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Discussion Starter #1 (Edited)
Can the Starter Solenoid be used as a continuous duty relay with Ignition On ?

For my cooling system, I am using aftermarket Foxbody Radiator with twin Ford Contour Electrical Fans which can pull 60 amps. For fan control, I am using Volvo Twin Relay and BMW Temp Switch with my battery in the trunk. I am also using nifty Volvo Fuse Box in my engine bay so everything is cleaned up. Right now the cooling fan comes on even after motor is turned off since the relay is hot all of the time. I also have EPS that can pull almost 40 amp in parking that is continuously powered but comes with ignition on. Since I am using starter mounted relay for starter, the original starter solenoid is not used.

Starer Solenoid are very heavy duty. If I use the Starter Solenoid as a continuous duty relay with ignition off, I can have everything off there would be zero power draw. With Ignition On, the Starter Solenoid used as relay would draw maybe half of what a starter would draw.

Waid

2020-03-30.jpeg Volvo Electric Fan And Relay Wiring_zpsjpl9zbt5.jpg 2020-03-30 (1).jpeg wiring_diagram.jpg
 

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I'm sure the Ford starter solenoid is not rated for continuous duty. There are many continuous duty solenoids/relays in different amp ratings available and some of them resemble the old Ford solenoid in appearance.
 

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The Ford solenoid is not rated for continuous duty. They are available however, golf carts, marine, motorhomes use them. Just do an amazon search for continuous duty solenoid.
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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Can the Starter Solenoid be used as a continuous duty relay with Ignition On ?

For my cooling system, I am using aftermarket Foxbody Radiator with twin Ford Contour Electrical Fans which can pull 60 amps. For fan control, I am using Volvo Twin Relay and BMW Temp Switch with my battery in the trunk. I am also using nifty Volvo Fuse Box in my engine bay so everything is cleaned up. Right now the cooling fan comes on even after motor is turned off since the relay is hot all of the time. I also have EPS that can pull almost 40 amp in parking that is continuously powered but comes with ignition on. Since I am using starter mounted relay for starter, the original starter solenoid is not used.

Starer Solenoid are very heavy duty. If I use the Starter Solenoid as a continuous duty relay with ignition off, I can have everything off there would be zero power draw. With Ignition On, the Starter Solenoid used as relay would draw maybe half of what a starter would draw.

Waid

View attachment 748787 View attachment 748788 View attachment 748789 View attachment 748802
I installed my battery in the trunk and ran power to the solenoid on the fender that you are not using. Then I ran a heavy wire to the solenoid on the starter from the same terminal. So my fender solenoid powers up my cooling fan, fuel pump, a.c. EEC relay and O2 relay. Then the fender wire triggers the starter relay just like it did the starter. If you want a wiring diagram I can get you one.
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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I installed my battery in the trunk and ran power to the solenoid on the fender that you are not using. Then I ran a heavy wire to the solenoid on the starter from the same terminal. So my fender solenoid powers up my cooling fan, fuel pump, a.c. EEC relay and O2 relay. Then the fender wire triggers the starter relay just like it did the starter. If you want a wiring diagram I can get you one.
This is for a 1992 f150. Back in late 80's at dealer we were installing gear drive starters that had original old school starters so they were basically wired like this diagram, hope this helps. Use your ignition switch as a trigger for your relays and power comes from fender solenoid
 

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75A relay at Amazon. It's wired just like a Bosch relay, only looks different. You should actually use a fender mounted starter solenoid with your PMGR starter. It will reduce the amps going through your ignition switch which will lead to a longer life for components.
 

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75A relay at Amazon. It's wired just like a Bosch relay, only looks different. You should actually use a fender mounted starter solenoid with your PMGR starter. It will reduce the amps going through your ignition switch which will lead to a longer life for components.
^ ^ ^ This. I'd also employ a diode with any relay powering a DC motor to prevent backfeeding when power is cut and the motor is winding down.
 

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If you use a fender mounted starter solenoid from a mid 80's FI Mustang, it had an internal diode to prevent backfeeding the electrical system. Be sure and get a genuine Motorcraft solenoid.
 

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Discussion Starter #9 (Edited)
Guys, please see my circuit diagram below and let me know what I am doing wrong. I ran battery cable from the Battery in the trunk directly to the Starter and then to the Alternator and then to the Fuse Box. From there, everything is fused. I am also using a separate ignition controlled relay to activate other things to keep the load down.

Currently the electric cooling fan is not ignition controlled so it comes on with motor off. Even though the Contour cooling fans can pull as much as 60 amps, its not continuous. Its a two speed fan so it goes on low power mode then it goes to high power mode when needed. I have many 30amp Bosch 982 relays and will try it and see if can handle 60amp in short intervals.

Waid

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Waid302, I do not have Contour fans but doing a google search, the Contour fans consume 20A running, 35A startup each - maybe 40A. For example.. Junkyard Contour/mark 8 E Fans Running a fan controller or PWM controller will help with some noise, load and only add fan speed and switch on second fan when required.
Do a search also on how to wire a trunk mounted battery.
Not sure what fuse you are using in your diagram which you noted as Fuse in Trunk, but it must be sufficent to power the starter motor, so if your battery lead is ever damaged it will take a lot to blow that fuse.
In this diagram for example, Catalog have a look at the bottom diagram. The cable running to the starter motor is not fused, like most modern and older cars, but it is only "live" when the trunk mounted starter solenoid is activated.
The cable which supplies the alternator, fuse panel, etc is fused at a lower rate in the trunk next to the battery, a safer alternative. Its up to you
 

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I've seen youtube videos where the initial start current for the Contour fans was 103 Amps, but dropped down to around 30Amps when running. The OEM circuit breaker for the Contour fan assembly is 60Amps. I'm using two 40 amp slow blow fuses, one for each fan and a PWM controller.
 

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Discussion Starter #12
I am using OEM fuse from a Lincoln LS which also had a trunk mounted battery. It's mounted next to the battery in the trunk and is rated at 175 amp and have no issues starting my car.

Wiad

2020-03-31.jpeg
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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Guys, please see my circuit diagram below and let me know what I am doing wrong. I ran battery cable from the Battery in the trunk directly to the Starter and then to the Alternator and then to the Fuse Box. From there, everything is fused. I am also using a separate ignition controlled relay to activate other things to keep the load down.

Currently the electric cooling fan is not ignition controlled so it comes on with motor off. Even though the Contour cooling fans can pull as much as 60 amps, its not continuous. Its a two speed fan so it goes on low power mode then it goes to high power mode when needed. I have many 30amp Bosch 982 relays and will try it and see if can handle 60amp in short intervals.

Waid

View attachment 748858
Yes, you need to add a ignition controlled relay for the fan.
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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Yes, you need to add a ignition controlled relay for the fan.
Actually your Volvo relay will work, the middle 2 wires should come from the igniton switch. They are the trigger wires.
 

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Actually your Volvo relay will work, the middle 2 wires should come from the igniton switch. They are the trigger wires.
Your temp sensor should be in between the igniton and relay.
 

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FWIW, I recommend the cooling fans be wired to run with the ignition "off". This helps with shedding underhood heat after shutdown to aid with "percolation" issues.
 

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Not that it helps with the subject matter at hand, but I had to smile when I remembered using an old starter solenoid to run the fire engine siren I put in my '57 MGA. Thanks for the reminder!
 

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Discussion Starter #18
FWIW, I recommend the cooling fans be wired to run with the ignition "off". This helps with shedding underhood heat after shutdown to aid with "percolation" issues.
Yeh that was what I was trying to do but the fan ran my battery down! Maybe my battery is on weak side!

Waid
 

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Discussion Starter #19
Actually your Volvo relay will work, the middle 2 wires should come from the igniton switch. They are the trigger wires.
I could do that but then I would need to use two ignition controlled relays. Per the diagram below, I thought I can control the ground but that did not work. The Volvo Relay with BMW dual temp switch (180/195*F) is a very popular combo to trigger a Ford Taurus or other 2 speed fans. It seams that most people are using 30amp relay to control the Volvo relay even with high amp Taurus fans. Even the Volvo is rated for 30amp only. I have bunch OEM Bosch 30 amp relays and I am going to play with it to see how hot it get when I trigger the high speed circuit intermittently. I don't continuous 60amp relay.

Waid



volvo_relay_diagram.png
 
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