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battery in trunk
https://slantsix.org/forum/viewtopic.php?t=60352		 Page 1 of 1
Author:  slantfin [ Sun Oct 23, 2016 11:12 am ]
Post subject:  battery in trunk
The person who had my Barracuda before me moved the battery to the trunk. I might as well keep it there, but I am wondering about using a Ford solenoid, so there won't be full current to the starter except when starting. Has anyone done this modification? I'm wondering if you get rid of the Mopar starter relay, or hook up to it?
Having solved a lot of the major issues, I'm getting into unfamiliar electrical territory. Next are headlight relays and a charging circuit.
Author:  Joshie225 [ Sun Oct 23, 2016 11:38 am ]
Post subject: 
If you put a remote solenoid in the trunk you can connect the starter's solenoid directly to the main cable. At that point the starter relay is still playing a key role if you have a neutral safety switch and the starter relay should be used to trigger the trunk-mounted solenoid.

Was a battery cutoff switch installed? And if so where/how is the alternator output connected to the battery?
Author:  slantfin [ Sun Oct 23, 2016 4:55 pm ]
Post subject: 
No neutral safety because it's a manual. I think it's the stock setup with a big wire going from the battery in the trunk up to the starter.
Author:  slantfin [ Sun Oct 23, 2016 4:58 pm ]
Post subject: 
Also, no battery cutoff, although it sounds like a good idea. I generally take the ground wire off the battery when it's not being driven, as a theft deterrent.
Author:  Joshie225 [ Mon Oct 24, 2016 6:59 am ]
Post subject: 
If there's a chance the battery will go back under the hood I'd leave the Chrysler starter relay in place and wired as original except for extending the wire for the starter solenoid to the trunk-mounted solenoid. This makes for a minimum of changes.

I typically bracket race my slant 6 cars so when I trunk mount a battery I install a cutoff switch to be NHRA legal. In order for the battery switch to cut off the engine and other electrical accessories I run a wire from the alternator output to the battery side of the switch. This keeps the alternator and battery connected when the switch is off and removes power from everything else including the ignition system. If you disconnect the battery while the engine is running and the alternator is charging the engine will keep running and you can damage the alternator and other sensitive electronics. With the remote solenoid you then need a separate wire to feed the rest of the electrical system. So to keep the battery in the trunk, have the car NHRA legal and not have the starter cable energized full time you have to run the starter cable and two 8 AWG wires from the engine compartment to the trunk. If all you want is weight loss or better weight distribution buy a smaller battery and leave it under the hood.
Author:  slantfin [ Mon Oct 24, 2016 8:01 am ]
Post subject: 
Thanks for the reply. I am also in favor of keeping everything as original as possible. I was, coincidentally, planning to have that exact set-up with the two 8 gauge wires, with twin 50-amp fuses at each end, as described by Slant-Six Dan elsewhere on this site. Having the Ford solenoid in the trunk also makes sense, since that would inactivate the starter cable as close to the battery as possible.
Consensus seems to be that the battery-to-starter cable should not have a fuse, which would reduce the amp carrying capacity on start-up?
Author:  slantfin [ Mon Oct 24, 2016 8:05 am ]
Post subject: 
If you have the time, Josh, could you do a quick sketch of the cutoff switch circuit? I'm a little unsure of what gets connected where.
Author:  Joshie225 [ Mon Oct 24, 2016 9:50 am ]
Post subject: 
I don't have the facilities here to draw something and post it.

For the battery switch:

1. 2 or 4 AWG cable from Battery + to battery switch terminal 1.
2. 2 or 4 AWG cable from battery switch terminal 2 to solenoid switch.
3. 8 AWG wire from battery switch terminal 1 to alternator output terminal.
4. 8 AWG wire from battery switch terminal 2 to the body feed where the battery used to connect.

Your ammeter will no longer work once the alternator feeds the battery directly so you'll want to add a volt meter to monitor the charging system.
Author:  slantfin [ Mon Oct 24, 2016 11:57 am ]
Post subject: 
All right, that's clear enough now, thank you.
This is my 8- cylinder car, but I'm going to address the wiring on my slant six car next. That has the battery in the stock location, so it won't be as tricky.
Author:  slantfin [ Mon Jun 26, 2017 2:17 pm ]
Post subject:  Finally getting to this project
Well it's 8 months later, and I'm finally getting to this project. Question for Electrical People: I'm running two fused wires directly from the alternator to the battery in the trunk, using the modifications suggested by Joshie225 and Slantsix Dan. Should I disconnect the large wire that has been factory connected to the alternator, or leave it connected? I'm going from an ammeter to a voltmeter at the instrument panel.
Author:  slantfin [ Thu Jun 29, 2017 8:11 am ]
Post subject: 
The modification I'm attempting is described in this thread, but it's not clear to me whether the existing alternator output wire should remain or be disconnected. I'm inclined to disconnect the old alternator wire, so the shut-off will stop the engine from running. The non-ignition part of the system is being fed through a fused wire from the switched part of the shut-off to the hot on the Mopar starter relay. With the new setup, the alternator feeds the battery, bypassing the emergency shut-off through the new wires.
Author:  Joshie225 [ Thu Jun 29, 2017 9:39 am ]
Post subject: 
Yes, the existing alternator output wire needs to be disconnected so that the kill switch actually kills the car.
Author:  slantfin [ Fri Jun 30, 2017 7:42 am ]
Post subject: 
OK, thanks, that makes sense!
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