Parasitic Draw Test - Electrical issues...

Tom P

Tom P

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Hi there,

I tested my electrical circuit tonight due to suspected drain on my battery. I found 3 circuits causing issues totaling 220mA draw which I understand to be more than 4x the so called "limit" of current draw to keep a battery healthy.

Fuse #4: Clock circuit - I expected this but the draw is 60mA on a recently freshened up clock by Palo Alto Speedometer. It's keeping great time now with a new quartz movement but the draw on this circuit seems excessive!

Fuse #5: Cigarette Lighter - I have my constant power to a new radio coming off of this circuit which may not be best however I suspect that to be causing the drain. At 40mA, this too seems high.

Headlight Switch circuit: I added a fused low beam beam relay to my headlight switch circuit along with new wiring for small city lights. My switch now operates cooler than ever with brilliant light output however something is drawing 130mA on this circuit which is concerning.

Any ideas or suggestions for next steps to resolve these issues - especially the headlight circuit (lots of sub circuits route from that switch!)? Your input is appreciated as always...

Thanks!
 
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Tom, please keep posting on this issue as I also have drain(s) on my battery and my battery goes dead in about 5 days if I don't disconnect it. I have not looked into it as deeply as you seem to be doing. I was thinking of putting in a discrete battery shut-off somewhere easy to reach because it is a bit of a bother.

Thanks
 
Tom,

A 130mA draw on the headlight circuit seems very excessive. I would expect to see no draw at all when the lights are off. Is it possible that the relay coil is active when the lights are off? Maybe you could look at the draw with the relay installed and removed?
 
Many newer radios have a display the operates even when switched off. They also will maintain charge in the capacitors when power is available. I would wire the radio to a circuit that is only powered when the ignition switch is on, even if you have to create a separate new one.

As noted, it seems like there is something wrong in the light circuit. That is way too much current draw.

Old analog clocks often are a problem. I never did resolve the clock drain on my old Saab, and bought a battery tender instead.
 
Special thanks to m_thompson for his suggestions on my headlight circuit - it turned out to be the relay. I simply unplugged the current relay and replaced it with a new one and that solved the problem. Headlight circuit draw is now zero!

Moving on to cigarette lighter next - will remove the radio from that circuit to see what happens to the current draw...

Thanks for the ideas.

Tom

PS: I'd be curious to hear about other current draw findings on our clock circuit. 60mA still seems too high to me. This is a simple test if interested to perform it yourself and can write up the steps.
 
m_thompson said:
Tom,

A 130mA draw on the headlight circuit seems very excessive. I would expect to see no draw at all when the lights are off. Is it possible that the relay coil is active when the lights are off? Maybe you could look at the draw with the relay installed and removed?
Click to expand...
^
This. But usually the relay clicks on and off as it begins to fail. If the relay was closed all the time, you'd eventually fry the headlight switch.
 
Somebody else is going to have to jump in here; my clock is not working and right now its pretty far down on the list of things to get after.


Tom P said:
Special thanks to m_thompson for his suggestions on my headlight circuit - it turned out to be the relay. I simply unplugged the current relay and replaced it with a new one and that solved the problem. Headlight circuit draw is now zero!

Moving on to cigarette lighter next - will remove the radio from that circuit to see what happens to the current draw...

Thanks for the ideas.

Tom

PS: I'd be curious to hear about other current draw findings on our clock circuit. 60mA still seems too high to me. This is a simple test if interested to perform it yourself and can write up the steps.
Click to expand...
 
I have some readings I did earlier I could share from when the car was in "sleep" with battery connected.

Conditions:
Stock csi
Blaupunkt Bamberg radio.
Clock working fine
Multimeter of better quality

Total current at battery = 30.5mA

Fuse #4 - Clock circuit, interior light = 12.8mA
Fuse #5 - Cigarette Lighter, radio = 7.2mA
(All other fuses shows zero)

I guess the rest 10.5mA to summarize 30.5mA is drain from generator or starter.

Note. I noticed that with open door only the interior light relay was taking an extra 110mA (lights in off position) and not supported from any of the fuses 1-10 for some reason.

Cheers!
Stefan
 
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Fuse #4 on the same circuit as the clock carries the glove box light.

I bet that half the coupes here have that light always on, another half always off, and the third half works as expected.

It is just very hard to diagnose...
 
its easy to diagnose - turn your smart phone on - in video mode ... put in the glove box and close it. then watch the video. works in the trunk and under the hood too.
 
Confirming glove box light is off. Thanks for that suggestion Arde.

Stefan, thanks for your data. Your data is what I had expected to be considered "normal" and getting down under 50mA is my goal, ideally lower.

Update on the relay that I swapped out - I compared the good one against the "bad" one and found that they both still work but they they have a different pinout. Simply pin 30 and pin 68 are swapped in position between them which created a constant closed state based on how I wired it. Had I known, I could have just flipped the wiring between those pins to correct the problem. I got lucky by trying a different relay altogether. Little did I know that one had the different pinout configuration I needed.

I compared the rest of my relays that were lying around and a majority are one way and a handful are the other. It was simply a rookie mistake on my part but live and learn I guess - that's what this is all about...
 
I think any car not working correctly on original can relays should check their pin configuration, quite possibly these were changed over time as availability of correct relays changed.

Tom P said:
Update on the relay that I swapped out - I compared the good one against the "bad" one and found that they both still work but they they have a different pinout. Simply pin 30 and pin 68 are swapped in position between them which created a constant closed state based on how I wired it. Had I known, I could have just flipped the wiring between those pins to correct the problem. I got lucky by trying a different relay altogether. Little did I know that one had the different pinout configuration I needed.

I compared the rest of my relays that were lying around and a majority are one way and a handful are the other. It was simply a rookie mistake on my part but live and learn I guess - that's what this is all about...
Click to expand...
 
rsporsche said:
its easy to diagnose - turn your smart phone on - in video mode ... put in the glove box and close it. then watch the video. works in the trunk and under the hood too.
Click to expand...

Bummer, I hired a guy from Cirque du Soleil to get inside the glove box and tell me.

I didn't quite have the cash then so I kept him inside and will only let him out when I am ready to pay.
 
Steve, that's good advise for all and was my issue exactly. I returned the orginal can relay to the socket since that pin out is correct for original wiring. The more modern relays have changed their 30/86 pinout and will cause issues like I experienced.
 
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