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Voltage at battery when running - GMC Cars & Trucks

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See the diagram attached. God bless you
voltage at battery when running - 3d7cd3ab-408c-4822-a779-153b47238007.jpg

Posted on Jul 28, 2013


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My 1998 ford windstar hasnt ran for awhile. i got the altenator tested and replaced the battery, checked the fuses in the fuse panel, tested the relays and she still has a problem keeping battery charged...

Check the fusible link between the alternator thick red wire and positive terminal of the battery with the battery disconnected. If that's OK, compare the non-running battery voltage to the running battery voltage and see that it is about 12.7 volts not running and 13.7 to 14 volts running. If you don't see the higher voltages when the engine is running, your alternator is not producing the required charging voltage. At that point you need to determine if you are getting the field voltage to the alternator rotor which is the smaller wires on the alternator. The voltage will vary with the charging demand and electrical load on the system. These voltages come from the engine control module. The belt is turning the alternator, right!

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Alternator problem

Easy way to check with a voltmeter. Check battery voltage on the battery terminals with key off, engine off, and then check voltage with engine running.
Engine off, a good battery should have voltage between 12.6 volts and 12.9 volts. With engine running, battery voltage should be a minimum of 13.5 volts, somewhere between 13.5 and 14.5 volts. This would indicate the alternator is good and is charging the battery. If voltage is less than 13.5 volts, if it only shows same volts as when not running, the alternator is not working right. Take it off and have tested for free at a parts store. It could be a bad alternator or it could be that the wiring between alternator and battery has a problem. If alternator tests good, start looking into the connections between alternator and battery.
Does your battery or alternator light stay on when engine is running? This would indicate a charging system problem. Time for the voltmeter test.

Apr 10, 2014 | 2000 Toyota Avalon

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How do I know if my altinator is working

If it is not working, your battery light would be on, and the battery would eventually go dead.

Dec 13, 2012 | Cars & Trucks

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How can i tell if the battery or alternator is failing?

Get a cheap digital voltmeter. Check the voltage at the battery. Start the vehicle, checking voltage at battery. It should be greater than when the vehicle wasn't running. With vehicle running turn on the lights and heater blower, does voltage stay up or go down? Voltage should be at least 13.5 volts with the motor running. If the voltage goes down when the lights and heater are turned on then the alternator is not charging enough. If the voltage is up (13.5 or more) with it running and it will not start after sitting a short time then the battery is probably bad. Or go somewhere like Auto Zone and they will normally check it for free!

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Battery light is on. i changed the battery and altinator

If the battery light is on, this is an indication tha the generator is not working.
A simple check of the generator is to measure the voltage over the battery in 2 steps. The battery voltage - engine not running = 12VDc
voltage - engine running = around 14.2VDc or defenately higher than the voltage in situation where the engine is not running.

If the generator is is ok the voltage measured over the battery wil increase as a result of charging.

If no increase of voltage - charger defective - or eventually poor cable connections between the charger unit and "the engine".

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Car will start when it is being charged, after charger is removed car still runs, when car is shut off it will not restart

could be battery or alternator. Check voltage at battery with engine running. Should be at least 14 volts. If yes, alternator is working.
After charging, battery voltage should be over 12 volts, with engine off. When starting, battery voltage should not drop a lot. If battery voltage does not drop while trying to start, you may have a bad connection--loose terminals.

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Wouldn't run with out battery. change alternator, disconnect battery leads and engine shut off. What is the problem.

It won't run without a battery, It won't run without the alternator either. I am thinking the battery is dead, or not charging, even the new alternator doesn't mean it is good, Get the battery tested for electrolyte level and voltage, get the alternator tested or at least see if the voltage goes up with with the engine running. Not running, check the terminals on the battery, make sure they are squeaky clean. Voltage above 13+ V. All 6 cells good, check it out. hope this helps.

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Battery light is on

this light points to the alternator not providing enough voltage to keep the battery charged. most alternators should have 13.5 to 14.5 volts output. continuing to drive the vehicle like this will cause the battery to go dead. have your alternator tested on the caravan by your local dealer,repair shop or some auto parts stores can do it. a remanufactured alternator will cost around $100 to $200 plus diagnosis and installation.

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Battery light comes on and off, changed battery cleaned all connections light still comes on and off

Battery light is a signal from the alternator that charge is below a given voltage , check charging system.

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The car battery light is on but the vehicle runs normally.

Battery light being on indicates low or over voltage at the battery. Have some one check the voltage with a voltmeter. Voltage too low will eventually run down the battery and voltage too high can damage the battery and other parts.

Oct 17, 2009 | 1997 Pontiac Grand Prix

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