Does the starter relay 12v battery post need 12v?

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74Scooter

74Scooter

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Prior owner of my car installed a Painless harness for the entire car... then went off the reservation. I've been kinda turning a blind eye to the issues I've seen as everything works for now. Want to add a pre-amp for the stereo into the trunk and I've finally decided I cannot stand the rats nest of unfused and improperly fused circuits. The 12v post on the starter relay is currently being used as the 12v "gang" post for most of the mess. See photo below:
20230612_113126.jpg


There is a circuit breaker to the left of the relay I believe was for the fans. And that 75A "mega" fuse above and to the left of the starter relay that came with the painless kit. I'm absolutely positive those tiny wires attached to it would melt to the fender at less than half that amperage... just one of many WTF items I've noted. I've already installed an inline fuse to the alternator charging circuit and will eliminate the 2 other circuits coming off the alternator. Plan is to get everything off that relay post and onto a fused bus bar fed from the battery. So the million dollar question... does that post on the starter relay need 12v or can it be bypassed completely?
 
I believe you need it since you are using the relay as it’s intended instead of just as a gang junction.

Or trace back the solenoid power wire to the painless fuse block if being used. Some of those kits are basically GM blocks with mods

I think you will need the 12v big gauge to make sure you can deliver the continuous need for the starter.
 
Broke Farmer said:
I believe you need it since you are using the relay as it’s intended instead of just as a gang junction.

Or trace back the solenoid power wire to the painless fuse block if being used. Some of those kits are basically GM blocks with mods

I think you will need the 12v big gauge to make sure you can deliver the continuous need for the starter.
Click to expand...
Thanks for the info. The starter solenoid has a heavy gauge wire directly from the positive battery post. I was thinking the relay just sent signal to the starter solenoid and possibly was powered from the ignition circuit.
 
The ST wire closes the relay off the ignition switch when in key start.
But you would still need 12 V like a typical relay once the ST wire is energizes to close the circuit.
The wire to solenoid and wire on relay aren’t connected until ignition energizes and closes the circuit.

But hey. If there is a mass of goofiness just pull it and see if it starts?

I like the idea of getting all that extra junk off the terminal though and running it though am independent bus bar.
 
Oh my goodness. I feel plum good about my electrical work now.
 
That relay stud is commonly used for a "main" branch off terminal, but it also forms 1 of the two contacts for the start relay. The reason for that relay is that the Chrysler starter solenoid draws considerable current. That relay ALSO FORMS the neutral safety switch circuit for the automatic or clutch switch circuit for a stick shift.

You have 4 terminals. The two small "push on" flag terminals, one is start voltage from ignition switch, remaining one goes to ground through neutral start switch.

The big stud gets "major" 12V power, and the remaining "square screw" feeds to the solenoid. That one needs to be about a 12ga wire.
 
Thanks all.

I'll try removing the all the 12v from the stud and see if it still spins. I've already pulled wads of wire out of this rig... and it still looks not so good.. lol.

A lot of the Painless harness is not too bad.. but some of the stuff is a real head scratcher. They did away with the bulkhead connector... good. They have a single 10ga wire attached to a 75A fuse feeding the entire fuse block? Great.. the 10ga wire is now the fuse.

Already bypassed the ammeter because who needs that headache. The entire electrical ecosystem is a loop. It either gets juice from the battery or the alternator... or both... what a mess. I'll get it where everything is fed from the battery and on a fuse of appropriate size.

^^Painless.. yes...lol. This is what the guy who installed the harness thought of it... and he is an electrical engineer by trade.
20200502_075320.jpg
 
its supposed to be a loop

battery to bulkhead to master splice RED
alternator to other bulkhead to ammeter Black then on to master splice RED

i.e the ammeter has a wire from the battery and a wire from the alternator In a loop.

colours used on my car may not be used on yours.... and mine has 2 bulkhead connectors, yours probably never did :)

Dave
 
I modified my existing harness when I built my Hardtop. Doesn't mean it's right! lol, had a similar Delima so I added this.I used some fusible links as well that I know I will get critisized for but hey, It's my car and I did everthing myself. Maybe someday I revamp it but it's been about 10 years now. (yellow arrow unrelated)

219.jpg
 
Actually running an auxillery power distribution unit like that is a good idea.

For the OP my suggestion is to figure out how the power supplies are connected.
If system is using a regular ammeter in the battery line, then when the engine is running, power is going to run backward through the ammeter and fusible link when the amplifier is drawing power.

There's a couple of ways to solve that. One is to route power like one of the heavy duty/fleet options. Another is to add a line direct from the alternator to the battery positive (with a fuse). This will result in the ammeter not showing battery charging, so adding a voltmeter gage will help monitor system.
In either case, an auxillery fusebox or a fuse/relay box can be added in the engine bay.

Diagrams showing similar situations here
www.forabodiesonly.com

Alternator field wires

One a dual field alternator, would it still function the same if the two wires were swapped on the field connections?
www.forabodiesonly.com www.forabodiesonly.com
replace EFI with stereo.

Another one where someone wanted to add an auxilery box, but also using a Denso alternator with built in voltage regulator.
www.forabodiesonly.com

Fusible link or not?

I am going to install a relay to power a fused distribution block to power things like the line-lock, the efi, distributor, ignition box. Since I can put appropriate fuses for each item, would be beneficial or detrimental to put a fusible link in the line to power the relay. If so, would you...
www.forabodiesonly.com www.forabodiesonly.com
 
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^^ That's roughly the plan. There is a LOT of duplication in the current setup. I've got 3 wires coming off the alternator Bat terminal and I'm going to trim that down to one. I've added a big ole wire and fuse for the charging circuit. I'm currently using the side post on the Optima red top for the charge circuit.
20230612_113055.jpg


20230612_113111.jpg


Believe the other 2 wires coming off the alternator were for the ammeter and old charge circuit to the starter solenoid. Already bypassed the ammeter and have installed a volt meter so I should be able to go without both those circuits. These two are bothersome for me as they are not fused and have no protection at all for a direct short from the alternator and could potentially take out the entire harness behind the dash. I'll need to disconnect one at a time to see if that causes any unexpected issues.


I want to get back to a single disconnect point to deenergize the entire circuit. I'm likely going to grab a pair of these:

vgate batt term.jpg


Then run a good fused wire to something like this 300A bus bar for power distrubution instead of everything being ganged up on the starter relay stud:

300A bus bar.jpg


Well.. that's the "plan" at this point anyway...
 
No idea what the P.O. did, but the ammeter is not a seperate circuit. It's in the battery feed/charge line. If its a external shunted ammeter, then its two leads off that line. Regardless - its battery feed in a typical automobile wiring strategy that uses 'em. So kindof important. ;)
Maybe the PO didn't understand the ammeter's position. In industrial setups, there can be an ammeter on the generator to indicate how much current is being drawn.

You've got a bit of puzzle to figure out. Sounds like you're solving it.
The alternator shorting is, or was not, a real threat to the main circuit. Because the rotor is externally fed, any short kills the power to the rotor and alternator can no longer produce power. Additionally, the rotor is (was originally) on the run circuit. So the engine will stop running,also killing the alternator's power generation.

The big danger of a short in the main circuits was from the other power source, the battery. It will continue to feed power to short location until something burns through. If the short is in the alternator, electricity will flow through the easiest path, whether its the original line with a fusible link (which will melt) or an additional line someone added direct to the output stud. That's why when any additional lines are added to the battery, a breaker, fuse or link should be included.

see example 2 Fusible Links in Charging Systems with Ammeter
 
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^^ I'm already down the rabbit hole hoping it's not too deep... I'll sleep better when it's all sorted.
 
The previous owner sure didn't follow the wiring diagram the harness came with. I used a Painless harness on mine as well, and it was pretty painless, but I don't mind doing wiring. Thats a different kit part number than I used, but there should be a wire from the alternator to the fuse block and one from the battery to the fuse block. At least that's how my Painless kit is wired. And the wire off the alternator is only rated to like 60amps, if you go higher than that, you have to increase the size. It should all be in that instruction book if it's a complete manual.

You might be better off removing all of the main power wires and starting over versus trying to make what is there work.
 
^^ On my way there. Rough plan is to have all charging through the 2ga wire with the 95A fuse. Still don't understand these high output (amperage) alternators with a tiny *** charging stud.

Nothing coming from the starter solenoid or through the ammeter and as little as possible on the starter relay 12v stud.

There is a single 10ga feed to the main Painless fuse block and I've taken a lot off that circuit already ie: crackedbacks headlight harness, the fan controller and fans, stereo preamp, power seat, etc. I'll feed it off the bus bar with a 45A fuse and that should do it..... I hope... lol.
 
74Scooter said:
Still don't understand these high output (amperage) alternators with a tiny *** charging stud
Click to expand...
The alternator CAN provide 95 amps .

But it only provides the current that the loads require.

Think the 20 amp wall outlet in your house.

If you plug a 60W lamp in it. The lamp works and is only pulling 0.5A where as a hair dryer pulls 1200W and pulls 10 amps.

Both work, just fine.

The small guage wires might be going to individual circuits that only pull 5 amps?

Just guessing what the PO was thinking.
 
Dana67Dart said:
The alternator CAN provide 95 amps .

But it only provides the current that the loads require.

Think the 20 amp wall outlet in your house.

If you plug a 60W lamp in it. The lamp works and is only pulling 0.5A where as a hair dryer pulls 1200W and pulls 10 amps.

Both work, just fine.

The small guage wires might be going to individual circuits that only pull 5 amps?

Just guessing what the PO was thinking.
Click to expand...
My alternator is rated at 110A. The 2 Spal fans slapped on my radiator alone can pull 25A each at spin up.

Hard to say where his mind was at on some of this stuff.. but I'm not giving Painless a pass either

Think the Painless kit was meant to be an OEM style replacement or like kind... but I cannot imagine why they still only use a 10ga charge wire from the alternator to the battery and and 10ga main feed wire to the fuse block knowing what we are doing with these classic rods today.
 
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