Car Starts When Jumped but Wont Start Again

Car won't get-go unless jumped. How to tell if information technology's the battery or alternator?

• Thread starter daveymark
• Outset date Nov 8, 2005

• #ii

Put a DMM on the battery while it's running and meet what the voltage is.

• #3

exam the battery on a tester, or take it to a shop

• #iv

The alternator doesn't do anything until the motor is running.

• #five

Put a meter on the Altenator to see if information technology has any output tin can besides exist checked by your guages in the vehicle unless you have idiot lights..

Ausm

• #six

the old method of testing the alternator was to disconnect the neg terminal of the battery while the care is running. If it dies, the alt is the problem.

• #vii

anyone have an idea if will autozone test it for complimentary? I know they do the diagnostic code checker for free

• #8

if your alternator is dead, your battery won't charge and your automobile will prolly dice in short order. If it runs for hours afterwards jumping, it's prolly the battery.

I had the alternator become in my old volvo at school. I had to have a friend jump me 3 times to get me to the garage, at night. Boy that was fun. I call up being suprised at how quickly the auto died, specially with lights on.

• #ix

If your machine needs a leap then it is your battery

If it was your alternater your car would die in the middle of driving.

Peace

• #10

I drove 50 miles after I jumped it. Information technology didn't die, I arrived at my destination. Then this morning information technology wouldn't commencement once again. Does that mean information technology's probably the battery?

Apr three, 2001

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• #11

Originally posted past: daveymark
I collection l miles subsequently I jumped it. It didn't die, I arrived at my destination. Then this morning it wouldn't starting time again. Does that mean information technology'southward probably the bombardment?

Yes. 50 miles should accept put a bit of a charge into it, so information technology'due south probably not holding information technology whatsoever more than.

• #12

Sounds like the battery to me...

• #13

Originally posted by: daveymark
anyone take an idea if volition autozone exam it for gratis? I know they do the diagnostic code checker for free

Yes, AutoZone will exercise a load exam on the battery and allow you know if information technology'south expressionless. They do it for free. It takes but a few minutes.

They'll also test your alternator for free if you desire to accept it out. Same deal with the starter.

• #fourteen

Originally posted by: Heisenberg
Put a DMM on the battery while it's running and encounter what the voltage is.

To be a piddling more articulate... y'all take a 12V bombardment in your car. If you lot disconnect the battery and mensurate the voltage, it might read something similar xi.5V.

If yous turn on the engine, the alternator volition charge the battery and you lot'll read something higher... maybe 14V. If the alternator is dead, yous won't read "something higher".

• #15

Bombardment.....Or depeding on what blazon of vehicle, it could be something in between that'south not charging information technology. I would first with the bombardment first...

• #sixteen

Originally posted past: Aimster
If information technology was your alternater your motorcar would die in the middle of driving.

Not necessarily true. My Honda had a bad alternator, and it would drain the battery , and I would have to jump information technology.

Jun 5, 2000

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• #17

Originally posted by: robphelan
the former method of testing the alternator was to disconnect the neg terminal of the bombardment while the care is running. If information technology dies, the alt is the problem.

yip, i have used this method a few times and has always worked and was right.

• #18

Originally posted by: Heisenberg
Put a DMM on the bombardment while it's running and come across what the voltage is.

True.
A bad battery will drop to < x Volts under load.

• #nineteen

Originally posted by: robphelan
the old method of testing the alternator was to disconnect the neg terminal of the bombardment while the care is running. If it dies, the alt is the trouble.

That must be before stuff similar Fuel Injection, ECU and other electronics.
The auto will dice no matter what if you exercise that.

• #20

Originally posted by: robphelan
the onetime method of testing the alternator was to disconnect the neg last of the battery while the intendance is running. If it dies, the alt is the problem.

Exaclty what i was going to say. Just make sure the machine hasnt been runnign for a while. Some batteries are just weak, simply will take some accuse. So, just jump it, and then disconnect the battery immediately.

[edit] meant battery ... [/edit]

October twenty, 2003

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• #21

Alternators don't always fail completely right away, often they end charging gradually, so the only manner to be sure is to exam the charging output, however if your bombardment is more the 3-4 years old it may be dead likewise... be really conscientious if you get to Sears or somplace similar that though because they'll rip yous right off and take you replacing the bombardment & the alternator wether y'all need it or non.. best bet is to test yourself or remove the alternator and take information technology to Autozone as has been suggested.

• #22

Take out the bombardment and have it to AutoZone.

If non battery,

Accept out the alternator and take it to AutoZone.

Jun xiii, 2000

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• #23

What year is the car? Have y'all ever changed your battery? Usually batteries have 5 year warranties on them. Yous tin wait a battery to terminal at least that long....some will last 3-4 years....information technology's a mixed bag.

AZ will check your battery. The alternator can't accuse a bad battery.

If the alternator goes bad, information technology will sometimes draw current from the bombardment fifty-fifty when the auto is off... (bad diode tin brand the alternator (generator) plough into a motor) And so start with the battery and don't listen to any mechanics trying to talk you into replacing the alternator yet.....

• #24

Originally posted by: Aimster
If your car needs a bound then it is your battery

If it was your alternater your machine would dice in the middle of driving.

Peace

Unless a bad alternator crusade the bombardment to dice.

edit: You need to have the alternator tested, not the bombardment. You know the bombardment's dead, information technology's a affair of why. The fact it isn't charging doesn't mean jack. It could mean the alternator isn't charging, or the bombardment isn't holding a charge.

edit2: Chances are if the alternator is bad, the battery needs to be replaced, but non always.

May 27, 2002

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• #25

Take a drive...
Avant-garde machine will test your bombardment, starter, ignition, and alternator for free...

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Source: https://forums.anandtech.com/threads/car-wont-start-unless-jumped-how-to-tell-if-its-the-battery-or-alternator.1737470/

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