sametime to have it tested).
>
> If the problem is the alternator you can rebuilt it yourself. The most
> likely culprit are the brushes, which is pretty easy to replace and I
> don't think you have to do any soldering unlike the starter. But you
should
> make sure the bearings are in good condition at the sametime. The
> parts can be bought online from Obsolete Automotive in Point Edward, which
> is beside Sarnia; http://www.obsoleteauto.com/ .
>
> Hope this is of some help, best of luck.
>
> Dave |\ | | |
|