Should Aux Battery be Grounded to Block? Or Fender, Frame, Etc? (2 Viewers)

[JCruse]

I'm about done with the under hood portion of my dual battery install (first ever) and I've read a lot of conflicting opinions on where and how to ground the #2 battery. Originally I was just going to the fender (like #1) with some 4awg cable (the rest is 1awg) the way the factory uses a smaller ground wire to body. Now I'm second guessing.

 

[half k cruiser]

You do want a ground to the body, just like the #1 battery uses. However, you will notice the #1 also has a ground that goes to the block. You will want to replicate this on the PS somewhere. My 2nd battery has a big ground going to the head and a smaller 4awg going to the fender.

 

[george_tlc]

^2

Block and Fender, exactly like the main battery.

If you ever have to jump start yourself, then a GOOD SOLID ground from the aux to the block will make the starter motor happier.

cheers,
george.

 

[JCruse]

Well I'm all about happy starters, so... As it is written, so shall it be done!



Seriously though, thanks a lot guys.

I was thinking of running a ground to the same bolt as #1 uses all the way around the other side. And there's actually a tab sticking off a bolt right above that. Problem is reaching them.

Oh and what about using 4 awg for the ground instead of 1 awg? I'm making the ground cables now so I could go either way. except I'd have to order some 1 awg connectors.

 

[bsmart82]

Since I don't have a winch, i just have 4 gauge going to the block, and 8 to the fender.

 

[JCruse]

OK cool bsmart, thanks. I don't have a winch either so maybe I'll just go with the 4awg since I already have one finished and parts for another. I'll go to the block with 1 or maybe some 2awg I have if theres any left after I run it to the back for the amp, compressor and inverter. Yikes! Maybe I should get more 1awg, or 1/0!

 

[bsmart82]

My blue sea acr is rated for 120 amps, so I used 4 for all my dual battery wiring. 4 will easily carry that load the short distance it's ran. I also ran 4 to the back to a blue sea fuse panel which runs my puma compressor and back up led pods. Since you are running more stuff you probably be good with the 1/0 to the back.

 

[JCruse]

Yes 4 will cause no problems, but what about voltage drop? As I understand it, the wasted battery potential that one could have had access to had it not been lost.

With a 16' 4awg lead driving 20 amps you end up with 11.77V.

 

[george_tlc]

There's a tapped and unused hole on the block under the exhaust manifold area, just look for it - so no need to fish the cable all the way to the other side of the block...

cheers,
george.

 

[JCruse]

Is it at all visible from the top? That spot would be perfect but of course in the last hour I've searched high and low for a bolt to fit Bsmart82's spot on the head, and just found one.

Is the block really that much better than the head? Aluminum vs iron? Is that it?

 

[george_tlc]

The block is better - since that is where the starter motor bolts to. Probably doesn't make too much difference.

The tapped hole is visible from below. Pretty obvious, if you look for it. That's where my aux battery is grounded - and has been for 16+ years...

cheers,
george.

 

[Racerkit]

The identical bolt hole is not visible from the top. You can only access it from the bottom. It's adjacent or underneath the PS motor mount, I think it's M10 bolt.

 

[Cruiser804]

There is a threaded hole on the PS side of the block that can be used. What they said

 

[maxamillion2345]

Mine are both tied into body, block, and frame.

 

[JCruse]

Thanks again George, et al.

I'll go under tomorrow and get some measurements.

I was going to ask about the frame. I've seen frame grounds on here, recently in fact. What's up with that? I remember the tapped hole just behind the PS bumper mount being used.

I will say this, I never thought this job would be so involving and long. But then I made it harder too by putting nylon braid on the cables.

 

[rc51kid]

I did something smaller to the fender near the overflow bottle then ran some big stuff like 2 down to the block. I think there is a empty hole behind the ac compressor under the exhaust manifolds. It might be through the oils pan and block but I can't remember.

 

[JCruse]

OK guys, I went under there on the passenger side above the tie rod and sway bar and found 3 tapped holes. Two were only about a half inch deep, if that, and the third was bigger than M10 so I have no bolts to fit it. That hole is deeper than the other two. Two were just above the oil pan line (short M10-ish and the bigger one) and the third was much higher up. The 2 small I could get an M10 1.25 to turn about 1-1/2 turns, not sure if that's because of threading or depth.

Are any of these the ones mentioned here?


(I have my 2 fender ground cables all lugged up and braided)

 

[Dave 2000]

OK guys, I went under there on the passenger side above the tie rod and sway bar and found 3 tapped holes. Two were only about a half inch deep, if that, and the third was bigger than M10 so I have no bolts to fit it. That hole is deeper than the other two. Two were just above the oil pan line (short M10-ish and the bigger one) and the third was much higher up. The 2 small I could get an M10 1.25 to turn about 1-1/2 turns, not sure if that's because of threading or depth.

Are any of these the ones mentioned here?


(I have my 2 fender ground cables all lugged up and braided)

The 1.5 turns is not enough, I would try an M10 x 1,5?

regards

Dave

 

[JCruse]

Very cool, thanks Dave.

Do you know if I have the right holes?

 

[NCFJ]

More often than not, when I am dealing with electrical issues with a Toyotas the issue is in the ground circuit. Good grounds are important. When I am building a swap truck and building a complete new electrical system i run grounds to the frame, block and body. I also run the heaviest gauge (1/0) that will take the bends. I also add at least one ground strap from block to body.

I got accustomed to running larger POS and NEG leads when I was playing with boats. The theory is, nature is going to corrode any cable so the thicker the cable the longer you have between replacements and carrying capacity remains within spec longer. Don't skimp here!

I also use a star washer between the cable and it's attachment point. This allows it to dig in to both cable and base metal for a better connection.