Elusive Voltage Draw
03-16-2011, 03:40 AM
#1
Elusive Voltage Draw Elusive Voltage Draw
After my car sits for a week or so it wont start. It will crank a little but go. The battery drops down to 11 volts and some change. Typically I leave my battery tender on it and its no big deal. But I don't have any new parts to install right now so I figured I would try to fix something.
I put a volt meter between the battery and the positive cable and for a moment it shows about a 12v draw and then immediately drops the less than .02v.
I hear some solenoids clicking when I reconnect the battery. I'm not sure exactly which ones but I know if I remove the underhood fuses for the L/R headlights, the solenoids no longer click when reconnecting the battery.
The battery is an Optima red top. It's about 3 years old. I have left the battery disconnected for a few days and it shows no signs of losing voltage on its own. I load tested it and even reconnected the cables and the car started. So, I am almost positive the battery is good.
Right now I am leaving the headlight fuses out for a few days and monitoring the battery to see if it continues to lose voltage.
What else can I check? What other testing can I do? Has anyone experienced anything like this? If I am no longer losing voltage with the headlight fuses out, I will assume the problem is in the headlight circuit. But if that is true, what the hell could it be? All of those components work without flaw as far as I can tell.
After my car sits for a week or so it wont start. It will crank a little but go. The battery drops down to 11 volts and some change. Typically I leave my battery tender on it and its no big deal. But I don't have any new parts to install right now so I figured I would try to fix something.
I put a volt meter between the battery and the positive cable and for a moment it shows about a 12v draw and then immediately drops the less than .02v.
I hear some solenoids clicking when I reconnect the battery. I'm not sure exactly which ones but I know if I remove the underhood fuses for the L/R headlights, the solenoids no longer click when reconnecting the battery.
The battery is an Optima red top. It's about 3 years old. I have left the battery disconnected for a few days and it shows no signs of losing voltage on its own. I load tested it and even reconnected the cables and the car started. So, I am almost positive the battery is good.
Right now I am leaving the headlight fuses out for a few days and monitoring the battery to see if it continues to lose voltage.
What else can I check? What other testing can I do? Has anyone experienced anything like this? If I am no longer losing voltage with the headlight fuses out, I will assume the problem is in the headlight circuit. But if that is true, what the hell could it be? All of those components work without flaw as far as I can tell.
03-19-2011, 05:44 AM
#2
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Having your alternator tested is the first and easiest thing to do. I overlooked this for awhile because I saw the guage was in the normal range.
I too just trickle charged the car often, but a long trip with the headlights on forced me to finally fix it. Any knucklehead at any auto parts will have a decent load tester and be glad to do it. I went with a junkyard 145 amp truck alternator and I can let my car sit for weeks now with no trouble.
If that's not it, start pulling fuses and check for a drain across with an ampmeter. Look first to your aftermarket stuff. Check for corrosion, loose head or block grounds, etc.
Good luck!
I too just trickle charged the car often, but a long trip with the headlights on forced me to finally fix it. Any knucklehead at any auto parts will have a decent load tester and be glad to do it. I went with a junkyard 145 amp truck alternator and I can let my car sit for weeks now with no trouble.
If that's not it, start pulling fuses and check for a drain across with an ampmeter. Look first to your aftermarket stuff. Check for corrosion, loose head or block grounds, etc.
Good luck!
Last edited by Steve Gunn; 03-19-2011 at 08:45 AM.
