At 08:51 AM 10/11/2007 -0400, Early, Stephen wrote:
>A few simple tests can tell you the health of your charging system.
Steven gives some good advice.
>Next, reinstall the fully charged battery and start the car. Make sure
>no electrical loads are on (no headlights, no fan, no radio, etc.) Put a
>voltmeter on the battery posts. You should have a reading around 14
>volts. If the reading is lower, say any lower than 13.5 volts, you have
>a charging system problem.
You may not get 14+V when you read the battery if the car is idling. Many
alternators do not put out enough power at idle. You may need to increase
the rpms to about 1500 to 2000 to get the reading. In fact, as you increase
the rpms from idle to 1500ish you should see the voltage go up. The voltage
should not go above about 14.7. If it does, you can be over charging the
battery and boiling off the fluid.
This test is usually a good one and easy to do (especially if you are broken
down on the side of the road). But, you could have an alternator that can't
output enough current. Unfortunately, this test will not let you know that.
Take the car to an AutoZone or Advanced Auto. They'll hook up a real load
to the electrical system and check the battery and the alternator for free.
This test is a lot more reliable than the voltmeter one above.
An aside, I had problems with my 84 Accord. I took it to AZ and they said
that everything seemed ok, but the alternator looked like it couldn't charge
the battery. Given the price of the 2 parts ($160 for an alternator and
$70 for a battery) and the fact that my records showed the battery was over
7 yrs old, I replaced the battery. 2 weeks later I had problems with the
battery going dead - not starting the car. So I went back and had them
check it again. This time, the alt. showed bad. I then replaced that
alternator.
One other thing to check, all the connectors. Pull the 2 battery terminal
clamps and clean the clamps and terminals. Also pull the ground connection
from the neg. terminal of the battery. It is located under the car on the
chassis cross member. Clean the eyelet and chassis with sandpaper to make
sure you have nice clean shinny metal. Also do the same with the ground
strap from the chassis to the engine.
A bad ground, too much resistance due to a dirty or loose connection, will
cause a high resistance and limit the current that the battery can receive
or supply. This will cause problems.
continued
John T. Blair WA4OHZ email: jblair1948@cox.net
Va. Beach, Va
Phone: (757) 495-8229
48 TR1800 48 #4 Midget 65 Morgan 4/4 Series V (B1106)
75 Bricklin SV1 (#0887) 77 Spitfire 71 Saab Sonett III
65 Rambler Classic
Morgan: www.team.net/www/morgan
Bricklin: www.bricklin.org
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