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Is there an easy way to know if a battery is getting weak without buying a tester or having it tested at a service place that I am sure will say I need a new battery. On previous cars it seemed that the first and only symptom was that the engine would not crank at all. [thankyou]
 

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暗炎
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On stock batteries theres an "eye"
Using a flashlight look into it.
Green = Good
Other color = Not so good.

Its only checking one cylinder on the battery, but its free.
 

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it really simple start the car then while running pull the neg battery cable. the altanator should support the electrical system, if it dies then the alt is bad. or buy or 15 doller volt meter when the car is not running the battery should be 12 volts running 14 volts if it s not 14 when running then the alt is bad.

hope that helps
 

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^^^^^^Don't pull the battery cables while the engine is running. Very bad things can happen.

Taking a volt reading off the battery while it's just sitting there will tell very little. Even an almost dead battery will read 12V.

You really need to buy a battery load tester. Harbor Freight sells several kinds fairly cheap. It connects to the battery terminals, and puts a big load on the battery as you're testing the voltage. That sort of tester works best IMO.... There are electronic testers that don't load the battery, but I don't trust them.
 

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Don't disconnect the battery while the engine is running. That's a load dump. It'll result in a voltage spike that can damage the alternator &/or other electrical / electronic components.

The magnitude of the voltage spike & the probability of damage increases with decreasing battery state of charge / increasing current draw from the alternator. An alternator damaged by a load dump might appear to function properly for weeks before the it starts over-charging or stops charging all-together.
 

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Can't you use a simple multi-meter? You can get one for dirt cheap and should be good enough to get a reading from the battery. But I guess if you don't want to buy one, check if there is an "eye" like DarkFire suggested.
 

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can't u just use a volt meter and check as you are cranking? The battery needs what... 8volts to turn over i believe. see what its cranking when you try to start the car.
 

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Any auto parts store should be able to load test it for free........
 

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The problem......auto parts stores want to sell you something. So trusting their test results may not be the best bet.

Years ago my girl friend had warped rotors on her Maxima. I measured them and there was plenty of metal left to cut before it went below specs. But when I took them to Auto Zone to turn, they said the rotors were already below specs. I demanded to see the micrometer they used......they brought out one that did not zero when turned down.

The mic I had in my pocket worked normal.....obviously they were trying to rip me off for a set of new rotors. They turned my rotors. [V]
 

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can't u just use a volt meter and check as you are cranking? The battery needs what... 8volts to turn over i believe.
Yes that works.

Battery without engine on: Good >11v Bad<10v
Battery with engine/alt running: Good>13v Bad < 12v (this is an alt test)
Battery with engine cranking: Good > 10v Bad < 8v

Any overlapping areas are just warnings that the battery or alternator is nearly going. For example, an alt that puts out 12.5v will keep the battery charged unless you have a high draw, but will probably not last very much longer before you're on battery only.

Here's one weird thing that works- if you're having problems starting in cold weather, turn your lights on before starting. This warms up the battery and unless the battery is bad- will actually increase battery output. Of course, turn the lights off before you crank.
 
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