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1982 SC Battery Drain

I tested my battery on a load-bank and it is fine.

However, if I leave it connected for approximately two (2) weeks, the battery is too drained to start the car.

When I disconnect the ground strap and leave it disconnected for two (2) or three (3) minutes, it sparks when I reconnect it and I can hear a slight tick from somewhere towards what seems to be the passenger side of the car (I have removed the glove box, boot, and engine lid lights and checked that no other lights are lit).

Here is the deal, it appears to be some sort of load. That is, when I touch the ground strap to the negative post it initially sparks (and makes a faint sound like a closing relay or contactor) and then stops sparking. When I use my Fluke meter I show a four (4) or so amp draw that quickly tapers off to around 100ma. When I disconnect the ground strap and connect a test light to the negative post and remove the fuses and check the fuse panel, I have a couple of brightly lit terminals and the rest are faint but slowly fade to nothing.

WTF could this be? I disconnected the antenna, stereo, etc. and I still hear the faint sound of a relay but can't seem to locate the origin. It seems to be centered around the Smuggler's Box or fuel pump area. I don't see any contacts or coils in these locations (at least not on my one-line diagram) and shouldn't all of these loads be switched via the start-switch? I don't see any potential capacitive or reactive loads that are not switched. If I leave the battery disconnected, it holds a full charge. Additionally, I disconnected the clock and it is not the source of the drain.

My 79' Targa can be left for a couple of months and it holds a charge (although I typically start it every two (2) weeks at a minimum unless out-of-town).

Any suggestions would be appreciated. Is this intrinsic to this year or is it something wrong with the vehicle?

It's a low mileage (62,000) coupe originally sold from Brumos.
Old 09-11-2017, 10:39 AM
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Mine will generally last 2 weeks or 3 weeks but a month is a stretch. I usually keep it connected to a tender.

Do you have the factory or other alarm system?
Old 09-11-2017, 11:52 AM
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A failed diode in the alternator?
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Old 09-11-2017, 02:17 PM
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next step troubleshooting is to pull and replace one fuse at a time to determine which, when removed doesn't cause a spark when tapping the ground to the battery -- that will help you identify the open circuit.

Don't believe this applies to your '82, but I traced a battery drain on my '86 to a faulty driver's side door light switch -- the power windows used this switch to deactivate the window circuit when the door was open (designed to let you roll up the windows after turning off car, but before opening door) -- since the switch wasn't telling the windows the door was open, the circuit remained active/energized and would drain my battery after a week.
Old 09-11-2017, 03:40 PM
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Load test doesn't reveal a weak cell, new battery time
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Old 09-11-2017, 05:11 PM
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I would suggest that you connect your multimeter on the amp gauge setting in series with your + battery terminal and your battery cable. Check the current draw and then use the schematics for your model year and start removing the power connector wires on the battery cable. Does the current drop to zero? If it does then ignore the battery cable and connect the amp meter to the power connector wires and remove one fuse at a time and check the amp meter each time for a change. I would do this methodically because there are some items that require switched power i.e. new radio memory settings, factory alarm system, interior lights. This should help you isolate the offending circuit.
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Old 09-11-2017, 05:28 PM
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A stock car has a very small current load while parked if all consumers are off. Only the electrical clock demands a very small current. A stock size battery fully charged, in good condition, should last several months and start the car. If not... a consumer should be found and corrected. I would start by looking for interior lights, non-stock electronics and such.
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I had this exact problem. See what I did here:

120 mA draw

Pretty much what Pat described, but with pictures. Short answer- mine was the lambda system relay under the passenger seat, which cycled itself (buzzed and clicked) though the car was turned off. I replaced the relay and the problem was solved.
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Old 09-12-2017, 04:17 AM
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you did not say what year it is.

basically what targa said is a good start

you have also done good by removing bulbs.
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Old 09-12-2017, 05:24 AM
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It's an 82'
Old 09-12-2017, 09:06 AM
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It's been suggested to measure the current draw. But unless I missed it, has that been done?
A vehicle with a draw less than 60ma should easily crank and start after 1-2 weeks.
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Old 09-12-2017, 09:11 AM
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I had a similar issue (2 weeks then drained) and found that it was the frunk light. I cover my car and leave the frunk unlatched but down. The frunk light would stay on. I disconnected the frunk light and that solved my problem. I suggest checking the light even if you latch your frunk as it may need adjustment and be always-on. In addition, I bought a Battery Tender and now I never worry about my battery charge.
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Old 09-12-2017, 09:35 AM
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Quote:
Originally Posted by aoncurly View Post
I had a similar issue (2 weeks then drained) and found that it was the frunk light. I cover my car and leave the frunk unlatched but down. The frunk light would stay on. I disconnected the frunk light and that solved my problem. I suggest checking the light even if you latch your frunk as it may need adjustment and be always-on. In addition, I bought a Battery Tender and now I never worry about my battery charge.
If you read the OPs first post, he's already removed all the bulbs!


"When I disconnect the ground strap and leave it disconnected for two (2) or three (3) minutes, it sparks when I reconnect it and I can hear a slight tick from somewhere towards what seems to be the passenger side of the car (I have removed the glove box, boot, and engine lid lights and checked that no other lights are lit)."
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Old 09-12-2017, 11:03 AM
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Okay,

followed Targa's advice and I have an initial draw of around 0.440 amps quickly dropping a slowly oscillating 0.008 to 0.018 in about 4 second intervals.

When I disconnect the clock, the oscillating draw stops and I show a steady 0.007 amps. I disconnected all fuses (in tern) as well as the relays (including the ones in the engine compartment) and show no change from a steady 0.007 amps.

I would assume that the variable draw, when the clock is connected, would be due to the clock's internal capacitors.

With the clock connected, I show an initial draw of 0.648 amps (once again quickly dropping to the 0.008 to 0.016 variable.

Still sparks initially with the fuses disconnected.

Anyway, a variable 0.008 - 0.016 amp draw shouldn't discharge the battery in a two week period. The ground strap has was disconnected for over a month and when I hook it up, the starter spins her right up without any hesitation.

It doesn't act like a weak or shorted cell and the battery shows adequate voltage. That draw seems a bit low to drain the battery in less than two weeks.
Old 09-13-2017, 10:22 PM
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you are interested in the long term draw.
the initial could just be a circuit charging up like a capacitor. this is common especially with newer cars, that's why I asked the year.
radios can do the same thing. computers can do it.
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Old 09-14-2017, 04:00 AM
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The only capacitive load that I can locate (unswitched) would be the clock.
Old 09-14-2017, 09:54 AM
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its that initial .6 amps and .4 amps that would be conscerning to me

your other dras are fine.

have you tried disconnecting the battery between starts ( green knob) , ? if it doesn't start after that guess what , battery is toast . I don't believe in load tests
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Old 09-14-2017, 10:59 AM
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Here is the deal, if I disconnect the battery for a month or more, when I reconnect it spins the engine over as per a full charge. However, if I leave it connected, it won't start the car after a week and and a half or two weeks.

Actually, I had it disconnected for almost two months and when I reconnected it started just fine. Shows 12.8 volts after a month but only 11 if connected for a week or so.

That initial draw is not reflective of the minor continual draw (and once connected, it drops after a second or so to the 0.008/0.018 amps). I left my Fluke 87RMS on it for several hours (recording) and checked min/max and they were 0.008/0.018 respectively.
Old 09-14-2017, 11:50 AM
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Quote:
Originally Posted by b00mslang View Post
When I disconnect the clock, the oscillating draw stops and I show a steady 0.007 amps. I disconnected all fuses (in tern) as well as the relays (including the ones in the engine compartment) and show no change from a steady 0.007 amps.
How did you disconnect the clock? The entire circuit, or just the clock? Because there are other interesting things on that circuit.

If the battery is good (and it sounds like it is) and you're only drawing 8-18mA, your battery ought not be going dead. Joy of joys, it sounds like you have an intermittent fault. Here today, gone tomorrow. But coming back.

You haven't yet located the relay you mentioned hearing in your first post. I'd suggest you take a relay out of your bag of spares (you do have a bag of spare relays, right?) and replace the OXS relay under the passenger seat and see if your problem goes away.
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Old 09-15-2017, 12:00 PM
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I did just disconnect the clock and there was a pronounced difference in the current draw. The slight relay/connector sound has been hard to pinpoint. I will check under the passenger seat, per your suggestion.

There is nothing worse than intermittent and/or non-repeatable faults.
Old 09-15-2017, 01:12 PM
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