Why is my voltage drop so awful?

[Stalin-ohaulic]

Yes, a small difference. All my connections are soldered...
I'm talking about with the car running.

I know you're talking about with the car running, so how could the batts keep the voltage above 12.6v?

 

[hatedonmostly 5,000+ posts]

You need to listen to people and ground your rear battery somewhere else. The bed of a truck is not a good ground. Many people (such as yourself) fail to realize how important the ground is in a car electrical system. I really think this will solve the problem of the voltage difference.

Oh, I realize how important it is...but logically, if I'm not seeing any difference in voltage between the front and rear batteries, I'd think it should be a good ground. I've posted that multiple times, and no one has said anything about it being right or wrong. I'm not just trying to solve the problem, but I also want to understand it too...

I do believe that is my remaining option, so tomorrow I'll be up early to try that...

 

[hatedonmostly 5,000+ posts]

I know you're talking about with the car running, so how could the batts keep the voltage above 12.6v?

Alternator charging them?

 

[l7runner 10+ year member]

I have had seemingly "good" grounds that were actually terrible. Change your rear ground and test the resistance between that point and your front battery's negative terminal.

It would be best to grab some more wire and run it all the way to the front batt to avoid all of these issues.

 

[Stalin-ohaulic]

Alternator charging them?

They don't charge to 14.4v. They charge to around 12.6-12.8v. They can float up to 13's, but they rest and discharge most of their current at 12.6-12.8v. So, since they do basically nothing above 12.6v, I again ask how could batts help above 12.6v?

 

[RAM_Designs 5,000+ posts]

To the bed of the truck, paint sanded and bolted down. I know it's not to the frame, but my frame is rusty and I didn't think it mattered because I was getting the same resting voltage on both batteries.

Moving it to the frame could be the difference.

 

[RAM_Designs 5,000+ posts]

And x2 to the batts not helping above ~13V, anything above that is all on the alty until voltage drops to battery level.

 

[hatedonmostly 5,000+ posts]

I have had seemingly "good" grounds that were actually terrible. Change your rear ground and test the resistance between that point and your front battery's negative terminal.
It would be best to grab some more wire and run it all the way to the front batt to avoid all of these issues.

Eventually I will, if this works.

 

[hatedonmostly 5,000+ posts]

They don't charge to 14.4v. They charge to around 12.6-12.8v. They can float up to 13's, but they rest and discharge most of their current at 12.6-12.8v. So, since they do basically nothing above 12.6v, I again ask how could batts help above 12.6v?

I don't understand this...

Moving it to the frame could be the difference.

I'm kinda skeptical about it being the cure-all for all of my problems, but it's all I have left to try...

 

[Stalin-ohaulic]

I don't understand this...

LOL. This HAS to be a troll thread. Is this slappin?

 

[hatedonmostly 5,000+ posts]

LOL. This HAS to be a troll thread. Is this slappin?

No?

 

[Stalin-ohaulic]

No?

Then what don't you understand about batts don't charge to 14.4v?

 

[hatedonmostly 5,000+ posts]

Then what don't you understand about batts don't charge to 14.4v?

Shit, my bad. I know the batteries themselves do not charge to 14.4v, but the charging system runs at 14.4. A bit of miscommunication there...

So basically, if you don't have a HO alt up front, no matter how much reserve you have in the rear, you're always going to have voltage drop?

 

[9515ROB 10+ year member]

is your wire directional that might add a little resistance

 

[hatedonmostly 5,000+ posts]

is your wire directional that might add a little resistance

Nope.