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Re: 12V -side question

Reply #20 –
Quote from: wa_desert_rat –
I had to replace my boost switch a month ago, however... there was no increase to start bank when I was on shore power and turned the boost switch on.

Craig
Where did you get the replacement boost switch, have a part number? I need to replace the ether start switch with a normal on off switch.

Roland

Re: 12V -side question

Reply #21 –
It is nice and sunny today, with temperatures in the upper 50's to lower 60's, so I decided to see what I could see about my electrical problem. Since a couple of other questions got added into my original thread I decided to start a new one.

ALL house 12 volt circuits work fine as long as I'm plugged in. As soon as the 120VAC goes away, though, all house 12V stuff is dead. The two house batteries were new less than a year ago, and show 13.87 volts while plugged in. After about 15 minutes of being unplugged they showed 12.6 or so.

The generator starts from the house batteries, and it will not start even when plugged in. When we get ready to leave Monday morning I'll try jumping it from the Jeep.

The light on the boost switch does not come on, nor does it seem to make any difference whether it is turned on or not.

I crawled under the coach to look at the isolator. It has three large terminals across the top with two smaller ones between them (L s L s L) and what look like two solenoids in the lower right part, two automatic resetting circuit breakers and a couple of plugs in the lower left part. Since I was by myself then I couldn't trace all of the wires, but it looks like the far left large terminals go to the house batteries. Does this make sense, and does it sound right?

It appears to me that the two chargers/converters are supplying the proper current to the batteries and coach stuff when plugged into 120VAC. Somehow, though, the batteries are not able to provide current by themselves. On the other thread someone mentioned the reset button that is accessed from the utility bay. I tried pushing it, but nothing moved, so I'm assuming that it didn't need resetting.

My thought at this point is that after lunch I'll shut everything off again, disconnect all batteries, crawl back under the coach and take off each connection on the isolator, clean it up, and retighten it. If that doesn't solve the problem, what should I look at next?

Re: 12V -side question

Reply #22 –
Could it be that the terminals on the 12v disconnect switch (the one in the stairwell) are corroded?
Might also check the main 12V breakers (or high current fuse - not sure what your coach has) to see if there's voltage across them (should be zero)  Breakers get weak or fail over time.

And, of course, there's always the question of whether all the grounds, particularly the high current ones, are still good.  Any connections exposed to the weather may need to be tightened or removed and cleaned.

Are you measuring the house batteries directly on the battery terminals?  Might measure voltages with cables disconnected from the batteries after the surface charge dissipates (~1/2 hr), then measure current draw between ground cable and battery terminal with things in the coach turned off.
If voltages are still low after charging overnight and immediately removing the cable, I would suspect the batteries.

Re: 12V -side question

Reply #23 –
I'm back from crawling around under the coach. All connections were good. I cleaned off the top of the isolator and found what I believe is a brand and model number, Powerline PL1-190-3. I searched for that and found PLI-190-3, so I looked at it. The picture showed a much smaller isolator, with only three terminals on it.

We're scheduled to head back home Monday morning, and then head to Stillwater Wednesday morning. I'm thinking that maybe I ought to call Foretravel Monday morning and have them send a new isolator to the church in Stillwater. Does that sound reasonable? Maybe I should have them send all of the other things on that panel, too, so that while I'm underneath changing the isolator I can just do all of it and not have to crawl under again.

Any EE people here?

Dave, yes I have been measuring right on the battery terminals. It seems strange that I have 12V when plugged in, but not when not plugged in.

Re: 12V -side question

Reply #24 –
David, Does your coach have a transfer switch ? Some coaches have two, seems funny that 12V is available on shore but not on batteries, disconnect somewhere.  Sorry can't be specific.
I would start with a voltmeter from pedestal ( including  cord ) to isolator to inverter thru transfer switch. Got to be some point where current is not flowing.
Good luck.
Gary B

Re: 12V -side question

Reply #25 –
The isolator is just for alternator output-- nothing to do with shore power.

And, the ATS (Automatic Transfer Switch) is strictly 120 VAC (select only one-- shore power OR generator.  If two ATS, the second would be for inverter). Again, no relation to your "no 12 VDC to coach except with shore power.

With shore power off, start at the battery with a voltmeter.  Progress toward the 12 VDC fuse box and see where you loose power.  Be sure to check ground side as well.

Re: 12V -side question

Reply #26 –
You are getting 12 volts from your converter/battery charger and no voltage from the batteries themselves. As Brett indicates the isolator should not be in that circuit. There has to be a break/loss of continuity between the chassis batteries and the 12 volt panel. I think those sre the circuits that you should be ringing out. The generator not starting on shore power also points to a major break in the flow of 12v from the coach batteries as the converter cannot provide enough juice to start the generator. The boost solenoid gets its coil voltage from the coach batteries as well.  I would really focus on ringing out the 12v circuit beginning at the coach batteries. Interesting problem am eager to find out where the break is, not as eager as you I'm sure. Think I will study my 12vdc schematics maybe get a better understanding of your issue.

Roland

Re: 12V -side question

Reply #27 –
Kinda makes me wonder if the previous owner found some way to disconnect the coach batteries from the charger instead of replacing the batteries? If he did you'd have 12 volt DC power only when the charger has shore power. Your coach batteries are fully charged because the alternator charged them the last time you drove your coach... I dunno, that's all me wittle bwain can come up with! haha

Re: 12V -side question

Reply #28 –
ScubaGuy and I poked around a bit this afternoon. The boost solenoid is engaging and disengaging properly. The batteries are charging properly.

Roland, as I think about it, the problem has to be in some portion of the circuitry that is used ONLY when on battery power. I tried jumping the house batteries from the Jeep in order to start the generator, but that didn't help, either.

Scott, all was working fine until a couple of weeks ago. The current inverter and converters/chargers (2) have been in place since spring.

Re: 12V -side question

Reply #29 –
I got to spend a few minutes with David scratching our heads about his 12V issue.  What I can't understand is the generator not starting.  We even tried to jump it with his Jeep.  There's a "click click click" but the generator doesn't turnover at all.  In my very layman terms there's volts but no amps. 

We pulled the cover off the 12 panel in the bay.  There was an obvious 12V + & 12V - terminals.  Between the two was 13.4V.  There are two "breakers" toward the top, one I guess is self resetting, at each lug to the main 12V- terminal was 12.2-12.3V.  The other one, which can be reset through the hole into the next bay, showed 13.4V.  So my guess is that the one self resetting breaker is powered by the start battery, and the other is from the house batteries/chargers?  Wish I had taken a picture.  Everything in there seemed to be showing voltage.

I guess it's possible the battery chargers are able to keep everything going while connected to shore power but don't provide enough power to start the generator? 

Re: 12V -side question

Reply #30 –
Did your jumper from Jeep go from Jeep battery to generator positive and to good ground ON THE GENERATOR?

If that did not work, try turning the generator over by hand to make sure it is not seized up.

Re: 12V -side question

Reply #31 –
Brett - we went from the Jeep battery to the one of the house batteries.  Are you saying directly to the starter and a good ground?  That might be challenging to get to, but worth trying.

Re: 12V -side question

Reply #32 –
My guess would be it's probably something in the panel beside the batteries where ScubaGuy was looking. There are a bunch of self resetting breakers in mine too and I've attempted to understand them several times but failed to, even with the drawings. As I recall several of them are identical. I'd probably swap the identical ones to see if the problem goes somewhere else. It's also possible there's a fusible link in the cable between the charger and the batteries. To test that I'd disconnect the battery terminals and test to see if the charger is sending voltage to the battery terminals. You already know the charger is sending voltage to the rest of the coach... so I dunno?

Re: 12V -side question

Reply #33 –
Quote from: ScubaGuy –
Brett - we went from the Jeep battery to the one of the house batteries.  Are you saying directly to the starter and a good ground?  That might be challenging to get to, but worth trying.

That would prove that the generator is OK and the issue is between battery and generator (positive OR on ground side).

Re: 12V -side question

Reply #34 –
I suppose it's possible the coach batteries could have a bad ground, and obviously the charger has a good ground which would explain what you're experiencing. I have no idea how that would happen but hey, if you run out of things to check.

Re: 12V -side question

Reply #35 –
Quote from: ScubaGuy –
Brett - we went from the Jeep battery to the one of the house batteries.  Are you saying directly to the starter and a good ground?  That might be challenging to get to, but worth trying.
I don't believe you have continuity from the coach batteries to the rest of the coach. There is an open or current limiting resistsnce some where on either the positive or negative side. Just my thoughts on the issue as you describe the symptoms. Believe your attempting to start using an external power source, the jeep, but jumping on the coach batteries proves the point. Seems to be current limiting as you heard a click.

Roland

Re: 12V -side question

Reply #36 –
Roland, I think you are onto something. My simplified view of the system is that the converters/chargers provide power to the batteries, which provide power to the coach, just like on the engine side. BTW, I don't have the 12V with the engine running, either. That's going to make for a chilly run back to Urbana Monday.

So, how are the electrons supposed to flow when there is only house battery power compared to how they flow when there is shore power? What's different?

BTW, the chargers/converters were warmer than ambient air temperature but not by much. The fans were either not running or so quiet that I couldn't hear them. When the temperatures have been warmer I could hear the fans when I opened either door to that bay.

Re: 12V -side question

Reply #37 –
Disconnect the coach batteries with shore power on and see if there's any voltage on the battery cables from the charger. If not you know for sure that you don't have continuity from the batteries to the charger but you do have continuity from the charger to the rest of the system.

The charger is probably only about 70 amps or so, which won't be enough power to start the genset without the batteries, but it has enough power to close the starter solenoid, which explains why you heard the starter solenoid click but the engine couldn't crank, even with another vehicle jump starting the coach batteries, which are already fully charged from the last time you drove your coach.

You're probably gonna find a blown fuse or tripped breaker in that panel beside the batteries. It's a confusing panel that I can't understand even with the drawing in front of me. I'd swap the identical breakers to see if the problem moves with one of the breakers. If you can find any fuses or fusible links you should test those too. Check the ground for the coach batteries also. I suppose it's possible they've come ungrounded somehow.

Re: 12V -side question

Reply #38 –
Quote from: kb0zke –
Roland, I think you are onto something. My simplified view of the system is that the converters/chargers provide power to the batteries, which provide power to the coach, just like on the engine side. BTW, I don't have the 12V with the engine running, either. That's going to make for a chilly run back to Urbana Monday.

So, how are the electrons supposed to flow when there is only house battery power compared to how they flow when there is shore power? What's different?

BTW, the chargers/converters were warmer than ambient air temperature but not by much. The fans were either not running or so quiet that I couldn't hear them. When the temperatures have been warmer I could hear the fans when I opened either door to that bay.
with shore power the converter provides power to the batteries AND provides power to the coach, different paths. As there is no drain on the coach batteries perhaps that is why the converter was only warm to the touch, not working hard to charge the batteries. Could be a bad ground off the battery circuit somewhere. From your observations it appears that the coach batteries are OK so something is loose, disconnected or blown. There are a couple 90 amp fuses that I would check if you haven't already and I would make certain that the battery disconnect switch is actually making contact, not just clicking. After that I would scratch my head and start tracing wires.

Do you have a gate to prevent engine coolant from heating domestic water? If you do I would make sure it was turned off to give maximum cabin heat. Closing the bathroom door will also help keep the front area warmer. I reversed the locking mechanism on our bathroom door and keep it closed and latched when driving, both in winter and summer.

Good luck, if you were here in Arizona I would be happy to help you trace out the problem. Am very curious as to what is causing your problem.

Roland

Re: 12V -side question

Reply #39 –
David, I know you have checked and the salesman switch in on. But have you checked to see if the salesman switch is working?

Larry