Trunk mounted battery - wiring safety

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Joined Jun 3, 2014
First time to the forums, and I hoping to get some guidance on an idea that might sound logical but falls apart in application. Safety first, so looking for why this will not work.

For those auto enthusiasts out there one the things that is common is to swap to mini or PMGR starter and mount the battery in the trunk. The PMGR starter has an integrated solenoid and the primary battery power can be constant to the starter. The problem the trunk battery presents is having a large awg wire running from the trunk to engine bay that is unfused. A proven solution is to mount a high amp solenoid (like an old Ford starter solenoid) in the trunk next to the battery so that the power cable only has power during starting. However, this solution requires that a second power cable (of decent awg; i.e. 4-6 awg) be run from the trunk to power all the electronic requirements (besides the starter) for the car. This run can be fused with a mega fuse for fire safety. This all works, but I am trying to find a way to use the one large awg power cable for both the starter circuit and the primary power to the car.

Here is the idea:

Could we kill 2 birds with one stone (or cable, in this case) if instead we employed the trunk mounted solenoid to act as a by-pass for a mega-fuse only when engaging the starter?

1) High awg power cable from battery to distribution post in the engine bay with a 100 amp mega fuse in-line near the trunk battery
2) All other car electrical needs tap into the distribution post in the engine compartment.
3) A separate starter relay would trigger both the trunk mounted and PMGR starter mounted solenoids.
4) When engaged, the trunk mounted solenoid simply bypasses the in-line mega fuse only when starting the car. In theory the mega fuse will not blow because the trunk mounted solenoid bypassing the fuse provides the least path of resistance.

Again this is just an idea that might be riddled with other issues or miss understandings on my part but that is why I posting the thought rather than just doing it. If it works than you can have 1 large awg cable from the trunk to the front of the car to be used for starting and for car power, but it is also fused for fire safety.




Joined Nov 25, 2009
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