Quick electrical charging question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mountain Man · 07-11-2004, 11:30 PM

Working on a buddys vehicle tonight. Truck starts with a boost, then will only run a couple of blocks and then dies. I checked the battery with my volt/ohm meter while engine running and it was registering 9.7 volts, and it continually dropped down in voltage on the meter while the engine was running. After we shut off the engine, I checked voltage at the battery again and it was 10 volts even and held there. I suggest his alternator is bad as it is not charging the battery, and it is drawing off of the battery when running. Is this correct?

**kwmech** · 07-11-2004, 11:57 PM

Sounds correct to me.

shuttermutt · 07-12-2004, 12:35 AM

Yep, pull the battery and the alternator. Have 'em both tested at the same time. I'll bet a crisp $1.00 bill you'll walk out of the parts store with a brand-new one or the other.

angelsairman · 07-12-2004, 12:48 AM

Just a suggestion if you find that the alternator is bad which id say it definalty is you should also put in a new battery if that was run for awhile with the bad alt as in my experience it kills the battery so much(unless you can charge it seperate) that when you install the new alternator it will kill that alternator to. Ive had this happen to me on one of my previous cars and also on the diesal engines that i work on. Just my two cents...

A.P. · 07-12-2004, 04:33 AM

I you take your battery and alternator to get check and they test good. Next suspect the voltage regulator if you still have an external one.

07-11-2004, 11:30 PM	#1
Mountain Man Registered User Join Date: Jan 2002 Location: Calgary, Alberta, Canada Posts: 451	Quick electrical charging question Working on a buddys vehicle tonight. Truck starts with a boost, then will only run a couple of blocks and then dies. I checked the battery with my volt/ohm meter while engine running and it was registering 9.7 volts, and it continually dropped down in voltage on the meter while the engine was running. After we shut off the engine, I checked voltage at the battery again and it was 10 volts even and held there. I suggest his alternator is bad as it is not charging the battery, and it is drawing off of the battery when running. Is this correct? __________________ 72 C10 Cheyenne Super Full trim Factory tach dash A/C dash Factory tilt 350 / 350 power train - with Edelbrock components.

07-12-2004, 12:35 AM	#3
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Yep, pull the battery and the alternator. Have 'em both tested at the same time. I'll bet a crisp $1.00 bill you'll walk out of the parts store with a brand-new one or the other. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

07-12-2004, 12:48 AM	#4
angelsairman Future Owner Join Date: Jul 2003 Location: Grand Forks AFB, ND Posts: 151	Just a suggestion if you find that the alternator is bad which id say it definalty is you should also put in a new battery if that was run for awhile with the bad alt as in my experience it kills the battery so much(unless you can charge it seperate) that when you install the new alternator it will kill that alternator to. Ive had this happen to me on one of my previous cars and also on the diesal engines that i work on. Just my two cents... __________________ Its not the end result that counts most...its the journey along the way that's most rewarding My truck doesn't leak, it just marks it's territory

07-11-2004, 11:57 PM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,649	Sounds correct to me.

07-12-2004, 04:33 AM	#5
A.P. Black 72 Chevy Join Date: May 2002 Location: Los Angeles, California Posts: 662	I you take your battery and alternator to get check and they test good. Next suspect the voltage regulator if you still have an external one.



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