Battery drain - The 1947 - Present Chevrolet & GMC Truck Message Board Network

A.P. · 05-24-2005, 11:30 AM

Hi, to all. My truck seems to have a short somewhere, my battery dies after I let sit for week. I disconnected the battery and put a multimeter in series between the battery cable and battery. With the key off, I get a 3.4mA current drain. I removed all the fuses and nothing changes. But if I disconnect the two pin connector on the alternator, the current drops down to zero. I have an alternator with internal regulator, thats been in my truck for over 3 years. My question is, is a 3.4mA drain enough to drain a battery in one week? For those who have an alternator with internal regulator, have you measured the amount of current drain while the key is off? If you have, what is the drain amount? Thanks for any info. you all can provide.

A.P.

Old Dave · 05-24-2005, 12:45 PM

A.P. are you sure that's not 34mA and not 3.4? We have a problem with our boat that has a 350 TBI that has the internally regulated alternator and that's about what the draw is on it. We finally put a battery disconnect switch in because it would run the battery down after sitting for a week. Had the alternator checked several times and they couldn't find anything wrong or so they said. I don't think 3.4mA is enough to drain it in a week.

**VetteVet** · 05-24-2005, 01:31 PM

I agree with Dave about the 3.4 ma draw. If you disconnect the red wire on the back of the alternator and measure the resistance between the post and the alternator ground and then reverse the leads if you get readings bothe ways it will tell you if one or more of the diodes in the alternator is bad. A battery disconnect is a good idea but you will lose the radio settings and anything else like a clock that needs to have power full time. A small milliamp charger might be an idea. I made one from one of the power transformers for an old phone.

A.P. · 05-24-2005, 04:04 PM

Old Dave and VetteVet thanks for your replys. But it seems that the battery is the problem and its 3.4mA drain. I let the battery charge over night with my 10A battery charger. When I disconnected the charger and the battery were hot. I seen this problem before on my car. It seems that the battery has develop an internal short. It now only holds enough charge for one start up. My alternater is putting out 14.8V. Its time for a new battery.

A.P.

05-24-2005, 11:30 AM	#1
A.P. Black 72 Chevy Join Date: May 2002 Location: Los Angeles, California Posts: 662	Battery drain Hi, to all. My truck seems to have a short somewhere, my battery dies after I let sit for week. I disconnected the battery and put a multimeter in series between the battery cable and battery. With the key off, I get a 3.4mA current drain. I removed all the fuses and nothing changes. But if I disconnect the two pin connector on the alternator, the current drops down to zero. I have an alternator with internal regulator, thats been in my truck for over 3 years. My question is, is a 3.4mA drain enough to drain a battery in one week? For those who have an alternator with internal regulator, have you measured the amount of current drain while the key is off? If you have, what is the drain amount? Thanks for any info. you all can provide. A.P.

05-24-2005, 12:45 PM	#2
Old Dave Is a bullfrog waterproof? Join Date: Nov 2000 Location: OLATHE, KANSAS Posts: 1,130	A.P. are you sure that's not 34mA and not 3.4? We have a problem with our boat that has a 350 TBI that has the internally regulated alternator and that's about what the draw is on it. We finally put a battery disconnect switch in because it would run the battery down after sitting for a week. Had the alternator checked several times and they couldn't find anything wrong or so they said. I don't think 3.4mA is enough to drain it in a week. __________________ "It is better to remain silent and be thought a fool, than to open one's mouth and remove all doubt." Ben Franklin __________________ 1970 Chevy shortbed 2002 Harley Custom Chopper (Long sucker) 1998 K2500 5.7L 5-speed Longbed 1st two are My son's toys...they just live in my garage! 1997 GMC K1500 Suburban 1993 S-10 Blazer 4D (youngest son's daily driver) 2000 Dodge Ram 4WD Ext. Cab (5.9L) Wife is a late year 1951

05-24-2005, 01:31 PM	#3
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,717	I agree with Dave about the 3.4 ma draw. If you disconnect the red wire on the back of the alternator and measure the resistance between the post and the alternator ground and then reverse the leads if you get readings bothe ways it will tell you if one or more of the diodes in the alternator is bad. A battery disconnect is a good idea but you will lose the radio settings and anything else like a clock that needs to have power full time. A small milliamp charger might be an idea. I made one from one of the power transformers for an old phone. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

05-24-2005, 04:04 PM	#4
A.P. Black 72 Chevy Join Date: May 2002 Location: Los Angeles, California Posts: 662	Old Dave and VetteVet thanks for your replys. But it seems that the battery is the problem and its 3.4mA drain. I let the battery charge over night with my 10A battery charger. When I disconnected the charger and the battery were hot. I seen this problem before on my car. It seems that the battery has develop an internal short. It now only holds enough charge for one start up. My alternater is putting out 14.8V. Its time for a new battery. A.P.



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