12V -side question

Topic: 12V -side question (Read 2501 times) previous topic - next topic

Re: 12V -side question

Reply #25 – November 29, 2014, 04:45:33 pm

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 – November 29, 2014, 05:07:38 pm

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 – November 29, 2014, 06:15:28 pm

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 – November 29, 2014, 06:33:55 pm

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 – November 29, 2014, 07:02:30 pm

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 – November 29, 2014, 07:05:54 pm

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 – November 29, 2014, 07:15:30 pm

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 – November 29, 2014, 07:17:53 pm

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 – November 29, 2014, 07:55:26 pm

Quote from: ScubaGuy – November 29, 2014, 07:15:30 pm

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 – November 29, 2014, 08:15:27 pm

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 – November 29, 2014, 08:32:37 pm

Quote from: ScubaGuy – November 29, 2014, 07:15:30 pm

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 – November 29, 2014, 10:56:47 pm

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 – November 29, 2014, 11:53:38 pm

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 – November 29, 2014, 11:59:17 pm

Quote from: kb0zke – November 29, 2014, 10:56:47 pm

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 – November 30, 2014, 12:03:01 am

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

Re: 12V -side question

Reply #40 – November 30, 2014, 12:06:51 am

Quote from: LTG – November 30, 2014, 12:03:01 am

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

I just looked at the schematic again for the umpteenth time. The salesman switch is the biggest suspect. It appears by the schematic that it would give the symptoms that David has if it was turned off OR not making contact.

Roland

Re: 12V -side question

Reply #41 – November 30, 2014, 12:21:35 am

I don't think it could be the salesman switch. When I'm hooked to shore power and turn that switch off, all my 12v lights go out. All David's 12v systems work when he is plugged in. Also, I'm able to start the generator with my salesman switch off.

I could very well be missing something, but that just doesn't seem like it could be the problem.

Re: 12V -side question

Reply #42 – November 30, 2014, 12:43:13 am

Douglas, David said that he has an inverter and a converter/charger. I believe from his statement that his inverter and converter/charger are two separate units. I believe that your coach has an inverter/charger and no converter/charger. These two system function differently. I am not sure about David's Foretravel but on some motorhomes with a converter/charger, with using shore power, the converter powers the 12 volt system directly and at the same time provides a charge to the batteries. In those systems, when on shore power the converter will provide power to the 12 volt system even with the salesman switch is turned off. And, on some converter/chargers, they will function when on shore power even with the battery or batteries removed. Having said that, I am not sure how the converter/charger works on David's Foretravel.

Larry

Re: 12V -side question

Reply #43 – November 30, 2014, 02:43:44 am

Normal lead acid battery voltage is 12.6 , would suggest using a Volt meter and start snooping.

Re: 12V -side question

Reply #44 – November 30, 2014, 02:45:13 am

Quote from: LTG – November 30, 2014, 12:43:13 am

Douglas, David said that he has an inverter and a converter/charger. I believe from his statement that his inverter and converter/charger are two separate units. I believe that your coach has an inverter/charger and no converter/charger. These two system function differently. I am not sure about David's Foretravel but on some motorhomes with a converter/charger, with using shore power, the converter powers the 12 volt system directly and at the same time provides a charge to the batteries. In those systems, when on shore power the converter will provide power to the 12 volt system even with the salesman switch is turned off. And, on some converter/chargers, they will function when on shore power even with the battery or batteries removed. Having said that, I am not sure how the converter/charger works on David's Foretravel.

Larry

That's all news to me.

Yes, David definitely has a separate inverter and from his (converter/)chargers. Actually he has two chargers. Well, now I'm going to have to re-think this whole thing with that extra info.

Re: 12V -side question

Reply #45 – November 30, 2014, 11:03:15 am

Quote from: LTG – November 30, 2014, 12:43:13 am

Douglas, David said that he has an inverter and a converter/charger. I believe from his statement that his inverter and converter/charger are two separate units. I believe that your coach has an inverter/charger and no converter/charger. These two system function differently. I am not sure about David's Foretravel but on some motorhomes with a converter/charger, with using shore power, the converter powers the 12 volt system directly and at the same time provides a charge to the batteries. In those systems, when on shore power the converter will provide power to the 12 volt system even with the salesman switch is turned off. And, on some converter/chargers, they will function when on shore power even with the battery or batteries removed. Having said that, I am not sure how the converter/charger works on David's Foretravel.

Larry

That is what the OEM schematics show an inverter and a separate converter.

Roland

Re: 12V -side question

Reply #46 – November 30, 2014, 12:36:40 pm

Keep in mind that the salesman switch only powers off the circuits that are not directly wired to the battery.

Very old style converter/chargers has two circuits, one to power circuits that could operate with dirty dc, notable incandescent lights, and one to charge the battery, which in turn provides clean dc power to tvs, radios, and other noise sensitive electronics.

Newer style converter/chargers were really chargers only. Smart chargers too. All dc power came from the battery, with no separate converter sourcing dirty power.

Re: 12V -side question

Reply #47 – November 30, 2014, 04:31:44 pm

Latest update: I shut off all power to the coach, disconnected all four battery terminals on the house batteries, then turned the power back on. The battery cables showed 14.46 volts, which tells me that the charger/converter is working properly and the house batteries are being charged.

I turned the power back off and headed to the other side of the coach where I put a towel over the copper gas lines under the salesman's switch. Either the factory or a PO decided that four screws weren't sufficient to hold up a small plastic cover, so some sort of sealer was added. Once I got that cut I found that the whole underside of the switch is covered in black electrician's tape.

I put the cover back on, without adding more sealer, and went back to the other side of the coach. The batteries had been disconnected for 20-30 minutes, so I checked their voltage. 12.86 on one and 12.87 on the other.

I put everything back together and checked for any inside 12V activity. Nothing.

Re: 12V -side question

Reply #48 – November 30, 2014, 05:00:00 pm

All the electrical tape around the switch seems suspicious to me, but maybe I am a suspicious type of person when it comes to PO's. I would have removed the tape and made sure the switch is functioning properly. Process of elimination.

Roland

Re: 12V -side question

Reply #49 – November 30, 2014, 05:03:10 pm

My son is here, and he came up with another test. I put the meter on the battery while someone tried to start the generator. We wondered what happened to the battery voltage. The drop was only 0.04V.

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