Timing light battery cables not long enough
Thread Starter
Racer
Joined: Oct 2007
Posts: 270
Likes: 0
From: Chapel Hill NC
Timing light battery cables not long enough
So, is it OK to hook them up to a separate stand-alone car battery???
or, Can you hook the light up to a set of booster cables in order to reach the battery?
or, Can you hook the light up to a set of booster cables in order to reach the battery?
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,376
From: At my Bar drinking and wrenching in Lafayette Colorado
Just clip them onto the alternator - red timing light wire to the alternator output post and the black one to the alternator ground lug or case.
Instructor
Joined: Jun 2010
Posts: 130
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From: Summerville SC
I've used these retractable test leads for a lot of long range electrical issues, but the alternator trick also works well. I've not used an external battery.
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Instructor
Joined: Jun 2010
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i ran a coil of 12g wire from the terminal like a jumper worked fine for me but my windsheild is out so i went straight threw and not around. i tried the alt to find out i got a faultly output seems someone tried to be the incredible hulk and tighten the nut and it just spins but ya thats another project for me.
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Where is the problem ?
If you use a separate battery, all you have to do is just to connect its negative terminal to the car ground ( chassis, engine, it doesn't matter ).
You can even use any 12V power supply ( rectified and filtered ) the same way.
If you use a separate battery, all you have to do is just to connect its negative terminal to the car ground ( chassis, engine, it doesn't matter ).
You can even use any 12V power supply ( rectified and filtered ) the same way.
Pro
Joined: May 2001
Posts: 608
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I use a spare set of jumpers here. Its how I've done it for over ten years, and it works for me, even if using the alt. is a smarter method. I don't mind the extra cabling, usually when I'm playing with the timing, I've got a mity-vac hooked up to the vac advance, and a vacuum gauge or two connected to the carb/intake - so its already a spider's web of extra hoses. I also like the way the cables are further away from the belts and pulleys.
I keep the jumper cables in an old gym bad to keep 'em clean and roll'd up nicely. I also have an old, broken ice scraper in the bag. I hook up one end of the jumpers to the plastic scraper to keep the leads from touchin, then I hook up the other end to the batt. terminals. I then connect my timing light to the leads on the scraper. No sparks here.
I keep the jumper cables in an old gym bad to keep 'em clean and roll'd up nicely. I also have an old, broken ice scraper in the bag. I hook up one end of the jumpers to the plastic scraper to keep the leads from touchin, then I hook up the other end to the batt. terminals. I then connect my timing light to the leads on the scraper. No sparks here.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
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From: St Louis MO
And that is the key - if a separate battery is used, that battery must be connected to car ground and you'll be fine. But I answered the question assuming that the separate battery had no connection to anything except the timing light. And if you do that you will probably get a shock from the timing light as it is connected to the spark plug wire. If the timing light is well insulated, you might not, but it is still important that the separate battery is connected to car ground.
I've got a plastic one now. 
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
And that is the key - if a separate battery is used, that battery must be connected to car ground and you'll be fine. But I answered the question assuming that the separate battery had no connection to anything except the timing light. And if you do that you will probably get a shock from the timing light as it is connected to the spark plug wire. If the timing light is well insulated, you might not, but it is still important that the separate battery is connected to car ground.
I absolutely agree !
Drifting
Joined: Nov 2002
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From: Shore NJ
Melting Slicks
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From: Vero Beach FL