Custom Wiring - Switched power question

[Doug1]

I have this posted on Lateral-G as well since I needed a quick reply. Please disregard if you've seen it there as well!.

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

[parsonsj]

Here's something I've used in the past:

https://www.waytekwire.com/item/4605...S-000-0-ssVEC/

A bit spendy, but a sweet way to distribute power. You could replace your existing always-on bus bars with this and configure it for both battery and switched power.

[dhutton]

This is getting overly complex imho. I would delete the alternator solenoid and the master kill switch. It seems like overkill...

Take a look at a new Camaro with the battery in the trunk. Not a single relay or solenoid as near as I could tell. When in doubt I trust the OEM engineers....

Don

[Doug1]

I think there is some confusion as to my question.

1. Below are the instructions from Painless that explain why to use this with a Master Disconnect Switch.

2. The question I'm trying to get an answer to is how best to supply 2 power buss bars in the car so that they only have power when the switch is on. These busses will supply multiple accessories so they need to support over 100 amps each continuously. They will be the high power feeds for the relays for things like water pump, fuel pump, AC Compressor, AC Fan, MSD box, etc.

3. I also have 4 bus bars that have power all the time. One in the trunk, one at the back seat, one under the dash and another at the radiator support. These are for things that might need power all the time such as headlights, interior lights, tailiights, etc.

The point of this setup is to run everything over 2 circuit breaker protected legs while also providing a remote power shutoff switch that might be useful in the event of an emergency on the track or street.


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

[dhutton]

I think I understood your question but was hoping to convince you this is too complex. The more components in a system the lower the reliability.

Anyway, you could use the "pink" wire to energize a couple of high current relays or solenoids.

Don

[Doug1]

Thanks Don. I know it's more complex and may regret it later but thought it would be a cool setup that would be easy to add peripherals down the road. Having a always hot power buss and a switched power buss to tie into at several points throughout the car would leave little need to splice wires down the road. I'm doing the same with ground busses so that I don't have to try to find a good ground anytime I add anything. Just hook it to one of the ground busses nearby. I just haven't seen any examples of anyone doing it. I guess it is easy enough to thrown another relay in whenever you need switched power but thought this would be very clean and planning for expanding capacity as needed down the road.

I already built this relay and fuse center, so it will do anything I need at the moment.


In the picture above you can see the large starter wire (hot only at cranking), a 4 gauge feed wire to the panels and a 4 gauge single return from the 200 amp Alternator to the battery in the trunk. If I ran a separate switched circuit, I'd add another 4 gauge wire to supply those switched buss bars.


The cutoff switch and high amp alt disconnect switches are pretty heavy duty. What I was trying to find is something of a similar nature with proven continuous use reliability BUT is a reverse of the disconnect switches. So getting something normally open verses normally close.

Anyway, seemed like a good idea for a few moments anyway. :-)

[andrewb70]

Here's something I've used in the past:

https://www.waytekwire.com/item/4605...S-000-0-ssVEC/

A bit spendy, but a sweet way to distribute power. You could replace your existing always-on bus bars with this and configure it for both battery and switched power.

Those are sweet!!! I just installed that guy's little brother. The Bussmann parts are super cool and are an upgrade to the Delphi parts that serve the same purpose but are not water sealed.

Andrew

[andrewb70]

This is getting overly complex imho. I would delete the alternator solenoid and the master kill switch. It seems like overkill...

Take a look at a new Camaro with the battery in the trunk. Not a single relay or solenoid as near as I could tell. When in doubt I trust the OEM engineers....

Don

I agree with Don. On a new Camaro the battery cable runs inside the cabin, then to the engine compartment. From there it connects to an underhand power distribution center (maybe two) and there is a large cable going right to the starter. No breaker in the battery cable and no breaker going to the power distribution center.

Andrew

[Doug1]

I prefer to not have a hot battery cable to the starter all the time. Particularly such a long one. The Ford solenoid takes care of that. I do prefer to run everything else off of large breakers. New Camaros are no real comparison. They are computer controlled and have an entirely different set of needs. These relays are also pretty expensive so to speak so I can't imagine they would throw them in and run up the price because they are not selling cars to be raced. That's similar to saying since they don't have a roll cage or roll bar from the factory, you don't need one.

I'm happy with the setup, other than I thought I'd add a separate switched only circuit just to have it. Looks like it would add about $200 to the cost for that one circuit due to the expense of the heavy duty continuous feed relay. Clearly, I can get by with basic relays for far less and already have them installed. I may add the circuit anyway just for future expansion use but don't need it to run what I have already.

[dhutton]

I see guys obsessing over a shorted starter cable but they give no thought to failure mechanisms of the parts they use to keep it unpowered. Fused solenoid and relay contacts, shorted coils, inductive voltage spikes etc. This is coming from an electronics engineer with 35+ years of hardware design experience...

How difficult is it to protect a battery cable running through the cabin of a car?

Don

[Doug1]

I see guys obsessing over a shorted starter cable but they give no thought to failure mechanisms of the parts they use to keep it unpowered. Fused solenoid and relay contacts, shorted coils, inductive voltage spikes etc. This is coming from an electronics engineer with 35+ years of hardware design experience...

How difficult is it to protect a battery cable running through the cabin of a car?

Don

I'm no electrical wizard by any means. I do want to be able to disconnect all circuits in the event of an accident or fire, especially the fuel pump. I also don't see the need to energize a non fused cable for no particular reason. I don't need that big of a wire for anything but cranking so why leave it hot? The starter relay is required no matter how you go, so why not put it by the battery instead of by the starter where it can get heat soaked?

[andrewb70]

Run an inertia switch.

Also, I don't know what engine you're running, but if its a LS and stock or even aftermarket ECU, the fuel pump circuit gets shut down if the there is no RPM signal.

Andrew

[Doug1]

535 Pontiac IA2 block makes 700+ pump gas. LS on the next one :-)

So I need ANOTHER switch? LOL

[CarlC]

.... inductive voltage spikes etc. Don

Ugh, and relay solenoid voltage spikes, a small story of my vaporworx life.

[dhutton]

Ugh, and relay solenoid voltage spikes, a small story of my vaporworx life.

Yep, anytime you change the current flowing through any coil or inductor it generates a voltage spike to cancel that change in current. The bigger the change in current and the bigger the inductor the bigger the voltage spike. Just about all relays and solenoids have coils with the exception of solid state relays. The voltage spikes can be quite large...

Don

[andrewb70]

....

So I need ANOTHER switch? LOL

Yes :-)

Andrew

[andrewb70]

Ugh, and relay solenoid voltage spikes, a small story of my vaporworx life.

Yep, anytime you change the current flowing through any coil or inductor it generates a voltage spike to cancel that change in current. The bigger the change in current and the bigger the inductor the bigger the voltage spike. Just about all relays and solenoids have coils with the exception of solid state relays. The voltage spikes can be quite large...

Don

In the Holley EFI instructions, they make a huge deal out of this issue, since it can easily fry the ECU. Items like line lock, nitrous, trans brake, all use coils, so a relay with a resistor or diode is essential to protect the ECU.

Andrew

[CarlC]

Starting in October 2013 we had three failures in vaporworx controllers. Two were from James Shipka's OLC, the other Bob Bertelson's orange C10. James had the first commercially sold controller and it had been working well for years, but the replacement died in three weeks. Bob's also failed after several weeks. The common thread was that both cars had recently-installed Holley Dominator ECM's. Upon failure analysis it was determined that an op-amp had been damaged likely due to a voltage spike at key-off that was low enough to not cause instant failure but high enough to eventually kill the part. This was not seen on any other ECM type, and the Holley system was so new that getting one to test could not yet be done. It was a simple fix that is now used on all controllers for circuit protection, and a good example of how circuit protection should be addressed on all levels (input and output devices.)

Folks will also attach intercooler pumps to the same turn-on wire for the VaporWorx controller. This is quite common on LSA installations since the fuel pump circuit can be used to drive the IC pump. Higher power circuit protection is enabled here to deal with the inductive load at key-off as well.

[CarlC]

I'm no electrical wizard by any means. I do want to be able to disconnect all circuits in the event of an accident or fire, especially the fuel pump. I also don't see the need to energize a non fused cable for no particular reason. I don't need that big of a wire for anything but cranking so why leave it hot? The starter relay is required no matter how you go, so why not put it by the battery instead of by the starter where it can get heat soaked?

How do you plan to control the fuel system? Relays? pwm?