1985 QV Parasitic current draw

My first guess is the clock or radio. They may have inline fuses, but I don't know for sure. IMO, if there was a broken wire covering, it would short out quickly with sparks and burning if the break was significant. I think you have an excessive amp draw by something like the clock, but not enough to blow a fuse. I am sure a few others may have ideas, but look to see if there was something added as aftermarket that may be causing drain.

Sorry, I couldn't help more. You may have to disconnect a few things like the clock, to see if the power drain goes away.

 

The clock is about the only thing drawing current with the ignition off so that’s a good suggestion, though if you have an aftermarket amp or radar detector installed that might be another place to look. A glovebox lightbulb being on is enough to kill a battery which makes me suggest looking at your dome light to see if you have it switched on? They’re so dim even if you turn it on on purpose it’s hard to see! That would also suggest looking at your footwell lights or the light on your door that comes on when you open it? If the switch doesn’t shut it off when you close your door you wouldn’t see it if it was on. Just a few thoughts for what it’s worth!

 

As asked, is there an aftermarket radio or an alarm installed? If so, it's the most likely source of the problem. ANY aftermarket items are notorious for rapid battery draining, often due to poor installation procedures. Aftermarket alarms often cause such problems even when properly installed. My advice is that if you have an alarm, remove it!

 

A whole bunch of stuff is unfused. At the bottom of the relay panel is the white plastic 4-way connector (this one just happens to have a frazzled big red wire, but is the only photo I have):

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The big red wire at the 4-way connector is +12V coming directly from the battery that then gets split off to the fuseblocks, etc. (but not the alternator). Easiest thing to do would be to disconnect that big red wire from the other wires at the 4-way connector and remeasure the parasitic current:

If it goes to zero = problem is something inside the cabin

If it stays high = probably the alternator internals need repair

Likewise, there is a large red wire going from the post on the starter solenoid with the +12V battery cable going to the alternator -- if you disconnect this cable (either at the starter solenoid end or the alternator end), and:

1. the parasitic current goes down to a reasonable value = bad sign for the alternator internals.

2. the parasitic current stays high = alternator probably OK.

edit: If your + battery cable terminal has a super-huge red wire (going to the starter) and some still big but smaller red wires bolted to it, you could unbolt these cables and make the same tests (you won't know which is which, but by measuring the voltage on the big red wire at the 4-way connector (without needing to disconnect it) you can determine that one. Of course, if all the wires are cast into the + battery terminal, this idea is out.

 

You said the clock is not working so maybe the internal motor seized and it's just making heat/noise at this point. That would definitely pull some amps (compared to normal operation which should take much less current). I would really expect the clock to be downstream of some type of cabin fuse, but it would be worth looking through the wiring diagrams to know for sure. Steve's suggestions above are a great way to quickly sort out possible issues.

 

Soldier on - I look forward to your finding the gremlin!

 

I had a similar issue in a car. I was actually able to find a shorted wire using a thermal imaging camera. With the car cold, you can look over the car and find hot spots. It may help you locate a component that is not working right or a shorted wire.

If you have access to a thermal camera, it may be worth a shot.

 

Not really helpful at this point, as you've determined this is not the cause... But for others' reference, the clock is indeed fused.

The only stock components that I can think of that have a direct unfused line to the positive battery terminal are the starter and the alternator.

 

Bad diode in alternator

 

Yup. Seen it many times.

 

4.5A is 54 watts. That is a significant draw and should be generating heat. I would start with the diode as previously noted. Keep your ground disconnected until you figure it out.


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400mA is a lot of quiescent current. That is a 30 Ohm load at 12V. I don't think dirt/grime would cause that low of a resistance. Perhaps the key warning buzzer is being activated, is defective and not sounding an audible alert? Even 5mA seems a lot to me for a car of that vintage. Back in '85 there was not that much electronics that needed to be kept alive continuously. I would expect the draw to be closer to 1mA. Not that I ever measured a QV current draw...

 

"With the key out, it drops to 0.005 amps."

Five milliamps is an excellent reading. Don't leave the key inserted!

 

I replaced my mirror switch once. It worked great, and I went in the house. The next morning, the battery was completely dead from a parasitic drain.

Put the old switch back on, never happened again.

 

FWIW, I don't know if this is true with these cars since I never checked my '89 328's parasitic draw with the key inserted, (four milliamps with key out) but many cars activate some circuits when the key is inserted in the ignition. If I was where my car is, I'd check both scenarios out of curiosity. But we're not and won't be for six months. Maybe some folks here could test that and report!

 

Ferrari did'nt put a cut off switch for nothing....I cut my power every time a put my car to sleep....even after 6 months of absence, switch it on and the car starts right away.

 

Not aware of a cutoff switch. Are you referring to the negative cable disconnect? In any case - I do the same, disconnect the battery for long term storage. I do not use a charger, smart or otherwise.

 

Did USA cars have a buzzer circuit when the key is in the ignition and the door is open? Seems like that was really popular in the '70's and 80's, must have been a federal mandate. In any case, if it did then there's a switch in there for just having the key inserted.