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Discussion Starter #41
Interesting, see 2 posts back.I measured 3.x amp on the fenderwell as well, but 7.8 amp on the starter solenoid. We see 30 amps on large diesel solenoids, definitely not on these tiny things!
 

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Interesting, see 2 posts back.I measured 3.x amp on the fenderwell as well, but 7.8 amp on the starter solenoid. We see 30 amps on large diesel solenoids, definitely not on these tiny things!
It surprised me too. I have an OEM type PMGR starter where the solenoid physically moves the starter shaft out in addition to making contact for the high current to the starter itself.

Be interesting to see a few more data points.
 

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Apparently there are a few different designs, in the link I posted they showed the earlier version @ 16 A. 30 does seem unusual, but they put in a 40A fuse instead of a 20 for a reason.
 

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Discussion Starter #44
Thought I had replied to this but it seems I hadn't. You will always have a large hot wire going to the starter, even using the fender solenoid.
To wire up the new style starter using the fender apron, you would have add a +ve wire from the hot side of the fender solenoid to the new starter regardless.
I have tried running the power wire and the solenoid wire from the triggered side of the fender solenoid, and it causes the starter to hang up for 3 seconds (turns out that's common).

But yes, I could just remove the starter solenoid if that's what you mean and keep using the fender solenoid by itself.

Johnny, not sure why you'd want to risk having a large, always hot wire on the starter ? The Ford Solenoid is up on the apron to prevent this problem. Chevy guys with starter issues buy Ford apron solenoids and use them instead the solenoid on the starter- look at the MAD 'start em up' kits. I believe you're thinking backwards. LSG
 

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For my application - FE in 67 Mustang with RobbMC mini starter - RobbMC recommends a 10AWG wire or larger. If we work backward from that recommendation, their starter trigger wire (coil) needs about 30 to 40 amps. I then found this note on their website on the last paragraph, also stating 30 to 40 amps:
http://www.robbmcperformance.com/news/news_v2i4.html

Personally, I wouldn't run that through the ignition switch if not using the fender solenoid, so I would wire in a minimum of a 40 amp relay. I haven't installed all this in my car yet, so this has been good research. I have an American Autowire kit and they don't include this relay, so I'll have to add it - because I also want to remove the fender solenoid.

That's for my starter and it may be different that the SN95 current draw but it doesn't hurt to go big. I think it would also be good to run a 40 amp fuse to protect the relay and wire.

American Autowire has a good PDF reference for wiring the power feed for this type of starter that uses 6 AWG wire and a 175A fuse.
https://smhttp-ssl-87263.nexcesscdn.net/pub/media/productattachments/files/92972153_510476_IN_0.1_5.pdf
 

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Discussion Starter #46
Personally, I wouldn't run that through the ignition switch if not using the fender solenoid, so I would wire in a minimum of a 40 amp relay.
I would not, since I measured it at 7.8 amps draw.
 

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JohnnyK, I’m wondering if you measured the solenoid hold in current only, and didn’t see the pull in coil current draw? The PMGR starters use a solenoid that has two coils; a strong one to pull all the bits into place and then a smaller one to hold it there (as once the starter is engaged and spinning it helps hold it all in place).

We gotta find a wiring diagram of the internals of the starter so we can figure out a way to test this repeatedly and reliably. An 8A to 30A spread is a huge difference!
 

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Discussion Starter #50
Well I used an analog multimeter to double check. Nothing spectacular to report if I recall. That 30 amp seems erroneous.
 

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Sometimes dmm's won't give you an accurate in rush current reading. Analog might but the needle would have to swing fast. Higher end digital Flukes will but you have to enable the Max reading setting, so it'll catch the spike. You won't see it in the main readout though in the situations I've used them in, like when closing a relay's contacts fills up a capacitor on the other side. The only way to really tell is to wire in an oscilloscope. These spikes will reduce the life of all the contacts in the circuit, like the contacts in the relay. Higher rated relays have better and bigger contacts.

That's why going big never hurts. A 40 amp relay will last longer. Overkill is good in this circuit.

Sent from my SM-G973U using Tapatalk
 

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In my job I troubleshoot Industrial motor contactors, Multimeters and Amp Clamps won't record most transient spikes, even ones that trip breakers and blow fuses. Even with Peak and Min./Max. settings they just can't respond that quickly.
 
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