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Battery Relocations

4K views 29 replies 11 participants last post by  Rip VW 
#1 ·
Hey Guys,

I'm in the middle of my restoration of my 71 Challenger Convertible and was thinking about cleaning up the engine bay by installing a battery relocation kit in the trunk.

What are your opinions on this (good vs bad?). Is it easy to do? I'd like to buy an entire kit to make it easier. I would also include a shut off in the trunk. I've seen some posts on here but many are old and I would like a current way to do it if there are better components, etc. Let me know your opinions. Thanks

Dave
 
#2 ·
I have trunk mounted batteries in both of my cars, and it's very simple to do. I also have battery shut off switches, but not in the trunk. I have always installed mine in the floor of the passenger side front area, just under the leading edge of the seat. This isn't where NHRA wants them for a car that needs to pass tech, but it's where I like them for ease of operation and security. I use switches with removable keys, so I take them with me when I park the car.
Kits make it much easier, but need to watch what kit you buy! Some come with too small a gauge cable, and don't work well. I always build up my own, and use oversized cables of around 1/0 awg. to ensure I never have voltage drop issues. Be sure your engine is well grounded to the frame, and that the ground cable is also large, and where it bolts to the frame and engine, that the metal is bare before attaching it.
One other thing I do is to make sure the cars have a divider between trunk and rear seat area. If you can see the interior of the back seat, then I'd pull the seat back, and put a thin aluminum sheet in to divide the trunk from any fumes getting to the passenger compartment. It's just a safety thing for me, and not necessary, but I feel the setup is safer doing it.
 
#3 ·
One other thing I do is to make sure the cars have a divider between trunk and rear seat area. If you can see the interior of the back seat, then I'd pull the seat back, and put a thin aluminum sheet in to divide the trunk from any fumes getting to the passenger compartment. It's just a safety thing for me, and not necessary, but I feel the setup is safer doing it.
Great tip!! Not only does it keep out the smell but also the hydrogen gas a battery emits when charging.

[Edit]...I see 1971BB427 already addressed the fumes issue. (I need to pay more attention. LOL)
 
#4 ·

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#5 ·
I also buy batteries with top and side posts. This way I connect my cable to the top posts, and use bolts with insulators on the side posts. My side posts extend through the side of my battery box, which allows me to jump my car, or someone else's car without removing the top off my box. I have nylon insulators that thread over the side posts when not being used, to eliminate any chance of shorting them by putting something in the trunk next to the battery. I found the insulators with 3/8" threaded hole at a local electrical supplier pretty cheap.
 
#6 ·
8:1 BATTERIES
All batteries must be securely mounted; must be of sufficient
capacity to start vehicle at any time. Batteries may not be
relocated into the driver or passenger compartments. Rear
firewall of .024-inch steel or .032-inch aluminum (including
package tray) required when battery is relocated in trunk. In lieu
of rear firewall, battery may be located in a sealed .024-inch
steel, .032-inch aluminum, or NHRA-accepted poly box. If sealed
box is used in lieu of rear firewall, box may not be used to secure
battery and must be vented outside of body. Relocated battery(s)
must be fastened to frame or frame structure with a minimum of
two 3/8-inch-diameter bolts. OEM located batteries without
complete OEM hold-down hardware must be secured to OEM
battery box/tray using the same 3/8-inch-diameter bolt hold-down
method described in previous sentence. (“J” hooks prohibited or
must have open end welded shut.) Metal battery hold-down
straps mandatory. Strapping tape prohibited. A maximum of two
automobile batteries, or 150 pounds combined maximum weight
(unless otherwise specified in Class Requirements), is permitted.
Maximums may vary according to Class Requirements.

8:4 MASTER CUTOFF
Mandatory when battery is relocated, or as outlined in Class
Requirements. An electrical power cutoff switch (one only) must
be installed on the rearmost part of each vehicle and be easily
accessible from outside the car body. This cutoff switch must be
connected to the positive side of the electrical system and must
stop all electrical functions including magneto ignition. The off
Section 20, page 35 General Regulationsposition must be clearly indicated with the word “OFF.” If switch is
“push/pull” type, “push” must be the action for shutting off the
electrical system, “pull” to turn it on. Any rods or cables used to
activate the switch must be minimum 1/8-inch diameter. Plastic or
keyed switches prohibited. Switches and/or controls must be
located behind rear wheels on rear-engine dragsters.
 
#10 ·
When one does the terminations I tin the end of the wire with solder and then sweat it into a copper socketed fitting. the wire I use is welding lead as I can get that in bulk from from the local welding goods vendor..

Sam
 
#20 ·
Actually it's not more than I think as I'm familiar with tech inspections, I was supporting Techinspector's reasoning and opinion....... most people not needing the add-on information about the shut off switch, it's purpose and how ugly it is etc...... Pretty sure if a person didn't like how it looked they wouldn't put one in....... just say'in
 
#22 · (Edited)
Interestingly, mounting the battery in the trunk is also good for traction and general road holding: it moves weight to the back and your usual front engine-rear drive car will be better balanced and you can feel the difference.
As for the battery fumes, an easy way to take care of that is to use an air-tight battery box and a small hose to vent the fumes outside the trunk: no need for a wall behind the rear seat.
One can never stress enough the importance of excellent grounds in a rear battery set-up: battery to body, battery to rear chassis, rear chassis to body, engine to front chassis, engine to body, body to front chassis, nice and big straps with clean connections. Bad grounds can cause some funky issues in a car!
It is also convenient to have a positive connector/junction box in the engine compartment, to connect wiring or to boost the car, or just to have a convenient positive when you work on the engine; with a bit of luck, you can mount this connector in the area where your battery used to be and you can use the stock wiring (that used to connect to the battery)!
 
#25 ·
When I did my brothers mustang I mounted the battery in a steel box in the trunk. I did not use a disconnect. I had a large breaker in the battery box with the battery. I ran the heavy cables through the floor and routed the cables alongside the sub frame connectors. I made sure they were tight to the sub frame connectors and did not hang down any where. The ground cable went to a "Bonded 5/16 ground lug attached to the body thu the floor pan under the rear seat. That Bonds the base sheet metal of the body to Ground. The cable is then routed from that lug direct to the bell housing and another from the Bell housing to the front frame rails for what they were. The positive made a straight run to the solenoid.

There may be questions about going overboard with grounds. Being a Radar Specialist for 25 years taught me to ground ground ground. If you want to read about bonded grounds find a copy of the Faa AC 43.13 -1B/2A Aircraft Inspections Repair & Alterations book. Of course there may be a newer version as the last time I needed the book for my job was 1998.

To sum it up there were No problems with grounds and voltage supply on the car. No weak headlights or any of the stuff ya hear about. Works good lasts a long time.

I want to say one more thing and that is to those whom Solder their large lugs, myself included. Actually the wire should be crimped only. The problem is when you solder the wire the solder bonds all the small copper wires and in essence turns the cable solid at the wire to lug junction. The copper without solder allows all of the wires in the cable to move a little and release stress. When the wire is a solid block there is no movement you will eventually break wires in the cable.

Take a piece of stranded wire or even better one of the strands hold the ends of the wire with your left and right index finger and thumbs. Move your hands back and forth trying to bend the wire to failure. Don't abuse it to get it to fail. You will notice you can break the wire eventually by repetitive bending.

Now get another wire strand and instead clamp each end in a pair of vise grips. Do the same bending motions holding the vice grips and the wire tight.

The way this is supposed to work is it was easier to break the wire with the vice grips holding the wire. That is because the vice grips do not allow any movement right where there held by the grips.

I will say there are special circumstances when you do the solder the lug. I know someone out there is going to jump and say "I been soldering my wires for years and never had a failure. That's ok by me as I said I am guilty too of doing it. That and I didn't have access to the proper crimper either then.

Just an old mans ramblings..:cool:
 
#26 ·
I want to say one more thing and that is to those whom Solder their large lugs, myself included. Actually the wire should be crimped only. The problem is when you solder the wire the solder bonds all the small copper wires and in essence turns the cable solid at the wire to lug junction. The copper without solder allows all of the wires in the cable to move a little and release stress. When the wire is a solid block there is no movement you will eventually break wires in the cable.
Those large cable ends that bolt go onto the battery terminal would be very difficult to just crimp.
I do agree with your crimp don´t solder theory in general.
Overdoing it can run solder way up into the wire.
I just crimp and shrink wrap terminals now.
 
#28 ·
#30 ·
I have done the crimp and solder but about 10 years ago I bought a commercial crimper to the tune of 150.00 It works on a lot of different type terminals. The big part is the handles which are about 3 feet long.. It makes doing the real big terminals easy.. :cool:
 
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