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Is this a short?

jjoerger

jjoerger

Veteran Expediter
Owner/Operator
US Army
Is this a short?
I was testing my batteries with a volt meter this morning and discovered something odd. With the ground cables removed from the batteries I tested between the negative battery post and the fuel tank and got a reading of 12.8 volts.
I repeated this test at several other points, steps, frame, etc., and got the same reading. With the ground cable connected to the batteries the reading is 0.00 on these same points.
 
Slo-Ride

Slo-Ride

Veteran Expediter
I'm thinking by disconnecting the battery ya just lost your frame ground and completed it with your tester. But like Murray said, Wait for the Master Electrician to chime in..
With electricity what I cant see, I am scared of..:cool:
 
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xiggi

xiggi

Veteran Expediter
Owner/Operator
Murraycroexp said:
Or call him on the 9-line.
999-999-9999

Oh wait, that won't work. My bad.
Click to expand...

No its turtle it would be 999-999-9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999. :)

Sent from my Fisher Price ABC-123.
 
Turtle

Turtle

Administrator
Staff member
Retired Expediter
Slo-Ride said:
I'm thinking by disconnecting the battery ya just lost your frame ground and completed it with your tester.
Click to expand...
Sort of. Measurable volts is a measure of differential. When the ground cables aren't connected and the circuit is completed with the tester, the electricity flows through the circuit. When the ground cables are then connected and the current is flowing through that particular circuit, the electricity won't re-route itself to also flow though the tester, unless the tester draws enough power to force a different path for the current.

But like Murray said, Wait for the Master Electrician to chime in..
With electricity what I cant see, I am scared of..:cool:
Click to expand...
Electricity confuses me. I'm just a battery guy.
 
P

purgoose10

Veteran Expediter
You have alternating current so anytime the circuit is connected your going to get a reading. When you connect the ground you can get an amps reading from the positive as well as the negative because the circuit is completed.
 
xiggi

xiggi

Veteran Expediter
Owner/Operator
I thought batteries were direct current?

Oh maybe that was in reference to turtles electricity comment, my bad.
Sent from my Fisher Price ABC-123.
 
P

purgoose10

Veteran Expediter
xiggi said:
I thought batteries were direct current?

Oh maybe that was in reference to turtles electricity comment, my bad.
Sent from my Fisher Price ABC-123.
Click to expand...

Batteries are but when it goes through the grounding and back to the battery its alternating. It comes from the Alternator. If you touch your plugs and get shocked that's direct and it's also the worst kind of shock. A direct shock will stop a heart faster than alternating. Doesn't make sense does it??
You can check your amps on ether the positive side or the negative. You can check the amps going and coming from any wire in your truck (head lights etc.). Helps you find out if your grounds are bad. When I buy a gas powered vehicle I always change the main current wiring to a larger scale and use better cable such as Tinned marine cables. I run new and larger cables from the Alternators and Battery's. If you check your amps now and again after the winter you will see you dropped amps and current. A truck looses 75% of it's ground the first year. It also effects your fuel mileage because the current is reduced to your plugs and your Alternator is working harder. That's gas or diesel engines. If you run a Cat or Detroit you can run a 4OT cable from your grounding stud on the frame to the side of the block, then from that bolt to the head notice a distinct difference in your power, torque and fuel mileage. Sounds crazy? Been doing it for years and never had a failure.
Every block has threaded holes in the block. Use a 10 mm SS Bolt. Regular bolts have Zinc and doesn't conduct electricity well, while SS will and last longer. Never connect to a bolt that's black, they will stop the current. Try it you'll be amazed.
 
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P

purgoose10

Veteran Expediter
jjoerger said:
Is this a short?
I was testing my batteries with a volt meter this morning and discovered something odd. With the ground cables removed from the batteries I tested between the negative battery post and the fuel tank and got a reading of 12.8 volts.
I repeated this test at several other points, steps, frame, etc., and got the same reading. With the ground cable connected to the batteries the reading is 0.00 on these same points.
Click to expand...

See if I can explain this. Everything is acting as a ground when your ground cable is disconnected. When it's grounded by the cable from the battery it's current is broken or returned to the battery. When you have a bad ground on any appliance it acts in the same way and that's what kills the appliances, radios, TV's because it's getting direct current with no way to relieve it. Another words the current has to keep flowing to work properly. You get to much positive voltage and it make everything heat up. In an engine a larger grounding cable relieves the engine of static electricity from the cylinders and head. Detroit and Cats use a different type head gasket so electricity that's called perpetual electricity gets trapped and causes everything in the engine to work harder. I know I'm crazy, but it does work. If you look at your ground right now your cable is going to your starter. Well that's enough to get the engine running but efficiency is out the door. Manufacturers don't care they just want it to start and get out of they're hair. Grounding cable is to expensive for them to worry about. Engine are tested at the factory before they are installed in vehicles on a dyno. That's where the term ground horse power came from. I know I lost you.
 
Murraycroexp

Murraycroexp

Veteran Expediter
I'm gonna do it!!! I have an Express with a 4.8 that's "getting a little tired". 374,415 on the clock. It's plenty strong enough for everything I ask it to do, but every little horsey I can muster up would probably extend its life a little more.

So, replace the negative cable with 4 gauge "tinned marine cable" (whatever that is) and run two grounds to stainless bolts on the engine and the frame?
Am I understanding it?
 
jjoerger

jjoerger

Veteran Expediter
Owner/Operator
US Army
I tried the same ting on my tractor and got the same result with the key on. Guess it wasn't a short after all.
Thanks everyone.
 
M

mjmsprt40

Veteran Expediter
Owner/Operator
purgoose10 said:
Batteries are but when it goes through the grounding and back to the battery its alternating. It comes from the Alternator.
Click to expand...

I worry about you guys. The very thought of you around the battery electrical system......

The alternator produces alternating current, to be sure. Your vehicle can't use AC current, so it's piped through a bridge rectifier that changes the AC to DC. At the output terminals, you're getting direct current. The rectifier-- actually the diodes-- are built in to the alternator so you replace the whole business as a unit.

At the battery, you're measuring direct current because that's the only kind the battery can produce and/or handle. When JJ dropped the ground connection from the battery, he broke the ground circuit. When he put the leads of his tester on the negative terminal and any chassis ground, he re-connected the ground through his tester and the voltage he measured was the voltage that something like his clock, or the computer's "sleep mode", or any device he may have plugged into the power outlet may be using. Connecting between the fuel tank and the negative battery terminal has nothing to do with where the voltage is actually being used, it only completed the chassis ground connection for this purpose. Measuring 12.Something volts is completely normal, given the power vampires that exist in automotive circuitry.
 
Murraycroexp

Murraycroexp

Veteran Expediter
So he just "completed the circuit". Simple a that. Clock, computer, phone charger, memory module, gumalator valve, etc pulls voltage so it read voltage.

10-4.
 
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