Neg Batt Terminal Spark

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70DusterBob

70DusterBob

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I know it is normal for a neg batt terminal to spark a tiny bit when you connect it. But mine kinda sparks more than that. I have an MSD 6AL, and a Derale fan system that has a controller that turns the fans on when the radiator gets hot even if the key is off. Is it possibly one of these?

I called Derale, asked if their system would make my terminal spark, he said, "It is normal for a terminal to spark when you connect it.... That is not what I asked. I asked if their system would cause a spark when I connected the terminal.

Anyway, I thought I would ask you guys. Is there anything else that would normally cause a sort of hotter than normal spark when connecting the neg terminal with the pos already connected? I had a lot of work done to it recently.
 
Don't depend on "looking for a spark." Take a test lamp and put it in series with the battery ground. If it lights, "judge" how much current is flowing. If it seems to be not much, set your multimeter up for the highest current (amps) scale and wire it in. There should normally be very very little current draw, a few milliamps
 
I do have a multi meter. I'll go ahead and put it inline to see what it says and get back with you guys. May be a week though.

Thanks,
Bob
 
You could also pull the control fuses for the 2 systems you referenced and see. The fan control more than likely is live to retain the settings if it’s digital.
 
Lets hope your right that the fans are drawing power. I disconnected it for now, but it seems that since they sense the temp of the radiator all the time that they are probably it.
 
You guys may or may not have caught the idea that when checking draw (current) I ALWAYS RECOMMEND STARTING with a test lamp. I actually have 3. A stop/ tail light socket/ pigtail, a small incandescent test lamp "from the old days" and an LED tester

I always start out with a "big" wattage bulb---a stop lamp

!!!WHY!!! ???

WHY is this important?

It's because old school multimeter current/ amp scales were not well protected from damage, AND modern meters like Fluke us AND EXPENSIVE FUSE for protection. So every time you waste that big fuse, it is EXPENSIVE


Using first a large wattage lamp and next a smaller test lamp can, with practice, give you "some idea" of the draw you are dealing with. A stop lamp that lights to nearly full brilliance indicates a fairly large draw. You can experiment by putting the lamp in series and then energizing various loads such as dome lights, brake lights, etc to see

Bear in mind that current measurements are in SERIES and if you happen to have something turned on in the car that exceeds your ammeter capacity, it is going to peg/ damage/ flame out an old school none or poorly protected one, or it is going to waste the expensive fuse in your fancy new digi meter

If I had a buck for every Fluke meter fuse I've blown over the years.........I'd have about 10 bucks LOL
 
Put the multi meter to AMPS and measure the draw most are good up to ten amps which would be a very big spark!
 
Well, I am not an electral engineer, but I put the neg lead on the neg terminal and the red lead on the positive terminal, got 12.56 volts. Fair enough. But then I kept the neg lead on the neg terminal and the red lead on the negative clamp while it was disconnected and guess what, it reads 12.55 volts. I put the red lead on the alt pos, neg on battery neg, 0 volts. Put the red on the fan relay, neg on batt neg, 0 volts. What the hell?
 
OK you have a draw. See what amp the draw is then start pulling fuses that ae above that draw and start to find out which circuit is drawing it.
 
halifaxhops said:
OK you have a draw. See what amp the draw is then start pulling fuses that ae above that draw and start to find out which circuit is drawing it.
Click to expand...

2.20 Milli amps. Fuse box is a nightmare. Is 2.2 milli amps big or small?
 
See what you get in voltage first on the positive side then the negative. If you are getting voltage on both sides pul the relay plug and see if the draw went away from the battey. Radiator fan relay?
 
halifaxhops said:
See what you get in voltage first on the positive side then the negative. If you are getting voltage on both sides pul the relay plug and see if the draw went away from the battey. Radiator fan relay?
Click to expand...

Yes the radiator fan relay has 12.56 on both sides of relay. Pull one side or the other? Pos has vacuum cap to keep from accidental connections
 
Can you take a picture? And pull the relay did the draw go away?
 
Look you can't just stick your probes on stuff. You have to do this RIGHT

You sure you know how to set your meter up for current? This varies meter-to meter. If you post a photo of the meter and or the brand/ model number we can sort that out

There is only ONE way to measure current draw PERIOD

You REMOVE the negative cable from the battery. You connect one probe to the NEG battery clamp and the remaining probe to the battery NEG post

If you are actually really only measuring 2.*** milliamps that is a VERY small draw.
 
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70DusterBob said:
Well, I am not an electral engineer, but I put the neg lead on the neg terminal and the red lead on the positive terminal, got 12.56 volts. Fair enough. But then I kept the neg lead on the neg terminal and the red lead on the negative clamp while it was disconnected and guess what, it reads 12.55 volts. I put the red lead on the alt pos, neg on battery neg, 0 volts. Put the red on the fan relay, neg on batt neg, 0 volts. What the hell?
Click to expand...

He did that already.
 
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