Start battery switch/solenoid. I need a new one.

[Chaz]

Hey Folks,
  My 4108 has some sort of short/drain on the start batteries so I always have to remember to throw the main disconnect (above the batteries) when I park. Well....... I guess it was too much use or old age and it laid down on me.
  I have been thinking about putting some sort of solenoid there instead and run wires up to the driver panel so I can disconnect from there. Actually, I wanted to do that since I bought it.
  Soooo..... any suggestions on which one or any tricks to go about it? I figure it is pretty straight forward.
  And yeah, I'd like to just find the problem and "cure it" but.... I still would like to do this. Heck, I'd like to completely strip ALL non essential wiring out but I have no clue as to what is what. I'd like a professional help me with that. My guess is there is at least a little money in copper in there. (might even be enough to buy me a margarita! )
  Thanx a bunch!!!!!!!!!
    Chaz

[bevans6]

The issue is usually the high current load from the starter motor, particularly a 12v starter motor.  It can be as high as maybe 900 amps, 500 amps might be more typical.  Most high current solenoids are momentary on so to stay on they need a constant current in the coil and can overheat.  So you need a 12V latching solenoid (latching solenoids use a coil to switch from on to off, but need no current to stay on) that has a surge current rating higher than your starter load, and a continuous current rating higher than your alternator output.  Not to say they aren't out there but I've never found one.

Brian

[luvrbus]

You can buy a 800 amp continuous duty and 1500 amp intermittent from Texas Industrial Electric I know they have that one probably they will have a higher rated but that is the highest rated I ever bought from there

[Chaz]

Luvr,
  I'm assuming that would be big enough??
  BTW, in case some of you didn't know, my bus is 24volt. I was wondering if that had any effect?
  Thanx guys!
  Chaz

[bevans6]

A 24v bus will need a switch with half the current capacity (ampacity) rating as a 12v bus will.  That makes a big difference in finding a switch, since the are rated in current capacity.

Brian

[pvcces]

Our system is all 12 volt, so you may have trouble on 24 volts. However, we have never had any trouble on 12 volts.

We installed Xantrexs' Pathmaker. We burned up a couple of their relays and then took out the relays. We replaced them with this eBay item: 390649001828. The relay does not run hot, even after hours on the road, and it takes a small fraction of the original relay's coil current.

The only improvement I could ask for is if the Pathmaker had temperature compensation. We have been able to avoid problems by adjusting the cut-in voltage to the high side and letting the controller do the compensation. So far, so good for over five years.

[bevans6]

If you could find a used Pathmaker rated for 250 amps (presumably the relays that pvcces changed out are the difference between the models) then it should work.  It's been discontinued for a few years now, but the literature is still on-line, it is supposed to automatically detect 12V or 24V operation and select it's voltage trigger ranges accordingly.  Kind of neat.

Brian

[belfert]

I have an unused Xantrax Pathmaker I will practically give away.  It was mounted in the bus for a few years, but never connected.  Contact me via PM or email.