[JamesWnew]

Ok, I've searched this topic and read till my eyes are crossed. I'm trying to hook up my rear battery to my mini starter, move the solenoid to the trunk, and not have an always hot wire running the length of the car. The mini starter requires a signal to fire the solenoid, so I'm thinking wiring like below.

Will this work and have any detrimental affect on the EFI, such as power feedback or spikes?

 

[resto-65]

Why not just put a fuse at the battery and not worry about the long hot wire shorting out? You should always have a fuse anyway just in case something shorts out to prevent a fire.

 

[ozarks06]

Yes. That is correct. Switch both solenoids from the key and you should be fine. The only thing I see that might be helpful is a diode across the trunk solenoid, but it's probably not necessary since you are switching with the ignition switch instead of a relay.

Why not just put a fuse at the battery and not worry about the long hot wire shorting out? You should always have a fuse anyway just in case something shorts out to prevent a fire.

The long hot wire will pull several hundred amps for a very short time (milliseconds) and blow a large fuse (like 175 amp). That wire is only hot while the starter is cranking so it is about as safe as possible. Another wire, which is fused, is used to run from the trunk battery to the alternator, and the rest of the circuits. This wire is hot all the time so it is fused, but the starter wire doesn't need to be.

 

[JamesWnew]

Recommendation on diode to use?

 

[JohnnyK]

You will ALWAYS have a hot wire running the length of the car. The difference is you can fuse a smaller one, even if it's running the EFI.

Myself, I said eff-it, and I'm running a 1 gauge cable the length of the car, to the solenoid up at the front. I may put a mega-fuse in down the road, but for now, I'm happy.

 

[ozarks06]

Recommendation on diode to use?

This should work okay. Band toward the positive.

3A Barrel Diodes : Diodes | RadioShack.com

 

[angrywombat]

I used this guys setup for the trunk mount battery.

Catalog

I used a Megafuse instead of a fusible link.

It works fantastic.

 

[JamesWnew]

I used this guys setup for the trunk mount battery.

Catalog

I used a Megafuse instead of a fusible link.

It works fantastic.

it is a nice kit. how did you trigger the PMGR starter's solenoid?

 

[ozarks06]

it is a nice kit. how did you trigger the PMGR starter's solenoid?

The price is pretty good too. I think I spent that much for 20' of #2 welding cable, not to mention 20' of #4 on top of that, the solenoid, megafuse holder, megafuse, and a terminal block like that up on the apron.

 

[brianj5600]

Are y'all routing the starter cable in a way that you fear it will short?

 

[JohnnyK]

No, we are routing the 1 large cable up to the front of the car, so if it chafes or gets smashed, it will short, while still being connected to the battery, so some wire the solenoid in the trunk so the huge 1gauge cable isn't always hot. I however, just ran a hot cable.. You could spend your entire life making these cars 'better', but eventually, I had to call it quits at the battery, plus math tells me there is a much easier way, using a huge fuse that will blow if it shorts..

 

[Harleydave]

Aren't there new very lightweight batteries that could be left up front?

 

[angrywombat]

it is a nice kit. how did you trigger the PMGR starter's solenoid?

Not familiar with the PMGR but I have used Tilton and Powermaster, on both of those you just run a jumper wire from the starter mounted solenoid to the power feed.

 

[ozarks06]

Not familiar with the PMGR but I have used Tilton and Powermaster, on both of those you just run a jumper wire from the starter mounted solenoid to the power feed.

This is the problem with that (from Powermaster's website):

Why does my starter seem to "run on" after the switch is released?
This is a common complaint on Ford permanent magnet starters, although it can occur on any permanent magnet starter in the right conditions. This situation develops when the ignition terminal on the starter is "jumpered" to the battery terminal on the starter and a remote solenoid is used. Permanent magnet starters can actually produce power if they are driven from an outside source (i.e. the starter will act like an alternator once the engine fires and starts spinning). The current produced in the starter for this second or so will flow from the starter's battery terminal to the starters ignition terminal and hold the solenoid in. This will cause the one to two second delay in the solenoid release and an irritating noise. The solution is to wire the starter per the instruction sheet, which will ensure that the ignition switch terminal goes dead the instance the key is released.


Their instruction sheet is here: http://www.powermastermotorsports.com/027___IS_PMGR.pdf

 

[ozarks06]

No, we are routing the 1 large cable up to the front of the car, so if it chafes or gets smashed, it will short, while still being connected to the battery, so some wire the solenoid in the trunk so the huge 1gauge cable isn't always hot. I however, just ran a hot cable.. You could spend your entire life making these cars 'better', but eventually, I had to call it quits at the battery, plus math tells me there is a much easier way, using a huge fuse that will blow if it shorts..

I think that this is a fairly simple and cheap way to insure you aren't burnt to a crisp in an accident (or just wear and tear) if the always hot cable shorts to the car body. Run the 'starting only' large wire unfused, and a smaller 'always hot' wire that is fused. The one that is always hot is fused so it will blow if it shorts.

A fuse on the starter cable would have to be able to hold several hundred amps (500 per the catalog for the wiring kit above) in the first few milliseconds when the starter begins to run. A fuse that large will still allow the always hot starter cable to become a pretty good arc welder for a few seconds. In other words, a fuse large enough to handle the inrush load on the starter will be too large to provide you much protection, thus the need for a second 'always hot' wire that is fused and a starter wire that is only hot when starting.

 

[JamesWnew]

On the pmgr starters, the solenoid post is quite large. Much larger anyway than on a repost solenoid. Is it supposed to have a higher current to trigger it? The start wire from the ignition switch is about an 18 gage......

 

[ozarks06]

I think you'd be okay with the 18 ga. It is just a solenoid. Tilton starters have a push-on tab, but Powermaster says to use a 12 ga., but that's probably overkill. If it takes that much current your old ignition switch probably won't hold up long!

 

[ScottsGT]

Why not just run the cable correctly and use grommets where necessary so you don't burn to the ground? Battery mounted systems are done all the time. Wired correctly using a little common sense you won't have any problems at all. I'm thinking you are being a little over paranoid over this.

 

[sanch052]

Okay I went through this a couple of months ago and basically gave up. I installed the pmgr starter into my 66 (running the alway hot wire from the trunk mounted battery) to test if I even like the upgrade before changing everything in my 65. The 65 has the trunk mounted solenoid & battery.

Well I finally like the new pmgr starter. Don't get me wrong I get the added benifits, but the new start up noise took some getting use to. Sounded like a Honda to me. Anyhow I haven't tried this on my 65 yet, but came across the post on the bronco site. Looks like it will work. Read post#4

PMGR Starter Wiring Question - FSB Forums

 

[JohnnyK]

Why not just run the cable correctly and use grommets where necessary so you don't burn to the ground? Battery mounted systems are done all the time. Wired correctly using a little common sense you won't have any problems at all. I'm thinking you are being a little over paranoid over this.

Agreed