If your car won't start and you suspect the battery, are the headlights and horn operation a good test?

If your car won't start and you suspect the battery, are the headlights and horn operation a good test of the battery's strength? Explain your answer.

If your car won't start and you suspect the battery, are the headlights and horn operation a good test?
When you say it won't start, do you mean it won't crank? If it cranks at a good normal speed then the battery is fine. Checking the headlights is an OK test, if the battery is really low you will see it in the headlights. However if it's a little low you may not notice the headlights being dim until you try to start with them on. If they dim some, your battery is OK, if they dim a lot, your battery is low. But some cars shut the lights off while the starter is on. So that might not be a good test either. Is it cranking slow or not at all?
Reply:headlight yes horn has nothing to do with battery. If your headlights are dim then yes it is probably the battery.
Reply:You need to be sure it is the battery and not the starter itself. A faulty starter motor can slowly draw down the power from a battery. In a few hours, sometimes less, a battery can we so drained it will light the lights right up to the point of attempting to start the car, then the lights usually go out and you'll get the clicking sound on further attempts. Other times, after trying to start and the lights go out, when the lights return they will be dramatically dimmer.


As the temperature decreases the starting amps required will increase to a point. Usually a faulty starter is the cause of my starting problems, only one time was it ever the battery itself.


Be sure your negative is very clean and tightly connected - no corrosion. Be sure your battery terminals and connectors are very clean as well. Try another battery in the vehicle if the results are the same it is more likely the starter, or try to over nite charge the battery and in the morning if it still don't start, but tries to then it probably is the starter draining the battery.


Items that may cause starting problems:


Battery (if faulty may not hold sufficient charge)


Battery cables (if faulty could limit current )


Starter (if faulty could drain battery)


Selenoid ( if faulty will exhibit a loud clicking sound)


Voltage regulator(if faulty may not permit current)


Alternator ( not recharging battery)
Reply:Not the horn but the head lights are. The horn doesn't draw much current, so it will probably still work. The headlights are a very good test. The headlights, which turns on the tail lights and dash lights also, are the second largest power consumers on a car, after the starter, and it's very easy to see if they are dim.
Reply:not really - just because they are 'on' does not mean the battery


has the strength to pull the full load of a starter





battery has over 500 cranking amps - but may only need 10 to work the lights and horn - see?





may need to have someone check the battery out - then check the alternator to see if it is generating enough juice



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