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Battery Load Test Without a Tester (OT)


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Posted

Not really related to Plymouths except from an electrical theory point of view. Our 2001 Taurus wouldn't start for my wife a couple of days ago. She was in a parking lot and the car was already warmed-up. She said it made a rapid 'dead battery' noise, not a one-time 'solenoid' click. About 15 minutes later, she tried it again and it started right up. The battery is original with clean tight connections and has 12.6 V at rest. With the engine running the alternator output is 14.5 V. Is there any way to do a load test without a meter? Like turn on the headlights for a minute or two then see how low the battery gets while cranking? I know the first reaction is to throw in a new battery, but I'd like to avoid that expense if I'm barking up the wrong tree.

Any thoughts appreciated.

Harold

Posted

First of all ask yourself. How old is the battery? If it's more than about 4 to 6 years old, it's a good indication it may be time for a new one.

The battery in my van is about 8 years old. It was only rated for 72 months when I bought it. The other day I got in the van to go to the store. On the way home with the lights, wipers and heater on, the gauge read about half way down between normal and full discharge when I stopped for a traffic light. Normally with all that on it runs a little over the center mark. I also noticed it takes a little more cranking this past summer to start up. So......sometime this week the battery is going to be replaced. Sounds like that could be your problem too. My charging does go back to just a little over the center mark when running. However, it should be at about the 3/4 mark then.

Posted

An easy way to test the battery without a load tester is to assure that you have charged the battery fully. With todays batteries it can take up to 3 days to reach full charge. Really, 72 hours!!! But generally, after a number of hours on a real battery charger it should be up enough to check. What you do is attach a volt meter to the battery. Disable the ign. or fuel system so that the car will not start. Now, crank the engine and observe the voltage. If the battery drops into the 9 to 10 volt range the battery probably is bad. The computerized engine control systems require 9.3 to 9.6 volts to operste on most vehicles. Below this range it will just not operate resulting in a no start condition. If the voltage drops below this a bad battery MAY be the trouble. A starter that is drawing too heavily due to internal engine or worn starter motor conditions may also cause a low voltage reading. Batteries, generally, give us trouble when the weather changes. Hot to cold and cold to hot. Which is where we are at the moment. Also, if it is older than 4 years or so, no matter what the warrantee is, it probably is in need of replacement.

Posted

I would think that any test that is done without any testing equipment might not help you pinpoint the problem area. As long as connections are tight, turning the headlights on and cranking the engine, the lights should still be fairly bright while it's turning over. If they all but crap out, then it's likely the battery. Just take your car to Advance, they'll load test it. And yes, they've tested batteries for me and told me I didn't need a new battery before.

Posted

We let the Taurus sit for a week and tried to start it this morning. I put my volt meter probes on the battery terminals (read 12.3 V...slightly low) then had my wife turn the key. The voltage dropped to 7 and the car wouldn't start. One quick trip to Sam's Club for a battery and we're on the road again.

Harold

Posted
We let the Taurus sit for a week and tried to start it this morning. I put my volt meter probes on the battery terminals (read 12.3 V...slightly low) then had my wife turn the key. The voltage dropped to 7 and the car wouldn't start. One quick trip to Sam's Club for a battery and we're on the road again.

Harold

Harold, Take the car to Auto Zone or Advanced Auto, they will test the battery in car for free.

Posted

In answer to your original question, yes there is a way to test. Start the car to see if starting system functions well. Turn off the engine. Turn on your headlights for 15 minutes . Then see how well the car starts . Your welcome, Frank

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