[Geoff]

The factory battery-to-frame ground is there to ground components that are connected to the frame. Such as the horn button via the steering box.
If you are going to use the frame for the grd return for a trunk mounted battery, I would bolt the cable to the engine mount. It keeps the cable length short & direct.

[HWYSTR455]

Yup, I use one of the unused engine mount holes in the block.



.

[Geoff]

I am blaming my comments in post #41 on a seniors moment.....
The info in post #41 works for the battery in the engine bay.

Of course, this thread is about a trunk mounted battery...

With a trunk mounted battery, bolt the grd cable to one of the bellhousing bolts, lower bolt to keep cable as short as possible. Leave a small loop in the cable to allow for movement/vibration.

[HWYSTR455]

I'm on board with using the bell housing ONLY if you make sure the contact(s) are not compromised by paint.

An engine mount bolt/bolt (block side) hole has less chance of being compromised in that way.



.

[george kujanski]

A word about the role of a battery.. it also provides electrical noise filtering in the electrical system, but in order to do that, the cabling between the battery and the system has to be low impedance and low inductance, i.e. short and good cable. On modern systems with various sensors, the sensor grounds are right at the engine metal with short connections from the engine metal to the battery. This eliminates ground loops, i.e. where ground points have different voltages compared to the battery negative. Ideally, there should be zero voltage difference between the battery negative and any other ground.

A short story... when I worked at Motorola Charging Systems, we provided systems to Volkswagen of America. and had to meet charging specs for various models. Some had batteries under the hood, some under the rear seat, and some in the back of the vehicle. The voltage regulation was slightly different due to noise present at the regulator due to cabling differences. We proposed that a standard cable setup was to be used for testing to provide consistent results.

George

[HWYSTR455]

Good advice and understand. Quality cables are a must.

My engine ground to frame is @ 12", and my frame to batt is about the same.

My ALT ground is about 8", which connects to the same point on the engine as the frame ground.

I have a ground that goes from the frame right next to the body mount to the body, both with riv-nuts.

I have one ground from the back of engine to the firewall with a riv-nut.

One more ground goes from the frame to the junction of the inner & outer wheel housing, all riv-nuts.

Also have a core support to frame by the batt, both w riv-nuts. At the core support junction where the ground meets the core, I ran a wire over to the fender. Overkill, but fine by me.

Basically, the entire left frame rail is a ground (on the GTO). The body has those 3 mentioned ground points on the frame. Frame has been blaster and powder coated, another reason for the riv-nuts.

For the passenger compartment, the lower dash rail is the ground for everything in the dash, and from the driver's side lower dash rail mount, it's inches from the body ground-to-frame point.

All but one frame grounds are 6AWG, the ALT-block-frame-batt run is 2AWG (maybe 4AWG, would have to actually check, but pretty sure it's 2AWG).

On the bird, being a unibody, I will run a dedicated ground the length of the car on the driver's side, with 4 mount points along the way using riv-nuts. Will use the dual-cable batt terminals.

.

[Jimbobeast]

Thread update:
The starter problems in the red modified 70 Judge convertible were put on hold due to yet another set of broken pushrods in the stock Orbit Orange RAIV 70 Judge vert, ultimately traced to incorrect Comp Cams roller tip rockers that were breaking the upper balls of the pushrods. Thankfully that problem has been fully sorted and only cost 4 sets of pushrods, a new cam and lifters, new springs and pulling the motor and heads for machining. The heads were assembled by a reputable machine shop and I never imagined they could install the wrong parts.
Anyway, I cleaned all contacts for the pos and neg battery cables. I installed a 2/0 cable from the neg battery connection at the rear frame to one of the starter bolts. MINIMAL improvement.

Perhaps I should describe the entire circuit in more detail:
The battery negative terminal goes to a cut off switch in the trunk, and from there to the frame. There is now a 2/0 cable running from that frame point to the inner starter bolt. A 2 gauge ground runs from the outer starter bolt to the frame.
The pos battery terminal runs to a trunk mounted solenoid (activated by the same circuit as stock). From the solenoid a 2/0 cable runs to the Hi-torque mini starter (rated at 1.4). There is an asbestos heat shield in place (soon to be replaced by a tin shield).
Again, when cold this system spins the engine like a banshee. When warm it turns over 2 or 3 times slowly and then catches.
What would be the next logical step?

[Jimbobeast]

Here are some photos to better explain above. The third photo shows the cut off switch and the black box hanging off the battery box is the remote solenoid. The plastic box is a power connection for the stereo sub-woofer.
The last photo shows the ground to frame connection (since removed, wire brushed to extreme shininess and put back together with new dedicated 2/0 cable ground also attached.

[Bill Hanlon]

Instead of just guessing at the problem why not troubleshoot it?

Get a voltmeter. Analog (not digital) is best for this kind of test because a digital meter will be jumping around a lot. Put the meter on the lowest DC volts scale it has. You may have to substitute a long piece of wire (16 gauge is plenty big enough) for one of the leads for some of the measurements. Invite 2 friends over and get a cold 6 pack or two. Friend 1 to activate the starter. Friend 2 holds the test leads in place. You can read and record the measurements and get more beer.

1. Turn on the battery cut off switch.

2. Place the positive meter lead on the battery + post.
3. Place the negative meter lead on the positive cable at the battery.
4. Engage the starter and record the voltage.

5. Place the positive meter lead on the positive cable at the battery.
6. Place the negative meter lead on the cable at the hot side of the battery cut off switch.
7. Engage the starter and record the voltage.

8. Place the positive meter lead on the cable at the hot side of the battery cut off switch.
9. Place the negative meter lead on the stud of the hot side of the battery cut off switch.
10. Engage the starter and record the voltage.

11. Place the positive meter lead on the stud of the hot side of the battery cut off switch.
12. Place the negative meter lead on the stud of the cold side of the battery cut off switch.
13. Engage the starter and record the voltage.

..,. keep going like this through each component/connection all the way to the starter motor. You'll need to use that long piece of wire as a meter lead when testing the battery cables from the trunk to the engine compartment.

Then work your way in the ground circuit from the starter motor case back to the battery's negative post.

Look for a high voltage at any one measurement. 1/4 volt is too much if you have more that one or two like that. Fix it and try again.

Then test from the power stud on the starter to the starter's case. This will show how much voltage the starter is actually getting.

The last measurement should be between the battery's posts to see how much it is actually being pulled down while starting.

[Scarebird]

Lose the blanket and see what happens.

[Bill Hanlon]

I needed to use my (under $20 today at Walmart's online store Habotest HT113B) digital meter for something else this morning and noticed that it has a "max" button that would hold the maximum reading until reset. That would make it better than an analog meter to take the all the readings listed above except for the "across the battery posts" and the "power stud on the starter to the starter's case" measurements where your are looking for minimums instead of maximums.

I've had the meter for 6+ years and it has never failed me.

[Formulas]

I have never seen a Banshee Crank, In fact i have never seen a Banshee at all except my 10mm, must be impressive possibly like a raped Ape

[Jimbobeast]

I just got my RobbMc starter, which I will index to get the solenoid as far from the exhaust as possible. I'm gonna lose the blanket. Should I construct a heat shield for the whole starter or just the solenoid?

[Sirrotica]

Originally Posted by Jimbobeast

I just got my RobbMc starter, which I will index to get the solenoid as far from the exhaust as possible. I'm gonna lose the blanket. Should I construct a heat shield for the whole starter or just the solenoid?

The whole starter, the windings in the motor raise electrical resistance as the temp goes up. The important thing to remember is to leave at least some air gap so air can act as an insulator, and also carry heat away as it passes between the shield, and the body of the starter.

Recently I was reading up on electrical underground wiring specs as opposed to wiring that is above ground. The article explains that since the earth around the wiring acts as an insulator that inground wiring specs a larger gauge of wire to carry the same load as above ground wiring. It went on to explain that the air will dissipate heat more readily than the earth covered wiring. The additional heat will lead to voltage drops with too small of a gauge wire, roughly 3%.

[HWYSTR455]

I've never had to use a shield or wrap with a mini starter. The draw is less than an OE delco starter, due to gear reduction, that's one of the points of using one.

One thing to look out for tho is you need to make sure the positive post on the starter/sol is at least an inch from any ground, and use a boot if possible. Block and header are common arc points.

The initial hit when you turn the key can jump to a surrounding ground. Have personally experienced this. Everything was 'right', but with minimal heat up, it would arc, and not spin as good. Had a friend watching when it happened, he saw it arc, and then I found the post was arcing to the block, paint was burned off.

For me, it was the terminal body on the 'battery' wire the boot I had didn't cover the end of the terminal. Now when I put the terminal on the post, I position it so it points forward, due to the type of headers I have, and gives plenty of space. I remember one of the mini starters I had the post was on the block side, and the one I have now is on the header side.

You can also bend the end of the terminal to gain space, in one direction or the other.

I always use a remote starter sol now too, not sure how much that helps, but I sure feel more comfy not having the wires run hot down there while engine is running. I move the charge wire too, obviously.

EDIT: I also use a ram air harness battery tube, and run it on the rear of the driver side head pointing down & forward. You can route the wire towards the starter on the block side.

.

[HWYSTR455]

Here's a crappy pic of what I'm talking about, it's a little hard to make out some of the surrounding areas & clearances, but I wasn't going to jack it up and slide under it to get a better pic.

The Yellow arrow is the block pan rail.

The Red arrow is the ram air battery tube.

The Blue arrow is a header tube. (manifolds may have more clearance).

So this obviously is a mini starter that the batt post is on the block side, so had that backwards when I mentioned it before.

When using the batt tube that runs between ports 5 & 7, be it manifolds or headers, you're inclined to orient the batt cable pointing up, and that makes even closer to the pan rail, and you can see how not having a end of the terminal insulated could be a problem. And you can only bend the terminal towards the starter sol so much, which isn't enough.

Also added a pic of the ram air tube.

EDIT: With the batt tube on the lowest head bolt hole on back, you have room to 'swing' the tube to point more on the block side, or the header/manifold side, depending on your setup, to orient the batt cable to get best clearances.

.

[Jimbobeast]

Is it possible for the trunk to starter positive cable to be too big in diameter? My neighbor, a die-hard drag racer, uses trunk mounted batteries all the time and he says too large a starter hot cable will decrease the current at the starter. Is he correct?

[Jimbobeast]

Bill Hanlon's advice solved the problem. With the Orbit Orange Judge sold, attention was turned to the red Judge convertible. Armed with my trusty voltmeter I found the following:
Voltage across battery terminals 13.1 v
Battery pos to near side of neg cut-off switch 13.1 v
Battery pos to far side of neg cut-off switch and frame 13.0 v
Batt neg to input side of trunk mounted starter solenoid 13.1 v
Batt neg to output (to starter) side of solenoid when cranking 8.9 volts!
Now we're onto something.
Since the battery is in the trunk, the start wire from ignition switch, through 50 year old wiring and the neutral start safety switch to solenoid was reading only 7.8 volts instead of 12.
With the solenoid getting lower voltage, the contacts were not closing completely and the output to the starter was miserable. Just to make sure I jumped a wire from the battery pos to the solenoid and presto - 12.9 volts out to the starter. Problem found! I had previously tested the mini starter and it tested perfect.
I then fabricated a relay using the blue wire from the ignition switch to activate the relay and connected the relay input to the battery positive side of the solenoid and the output to the solenoid "I" terminal.
I am overjoyed to report that any and all hot start problems are solved. I never got to remove the heat blanket on the starter. Now I can't make it hesitate on hot starting and she cranks in all situations like the proverbial banshee (a supernatural female spirit in Scottish folklore known for her high pitched wail. Also a Pontiac concept car from 1964 that was decades ahead of its time. I got to see it once in an old barn here in Florida).
Life is good and I'm driving the heck out of her now.
Thanks to all who commented.
Also, I found out that because of its design my Robb starter cannot be used with a remote solenoid (my starter has the solenoid "I" terminal and the battery terminal connected with a bar since my remote starter solenoid is in the trunk and the starter pos wire is only hot during cranking). It is a beautiful and expensive unit that now will just sit on the shelf. Oh well.

[johnta1]

Why can't you do the same thing on the Robb starter?
(I don't have a Robb starter to know why it can't work)

[Bill Hanlon]

Glad I could help.