BobE wrote:

With additional time at home, my long put off project of moving the battery to the trunk in my 65 Fastback is back.  So, some questions for those that have done this …
    Did you mount on the passenger side?
    If so, what did you do with the spare tire location?
    Did you run the ground cable to the front, or just ground it to the frame in the rear?
Any other info or pictures of your installation is appreciated.
 

In my 68 I put the battery on the passenger side. it has a custom billet hold down.
I have not had a spare tire for over 15 years but I carry an inflator with Green Slime sealant for small punctures and a AAA card for large holes and blow outs. Have not used either ...yet!
 I put large ground cable to the frame right by the battery tray, no need for an extra cable to the front.
You guys must be getting sick of me posting these same pictures but here we go again.
The Optima does not need a battery box for street use.

Modified stock 68 battery tray withextra brace that goes on the other side of the trunk drop down.

Tray mounted.

Last edited by Rudi (4/11/2020 10:45 AM)

Yeah, I like that setup a lot Rudi. 

As far as a ground to the front, no reason.  People get caught up on grounding without really understanding it.  Though the engine may be the best ground when you're near it the unibody of the car has significantly more cross sectional area than the engine does.  In truth its a better ground.  I learned that from an electrical engineer.  I always thought a single point of ground was superior, and that the OEMs were just cheap using a bunch of grounds going to the body.  That's actually not the case.  I've used trunk mounted batteries in two cars and grounded them just like Rudi said and they both worked just fine, and one is EFI which is much less tolerant of bad grounds. 

Nos681 wrote:

So you have 2 bolts holding entire assembly in place?
Does exterior have a reinforcement strap with 2 holes?

Neat setup Rudi.

This has the same bolts as it had when mounted in the engine bay, two on top and two on the brace.
 Don't rely on the dinky little ground strap from the right side head to the firewall. I used a  #4 gauge cable from the frame rail to the engine block, ya gotsta have really big grounds  because of the current  capacity needed for the starter.
 Here is a picture of the brace back up which goes under the trunk floor and the exterior trunk floor pan drop off.

That looks nice too Barry.😎

I tend to over do things .I  ran main power to front in that cable there is a mega fuse i n line at battery.Also ran a cable to the starter it is not fused could not figure a good amp draw for starter so it's only powered when starting.The ground is attached to frame rail in rear and the goes to the block,It's jumped from there back over to a ground bar I made..All the motor loads tie to the bar .My thoughts on this process were that this is a forty nine year old  car with some hidden rust affecting grounds.And this is a fuel injected car a was trying to eliminate as much noise as possible in the electrical system.

TKOPerformance wrote:

Yeah, I like that setup a lot Rudi. 

As far as a ground to the front, no reason.  People get caught up on grounding without really understanding it.  Though the engine may be the best ground when you're near it the unibody of the car has significantly more cross sectional area than the engine does.  In truth its a better ground.  I learned that from an electrical engineer.  I always thought a single point of ground was superior, and that the OEMs were just cheap using a bunch of grounds going to the body.  That's actually not the case.  I've used trunk mounted batteries in two cars and grounded them just like Rudi said and they both worked just fine, and one is EFI which is much less tolerant of bad grounds. 

TKO - the reason I ask about running the ground wire up front is that years ago I had a race car (unibody) w/a trunk mounted battery that we grounded in the rear and ran a ground cable from the starter to the frame and had trouble with starting.  When we ran the ground cable directly from the battery to the starter, we didn't have any other issues w/starting.  Anyway, seems like I will ground it in the rear like many posts have responded.

Thank you to all who have responded.
 

Last edited by BobE (4/12/2020 10:03 AM)

Nos681 wrote:

What size cable are you guys running from trunk to engine compartment?

What route?...and why?

Big cable, #2 I believe.

I ran my cable over the rear wheelhouse and down the front,thru the bottom gap of the lock pillar, along the recess on the rocker panel, thru the lower gap in the hinge pillar, exit the upper pillar area into the cabin and thru the wheelhouse behind the heater box, tucked up under the upper inner fender at the top flange, pass thru the inner fender below the solenoid.

I used this path as it's protected pretty well, is used by others, and is mostly the same path as Ford used.