battery relocation

[ushp12]

I wish to move my battery from underneath the front seat to the trunk of my '40 Plymouth p10 deluxe.  I was wondering if anyone has done the same and what it takes to get there.  I will also be converting from 6 to 12 volt.  I have seen some kits, but am wondering if that would be the best way to go.   Thanks for all your responses in advance.

[vintage6t]

If you change to 12v , battery in the trunk would be ok, but you'll need a large gauge  cable, like a welding cable to the starter. With 6v may the trunk might be problematic because you'll need a very large gauge  cable to avoid dropping the voltage too much.

 

My 41 Plymouth has the battery king of tucked under the front fender. I'm wondering if you can do the same.

 

12v conversion is pretty straight forward. Don't think you need a lot, but will need 12v bulbs, generator, etc. and possibly 12v to 6v reducers for some of the guages. Lots of info on the net.

[ushp12]

Thanks vintage6t...  I also was thinking the same thing about moving it to under the hood.  I have a '41 Plymouth p12 where the battery is under the hood, i'll have to take a look and see what can be done to put the tray in the '40.  The 12 v will be necessary for some of the other things i have planned.   Thanks

[Plymouthy Adams]

consider that the relocation to the trunk if placed near the axle hump will be about 10 feet of cable to the starter which will be the distribution point.  This length with excellent connectors/connections will equal about a .55 volt drop using 1 gauge wire...you should be fine.....there is way less current drawn on 12 verse the 6 volts also.  AND if you are wise...you will use tie points from the battery to a post that will also run to a set of covered post that can be used to charge or jump the battery without disturbing the actual placement of the battery.  I have done this with zero problems.  These posts will mount out of sight and easily accessed if placed beneath the rear bumper...they come with protective caps when not in use

Edited March 13, 2018 by Plymouthy Adams

[Andydodge]

With my Oz 1940 Dodge sedan I mounted the battery in the trunk about 20yrs ago, the car has had a 318 poly since 1973, I made a battery box and sunk it into the side of the trunk and have run the cable thru to a cut-off switch mounted on the side of the console, then a shorter cable down to the starter solenoid......not sure of the cable gauge however its about 7/16th thick, you can see it in the trunk pic and also the interior pic showing it when I installed the heat & sound material.....seems to work fine and its much easier than pulling the seat out to get to the battery.....as for installing it in the engine bay I also had a 1941 Plymouth which was the 1st year that had the battery in the engine bay and if you intend to do it this way then make sure you recess the battery box sufficently under the hood sides and make sure its made from at least 14-16 gauge steel.............regards, Andy Douglas

[ushp12]

Thanks for the input and the advice on using satellite posts for charging and jump starting

Andy...i to have the opportunity of putting a 318 poly in my Plymouth, i already have one.  If you don't mind could you tell me the transmission you decided on and what if any adaptor plate you used.  I am thinking of changing the rear end to an 8 3/4 with 3.55 to 3.73 gears, but still deciding between an A-518 overdrive or a A-833 4 sp.  Thanks.

[DrDoctor]

   I’ve done this on several cars, with no problems. But, for convenience when charging your battery, or jump-starting the car, put an auxiliary battery post under the hood. If you can’t fabricate one, Ron Francis has one.

[Adam H P15 D30]

18 hours ago, ushp12 said:

Thanks for the input and the advice on using satellite posts for charging and jump starting

Andy...i to have the opportunity of putting a 318 poly in my Plymouth, i already have one.  If you don't mind could you tell me the transmission you decided on and what if any adaptor plate you used.  I am thinking of changing the rear end to an 8 3/4 with 3.55 to 3.73 gears, but still deciding between an A-518 overdrive or a A-833 4 sp.  Thanks.

Just an FYI, the 518 will require floor modifications.  It is a biiiig looong thing.

Edited March 15, 2018 by Adam H P15 D30

[Bob Ritter]

I think it would be better to go with an alternator that looks just like the factory generator, they idle at 60 amps, cruise 55 amps, and top end is 60 amps. The best part is that you don't have to have a volta drop for your radio, heater, and lights. Any way something to think about. Why move the battery that is a great place for it, it's out of the way and how often do you need to check it. I have a 38 Dodge with the battery under the front seat and mounted in the floor and really like not seeing it until I need to. Thanks, Bob Ritter

PowerGen (powermasterperformance.com) (630/957/4019)

[Plymouthy Adams]

1 hour ago, Bob Ritter said:

I think it would be better to go with an alternator that looks just like the factory generator, they idle at 60 amps, cruise 55 amps, and top end is 60 amps. The best part is that you don't have to have a volta drop for your radio, heater, and lights. Any way something to think about. Why move the battery that is a great place for it, it's out of the way and how often do you need to check it. I have a 38 Dodge with the battery under the front seat and mounted in the floor and really like not seeing it until I need to. Thanks, Bob Ritter

PowerGen (powermasterperformance.com) (630/957/4019)

an alternator with a field current to output 60 amps at idle will bog the engine down till it shuts off.....it is never a good idea to load test an alternator over 40%...if its going to show charging problem, it will be within this output range...

[Frank Elder]

If the inner fender on the 40 and 41 interchange it would look stock..........

[Andydodge]

I moved the battery as I have bucket seats in the car and it was a PITA to move the passenger seat to check the battery, the cars been hotrodded since 1973, when I installed the OZ 313 Poly and cast iron trans as that was all I had...........if I was doing it again I probably wouldn't use a Poly but at the very least I'd use one that had the 727 alloy trans but experience is a wonderful thing......lol...........Frank Elders idea regarding the 40 & 41 innner fender is worth checking as while they may NOT be listed as an interchange they SHOULD in fact do just that as the 40/41 Plymouth front fenders have the same basic design/shape and the inner fender should work..........andyd

[dale]

I relocated the battery on my 46 Ply into the trunk as with the 350 V-8 there was no room under the hood.  Ran cables I bought from Speedway in a kit for that purpose along with a battery box.  Ran the lead cable out of the trunk and inside the frame to the solanoid.  Should be room under the hood though on your 1940 though.