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#1073476 - 03/18/22 01:58 AM Battery keeps draining while cranking.  
Joined: May 2007
Posts: 5,130
Buick Runner Offline
10+ Year
Buick Runner  Offline
10+ Year
Member

Joined: May 2007
Posts: 5,130
Dharma station 1 the Hydra
Having issues with batteries dying prematurely. The battery doesn't seem to discharge unless the starter is cranking. When I hit the starter the battery rapidly drains down to nothing. Only takes a couple of cranks to drain the battery. This happens even right after charging a battery overnight. I tried a few different batteries only to repeat the same results. Frequent rechargings and short battery life.

I suspect the starter is drawing excessive current and killing batteries. The car sat over the winter without discharging to 0, the dome light still worked. The car does not seem to have a parasitic drain issue. I performed a voltmeter test on the fuse top contacts on fusebox and found no drains.

I used a carbon pile tester to measure voltage drop while the starter cranks. Before cranking the starter motor the battery voltage wax just shy of 13v. With the starter running the voltage drops to 8v and returns to 9.5v. I performed the same test on my tractor and it only drops to 9v and returns to 10v while the starter is engaged. According to the instructions for the tester, the voltage should not drop below 9v while cranking.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1073477 - 03/18/22 02:52 PM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Apr 2011
Posts: 1,259
Hunter79764 Offline
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Hunter79764  Offline
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Joined: Apr 2011
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Grand Prairie, Tx
Just a thought, you might see if you have crud that is allowing current to short circuit between the starter posts while cranking?
I'd also be interested to see if you can get an amp clamp to measure the current going to the starter vs other branches to confirm that it is losing everything at the starter and not some other circuit that happens to short while cranking.


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1073478 - 03/19/22 01:13 AM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Dec 1999
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86ttop Offline
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86ttop  Offline
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Joined: Dec 1999
Posts: 11,982
Brooksville, Fl
You probably have been using sulfated batteries. Have you tried the 3 minute test to see if they are sulfated?? You put the battery on charge with a regular strength battery charger on 6 amps of charge with a voltmeter attached and after 3 minutes, if the voltage is above 15 volts, you have a worn out battery(ies). Good luck!


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs
#1073479 - 03/19/22 07:40 AM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Jan 2008
Posts: 1,221
FinallySS Offline
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FinallySS  Offline
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Joined: Jan 2008
Posts: 1,221
Nice Sunny Hawaii
I once worked as GSE mechanic at the airport. Baggage tugs used in airport is very basic, simple design vehicles. It's basically engine, trans, radiator and axles on a shell. every so often, I get a call with vehicle not starting or have hard time starting. Come to find out that vehicle sat too long without moving, hence no charging done at the battery. I can't remember what the voltage was, but once the battery hit that low voltage, it's basically it's a dead battery. What I mean is it will hold charge for couple days but it eventually dies. It will pass battery test with tester since it will hold 12.5 or so voltage for certain amount of time, but come back in few days (usually within one or two days), battery is dead.

I also had to combat idiots driving the vehicles and every so often, they WILL try their own repair techniques. One very common one I had was for some reason, they kept playing with the negative cable. I don't know why the negative (although I have few theories but could not confirm it because everyone I talk to kept denying even though we have them on video footage), never the positive. Always the negative cable. When this happens, batteries and started kept dying. I can't remember how many batteries and starters I went through.


1986 Silver MCSS - Poly bushing and Hotchkis spring w/Bilstein, Posi w/3.73, MSD 6-AL, E-Brock 600cfm, Aluminum 2-row radiator.
1986 Black MCSS - R.I.P............Finally.
#1073481 - 03/19/22 06:08 PM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Feb 2008
Posts: 954
AkronAero Offline
10+ Year
AkronAero  Offline
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Joined: Feb 2008
Posts: 954
Akron OH
Buick, can you get it running? Unless deepdraw, batteries can die if fully drained. Does a fully charged battery hold charge when not sure installed and also when installed with everything turned off? Is there power drain above fuse, say measure amps from neg battery post to ground? Check for diode failure at alternator. Set you tester to alternating current and see if you can register any A/C across battery terminals, too, indictating diode problems. May be erratic.
Puzzling!
Gordon


1987 Aerocoupe. Frame-off, notched/mini-tub, 383 with AFRs @ 535HP/487TQ, March Serpentine, 304 SS headers (Jet-Hot) & 304 3" dual exhaust w/ Borlas, Janis 200-4R, TrueTrac w/ girdle and Moser 28, Hydroboost, computer delete, lowered, every part replaced or messed with (several times).
#1073482 - 03/19/22 09:15 PM Re: Battery keeps draining while cranking. [Re: 86ttop]  
Joined: May 2007
Posts: 5,130
Buick Runner Offline
10+ Year
Buick Runner  Offline
10+ Year
Member

Joined: May 2007
Posts: 5,130
Dharma station 1 the Hydra
Originally Posted by 86ttop
You probably have been using sulfated batteries. Have you tried the 3 minute test to see if they are sulfated?? You put the battery on charge with a regular strength battery charger on 6 amps of charge with a voltmeter attached and after 3 minutes, if the voltage is above 15 volts, you have a worn out battery(ies). Good luck!


I performed this test and didn't get above 13 volts. Also popped the caps off to look in the cells and didn't see sulfated buildup. One cell was a little low on water. Cleaning the cables now but I suspect its the mini starter. Found the insulation on the wire from the starter motor to the solenoid was melted which isn't good. Thinking about going with a LT1 mini starter.

Last edited by Buick Runner; 03/20/22 03:09 AM.

SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1073484 - 03/20/22 04:55 PM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Nov 2012
Posts: 1,157
Ole Blue Offline
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Ole Blue  Offline
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Joined: Nov 2012
Posts: 1,157
Lugoff, SC
Have you tested the alternator? I would have the battery tested at the same time also, since so easy to remove.
I've had problems as such back in the day and it usually came back to these two items.
Two easy tests to rule out before getting in-depth possibly unnecessarily.

#1073531 - 03/30/22 04:04 AM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: May 2007
Posts: 5,130
Buick Runner Offline
10+ Year
Buick Runner  Offline
10+ Year
Member

Joined: May 2007
Posts: 5,130
Dharma station 1 the Hydra
Did some research and according to the GM service manual, the starter voltage drop should not be less than 9.6 volts. So the 9.5 reading I got from performing the test 3 times indicates possible starter issues. Also found the insulation on the solenoid to motor wire has melted.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1073564 - 04/04/22 11:36 PM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Aug 2010
Posts: 307
tom demarco Offline
Member
tom demarco  Offline
Member

Joined: Aug 2010
Posts: 307
Mooresville
need to do a voltage drop test look at you tube

#1073565 - 04/04/22 11:37 PM Re: Battery keeps draining while cranking. [Re: Buick Runner]  
Joined: Aug 2010
Posts: 307
tom demarco Offline
Member
tom demarco  Offline
Member

Joined: Aug 2010
Posts: 307
Mooresville
is starter grounded


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