House Bank Solenoid Problem

[Geoff]

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

[Sean]

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
http://OurOdyssey.BlogSpot.com

[Geoff]

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

[belfert]

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.

[luvrbus]

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

[Sean]

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
http://OurOdyssey.BlogSpot.com

[Geoff]

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

[belfert]

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. 

[Geoff]

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

[wagwar]

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!

[luvrbus]

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

[belfert]

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.

[thomasinnv]

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.

[Sean]

...
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
http://OurOdyssey.BlogSpot.com

[wagwar]

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.