Got my battery relocated to the trunk and now the car struggles to start. Doubled up on wires and used thicker cables also. Anything else I can do to make the car start easier?

 

Aside from the obvious question as to why you would bother relocating the battery to the trunk, you obviously have too much voltage drop because the electrical run from battery to starter is too long. Remember that the run is actually twice the distance - positive to starter and negative back to battery. You have two possible solutions: Put the battery back where it was, or get a larger battery. Unless you are setting up a race car and need to change the balance of the car, my recommendation is to put things back the way they were.

 

What ga wire and where did you place the ground?

 

I got a supercharger installed 2 years ago and never relocated the battery. The battery used to sit directly under the blower making it impossible to get to without removing the supercharger. I could barely fit in my hand in there. Moved it to the trunk just in case I ever needed to get a jump so I wouldn't be stranded somewhere.

I believe the wire is 4ga and the ground was placed in the trunk underneath the boards.

 

I think others have used 4ga with no problems.

I ran 0ga and used one of the existing ground points in the trunk. No problems starting at all.

Is the battery the original?

 

I use 1 ga, but a proper ground to clean heavy metal is necessary, not to thin metal. I've even run the ground from the battery to the front, or have run heavy ga from the front to the frame in the rear, then the ground from the battery to the frame.

 

UA6: Thanks for the explanation. That makes sense; I would probably do the same. The suggestions for heavier guage wire and a thick, solid ground are valid ones. Make sure the cable ends are sturdy, as well, and are securely connected to the cables. Many auto and marine supply stores have the pressure crimper to securely lock the cable end to the cable. (Marine battery cables are frequently custom made.) Good luck, and I'd love to see photos of your supercharger installation.

 

No the battery is brand new.

Thanks. I'll double check the ground wire.

 

From my progress thread...you can just barely see the yellow top battery on the bottom right.

 

Thats a dang good looking motor!!! Where did you get the SC from? And who did the install?

 

Ordered the SC from Stillen. Got the install done at a garage in Vegas by the Speedway.

 

Did u have any other issues like running rough misfire or anything like that ?

 

No issues at all or anything like that. Turned out the battery itself was bad. Cracked plate on the inside of it.

 

Every battery relocation discussion I come across, there is a an opposition logic similar to yours. I am referring to the unless it is a “race car”, don’t do it logic. it is simple. When you have better weight distribution, your tires more evenly share the road, which extends the life of your tires.

Another flaw with this logic is failing to consider the weight of a driver in the driver seat. Remember, the driver and the battery are on the same side and at the front half of the car. Moving the battery to passenger side of the trunk will greatly improve the weight distribution. Motor trend has written extensively on this. In their experiment, their car’s weight distribution went from 54/46 to 52/48 once they moved the battery to the passenger side of the trunk.

As for the voltage drop. You wouldn’t be running the negative cable from the front to the back where the battery is located. You can find a good ground point in the trunk right by the battery. You don’t need to extend the starter cable or the cable going to the fuse box either. Cut off the positive battery terminal and replace it with a copper lug on both the starter cable and the cable going to the fuse box. Then install a battery power junction post to a secure location under your hood. The cable from your battery will connect here along with your starter and fuse box cable. Might want to also place a circuit breaker with a manual on/off switch in the cable that supplies the power to the junction post, ideally near the actual battery. This is the setup I’ve got and with no power loss or sluggish starts. Also helps prevents problems in the line that could lead to a bigger issue from the battery.

 

You need thicker cables. The distance is probalby 3 or 4 X. The longer the cable, the more resistance is added, and the higher the voltage drop over the cables. So get thicker cables to carry an ample amount of current.. Like THHN cables is telecom quality for powering devices. And 6awg would probably do just fine but I would just observe the size of the battery cables that your car had from the factory and go up at least 1 size.. Meaning.. Go thicker.. Which is technically a smaller number. Like 6 awg is thicker than 8 awg. So if you go thicker by 1 size, that should do it. Make sure to use copper cable.