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What happens if you disconnect the battery while the car is still running?
Wiki User
∙ 13y ago
Depending on the year, make and model, the engine may or may not keep running.
The best advice you can get is do not try it.
If you don't know how to check these parts yourself and you have any doubts about your battery, the alternator - or any other part of your car's charging system - it would be best to get them all checked thoroughly by a vehicle electrics specialist.
He or she will have all the right test equipment and will know what to do with it, so you will get the best advice.
Other opinions
It might, but it's very likely to fry the alternator. Alternators depend on battery impedance for current regulation. Disconnecting the battery with the engine running is just begging for a hefty repair bill.
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Yes it will , except some early model VWs as I found out, disconnecting the battery breaks the circuit
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Early VW will stop running , circa 1960.
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The battery provides voltage regulation. Without it, the bus voltage in your vehicle may exceed the working voltage of many electronics in your vehicle. Cars today have many digital electronics that are susceptible to voltage spikes and are often not well equipped to handle them. You could easily destroy the engine computer or your expensive music system for example.
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It will cut off on a new car because the computer system will shut down.
Not sure on older models.
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On a 95 Pontiac driven with a bad alternator, the lights dimmed to nothing but it still ran.
Wiki User
∙ 13y ago
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What do you do if you pull the key out of the ignition but the car still keeps running?
Disconnect the battery.
How do you diagnose bad alternator?
Start the truck then disconnect the battery if it's still running the alternator is good
97 astro that shorts out the battery charger when hooked up.?
Disconnect battery from vehicle - if this still happens battery is probably shorted internally and requires replacement
Your 1997 Mazda 626 will not start after an alternator malfunction why?
Battery will be flat because spark plugs were running straight off your battery because the alternator was not charging your battery as you were driving. You can test this by jump starting your car with another car and after your car is running you should be able to disconnect your battery and car should still run off the alternator. If your car stops than your alternator is RS. Battery will be flat because spark plugs were running straight off your battery because the alternator was not charging your battery as you were driving. You can test this by jump starting your car with another car and after your car is running you should be able to disconnect your battery and car should still run off the alternator. If your car stops than your alternator is RS.
How do you test an alternator on motorcycle?
put a voltmeter on the battery and test voltage, then start the cycle and check again. A battery at rest should be at about 13 volts, with the engine running it will be at 14 or above. to be sure disconnect the positive battery terminal while running, if there is still good volts there, or the engine does not die it is ok.
What causes your 89 Honda civic battery light to keep coming on and then goes away when engine idling change you disconnect the negative battery cable and the car did not cut off?
it still may put some voltage to keep the car running have it tested
What if your laptop is not running on battery it is running by an unknown?
the reason its still running is because your battery has transferred some juice into it already give life for a short period of time.
You changed the temp sensor why is your engine light still on?
it has to be reset if you disconnect the battery for a few minutes should do it
84 Chevy caprice when engine is off something is still running not the wiper motor or the windshield fluid motor what is it you have to disconnect the battery to make it stop?
i think i had the same problem with my 84 caprice. is the battery dead when u go to start it? i unplugged the clock in the dash and it seemed to fix it.
If a1973 dodge dart swinger 318 replaced everything battery still dies?
apparently you have a draw or a short when the vehicle is shut off, disconnect the battery when not in use and see if the battery stays charged.
Why won't 2001 ranger start without a jump but will stay running?
Sounds like a dead battery. You need the battery to start the car, but once it is running the engine runs completely off of the alternator (which also recharges the battery if the battery is still good).
If the battery is going out will the alternator still power the car?
the battery job is to start the car so the alternator will kick in after the car is running
