Starter solenoid information, voltages with small wire Options

[Tom]

Been meaning to get this done. I have a spare starter solenoid and wanted to see what would happen if I introduced a voltage drop like one would see if there were bad/dirty/corroded connections in the start circuit. Using a voltmeter from the spade terminal of solenoid ( where the large yellow wire would hook up) to ground for voltage measurements. First used a large 12 ga ground wire to the negative side of the solenoid. Same point as where the starter motor wire would connect.
Then using a 12.2 volt car battery, hook up a small (22ga) wire to positive spade connector. Voltage = 7.0 and solenoid would not operate. Next used a 20 ga. wire , voltage = 8.4 and solenoid operated, but slowly. Next used 16 ga. wire, voltage = 9.6 and solenoid operated fast. Finally used an additional 16ga. wire to double current carrying capacity and voltage = 10.2 and solenoid operated very quick.
Trying to count all of the connections between the battery and solenoid spade, I have found that there are a lot, and all cars will not be the same. However, in order of the probability that they are bad, here they are.
1- the 4 lugs at the positive of the battery clamp. They are exposed and could be corroded inside the barrel of the connectors.
2 - Next bad place would be the spade connector at the starter solenoid with the yellow wire. Exposed to water/heat,etc.
3 - the relay board 14 and 12 pin connectors. Dirt, oil film, corrosion, and heat.
4 - the seat belt ( if your car has them) relay connectors or jumper wire.
5 - the key switch and/or connectors at the key switch.
Due to the possibility of corrosion inside the barrels of the crimp on connectors, I think it would be a good idea to lightly solder these connections also. Keeps dirt and corrosion out.
While I had this inside and testing, I hooked up a diode across the solenoid coil and it made a significant difference in the arc when I disconnected the battery during testing. There is still some, but much less. I will be soldering a diode across the solenoid coil of mine before I bring it out for spring. I think it can help and it certainly will not hurt.
Hope this will help some of you guys with this mean old starter circuit.
Tom