Solenoid for start batteries

[Chaz]

Hey Guys,
  Would this work to turn my start batteries on from the drivers seat?
http://www.colehersee.com/home/item/cat/195/24824-01/
  It's a pricey little bugger but it would be nice to be able to turn the batteries on and off from the drivers seat. The poles are only 5/16" and that kinda concerns me.
  If not, any other ideas??
  Thanx a bunch,
    Chaz

[akroyaleagle]

I don't think so.

My two 8d starting batteries have a combined amp of up 3400 amps. Granted that is at 12V. I think 24V would use half the amps.

•BCI Group Size:8D
•CA at 32 degrees F:1700
•CCA at 0 degrees F:1400
•Reserve Capacity:430
•Volts:12

You would need a solenoid capable of handling your max amps AND cables heavy enough to hold the amps. If you are talking about locating the solenoid up front, they would have to reach from your batteries to the solenoid and back to the starter. Because of the distance, They would have to be a couple of sizes larger than the normal used now.

If you located the solenoid in the engine compartment, You would need two wires sized large enough to activate he solenoid. Much smaller.

This is probably doable but I think you will have a hard time locating a solenoid big enough.

Do you have a power drain now when the battery switch is on?

I turn my batteries on as part of the walk around when I want to start the coach. It stays on until I shut down for the night. I turn them off when I walk around and check for leaks. I have left the batteries on for several days when travelling.

[TomC]

Not enough surge amps to safely start the bus. Use a manual shut off switch or just plainly disconnect the batteries. Good luck, TomC

[Chaz]

Dang. And where I got it from, they talked with people from the company and they said it would work!
But ya know, it would been no big deal cause if I fried it, they only list for $399.45. (extreme sarcasm!) Thnx for helping me head that mess off at the pass guys!
I would still like to be able to do this as I "had" a manual switch till it just broke. And since I always wanted to do it this way anyway, I figured now is the time.
The reason being, is that I do have a draw on the batteries and I am blonde and getting older. (Brain fads, farts and memory lapses) I figure it would just be easier to shut them off before I get out of my seat and get side tracked with the other things I got to do. Or when people come up and want to see my big beautiful baby once I stop, etc.  
Any other suggestions besides "electro shook brain therapy"
Thanx a bunch again!
  Chaz

[junkman42]

Chaz, try to find a military surplus relay.  You will find quite a few relays with 28 vdc coils that were used for starting aircraft engines from recips to turbine also many items of military equipment use large relays in power supplys all of which run on 28vdc.  A master switch relay from any large aircraft would make You a happy camper.  Regards John L

[luvrbus]

Texas Industrial Electric will have what you need for under 100 bucks

[Len Silva]

I did use a solenoid to disconnect the batteries, I just did not include the starter in the circuit.  Use the solenoid to disconnect everything except the starter and you should be OK.  200 amp should be more than enough.  Be sure it is rated continuous duty.

[luvrbus]

It's not that big of a deal most 200 amp continuous duty solenoid have a high momentary inrush of 400 to 600 amps just think of it as a pair of jumper cables it goes through the batteries not directly to the starter if hooked up right

[sledhead]

I have a 200 amp 12 volt switched solenoid set up on my manual pull switch ( if the solenoid fails I can still use the org. pull switch ) Once in 7 years it did fail at a replacement cost of $ 75 bucks . The solenoid has about a 1.2 amp draw and it gets warm and the cables are only 4 " long . It is installed right at the manual switch with a remote switch at my drivers seat .I org. had a latching solenoid but it burnt out after 6 mths . I called cole hersee , talked to them about the set up I have now . ITs only been 7 years so the nat sayers say it can't work . Other then the start of the eng. there is not a lot of draw when on the road .no bus a/c.          I will try and get a picture of it        dave       

[bevans6]

Locked current draw on the 24V starter in my bus is supposed to be 500 amps, so a 12V starter might be 1,000 amps.  You never operate the starter locked for more than a second, so a typical inrush current might be 60% of that, so a solenoid that can handle momentary current in the 600 - 800 amp range would suffice for a 12V bus, half that for a 24V bus.  On my bus there is a 4/0 cable that goes from the batteries to the main disconnect switch to the starter and alternator.  I would personally never never connect that line through a solenoid that I could control from the driver's seat.  Too much potential for a brain fart or other unintended action opening that solenoid when the alternator is charging.  If that happens the alternator loses it's reference voltage and could free-run, which is bad for it, and could be terrible if you connected the alternator back to the bus when it was producing over 100 volts.  My bus has a 1/0 wire running from the disconnect switch to the AC junction box bus bar and then to the main bus bar, and all power to the bus systems (aside from the starter) are run from that wire.  I would put a solenoid on that wire to switch power on and off to the bus, and leave the master switch alone.  On my MCI the AC junction box has a little bus bar for this wire to connect to, and two big solenoids that switch power to the AC condenser fan motor and the AC evaporator fan motor.  Since I don't have the OTR AC any longer, I would just move the 1/0 wire from the main disconnect switch from the bus bar to the motor side terminal on the condenser fan solenoid and work out a way to switch it from the dash (like maybe the AC switch that is already there and not being used for anything).  Job done, cost zero.

Edit:  I recall from my days building race cars that by adding a resistor to shunt the alternator output to ground when the disconnect solenoid is open you can force the alternator to stop charging and eliminate the run-away high voltage issue.  That needs a ganged solenoid so that one is normally open (the high current one) while one is normally closed (the shunt one).  Control switch open, batteries disconnected and alternator cannot charge, control switch closed, batteries connected and alternator charges.

Brian

[luvrbus]

I have installed the Kilovac LE200A4NAA when the disconnect switch has gone bad  before it seems to work fine no one has had trouble with one yet (knock on wood) they are not cheap I paid $175.00 for the last one, people like the convenience of flipping a switch from the drivers seat I can't say I blame them

[sledhead]

My set up has a panel above the drivers seat ( I have to stand to turn off or on ) that has 3 switches . 1 for 12 v main off a latching solenoid .  1 for charging the 12 v off the 24 v bus system verner when driving . The last 1 is the 24 v main shut off .  After I turn on the 24 v main and sit down I still have two turn on the master switch on the dash plus push the start button to start the eng.  Just for the safety of not having to go out side to turn on or off the manual master switch I could not go back to the org. system.  In this day and age if someone is trying to hijack us in a rest stop at night I can turn on the inside switch and start driving and see how long they can hold on to the bus as I drive off                  dave

[TomC]

At least on my AMGeneral transit bus, I have a battery shut off on the back engine panel. Makes for convenient working on the electrical system (except if arc welding). Good Luck, TomC