Custom Electrical - Heavy Duty Relay Question

[Doug1]

I am using a Ron Francis Express Panel in the rear seat delete area and have the following setup with a Ford type solenoid in the trunk to keep from having the starter cable energized at all times. I laid out a very basic diagram up to the point that feeds the new fuse panel so that the basic setup is known, which should provide enough info to answer this question.








Rear seat delete fuse panel location. Driver side.


under dash relay station

The one thing I am not sure of is how to best way to get Switched power bus bars at the front and rear since I'm using the master power cutoff and high amp alternator shutoff solenoids. I already have "always on" bus bars at the rear seat area, under the dash and at the radiator support. Ideally, I'd like to place "switched power" bus bar at the rear seat and dash area to run my feeds for switched items. I don't think I need one for up front because the headlights and horn are "always on" circuits. If I can't run something from the existing solenoids in the trunk, I guess I'll have to have a heavy duty relay(s) capable of approx 200 Amps total. I'm using the Ron Francis headlight feeds from the fuse box to be the the trigger wires for the headlight relays since the panel is in the rear and I'd like a heavy gauge feed source close to the headlights.

I also built a separate relay station under the dash for things such as the water pump, 4 Window relays, the AC compressor, AC fan and the MSD box. I'd like for most of those to get their feeds from the under dash.

[Doug1]

Maybe something like this on each leg of the 2 "switched power" bus bar??
https://www.amazon.com/CONTINUOUS-SO.../dp/B008R1T5IM

[GregWeld]

Hard to tell --- but it appears you are connecting a positive to ground.... at the remote high amp alternator disconnect.

This appears to be a "low power" fused connection to keep electronic memories etc in play? If so - then it would simply be a fuse in a hot wire - not a hot connected to ground.

Personally - I would never have a disconnect switch on an alternator.... you can blow the diodes on it. There's really no reason to disconnect it. If you want to remove it - and not accidentally touch your wrench to ground -- just simply cut the battery off.... The problem comes from being able to start and run the car (thus spinning the alternator) -- and having no load for the alternator output. BAM go the diodes...

[CJD Automotive]

I would use a two pole master cutoff switch. It would simplify and clean up some of the wiring. One pole removes the battery from the system, and the other is usually connected through the coil power...no coils, engine shuts off, no alternator output.

[Doug1]

Originally Posted by GregWeld

Hard to tell --- but it appears you are connecting a positive to ground.... at the remote high amp alternator disconnect.

This appears to be a "low power" fused connection to keep electronic memories etc in play? If so - then it would simply be a fuse in a hot wire - not a hot connected to ground.

Personally - I would never have a disconnect switch on an alternator.... you can blow the diodes on it. There's really no reason to disconnect it. If you want to remove it - and not accidentally touch your wrench to ground -- just simply cut the battery off.... The problem comes from being able to start and run the car (thus spinning the alternator) -- and having no load for the alternator output. BAM go the diodes...

Hey Greg. Good to hear from you! Hope you are doing great.

The Alt shutoff is recommended by Painless Performance when using their master shutoff switch. I felt better to be safe that sorry. LOL

Their instructions are below... The part of the diagram that includes the remote alt solenoid (including ground) is from their instruction page.
Here's a direct link that includes their diagram.
http://www.painlessperformance.com/Manuals/50105.pdf



Painless Performance Item 50105

HIGH AMP ALTERNATOR SHUTDOWN RELAY INSTALLATION INSTRUCTIONS

FOR SYSTEMS WITH THE MASTER DISCONNECT SWITCH INSTALLED IN THE POSITIVE BATTERY CABLE.

THIS IS A WATERPROOF AND VIBRATION RESISTANT RELAY FOR PREVENTING THE CHARGING SYSTEM FROM BACK FEEDING CURRENT TO THE IGNITION SYSTEM. THIS RELAY PREVENTS THE ENGINE FROM RUNNING AFTER THE MASTER KILL SWITCH IS IN THE OFF POSITION.

1. MOUNT RELAY ASSEMBLY IN DESIRED LOCATION USING MOUNTING TABS. ATTACH THE BLACK GROUND WIRE WITH ONE OF THE MOUNTING BOLTS.

IMPORTANT: THE BLACK GROUND WIRE MUST MAKE A GOOD GROUND OR THE SHUTDOWN RELAY WILL NOT OPERATE PROPERLY.

NOTE: LOCATING RELAY FORWARD OF OR NEAR THE FRONT OF THE ENGINE WILL HELP REDUCE VIBRATION TO THE RELAY.

2. REMOVE AND DISCARD EXISTING OUTPUT WIRE FROM ALTERNATOR TO BATTERY.

3. RUN AND ATTACH (CUTTING OFF ANY EXCESS WIRE) ONE OF THE LARGE RED WIRES TO THE BATTERY SIDE OF THE DISCONNECT SWITCH USING THE RING TERMINAL PROVIDED.

4. RUN AND ATTACH (CUTTING OFF ANY EXCESS WIRE) THE OTHER LARGE RED WIRE TO THE OUTPUT POST ON THE BACK OF THE ALTERNATOR USING THE TERMINAL PROVIDED.

5. RUN AND ATTACH (CUTTING OFF ANY EXCESS WIRE) THE SMALL RED/WHITE WIRE TO THE STARTER CABLE SIDE OF THE MASTER DISCONNECT SWITCH WITH THE TERMINAL PROVIDED. 10-12-01

[Doug1]

Originally Posted by CJD Automotive

I would use a two pole master cutoff switch. It would simplify and clean up some of the wiring. One pole removes the battery from the system, and the other is usually connected through the coil power...no coils, engine shuts off, no alternator output.

I already have the stuff so I'm going to try to make it work. The thing I'm after is this...

1. How do I get power to 2 power distribution blocks so they are supplied power only when the switch is on. I already have power distribution blocks that always have power but want to add 2 that have power only when switched. I'd like each leg to support approximately 100 amps continuous use

[blitzer454]

I just read the documentation from painless. The relay that goes along with the cutoff switch is there to provide a load for the alternator when the cutoff switch is in the off position. This will prevent the damage that GregWeld was warning you about.

One thing that I would change in your circuit would be to connect a heavy gauge wire directly from the cutoff switch to the remote starter solenoid instead of going from the cutoff switch to the bus bar and then to the remote starter solenoid. You don't want to run the starter current through the bus bar as the bus bar may not be able to handle that current and it will present an additional resistive load that will steal power from the starter.

As far as adding switched bus bars, I can't think of any other way except to add high current relays downstream of the bus bars that you currently have. The relays would use the positive voltage from the ignition switch when in the key is in the run/start positions.

[CJD Automotive]

Originally Posted by Doug1

I already have the stuff so I'm going to try to make it work. The thing I'm after is this...

1. How do I get power to 2 power distribution blocks so they are supplied power only when the switch is on. I already have power distribution blocks that always have power but want to add 2 that have power only when switched. I'd like each leg to support approximately 100 amps continuous use

Something like this? https://www.waytekwire.com/item/7551...MOTE-HD-RELAY/

[Doug1]

Originally Posted by CJD Automotive

Something like this? https://www.waytekwire.com/item/7551...MOTE-HD-RELAY/

That does look sweet. Though I'm not familiar with phrase
"Bi-stable" for circuitry. I'll need to Google that 😏

[MtotheIKEo]

Look into Tyco Kilovac relays. Up to 500 amp continuous rated, operated with very little current from a switch. You can join the positive trigger wire with the high amperage cable terminal, and just switch the ground to make it real easy to install.

http://www.te.com/commerce/DocumentD...ocLang=English