What is a good solenoid to use with 24 DC for connectiong house and chassis?

[belfert]

The manufacturer ran two smaller circuits to the selenoid instead of a larger wire.  Each wire is protected by an auto reset 90 amp circuit breaker.  The solenoid is turned on/off by a switch on the dash that turns the A/C and heat on and off.  It is not always on.

I looked it up in the parts manual and the solenoid is only 100 amp which is why it seemed small.

Oh, I misunderstood. I thought this was the solenoid you already had hooked up as a battery crossover that is doing screwy things.

This is the old A/C solenoid that I am trying to use as a battery crossover.  Now that I realize it is only 100 amp rated I need to replace it anyhow.

[belfert]

I found a Cole-Hersee 24144 Solenoid at a place about a mile or two from home.  $45, but no shipping and they have them in stock.

[Len Silva]

I would like to suggest that you have a way to operate the cross over solenoid from the house battery.  However simple or complicated you want to make it, it would be nice to be able to connect both systems even if the bus batteries are too low to operate the solenoid.

[Chuck Newman]

Attach two low amp steering diodes (1N4004 to 1N4007) to the solenoid.  Anode of one diode to house batt side of the solenoid, anode of the other diode to the engine batt side of the solenoid.  Tie the two diode cathodes together (the end with the band), and send that wire to the new "boost" switch.  Typically on the dash.  Fuse it at the diodes.  Put a wire on the other terminal of the boost switch and send it back to the positive control lead on the solenoid.  Tie the negative control lead to ground.

When you close the boost switch it will utilize the greater voltage from either set of batteries to close the solenoid.  Usually a spring loaded toggle switch is used.  You can use a low current push button switch.  A typical DPST toggle switch is not recommended since you may leave it "on" and drain the charged set of batteries.  Leaving you with two sets of discharged batteries.  

My solenoid connects whenever the engine is running.  It automatically disconnects the two sets of batteries when gen runs or on shore power, whether engine is running or not.  If all else fails, I can manually connect/disconnect via a 500 amp switch.

FWIW  Chuck

[RTS/Daytona]

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http://commerce1.cera.net/tacbusparts/sections/catalog/catalog.asp?cat_id=70

http://www.hydrogenappliances.com/solenoidrelay.html


Another trick - buy 2 12 volt solenoids - put the coils in series for 24 volts and put the contacts in parrallel to double the current carrying capacity

with the coils in series - if one solenoids coil opens (coil falure) - the other solenoid will not energize to handle the full load.  (kind of built in safety ??) 

[belfert]

My plan is to hook the coil up to a power source that is only active when the ignition is on.  It will still have a switch too.  If I hooked it to the house batteries the selenoid coil could draw power all the time.

An overrise to jump the bus will have to come later.  I can always rig something in an emergency.

[bobofthenorth]

An overrise to jump the bus will have to come later.  I can always rig something in an emergency.

My thought exactly.  Once you have the heavy cables run to the solenoid the emergency rig is pretty simple - bolt the cables together IOW.  I can't see going to a bunch of bother setting up a switch to control the solenoid for a once in a lifetime event that you hope will never happen.