What Do Slave Cables Consist Of?

[tim292stro]

That sounds better than 2Ga for jumping.

I have some 4/0 clamps (1400Amp) I'm going to build a set of jumpers for - I tried jumping a friend's 5.0 Mustang with a Toyota Pickup and that taught me something... More battery, more alternator, more cable thickness - always a good thing

For the slave cable set I'm building, I have a LED circuit in the heads which change color if the polarity is not right, or the voltage is too low.

• Red = Reverse Polarity (center negative instead of positive)
• Green = Good polarity, voltage above 18Volts (probably a 24V system)
• Blue = Good polarity, voltage is too low (might be a 12V system!!!)

Plug that into an un-surveyed truck first and that'll keep me from doing some damage by hooking it up to my truck if "things aren't right".

 

[tobyS]

That sounds better than 2Ga for jumping.

For the slave cable set I'm building, I have a LED circuit in the heads which change color if the polarity is not right, or the voltage is too low.

• Red = Reverse Polarity (center negative instead of positive)
• Green = Good polarity, voltage above 18Volts (probably a 24V system)
• Blue = Good polarity, voltage is too low (might be a 12V system!!!)

Plug that into an un-surveyed truck first and that'll keep me from doing some damage by hooking it up to my truck if "things aren't right".

Where did you get the LED setup? It is possible for a person to get them reversed when changing batteries so would seem to be a nice addition.

 

[tim292stro]

That was my thinking too - and since I've seen people use NATO slave ports for non-standard purposes, I wanted to CYA on my own "A". I built it myself, I'll post the schematic, board file (ExpressPCB), and parts list tonight when I get home.

It's a pretty simple circuit, a bridge rectifier, an AND logic device, a voltage regulator, a comparator with a resistor divider, and a current limiter (some other support/protection parts too).

• The bridge rectifier makes sure that the circuit is always correct despite the actual battery polarity (since LED and logic only works one-way).
• The AND gate checks the polarity of the battery versus the "correct" polarity (ensured by the bridge rectifier) by requiring the rectifier positive (high) to be equal to the battery positive (high)
  • If it's wrong (high rectifier, low battery), the Red LED gets power
  • If it's correct (high rectifier, high battery), the Green/Blue LED portion of the circuit gets power
• The voltage regulator makes a reference 6V voltage out of whatever is put into the slave port (from +9V - 40V)
• The resistors make a voltage divider, which cuts the voltage down by 2/3
  • 24V / 3 = 8V
  • 22V / 3 = 7.333V
  • 20V / 3 = 6.666V
  • 18 / 3 = 6V
  • 16 / 3 = 5.333V
• The comparator tests the voltage made by the reference voltage regulator (6V) against the measured battery voltage from the divider circuit
  • If the measured voltage is higher than the reference, the Green LED gets power
  • If the measured voltage is lower than the reference, the Blue LED gets power

 

[gimpyrobb]

I'm sure if they are wired in reverse, the bolt of lightening(arc) coming from the connectors will let you know. No need for leds!















BWAAAAhahahahahaha

 

[tim292stro]

Ha, yeah, but only when you plug it into the second vehicle - and if a PCB in the "dead" vehicle was protecting that vehicle from a battery wiring mistake, it does nothing to protect your "good" vehicle.

If you have nice Hawkers and a relatively expensive set of high-output alternators and other gear in your own truck (radios, etc.) - I'd rather not let the smoke out of my own gear... (no good deed goes unpunished right?)

 

[tobyS]

I'm sure if they are wired in reverse, the bolt of lightening(arc) coming from the connectors will let you know. No need for leds!

Of course you're right about the arcing (that's what my first thought was). But if you hook the other vehicle up first, that arcing can be avoided (If I'm reading what he says correctly). I wonder if it can be made small enough to fit in one of the 500 amp ends??

 

[gimpyrobb]

A simple check with a dmm will let you know polarity.

 

[tim292stro]

A simple check with a dmm will let you know polarity.

Then of course you need to carry a DMM with a Slave cable set.

Of course you're right about the arcing (that's what my first thought was). But if you hook the other vehicle up first, that arcing can be avoided (If I'm reading what he says correctly). I wonder if it can be made small enough to fit in one of the 500 amp ends??

Yes, as designed, this circuit is a hole drilled in the back of each slave plug end and an LED glued in place (watertight), and the circuit taps power from the cable lugs inside the connector body (I've spec'd springs to do this in my design). What I'd like to do is make it so that a standard replacement back can be produced with this feature built-in and sold like that...

 

[gimpyrobb]

Then of course you need to carry a DMM with a Slave cable set.

I carry one in each vehicle. Too many times I could have used one and didn't have one available(same with lots of tools I now carry with me.).