Big boy question

[Cary and Don]

We had the great idea of running the front air conditioner off the bus generator through our big boy relay to the house batteries. It did run the air conditioner just fine.  The problem came with the big boy getting hot.  This doesn't have the latching relay in it since it was intended for the axillary start.  The reason we thought to run it through the big boy was so we could disconnect the house batteries from the bus batteries during hill climbing. Has anyone else tried this?  That puppy got real hot to the touch after about 10 minutes and we wouldn't want to burn it up. If we used a manual switch we couldn't disable the connection while going down the road.

Don and Cary
GMC4107
Neoplan AN340

[Sean]

.. our big boy relay to the house batteries. ....  This doesn't have the latching relay in it since it was intended for the axillary start.  ...

OK, I am officially confused.  The Intellitec "Big Boy" 200 amp isolator solenoid is a latching relay, by definition.

Perhaps you have a different brand/model of solenoid in this application?

The "Big Boy" is rated for 200 amps continuous, 1,200 intermittent (30 seconds).  The 200 amps should be more than enough to run your air conditioner.  I am guessing your alternator is the 24-volt 50DN model, which can only supply a sustained 270 amps anyway, and with chassis loads accounting for a portion of that, you could not exceed the rating by much even if you tried.

These solenoids will get hot to the touch at higher current loads.  However, they should not get "untouchably hot" unless there is a problem.

OTOH, if you have a standard, Normally Open (NO) solenoid, then there will be a certain amount of heat generated by the operating coil itself, even if no current is flowing across the contacts.

Lastly, note that the latching "Big Boy" solenoid is intended to be operated by a momentary application of voltage to the operating coil.  If you apply a continuous voltage to this coil, as you would to a standard NO contactor, you will overheat the coil and possibly damage it.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com

[Sean]

It occurred to me later in the day that Intellitec does sell a non-latching solenoid similar to the "Big Boy" disconnect.  AFAIK, they do not market it with the name "Big Boy."  It is their part number 77-90006-240 (or -120 for the 12-volt model).

This item is basically back-engineered from the "Big Boy" disconnect, omitting the patented magnetic latch mechanism that, frankly, is the only real reason to buy from Intellitec in the first place.  But because of the lineage, it requires a whopping 6 amps to pull the plunger.

For this reason, Intellitec does not permit it to be used in a continuous application without connecting it to their proprietary "Diesel Battery Controller," per the following:

The 200 amp version is not a continuous duty unit and requires an Intellitec Isolator - diesel controller to prevent it from overheating when it is used for continuous duty.

(emphasis mine), taken from the product specification: http://intellitec.com/pdfs/BATTERY_web/5390000.000.pdf

I strongly suspect that all the "controller" does here is supply the full 24 volts (or 12, as applicable) for a short period of time to pull the plunger, then reduces the voltage to something less to hold it in the closed position for the duration.

If your application does not require Intellitec's fancy control boxes, and all you needed was an auxilliary start solenoid, the one I recommended back a while back (http://www.busconversions.com/bbs/index.php?topic=12028.msg126976#msg126976) from Grainger will do fine.  It's less than half the price of the Intellitec model, and is rated for continuous use with simple application of the rated voltage.  It's also half the physical size.

So if what you have is the 77-90006-240, just change it out for one of these and you'll be good to go:
http://www.grainger.com/Grainger/items/6C025

If what you really have is the "Big Boy" (00-00507-524 or -512, http://intellitec.com/pdfs/BATTERY_web/5300507.000.pdf) then my earlier remarks are germane and you need to follow the wiring guidelines in their installation and service manual:
http://intellitec.com/PDF/5300507.100.pdf

Hope that clarifies further.

-Sean
http://OurOdyssey.BlogSpot.com

[Cary and Don]

We are 12 volt, however that probably doesn't make any difference.  Do you know of a good choice for a continuous duty unit that would work?  Obviously, it isn't going to tolerate being used continuous since it is made for intermittent.

Don and Cary
GMC 4107
Neoplan AN340

[Sean]

We are 12 volt, however that probably doesn't make any difference.  Do you know of a good choice for a continuous duty unit that would work?

White-Rodgers makes an identical solenoid in 12-volt, but Grainger does not carry it.  You can get one here:
http://www.randkproducts.com/product_info.php?cPath=27&products_id=354
among other places.

I see now from your sig that you have two buses, one 12v and one 24v.

On the 12-volt system, everything requires twice as much current.  The 12v 50DN is rated at a whopping 350 amps, and a single roof air will draw upwards of 145 amps  So for 12 volts you may need an even larger solenoid, depending on what other loads, including battery charging, may be trying to run off the alternator.

-Sean
http://OurOdyssey.BlogSpot.com

[Cary and Don]

We have a White Rogers 586-902.  Type 586-105111-3  12v d.c cont. It doesn't have the B1 on the number though. Is that the same?  The B1 just being the revision number?  If this will work for the air conditioning problem,  we can leave the Big Boy in there for the auxiliary start system.


Don and Cary
GMC4107
Neoplan AN340

[Cary and Don]

We have an open 135amp breaker coming off the bus batteries that we could attach this magnetic switch too.  The inverter's charger would be disabled during inverting.  Don't run the air conditioner until the batteries are up.  Since that big generator adds at least 5 degrees to the engine,   we want to drop the connection during hill climbing.  Now we have to start the gen set to run the air, and that burns a lot of extra diesel at $3.15 a gallon.

Don and Cary
GMC 4107
Neoplan AN340

[Sean]

We have a White Rogers 586-902.  Type 586-105111-3  12v d.c cont. It doesn't have the B1 on the number though. Is that the same?

Yes.  Actually, the W-R part number is 586-105111, and is in their catalog here:
http://www.emersonclimate.com/Documents/White-Rodgers/catalog_06_pages/Cat_06_pg0120.pdf

I believe the 586-902 is one of their distributors' part numbers, and I see that number repeated through a number of online retailers.

W-R recommends using 586-108111 (15 volt coil) in alternator-driven applications where continuous voltage will be closer to 14 than to 12.

-Sean
http://OurOdyssey.BlogSpot.com

[Cary and Don]

I think we are going to put it in and try it.  We got five of these for $10 each brand new.  We won't be using it all the time,  so I'll bet it will last a long time for us.  Our generator is set to about 13.7 with everything off and at idle.  We'll have to see if it gets hot too.

We tried one of those battery control boxes and it was a royal pain.  There was always something not working.

Thanks for the help.

Don and Cary
GMC4107
Neoplan AN340

[Jerry32]

I just went to the golf car place and got a relay  for 12 bucks works continuous.