Parasitic DRAIN

[911Cowboy]

Hope yall can help me out... I have a Parasitic battery drain on my '75 it drains the battery fairly quickly (over night) battery tests good when charged... Alternator has proper output... about 7 amps is going trough the battery cables when key is out... Pulled all fuses one by one with no change, Disconnected engine wire harnes with no change... Checked all lights and interior acc... The only think i can think of is Starter Circut fault... Maby today ill put it on the lift and check amperage leak there. any ideas would be helpful
THanks

Ive been readed this forum for ever and searching and found most all my awnsers so i havent needed to post but Here goes... So......... Nice to meet yall...

[911quest]

Welcome How are you checking thye amp draw? You need to check it between the neg. terminal or the battery and the negative disconnected.

[Brent Lineker]

I had a similar problem,turned out the trunk light was staying on when closed,fixed the switch and no problems since.

[ischmitz]

You need to measure the current draw as others suggested. Trunk ligth, glove box light or aftermarket alarm systems are know culprits to drain batteries. Did your problem simply start one day?

Another thought: Unless you do a real battery load test there is no way to know how much charge your battery is holding. I once had a battery that appeared to charge O.K. However, after cranking the car maybe five times or leaving the headlights on for 30 minutes it was empty again. So it simply had next to no capacity......

[911pcars]

"....about 7 amps is going trough the battery cables when key is out"

7 amps is quite a bit of current flow. There would be just a few unfused circuits that draw that much and/or create a short circuit to ground.

The starter and/or alternator are suspects. Disconnect the cables at the starter motor (don't forget to disconnect the battery first). Insulate the cable ends, then repeat the drain test with the multimeter. If the system is still draining 7 amps, look elsewhere.

If the drain is in this section of the system, determine whether it's the alternator or the starter; reconnect the battery cable to the starter but leave the alternator wire disconnected and repeat the drain test. In addition, at this branch connection (the starter), you can also connect the ammeter to individually test the alternator or the starter. Remember that the ammeter section of most multimeters has a capacity of measuring up to 10 amps. An internal fuse protects it thereafter. 7 amps is getting close.

I think that should do it.

Sherwood

[ischmitz]

OK, I did not read the entire post above. If you really have a 7 Ampere draw you are essentially sinking 7 x 12 volts = 84 Watts of power. Something should be getting hot to the touch and you should see a small spark when you connect/disconnect the culprit.

I would guess a bad diode in the alternator.......

[911Cowboy]

Thanks guys,
Yeah Battery load tested well, And i was measuring it with a clamp on amp meter at the battery.... I kept thinking starter circuit (knowing it wasn't a fused circuit) But thanks for the tip i almost forgot the alternator circuit is pretty much on the same starter curcuit. The alternator could make perfect sense seeing is that ive had psuedo alternator issuse recently and ive been trying to procrastinate a repair until snow flies. That would hopefully fix my occasional headlight brightening/ dimming issue and my Alt. light came on twice on me on the interstate and then slowely faded away so the alt could be the culprit... Thanks ill let yall know
I just have to get my '87 off the lift...

[911Cowboy]

Allright the DRAIN has been loacated...Well i put the car on the lift and let it all cool down with the battery disconnected. after supper i reconnected the battery and went to work with my amp clamp... while fittling it around the starter wire my hand brushed against the flexible hose that goes from the heat exchanger to the hot air duct, and the flexy tube was HOT... the rest of the engine ice cold... The amp meter still read a current draw... I disconnected the battery and then the flex hose. Then reconnected the battery and Amp drain dissapeared... After some examination i figured it out... a piece of wire from the flex hose was unraveling at the end and was laying itself against the starter lug... Snipped it off and Wrapped it up and FIXED.... i know i still have a alt issue but im hoping its just a bad ground...and for a later date
Thanks for the help

[3.2 CAB]

Hi, I had a problem a few years ago that was about the same. It was to the point that when I turned off the engine the next step was to pop the hood and disconnect the battery, I had installed a quick disconnect on it for this purpose. If I did this, I had no problems. I never could trace the exact cause of the problem. My Sons gave me a new stereo system for Christmas about 4 years ago now, and after I installed the new stereo, and amp, etc. my battery drain vanished!! I was replacing an aging Alpine, with a new Sony X System. I did notice that after I changed out the old stereo, I actually forgot to disconnect the battery after driving around taking in all the new system was putting out. About 3 weeks later I suddenly remembered that I had forgotten to disconnect the battery, so when I opened the garage, I was prepared to have to put the charger on the battery because I knew that it would be dead, but before I hooked up the charger, I decided to give it a try and see if it would start... to my surprise, it fired right up and gave no indication of the battery being down even a little. I tested my newly found "hot battery" several times by leaving it connected for longer and longer periods of time, and after leaving it connected for over a month and it still cranking right up, I came to realize that the hidden drain must have been in that old Alpine stereo system all along. Knock-on-wood, to this day I have still not have had the battery drain out again. I was amazed that replacing the old stereo would have corrected my battery drain problem. So I got 2 really nice results from 1 task done, an awesome stereo, plus a battery that does not go flat if it is still connected. This is just my experience, that I had with a constantly draining battery, if left connected. Good luck with yours.