Technical Parasitic Drain

I recently bought a 39 deluxe, fatman chassis, 400sbc, etc. It has a new painless wiring kit. I am trying to locate a parasitic drain and not the best at electrical. I did the test light on the battery and the only time it dimmed when the fuse was pulled was the electric choke circuit (demon 625). The ground wire on the choke is attached to the choke housing screw. I tired to ground elsewhere with the same results, dimmed test light. However, if I put the positive wire to the chassis, the test light is bright, what's going on here? Motor is grounded to frame and firewall.

Thanks for any insight

 

is the choke wired to "switched" power, or does it get power full time?

 

^^^^^yep- is the choke wired to a source that is hot all the time or only hot when the key is turned on.

 

I would assume full power, it is wired directly to the painless fuse panel

 

It should only have power when the key is in the run position.

 

Why would painless have this fuse always be hot if this is an issue. I have read of people wiring directly to alternator with mixed views, I have single wire alt.

 

Did that several years ago, on an OT MK VIII, I had a parasitic loss that was so low that it wouldn't light up the bulb in series with the battery ground cable, but it would drain the battery if the car wasn't driven at least every once a week.
Called a friend who was a GM "World Class" certified tech and he showed up with a first rate Volt/Amp multi meter and a pigtail with a 5 amp fuse in it. With this it showed a very small drain of less than a quarter amp with all accessories either off or disconnected thayt went away when we disconnected the main battery wire to the alternator. Turned out to be partially closed diode in alternator diode bridge allowing current to bleed thru.
But I would check out that wiring on the electric choke first of all.

 

If your battery could talk

 

Disconnect it and see if it still drains...you could bypass it running a wire to a keyed on circuit.. chokes do not pull a lot of power..

 

On newer cars, an amp draw of .100, less than 1/10 of an amp,is usual.

 

The choke heater should only be powered after the engine is running. Often it is done through an oil pressure switch that closes when there is more than 10 psi of oil pressure. The heater is to allow the choke to open as the engine warms up. With constant power to the choke heater, the choke won't be closed when you try to start the engine.

 

I use a main battery switch, under my seat, just in case. Disconnect everything in one go.

 

^^^^^ Does everything come back to life when switched back to on?

 

There’s not much in the Painless manual to go on here. The circuit list shows “choke” here:



but doesn’t note it as being switched or constant. I’d expect it to be switched, though. You don’t want the choke heater constantly powered.

Here’s the schematic:



Is your ignition switch set up correctly?




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Good call!

 

Clock? Radio memory? Alarm? D.

 

>>> I have single wire alt>>>

These often have a small drain because their internal voltage sensor isn't switched. Jack E/NJ

 

Thanks for the responses, Once the garage warms back up I'll study the diagram and get back with findings or questions

 

I'd make sure that the choke wire was plugged into the correct pin in the fuse block if it indeed has power all the time.

 

Painless has the block pre-terminated, so unless it was a manufacturing error, that shouldn’t be it.



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Always make sure your working with a good battery, that's step 1. Can we assume your battery is in good working condition, charges and holds charge...

How are you charging it back when it dies? Battery 1st.

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It's easy enough to disconnect the choke heater wire from the choke and check to see if it has an electric charge on it with ignition switch off. If it's hot, then there's your problem. How complicated is that? If it's not there, then you're going to have to do as I previously suggested and use a meter, rather than a damn light bulb, to test further.

 

^^^ what he said.

 

I pulled the heater wire, set multimeter to 20 on the dcv setting. Got a reading of 12.03 with ign off. According to the diagram it is wired correctly, does this mean I need to look into ign wiring or rewire the choke somehow

 

In a word:YES

 

Painless has a couple of techs that answer questions like this. You may find out that whatever circuit the choke draws power from is connected to the source incorrectly.... i.e. ignition switch.

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Are any other circuits you’d expect to be switched, like the radio, also hot when the key is off?



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I don't have a radio or clock, just necessities, gauges, fuel pump, fan, etc. I didn't check any of those as the dummy light only indicated the choke circuit when fuses were pulled

 

Just checked a few things, seem like everything is hot, fan, fuel pump, turn signals, headlights, cig lighter, gauges, that's all I have to physically turn on