| Sat in the car today tried to start it and power went off
completely. Had to
| jump it to get it to run. Worked for 8 hours sat in car it
turned on fine
| what is the problem? Thanks for any help!
Sure sounds to me like your battery is run down. This could be
due to two reasons:
- Your battery is too old and should be replaced.
- Your charging system isn't putting out enough juice.
Batteries deliver far less power when they're cold. It's possible
that your car sat in the sun all day and the battery became warm
enough to start the car, but is still low. You also may have an
intermittant short circuit or a switch that fails to turn off in
an always-on system (such as an electric antenna motor). Loads
like these drain the battery slowly or quickly.
Once the motor has started, the car's electrical requirements are
extremely low. You can almost run the car on a few flashlight
batteries once the engine is running. Of course, that's without
the headlights, blower motor, and that 200 watt stereo that's got
enough power to blow your mother-in-law clear to Alpha Centuri.
A voltmeter is a a cheap and handy investment. For $15 or less,
you can get a simple multi-tester that will show you your voltage
with the engine running. You can read across the battery, or
between almost any circuit that's "on" in the car and ground
(exposed chassis or body metal). Normal battery voltage at rest
is 12.6 volts. The battery can only be charged by a voltage
that's higher than that, so when the engine is running, you
should typically see a voltage of around 13.4-14.4 (numbers very
approximate -- I've forgetten the precise regulated range).
I use a handy little digital voltmeter that was marketed by
Whistler (the radar detector company). It plugs into the
cigarette lighter socket and gives a continuous readout of system
voltage while you're driving down the street or across the
continent. These may be imported by other companies, too. Cheap,
too. This little gizmo is very, very cool. Get one!