Posted By: ryanf
trunk mount battery diagram - 01/11/14 07:08 AM
Hello, i am trying to mount my battery in the trunk and the attached diagram is what i came up with after reading/reviewing other diagrams. This will be mostly a street car with a little strip. One wire 100a alternator. Thoughts/opinions? Sorry for the crude diagram
Posted By: ahy
Re: trunk mount battery diagram - 01/11/14 03:16 PM
Thoughts and opinions... I prefer to keep it simple. With careful cable routing I see no need for the added relay. I just ran heavy gauge cable ("0" I believe) from the starter to the back. 6 gauge from the starter to fender relay to feed the rest of the car. With the disconnect, you need to run the alternator lead to the back also, battery side of the disconnect. 6 gauge should do it with 125-150 amp breaker or fuse. If you are running lots of electrical load - accessories, big fan, ect 4 gauge for the charge wire would help reduce voltage drop.
I routed my cable under the car on the drivers side - similar to factory fuel line routing on the pass side. I grounded to the trunk floor through a brace under the floor to get more meat... then later added a 1 gauge ground wire from the battery to the engine block. Front chassis ground ran from the left fender apron just above the rail so I caught the heavier lip of the rail.
Starting current can be quite heavy... up to 300-400 amps? I don't think that breaker in the start circuit would take it and don't see the need for a breaker. A 200 amp switch can probably take it for the short time needed to get started.
I got the heavy gauge wire and terminals from NAPA.
Good luck!
Posted By: RapidRobert
Re: trunk mount battery diagram - 01/11/14 04:56 PM
Using large welding cable which by its nature its insulation is thick/heavy duty. Batt neg post to good ground in trunk (down to subframe recommended). Batt positive post directly up front under the carpet to the starter big "batt" lug (no trunk solenoid). A lead from the starter batt lug to the starter relay and from the starter relay to the alt. Power everything up front (switched power) from the batt lug on the starter relay to the ign sw just like normal. Back in the trunk put the on/off switch in either the positive or the neg cable. Use appropriate fuses/circuit breakers as desired (I do not). IF a person uses a trunk solenoid & it is going to be energized all the time get a "continuous duty" unit rather than a common parts house furd solenoid & it'd probably be a good idea to use a continious duty one either way just for longevity. (trunk solenoid aside) Just me, this keeps it simple with the only change being that the batt is now sitting in the trunk rather than sitting up front & there's the longer cable needed to reach it. I dont sweat having the cable under the carpet hot all the time (welding cable insulation is thick) & I do keep it away from any sharp edges that could fray it over time & that is a good use for black electrical tape. EDIT if keeping the ammeter, put the ammeter in series between the starter big "batt" lug and the big "batt" stud on the starter relay that's on the fender/firewall. MORE EDIT If not using a trunk solenoid run a lead (like OE) from the "st" terminal on the ign sw out to the "ign" terminal on the starter relay & a lead from the "sol" terminal on the starter relay down to the small terminal on the starter/solenoid
Posted By: RobX4406
Re: trunk mount battery diagram - 01/11/14 09:53 PM
Not what I would do.
You have to watch amp ratings on those 4 pole switches.
Posted By: stumpy
Re: trunk mount battery diagram - 01/11/14 11:09 PM
Yes it has to be able to kill the engine which means you have to wire the alternator cut off at main power switch in the rear. If not then the alternator will continue to feed the ignition circuit.
Posted By: ryanf
Re: trunk mount battery diagram - 01/11/14 11:14 PM
Which is the battery disconnect switch correct?
Posted By: RobX4406
Re: trunk mount battery diagram - 01/11/14 11:40 PM
You are making this more difficult than it needs to be.
Why a CD relay on the starter line. Wrong piece and totally unnecessary. Use a Ford relay, cheap and easy. Fuses and Breakers... ?????
You need to be aware of the amp load flowing through each device. Those 4 poles are not a great choice in some cases.
Use the appropriate device for the task.
You've seen a couple of methods to wire things up and got some confusing responses from a person on another board. That person knows what he's talking about most of the time. In this case he's way off base IMO. You've added items to them that are not really necessary. Keep it SIMPLE but safe. Just remember, there is a minimum standard and improvements on that minimum standard.
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Do you want a fat starter wire running forward being hot all the time? Yes, just run that fat wire forward direct off the battery. No, place a ford solenoid in line.
Want the alt line hot all the time? Wire it staright to the battery. No, place a CD relay in line.
Those are the two biggest issues IMO. Pick where you want the system to be totally dead in the car when the master is turned off.
Posted By: RobX4406
Re: trunk mount battery diagram - 01/12/14 12:13 AM
Paralysis by analysis. LOL
I do a Ford starter relay and a CD relay in alt line. Both of those placed in close proximity to your battery. Run one wire forward off an appropriately rated cutoff switch to the mopar starter relay lug, fuse it if you like. Pretty straight forward.
Just don't hook up your old alternator charge line. That will bypass/defeat the master cut off by feeding power back to the original mopar starter relay.
Posted By: RobX4406
Re: trunk mount battery diagram - 01/12/14 01:40 AM
yes.
Switch the CD relay on/off with a keyed/switched lead, not straight off the downstream side of the master cut off. That way it doesn't create a constant draw.
Posted By: filmsurgeon
Re: trunk mount battery diagram - 01/12/14 11:56 PM
Glad to see this topic posted. I will soon be relocating my battery to the trunk on my '70 Challenger, and have done some internet research in the recent past, but find it all a bit confusing. I am not very good when it comes to vehicle electronics/wiring. So hopefully this thread will give me some help and better understanding. I certainly don't want/need a complicated scheme; just one that is effective, simple and safe. Already planned on using "0" gauge welding cable for main positive/negative leads. Probably will be doing all the lug and terminal installations myself.
Posted By: stumpy
Re: trunk mount battery diagram - 01/13/14 12:14 AM
If you aren't building a race car there is no real need to move the battery to the trunk. Remember the battery off gasses acidic vapors when charging so you will be adding a corrosive gas to the trunk area.
Posted By: Polarapete
Re: trunk mount battery diagram - 01/13/14 04:09 AM
At NAPA in the Belden line are cable ends that are compression type, no crimping required. I believe they are intended for commercial trucks using heavy cables.
Posted By: 1964superstock
Re: trunk mount battery diagram - 01/14/14 08:26 AM
Forgive my ignorance, but what is a "CD relay in line?" Could someone post up some photos and part numbers please? I'm in the middle of wiring my car using the MAD electrical diagram for battery in the trunk with use of the Ford relay.
What changes need to be made if using the Mad Electrical trunk wiring diagram with use of the Ford Relay, to make sure the alternator can be shut off at the main battery positive kill switch?
Posted By: RobX4406
Re: trunk mount battery diagram - 01/14/14 08:40 AM
CD relay is a continuous duty relay. S605 relay works. Cole Hersee has spst CD relay in varying ratings. Make sure it's sized properly.
http://www.colehersee.com/home/grid/cat/169/See the diagram linked above, not the first post, down a few. On a street car, instead of triggering the CD relay using the cut off switch downstream side, use a keyed source. That way the CD relay only active when the car is running or key on.