alternator & voltmeter - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mark be · 09-28-2003, 04:31 PM

I've recently built a 72 lwb, I have a couple of questions. I have been having problems with my battery dieing every couple of days , so i bought a voltmeter
and my truck runs at 11.5 - 12 volts .I took the alt. & batt. in had them tested , replaced the alt. and regulator and nothing has changed (volt.) . Has anybody had this problem ? What should I do? Shouldn't my truck be running at 13+ volts?

jmanz69 · 09-28-2003, 05:06 PM

If you are having a dead battery, you have a drain somewhere in the system. Use your volt meter in it's ammeter setting to find your drain. Put it between the + post and the cable that hooks to it. If there is a AMP reading, then you have a drain. This is done, of course, with everything turned off. Then, start unplugging things one at a time. Like radio, heater, headlights, brake lights. You will narrow it down to the problem, and then fix it. You should draw no current when the engine is off and everything is turned off. If you have a modern radio installed, then you will see a slight current draw for the clock, but this should not kill your battery in a couple days time. Check all your grounds too. Make sure all your battery cables are tight. Check the body grounds, and the engine-to-body ground.

Good luck.

**truckster** · 09-28-2003, 06:08 PM

Yes, you should be getting about 13.5 volts with the engine running at idle.

krue · 09-28-2003, 06:40 PM

What they said, and welcome to the board!

09-28-2003, 06:46 PM

Welcome from So Cal.

sbrban · 09-28-2003, 06:47 PM

Make sure you have a good ground from battery cable to rad. suppt. I went through what you did a couple weeks ago and that was what I ended up with.

JimKshortstep4x4 · 09-28-2003, 08:06 PM

Welcome to the board from West Michigan!

Your battery voltage should read 13.5-14.5 with the engine running and the alternator working properly. If you have checked the grounds and wiring, then check the voltage at the regulator with the key on, engine off. Voltage should be approximately 8-11
volts at the brown wire connection. If this is good, then there may be something wrong still with the alternator or regulator, (wiring is good).

Here is a link for wiring diagrams, should you need it.

http://www.geocities.com/chevroletc1070/wiringdias.html

Good luck!

Jim

**Palf70Step** · 09-28-2003, 09:39 PM

Welcome to the board and yeah sounds like a short some where. You can try and pull fuses one at a time then retest it to see if that changes any of your readings to help isolate where the short might be. My guess would be in your park/tail/side marker lights. They are notorious for giving us irratations.

mark be · 09-28-2003, 11:13 PM

Thanks for all the help. I went out to do some of the suggested checks and battery was below 8v. I'll try tomorrow with charged bat.

mark be · 09-29-2003, 05:31 PM

Well I think I found my problem and it was none of the above . I think it has something to do with my ignition switch,because my batt. wasn't dead my voltmeter said 8 volts but my batt. was at 12.5 I didn't charge it at all and today the voltmeter read 12 volts and now the engine turns over but then it seemed to go dead again so I tried using a remote starter when my voltmeter said 8 volts and it turned over with no problem . I am really puzzled ,does anybody have any more sugg.? thanx

jmanz69 · 09-29-2003, 05:40 PM

Change your starter solenoid maybe. It sounds like maybe your solenoid is crapped out. They are cheap and not hard to replace. Where are you measuring that you get 8 Volts? But then get 12 Volts too? I am kinda confused as to where you are taking your measurements.

tom hand · 09-29-2003, 05:46 PM

How much extra stuff do you have on your truck ? I had a problem with mine with the voltage and it turned out all my accessories were pulling more amps than the alternator was putting out so if the truck was not running the battery would not discharge but the more I drove my truck the battery would discharge...it only had 12 volts while running. Put a bigger alternator on and solved the problem...13 plus volts while running

mark be · 09-29-2003, 06:07 PM

To answer jmanz69 question I have a hand held voltmeter so I ca n test the batt. alone. I have all ready replaced the solenoid and the starter and added a heat sheild.To tom hand what size alt I just bought a new one they said it is about 66 ?

mark be · 09-29-2003, 06:53 PM

Another question, would shimming the starter have any thing to do with it ,because I converted from a 4 on the floor to a automatic

mark be · 10-02-2003, 08:56 PM

Well I found my problems , the blue wire from my alt. was cut inside its wrapping and was not plugged in to the regulator correctly now my truck runs at 14 volts, thankx for all the help

09-28-2003, 04:31 PM	#1
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	alternator & voltmeter I've recently built a 72 lwb, I have a couple of questions. I have been having problems with my battery dieing every couple of days , so i bought a voltmeter and my truck runs at 11.5 - 12 volts .I took the alt. & batt. in had them tested , replaced the alt. and regulator and nothing has changed (volt.) . Has anybody had this problem ? What should I do? Shouldn't my truck be running at 13+ volts?

09-28-2003, 06:08 PM	#3
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,976	Yes, you should be getting about 13.5 volts with the engine running at idle. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

09-28-2003, 06:40 PM	#4
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	What they said, and welcome to the board! __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

09-28-2003, 06:47 PM	#6
sbrban Registered User Join Date: Sep 2002 Location: Iowa Posts: 236	Make sure you have a good ground from battery cable to rad. suppt. I went through what you did a couple weeks ago and that was what I ended up with. __________________ you never have too many suburbans....

09-28-2003, 09:39 PM	#8
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,216	Welcome to the board and yeah sounds like a short some where. You can try and pull fuses one at a time then retest it to see if that changes any of your readings to help isolate where the short might be. My guess would be in your park/tail/side marker lights. They are notorious for giving us irratations. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

09-28-2003, 05:06 PM	#2
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	If you are having a dead battery, you have a drain somewhere in the system. Use your volt meter in it's ammeter setting to find your drain. Put it between the + post and the cable that hooks to it. If there is a AMP reading, then you have a drain. This is done, of course, with everything turned off. Then, start unplugging things one at a time. Like radio, heater, headlights, brake lights. You will narrow it down to the problem, and then fix it. You should draw no current when the engine is off and everything is turned off. If you have a modern radio installed, then you will see a slight current draw for the clock, but this should not kill your battery in a couple days time. Check all your grounds too. Make sure all your battery cables are tight. Check the body grounds, and the engine-to-body ground. Good luck.

09-28-2003, 06:46 PM	#5
Linus0014 Guest Posts: n/a	Welcome from So Cal.

09-28-2003, 08:06 PM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Welcome to the board from West Michigan! Your battery voltage should read 13.5-14.5 with the engine running and the alternator working properly. If you have checked the grounds and wiring, then check the voltage at the regulator with the key on, engine off. Voltage should be approximately 8-11 volts at the brown wire connection. If this is good, then there may be something wrong still with the alternator or regulator, (wiring is good). Here is a link for wiring diagrams, should you need it. http://www.geocities.com/chevroletc1070/wiringdias.html Good luck! Jim

09-28-2003, 11:13 PM	#9
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	Thanks for all the help. I went out to do some of the suggested checks and battery was below 8v. I'll try tomorrow with charged bat.

09-29-2003, 05:31 PM	#10
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	Well I think I found my problem and it was none of the above . I think it has something to do with my ignition switch,because my batt. wasn't dead my voltmeter said 8 volts but my batt. was at 12.5 I didn't charge it at all and today the voltmeter read 12 volts and now the engine turns over but then it seemed to go dead again so I tried using a remote starter when my voltmeter said 8 volts and it turned over with no problem . I am really puzzled ,does anybody have any more sugg.? thanx

09-29-2003, 05:40 PM	#11
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	Change your starter solenoid maybe. It sounds like maybe your solenoid is crapped out. They are cheap and not hard to replace. Where are you measuring that you get 8 Volts? But then get 12 Volts too? I am kinda confused as to where you are taking your measurements.

09-29-2003, 05:46 PM	#12
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	How much extra stuff do you have on your truck ? I had a problem with mine with the voltage and it turned out all my accessories were pulling more amps than the alternator was putting out so if the truck was not running the battery would not discharge but the more I drove my truck the battery would discharge...it only had 12 volts while running. Put a bigger alternator on and solved the problem...13 plus volts while running __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

09-29-2003, 06:07 PM	#13
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	To answer jmanz69 question I have a hand held voltmeter so I ca n test the batt. alone. I have all ready replaced the solenoid and the starter and added a heat sheild.To tom hand what size alt I just bought a new one they said it is about 66 ?

09-29-2003, 06:53 PM	#14
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	Another question, would shimming the starter have any thing to do with it ,because I converted from a 4 on the floor to a automatic

10-02-2003, 08:56 PM	#15
mark be Registered User Join Date: Aug 2003 Location: oregon Posts: 54	Well I found my problems , the blue wire from my alt. was cut inside its wrapping and was not plugged in to the regulator correctly now my truck runs at 14 volts, thankx for all the help



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