hamimp

I have this problem on and off that:

"Battery voltage drops while driving and car stops - but, with jump start it will start again"

It happened in March twice, in April Once and now in June again twice.

I took it to 2 dealers and 1 said everything was fine. Another said, bad alternator.

Now, I dont understand why they differ.

Today, it happened again. I have a carchip that tells that voltage dropped to 9 voltage when the car stopped.

ABS light comes on first and then airbag light and car loses power.

Everytime it happens I could jump start and car would run.

If I disconnect the battery power after starting the car, the alternator does not stop running.

Also, when voltage drops, it drops sometimes suddenly and sometimes gradually.

Now, this time today, even though it started after jump start, but it did not allow to me go far and lost power.

I am willing to replace the alternator. But, I wonder if it is something else. Hence asking for your help.

Thanks.

slinky87

iTrader: (1)

have you checked your belt tension, also check out the ALT pos wire is tightened on the post,

hamimp

I saw the belt was tight. I am not sure if they are very close to the spec. I dont know how I can check that.

For the ALT pos - it looks ok to me. But, this is also hard to get access.

I will try both again.

Thanks.

Chunger

iTrader: (1)

When you state "disconnect the battery power after starting the car", i hope you mean the jumping starting battery and not your main battery.

Your battery and alternator are probably both shot now. Make sure your battery terminals aren't corroded. Check the voltage with a multimeter at idle. If the voltage is not above 14V then your alternator is dying which will cause your battery to slowly discharge and eventually be ruined (though multiple deep cycling cycles). You can trickle charge the battery overnight and have it load tested. If the battery is shot and you only replace the alternator, the alternator will have to work extra hard because the old battery won't hold it's charge and alternator will be overworked until it is ruined.

m00njal

hmmm, I just replaced my alternator last week because my car had the same issues with dying, and it solved my problem, but now that I read it could be stressed because of a dying battery, plus the two 12" subs I put in today, how can I go about doing this load test on the battery?

nlmaxima

iTrader: (10)

When the car shut off did you smell anything? Try smelling the alternator area after driving for a while and see if it smells like an electrical fire, if you don't know what that smells like find someone who does. Sometimes when an alternator is on the way out the stator shorts out causing the protective coating on the wire to melt causing a bad smell. If you smell this I suggest changing the alternator. Have the battery load tested to see if it is good. You should have a good battery with a new alternator so you don't put too much unneeded stress on the alternator. A bad battery can cause an alternator to fail.

Chunger

iTrader: (1)

Most shops and maybe even stores have a load tester...

But make sure you check the output voltage of the alternator at idle and at about 2K rpm...

hamimp

One mechanic here installed an alternator today in my car.

He is a good guy as he charged only $40 for it. He did it at his home though he works at a shop full time.

Now, he said, I did not need any new battery.

Since I had at least 6 times car stalled, is the battery replacement a must or I can wait.

I mean how do I know the battery is completely bad? or How do I know it will put too much load on alternator.

I dont want to spend another $300 on alternator and labor.

NevadaJack_9

iTrader: (3)

Check battery and alternator at autozone before you do anything. could be just a bad battery cable

hamimp

That was another mystery.

At one day, autozone/napa both said, charging problem.

And, another day, none could find anything.

One dealer spent a week and could not find anything.

Another dealer said, within 10 min of testing, it was alternator problem.

So, anyway, I changed the alternator today evening.

Now, I am thinking if I need to change the battery now. The battery gave 14 Volt according to the mechanic.

Thanks.

Chunger

iTrader: (1)

A car battery doesn't "give" 14V at rest (car has been "off" for 10 minutes+)... 12.4V normally...

Keep in mind salesman/shops can be bias and lazy so take their diagnostics with a grain of salt unless you actually see them test them with equipment.

Why don't you LOAD TEST the battery as suggested? If the battery was charged to its max with a working alternator that WILL tell you if the battery is bad....

slinky87

iTrader: (1)

12.4? mor e like 13.4-13.8 at idle and up

Chunger

iTrader: (1)

Read carefully... at rest after 10minutes with the car off...