Resistor cart wiper contact question

[rlw]

I cleaned up the wiper board on my '84 Marathon, and it occurred to me that the 6 gauge wire between the contact and the solenoid is the weak link in my high power wiring.

I pulled out the spring and copper contact, and couldn't really see anyway to easily replace the 6 gauge wire.

Is the wire soldered into the contact, welded, or crimped in somehow? There's plenty of life left in the contact itself, I'm just concerned that the wire's not gonna last with all of the extra current coursing through the 4 gauge cables. The copper bolt contacts (0, 1, 2, 3, 4) on the board are also in pretty good shape. When I cleaned things up, I put a piece of fine grit sandpaper between the contact and the copper bolt heads, and moved the arm back and forth to get the faces flat to each other.

I really don't want to buy a beefed up wiper board just to replace the contact and cable. Does anyone make and sell *just* the contact and cable?

Thanks,

RLW

[rib33024]

It should be fine like it is, because the cart burns off unwanted power through the coils

[scottyb]

Nobody makes a 4g Wiper lead I know of... The end is soldered on, I suppose you could change it to 4g but I'm not sure if there would be any real gains.

[rlw]

Originally Posted by scottyb

Nobody makes a 4g Wiper lead I know of... The end is soldered on, I suppose you could change it to 4g but I'm not sure if there would be any real gains.

Thanks, Scotty.

Looking at the schematic, when the accelerator is in position 4, that 6 gauge cable is carrying all of the armature current. Could be that a significant percentage of the entire system's current is distributed to the stator/field coil in the motor, so it (the wiper cable) isn't carrying everything.

This might be a good mental poser question for guru JohnnieB...

Let's see if he chimes in.

RLW

[gornoman]

Originally Posted by scottyb

Nobody makes a 4g Wiper lead I know of...

Future product idea, Scottyb? You could be the guy to work that out!

[scottyb]

I could ...? I'd prefer to see this person just go to solid state and do away with the toaster oven parts

[rlw]

If I didn't have to mortgage my firstborn to go solid state, I'd go for it! As it is, a conversion kit would cost just about what I've got in my cart at this point...


RLW

[JohnnieB]

Originally Posted by rlw

.............Looking at the schematic, when the accelerator is in position 4, that 6 gauge cable is carrying all of the armature current. Could be that a significant percentage of the entire system's current is distributed to the stator/field coil in the motor, so it (the wiper cable) isn't carrying everything...............

FWIW: Guru is the Sanskrit word for Teacher.

By definition, the armature and stator are wired in series in a series wound motor. Therefore the entire current flows through both armature and stator as well as every high current cable, connection, contact, component and battery in a series cart, which a resistor cart is a subset of.

Here is a drawing with the singular current path highlighted in purple and showing that the entire current does, in fact, flow the the 6Ga cable (Circled in red) on the wiper contact.

Since the intrinsic resistance of 4Ga is 0.0002485 Ohms/Ft while 6Ga is 0.0003951 Ohms/Ft, and the wiper arm cable is less that a foot long, there is not much performance gain to be had by going to heavier cable.

On the other hand, replacing the other 20 to 30 feet, or so, of high current cables in the system with 4Ga, will show some improvement. Partially due to reducing the intrinsic resistance and partially due to the the old cables having high resistance from years of corrosion build-up upon and within the lugs and within the cable itself.

As for mortgaging your firstborn to upgrade to a solid state controller system, He/She was already $50,000 in debt upon birth, so what difference does another grand make.

[scottyb]

LOL!

[rlw]

Ohmmmmmmmmmmmmmmmmmmmmmmmm.

Thanks for the excellent explanation, teacher!