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Author Topic: House Bank Solenoid Problem  (Read 2269 times)
wagwar
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« on: July 12, 2012, 10:35:11 AM »

I finally got to road test my house bank to coach bank solenoid system yesterday. All was well and both rooftop A/C running cold! That lasted for a couple of hours and then - nothing. It all shut down. I was able to continue running one of my rooftop units from the inverter, but that was running off the house batteries with no engine assist. Once we got parked, I tested the solenoid and it was open. It had a good 24vdc signal, but no continuity. I have to assume it is blown.
So, its a 200Amp continuous duty unit. There is no reason I can think of that it should blow!  Did I just get a bad one OR is this likely to happen to the next one, and the next one? Is it heat? The solenoid is in the front bay, so it is not in a particularly hot spot. I spoke to another bus nut and they said they got tired of replacing their solenoids all the time and went with a manual switch. Is this what I need to do or is there a solenoid out there that can do the job. If I replace it with a switch, will a 200A unit be sufficient?
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« Reply #1 on: July 12, 2012, 11:22:34 AM »

Just guessing here, but although 2 AC units could be running at less than 200 amps @ 24v, they could be drawing a good deal more at start up.  Over a period of time, it would certainly happen that both would be kicking in together.
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« Reply #2 on: July 12, 2012, 12:16:18 PM »

volts x amps = watts   ac running  14 amps each @ 120 volts    start up  up to  19-20 amps @120 volts   Most inverters rated at 4000watts are only like 3000 and change continious.  for what it's worth.     if you are charging off stock bus alternator it puts out more than 200 amps @ 24 volts
« Last Edit: July 12, 2012, 12:20:51 PM by robertglines1 » Logged

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« Reply #3 on: July 12, 2012, 12:26:57 PM »

But, since it is a 24v solenoid, the amperage is 5 times higher. So 2 units could be 200+ amps at startup depending on other charteristcs of the system.  My knowledge here is pretty basic though. I definitely could be missing something.
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« Reply #4 on: July 12, 2012, 12:58:45 PM »

what I as trying to point out was at start up they could draw 100amps each at 24 volts each plus any battery depletion the alternator was trying to replace plus other bus loads. Sean will probably be able to explain better.  need really big selonoids.  
« Last Edit: July 12, 2012, 02:42:20 PM by robertglines1 » Logged

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« Reply #5 on: July 12, 2012, 01:11:58 PM »

I second Bob's post.  Two AC's on one inverter and solenoid may be too much.  I went through dying solenoids with my SW2512 and one Coleman 13.5k btu.  I finally isolated it under a dust cover box and eliminated my failures.  I don't believe dust is your problem, however.  Sean will chime in and give you some ideas.  He's our inverter guru on the forum.

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« Reply #6 on: July 12, 2012, 01:18:58 PM »

I spent a lot of time researching the solenoid house bank charging options. I decided that the best case would be if I were just charging my batteries a 200 AMP solenoid would work but if I also wanted to run an AC unit or two, I had better plan to keep an inventory of spare solenoids. I am not sure what your charging output is but mine is in the range of 300 AMPs. I went with a isolatetor method as I knew I would eventually forget to switch a disconnect switch.

Jack
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« Reply #7 on: July 12, 2012, 02:52:01 PM »

You can always run two solenoids in parallel so that each shares 1/2 the amp load.
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« Reply #8 on: July 12, 2012, 04:26:52 PM »

so two or how about one of these:

http://www.ebay.com/itm/GE-EV-100-300-AMP-24VDC-SPNO-IC4482CTTA300AH124XN-/120567578558?pt=LH_DefaultDomain_0&hash=item1c12633fbe
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« Reply #9 on: July 13, 2012, 03:51:27 PM »

Parallel 200 amp units will give you 400 amp capacity, 33% more than the one in the link.
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« Reply #10 on: July 13, 2012, 04:08:24 PM »

Thanks Gus,

Sorry, but I'm not sure how to wire that. By parallel, do you mean the coach bank connects to one side of one unit and a jumper to the same side? Both units would be activated from the same signal.
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« Reply #11 on: July 13, 2012, 04:19:13 PM »

Both units would have like terminals wired together, then the bus wires connected just like to one. This way both will be activated at the same time and split the amps.

Same idea as wiring two batteries in parallel.

This will only solve your problem if it is actually caused by the single solenoid being of too little capacity.

It could also be caused by the large contacts in the single solenoid being so burned they have too much resistance to carry the current.

However, since solenoids aren't terribly expensive, having two in parallel is not a bad plan because it gives you an automatic backup.
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Sean
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« Reply #12 on: July 13, 2012, 09:27:14 PM »

... both rooftop A/C running cold! That lasted for a couple of hours and then - nothing. It all shut down..
... Once we got parked, I tested the solenoid and it was open. It had a good 24vdc signal, but no continuity. I have to assume it is blown.
...


First off, let me start by saying that I run two air conditioners, plus the rest of the normal bus loads, all the time using my 270-amp alternator ans a single, 200-amp solenoid.  The solenoid has lasted eight years and 140,000 miles and is still going strong, so there is nothing conceptually wrong here.

You may just have a bad solenoid.  But let me put the load issue to rest:  There is no way the actual load passing through the load contacts can cause the coil to blow.  Usually overloading the contacts has the opposite effect: welding the contacts in the closed position.

If you switch the solenoid on and off repeatedly under load, the arcing that inevitably results can pit the contacts and/or char them, leading to high resistance and which, left unchecked, can ultimately lead to an "open" reading.  For this reason I recommend that any high-current loads such as air conditioners be switched off while the engine is being started and the contactor closes, and likewise before stopping the engine when the contactor opens.  Note that I am too lazy to follow this recommendation myself.

But your description here suggests you have not had this system in place nearly long enough for carbon deposits to build up on the contacts.  Moreover, if this was the problem, you should still hear the plunger moving when operating voltage is applied.

I suspect instead that the operating coil is damaged.  This can come from improper voltage -- for example, using a 12-volt coil on 24-volts.  It can also come from high back-emf when the operating voltage is suddenly removed.

The first thing I would do here is to disconnect the operating coil and measure its resistance with a quality ohmeter.  The manufacturer of your solenoid should publish the specification for coil resistance.  If the coil reads either shorted or open, it's a problem.

If the operating coil reads OK, it might be possible to open the unit to look at the load contacts.  What make and model is your solenoid?  Also, see if you can find a part number on it -- it's possible they sent you a 12-v model in error.

You can always run two solenoids in parallel so that each shares 1/2 the amp load.

and
Parallel 200 amp units will give you 400 amp capacity, 33% more than the one in the link.


Actually, this is incorrect.  First of all, you can't simply double the rating when ganging relays in parallel.  That's because there is no way to guarantee that half of the current will go through each one, and, in practice, one always gets more than the other.  For double-pole relays, manufacturers usually publish the de-rating factor that needs to be applied when ganging poles together to increase capacity; when no specification is published, the accepted standard is 25%.  So a pair of 200-amp poles ganged together is good for no more than 300 amps -- not 400 amps as your post would suggest.

But when it comes to separate, power-to-hold, normally-open solenoids, there is an even bigger problem: a failure in one solenoid would shunt the full current onto the other solenoid.  For this reason, simple, single-contact solenoids are not permitted to be ganged together to increase capacity in this way.  Certain types of contactors can be ganged, but it requires them to have "auxiliary contacts."  The control power is wired through these contacts so that if any contactor drops (opens), then all contactors will open simultaneously.  Operating this type of ganged arrangement requires momentary, rather than continuous, control signals.

For applications in the under-1000-amp range, it's cheaper to just buy a contactor rated for what you need rather than buying multiple contactors with auxiliary contacts and ganging them together.

All of that said, 200 amps continuous-duty rating should be sufficient for this application.  Remember that the amount of current drawn by the air conditioners is not the controlling factor, but rather the amount of current that can be supplied by the alternator minus whatever is being used on the chassis side.  We have a shunt and a high-quality ammeter on our inter-tie, and while inrush current can spike to just above 200 amps when the house bank (920 ah) is depleted, I have never seen it remain above 200 for more than 2-3 seconds.  The alternator simply can not supply any more than that (the inrush spike is higher due to the chassis batteries).

-Sean
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« Reply #13 on: July 14, 2012, 02:26:32 PM »

Thanks to all who have responded!

I leave the solenoid connected all the time we are driving, so it doesn't get cycled very often. This is really the first time I've been able to test it thoroughly - as it always worked just fine in the driveway. I am also careful to turn the a/c units off before starting and stopping the engine.

The solenoid is a White-Rodgers Type 586. Part No.:586-114111

I'm using a 24vdc relay to send the signal to the solenoid, tapped off the main master bus in the front junction block. I'm sure it is a 24vdc signal and solenoid.

Sean wrote: We have a shunt and a high-quality ammeter on our inter-tie, and while inrush current can spike to just above 200 amps when the house bank (920 ah) is depleted, I have never seen it remain above 200 for more than 2-3 seconds.

Sean, I wished that I could also monitor at least the voltage running through the solenoid, but amperage would be even better. Please explain how you are using a shunt and ammeter to monitor the solenoid? I assume that by 'inter-tie' you are referring to this.

Thank you, in advance.

 
 
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« Reply #14 on: July 14, 2012, 09:48:03 PM »

The solenoid is a White-Rodgers Type 586. Part No.:586-114111

That model is perfectly adequate for this application, and, in fact, is usually the exact item I recommend.  It supports up to 600 amps of inrush current and is rated for 200 amps continuous  -- you'd be hard pressed to get more than 200 continuous amps to your house system from your alternator.

The coil resistance for this model is nominally 47 ohms.  Check the coil with a good ohmmeter and tell me what you read.

Quote
...
Sean, I wished that I could also monitor at least the voltage running through the solenoid, but amperage would be even better. Please explain how you are using a shunt and ammeter to monitor the solenoid? I assume that by 'inter-tie' you are referring to this.


I happened to have a 200-amp, 50 millivolt shunt lying around, and I put this in the line leading from the chassis system to the solenoid.  I bought a surplus 50-millivolt bi-directional meter that reads "0-10" (25 mv deflection) in one direction, and "0-20" in the other.  Since it's a 200-amp shunt, I just multiply the meter reading by 10 to get amps flowing in the intertie and through the solenoid.  I hooked it up so that the 0-200 side of the meter measures current going from the chassis system (alternator) to the house system (batteries and inverter), and the 0-100 side measures the other direction.  This comes in handy when manually over-riding the solenoid to allow the charger in the inverter to charge the chassis batteries, but, of course, it pegs if I need to use the house batteries to "jump" the chassis side.


(Pardon the dust -- never-ending projects.  Also, it's hard to take flash photos of gauges.)


Shunts and meters are available from many suppliers on-line.  You want a shunt rated at least 200 amps; 500 amps is another common rating.  Most shunts are 50 millivolts, meaning that will be the amount of voltage between the terminals when the full rated current is passing through the shunt.  Most meters have their full-scale deflection also at 50 millivolts, but different meters will have different numbers and graphics printed on them.  Ideally, with a 200-amp shunt, you would want a meter that reads "0-200" on the face, but one that reads "0-2," "0-20," or even "0-2000" would work fine, as long as you know to multiply or divide as appropriate.  One that reads "0-10" or "0-100" would also work, but I find it harder to know at a glance when I need to multiply by 2 or 20 vs. just moving a decimal place.

-Sean
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« Reply #15 on: July 15, 2012, 09:52:46 AM »

Humm...

Didn't we recently have discussion on 24v vrs. 12v house battery systems?

I don't have relay problems or even a battery relay with my 12v house batteries and inverter.  The 12v systems stands alone with it's own alternator, and works perfect with the generator or shore power.

--Geoff
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« Reply #16 on: July 15, 2012, 01:54:26 PM »

Didn't we recently have discussion on 24v vrs. 12v house battery systems?

I don't have relay problems or even a battery relay with my 12v house batteries and inverter.  The 12v systems stands alone with it's own alternator, and works perfect with the generator or shore power.

Well, sure, but you probably can't run two air conditioners from your 12v alternator.

Instead of having a relay that can break, you now have a whole second alternator that can break.  So you have not actually increased the reliability of the system in any way -- IOTW, it's not better, it's just different.

I'm not criticizing your solution -- it works for you, and it might indeed be the best solution for your application.  But neither should you be criticizing the OP's decision to do it a different way.  His solution might be the best fit for his application, too.

FWIW, I did an entire piece in the magazine a while back on choosing between 12v and 24v house systems.  It's definitely not a one-size-fits-all answer.

-Sean
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« Reply #17 on: July 15, 2012, 02:12:27 PM »

Actually, my point was that the 24v alternator with relay for the house bank is more complex and problematic.  So right there you have two things that can quit working, the alternator and the relay.  I only have the one alternator, $180 at any truck parts house, with a generator/inverter/12v charger backup.

Yes, 12 or 24 -- its all a matter of choice, and simplicity with backup.  I could of gone either way, I think I chose the right path.

Good luck! 

--Geoff
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« Reply #18 on: July 15, 2012, 03:49:28 PM »

If your main alternator goes out in either scenario you are going to be hurting.  A single 24 volt alternator supplying both the house and chassis needs isn't any more likely to go out unless it wear outs faster due to higher load.

A second 24 volt alternator is way down the list of things I would like to do to my bus.  I would keep the DN50 for the house bank, and the second alternator would be for the chassis needs.  The main reason is to have a three stage regulator for the AGM house batteries.
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« Reply #19 on: July 15, 2012, 04:13:23 PM »

What magazine Sean  I must still be waiting on that copy of the BCM lol
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« Reply #20 on: July 15, 2012, 05:19:46 PM »

What magazine Sean  I must still be waiting on that copy of the BCM lol

Clifford, I am not sure whether to laugh or cry.  Funny comment, but sad situation.

FWIW, the battery voltage article appeared in the April, 2010 issue of BCM.  One of these days, I really need to get around to publishing these on my web site, too, so I can just link them here.

-Sean
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« Reply #21 on: July 15, 2012, 06:44:29 PM »

If your main alternator goes out in either scenario you are going to be hurting.  A single 24 volt alternator supplying both the house and chassis needs isn't any more likely to go out unless it wear outs faster due to higher load.

A second 24 volt alternator is way down the list of things I would like to do to my bus.  I would keep the DN50 for the house bank, and the second alternator would be for the chassis needs.  The main reason is to have a three stage regulator for the AGM house batteries.

And several 24v solenoids?

Belfert, so your remedy is two 24v alternators?  And you are confident with your 24v DN alternator as being dependable enough?  I took off my 270 amp 24v 50DN and it is sitting on the floor of my shop.  Worked perfect when taken off.  I just don't trust it to keep from blowing up and taking out my engine gear train with it.

24v house systems with equalizers, relays, and expensive inverters (etc) does not equal having a 12v belt driven truck alternator/inverter system  that you can buy in town without $pecial order.  Just run your generator if you want to run more than one roof air.

--Geoff


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« Reply #22 on: July 16, 2012, 08:57:17 AM »


Belfert, so your remedy is two 24v alternators?  And you are confident with your 24v DN alternator as being dependable enough?  I took off my 270 amp 24v 50DN and it is sitting on the floor of my shop.  Worked perfect when taken off.  I just don't trust it to keep from blowing up and taking out my engine gear train with it.

My DN50 is belt driven since I have a Series 60.  The DN50 has been around for many years and has proven to be fairly robust.  I suspect most of the issues busnuts have with the DN50 is they have a 30 or 40 year old bus with a 30 or 40 year old DN50 and they have problems when the DN50 gives up the ghost after a million or more miles on it. 
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« Reply #23 on: July 16, 2012, 04:52:52 PM »


Belfert, so your remedy is two 24v alternators?  And you are confident with your 24v DN alternator as being dependable enough?  I took off my 270 amp 24v 50DN and it is sitting on the floor of my shop.  Worked perfect when taken off.  I just don't trust it to keep from blowing up and taking out my engine gear train with it.

My DN50 is belt driven since I have a Series 60.  The DN50 has been around for many years and has proven to be fairly robust.  I suspect most of the issues busnuts have with the DN50 is they have a 30 or 40 year old bus with a 30 or 40 year old DN50 and they have problems when the DN50 gives up the ghost after a million or more miles on it.  


Belfert, just how many miles have you run a DN50 to give you the idea that they will stay together a million miles??  They are usually overhauled at the same time the engine/transmission are overhauled (if they last that long), and last no longer than a newer, lower amp truck alternator (100k plus miles).  They are a maintenance accessory that usually are replaced much sooner than the engine.

--Geoff
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« Reply #24 on: July 16, 2012, 05:08:10 PM »

latest update:

We were on the road to Louisville when the first solenoid bought it. I procured another identical solenoid in Louisville, installed it and we used it for two days with absolutely no  problems. I was careful to run only the front A/C unit and the Norcold refrigerator - both running off the inverter via the solenoid.

So to test the theory that I just had a bad solenoid, I waited until we were an hour or so from home and activated the second a/c unit:

Everything quit instantaneously. No a/c, no refrig, etc. However, the solenoid itself did not blow - it was an Overcurrent error on the inverter! Since I was driving, I was not able to clear the error condition and retry the experiment.

When I got home, sitting in the driveway, I recreated the situation and all worked fine!?: I cleared the errror, started one a/c unit, started the second a/c unit, and started the refrig.  Everything worked fine (again) as I was sitting in the driveway. I let it run for 10 or 15 minutes and all was well. Since I was home and not rolling, it is very difficult to say what this means. 

The other factor to be aware of is - heat. It is hot here in the midwest KC area!  Today on the highway, the temp was 95+. So, it could be that the inverter was just hot. 

I would greatly appreciated your opinions!
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« Reply #25 on: July 16, 2012, 05:18:01 PM »

Belfert are you sure you don't have 40SI instead of the DN50 ? The Delco manual recommends bearing at 100,000 miles on the gear drive driven oil cooled same for the belt driven air cooled

Boomer on this board followed the book when it came to servicing the DN50
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« Reply #26 on: July 16, 2012, 05:36:12 PM »

Belfert are you sure you don't have 40SI instead of the DN50 ? The Delco manual recommends bearing at 100,000 miles on the gear drive driven oil cooled same for the belt driven air cooled

I am sure it is a DN50.  It is oil cooled and heavy as all get out.
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« Reply #27 on: July 16, 2012, 05:39:08 PM »

Jim, have you checked and verified the voltage being put out by the alternator? I don't know if it could be an issue or not, but it's worth a look at and it don't cost ya nothin. I would check it at cruising rpm while applying each load item one at a time until everything is on and see what happens.
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« Reply #28 on: July 18, 2012, 08:03:26 AM »

...
Everything quit instantaneously. No a/c, no refrig, etc. However, the solenoid itself did not blow - it was an Overcurrent error on the inverter!
...
When I got home, sitting in the driveway, I recreated the situation and all worked fine!?: I cleared the errror, started one a/c unit, started the second a/c unit, and started the refrig.  Everything worked fine (again) as I was sitting in the driveway. I let it run for 10 or 15 minutes and all was well. Since I was home and not rolling, it is very difficult to say what this means. 


This is all "normal."  It happens to us, too, on occasion -- usually when it is very hot out, and usually when the driver air is running, which is a higher load than the roof units.  Remember that these compressors go up to the "locked rotor amps" briefly when they start.  The 4000-watt inverters can usually handle this if it is the only major load, and can handle it most of the time even with another load such as another running A/C unit.  But on those really hot days, pressures in the refrigerant system can cause the draw to remain too high for too long, exceeding the inverter's surge capacity.  The inverter shuts down to protect itself, displaying an overload error condition.

There are a few things you can do to mitigate this.  One is to set the internal thermotats on the A/C units to their coldest setting while driving, to keep the compressor from cycling on and off -- steady running is easier on the inverter.  Never re-start an A/C unit too soon after it is shut down; wait a good 4-5 minutes in between.  And when starting a unit, switch the fan on first, and let it fully come up to speed before switching the compressor on.  This will keep the unit from present both start-up loads at the same time.

HTH,

-Sean
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« Reply #29 on: July 18, 2012, 12:20:19 PM »

Thanks Sean, that is very reassuring. I think I recall that you installed some small DC fans on your inverter that are controlled by a thermostat. Do you think that would help in my situation? The inverter is in a small bay with two 5x8 in vents in the doors, but still close to the pavement and no active ventilation.

If I add some fans, should they be 12vdc, 24vdc or 120vac. I was thinking I could put a pusher on one end of the inverter and a puller on the other and control it with a thermostat. However, one thing I'd like to do is only have the fans come on if the inverter itself is on.
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