Trunk Battery Relocation Thoughts

screamin gt · May 5, 2016

I moved my battery to the trunk a few years ago but have had some issues since then. I think I need to find a better ground but to be honest without tearing things apart I don't even recall where I ground it. I want to say I just grounded it to a convenient place on the floor pan somewhere around the passenger side wheel well.

It works and charges etc but another issue I'm having is at night on a bumpy drive, the headlights dim sometimes and it doesn't seem to go up with throttle if anything hitting the gas actually makes it dim even more. The battery light comes on as well when this happens.

Another unrelated issue I'm having is the interior light staying on for extended periods. Kind of random. I figured due to a bad door sensor but I can't seem to find it.

Noobz347 · May 5, 2016

There's a lot going in in your original post.

You may be right and this may be related to your battery relocation. Hopefully you used heavy gauge wire and that's not a consideration. Next would be to run 1 or two more grounds. One to the block and one to some other solid portion of the chassis like a frame-rail or sub-frame connector and maybe even a third to the ground post of the starting solenoid.

This may still not fix your problem. Under normal circumstances (battery in stock location) your symptoms sound like a blown fuse or a disconnected (incomplete) ground for another electrical device (under the dash for instance). If this has happened, then you have electronics that are finding unintended pathways to ground.

If it were me... here's what I'd do:

Paragraph 1 and then start troubleshooting wiring diagrams for the items that you listed are malfunctioning.

The possibility exists that paragraph 1 and 2 are both true so eliminate #1 first.

screamin gt · May 6, 2016

Noobz347 said:
There's a lot going in in your original post.

You may be right and this may be related to your battery relocation. Hopefully you used heavy gauge wire and that's not a consideration. Next would be to run 1 or two more grounds. One to the block and one to some other solid portion of the chassis like a frame-rail or sub-frame connector and maybe even a third to the ground post of the starting solenoid.

This may still not fix your problem. Under normal circumstances (battery in stock location) your symptoms sound like a blown fuse or a disconnected (incomplete) ground for another electrical device (under the dash for instance). If this has happened, then you have electronics that are finding unintended pathways to ground.

If it were me... here's what I'd do:

Paragraph 1 and then start troubleshooting wiring diagrams for the items that you listed are malfunctioning.

The possibility exists that paragraph 1 and 2 are both true so eliminate #1 first.

Thats very helpful, thanks. Yes I used the wire recommended for doing the relocation, I believe 1 gauge or something. Like I said it was a long time ago so my memory is vague but I know I used the right size wire. I did a lot of research on it at the time.

My only thought is how do I run more than one ground? Is there some sort of different terminal end I need to buy? To be able to run big ground wires to multiple locations? The terminal I currently have on there has some ports so to speak (like for accessories) but they are for smaller gauge wire not the same as the huge one.

Noobz347 · May 6, 2016

Locate both ends of your current ground. One will be at the battery terminal and you'll need to discover what you did with the other.

Clean both and reinstall. You will need two new lengths of cable with terminal ends on them. Run additional grounds (they don't have to be nearly as big). In the end, you will be grounded in 3 places. The chassis, sub-frame, or sub-frame connectors, the engine block, and the negative side of the starter solenoid.

Get terminal ends and ground cable appropriate to the size. 1/4 or so ... shielded. Get a tube if dielectric grease to coat your terminal ends and connection points. All grounds should be solid. Solder the ends if you have the means to do so. Use a real terminal end crimper if you don't solder. You need good, clean, metal on metal contact for each ground. Use a wire brush to clean up the old ones.

screamin gt · May 10, 2016

Noobz347 said:
Locate both ends of your current ground. One will be at the battery terminal and you'll need to discover what you did with the other.

Clean both and reinstall. You will need two new lengths of cable with terminal ends on them. Run additional grounds (they don't have to be nearly as big). In the end, you will be grounded in 3 places. The chassis, sub-frame, or sub-frame connectors, the engine block, and the negative side of the starter solenoid.

Get terminal ends and ground cable appropriate to the size. 1/4 or so ... shielded. Get a tube if dielectric grease to coat your terminal ends and connection points. All grounds should be solid. Solder the ends if you have the means to do so. Use a real terminal end crimper if you don't solder. You need good, clean, metal on metal contact for each ground. Use a wire brush to clean up the old ones.

I guess I didn't really ask my question well enough... So there is only one spot for a terminal/cable end to go on the negative battery post. So that is one cable going to ground. What I'm not understanding how to connect a second cable (let alone a 3rd or 4th) to the negative battery post. Or would the multiple other grounds just be connected to the spot I originally used for the ground?

And what gauge am I looking at for the other grounds? 1 gauge as well? Or can I go smaller since there will be more?

Az Pete · May 10, 2016

Just wondering if you have checked the output of the alternator? The grounds refered to run from the engine block to the frame and another from the fame to subframe.

Noobz347 · May 11, 2016

There are a few different things you can do screamin:

As I understand you, currently, you have one wire going from the negative battery to terminal to somewhere (we're not sure yet where but it doesn't really matter).

When you find that end, you are going to make sure that the connection it has is GOOD GOOD GOOD. It needs to be TIGHT, and have great METAL TO METAL contact. I needs to be secured with a bolt... a decent bolt.

From that connection, you will place ANOTHER length of ground wire. It will extend from this position using the EXACT SAME attach point that your ground wire is using. It will also be TIGHT and have great METAL TO METAL contact. The other end of this wire, will go to your next grounding location. We might go from the chassis to the engine block with this one. We'll find a GOOD place to connect it that has great METAL TO METAL contact and secure it tightly with a nice sized bolt.

From that connection point we will tie in our last ground connection. This will be a smaller wire and it will be routed very neatly. This one will go to the negative terminal of the starting solenoid.

At the end of all of this we will have 4 ground connection points. One at the battery terminal, one to the chassis (wherever it is that you installed it), one to the engine block, and one to the negative start solenoid terminal.

You will have to install cable terminal ends on each end of each cable in order to secure them to the attach points. Soldering is a great idea if you have the resources.

screamin gt · May 17, 2016

Noobz347 said:
There are a few different things you can do screamin:

As I understand you, currently, you have one wire going from the negative battery to terminal to somewhere (we're not sure yet where but it doesn't really matter).

When you find that end, you are going to make sure that the connection it has is GOOD GOOD GOOD. It needs to be TIGHT, and have great METAL TO METAL contact. I needs to be secured with a bolt... a decent bolt.

From that connection, you will place ANOTHER length of ground wire. It will extend from this position using the EXACT SAME attach point that your ground wire is using. It will also be TIGHT and have great METAL TO METAL contact. The other end of this wire, will go to your next grounding location. We might go from the chassis to the engine block with this one. We'll find a GOOD place to connect it that has great METAL TO METAL contact and secure it tightly with a nice sized bolt.

From that connection point we will tie in our last ground connection. This will be a smaller wire and it will be routed very neatly. This one will go to the negative terminal of the starting solenoid.

At the end of all of this we will have 4 ground connection points. One at the battery terminal, one to the chassis (wherever it is that you installed it), one to the engine block, and one to the negative start solenoid terminal.

You will have to install cable terminal ends on each end of each cable in order to secure them to the attach points. Soldering is a great idea if you have the resources.

Now I get it. Before when you talked about the multiple grounds I had pictured a ground going directly from the battery terminal to each location separately. lol

Thanks for the help!

My mustang is trapped in my garage currently because my driveway is getting paved this week. So it will be a while but I will update if this helps when I'm done.

Noobz347 · May 18, 2016

Let me know how it goes.

Trunk Battery Relocation Thoughts

screamin gt

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

screamin gt

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

screamin gt

Az Pete

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screamin gt

Noobz347

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Trunk Battery Relocation Thoughts

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