Isolator, Coach Batteries Issues

[gksmith]

WOW! I am really impressed with all of the help I am getting! I am new to having a motorhome and new to this site, but you all are great! I anticipated having problems with an older motorhome, but I did not anticipate the problems of getting help from dealers and repair shops. This started with the alternator problem and continued with a brake problem I had. No one would even consider looking at my van, which suddenly developed a grinding noise when pushing on the brakes upon leaving the interstate exit for my daughter's residence. They saw a motorhome and said their lifts would not handle it, as there were no points to lift at. I finally found a place that would use a front end jack so that they could service my brakes. BUT, I tried at least 5 places before I found them! And even they said their insurance would not cover motorhomes, but they thankfully agreed to do the work since the chassis was based on a van!

In response to Boosters suggestion, I am at Lebanon, Tennessee, close to Nashville. I am enjoying our stay at our daughter's, but we did not anticipate having these problems while there! If anyone has any suggestions as to where to go for advice in this area, that would be great!

Cruising7388 is certainly correct--many aspects of this problem is correct above my pay grade! I do not mind admitting it. Hence, my appreciation for your help. And he is correct about the garage's solution-- disconnecting the coach from the engine and disclaiming any responsibility of anything further. Very frustrating! Also frustrating is that I have an OBD at home, as well as other diagnostic items, so I do not want to purchase anything more than I need to get a satisfactory solution, even if it is a temporary solution to continue some travelling and then home.

This afternoon I have purchased an inexpensive digital multimeter and battery hygrometer. I will make use of them in the AM. I will then test the batteries and make a decision regarding their replacement. I will also test the isolator per the documentation I found regarding it, using the digital multimeter. If it tests OK and if I find that I need new batteries, I will reconnect the isolator to see if I receive the "Check Gauges" signal that that the garage mentioned. If the signal does not appear, I will assume everything is OK, but if it does appear, I will certainly disconnect the isolator. I am still speculating that one bad coach battery was a major instigator of my problems. But time will tell! If you think I am proceeding in the wrong direction, PLEASE tell me!

Hopefully this saga can come to an end soon! Thanks again.

[cruising7388]

Originally Posted by gksmith

Hopefully this saga can come to an end soon! Thanks again.

If you are going to troubleshoot this tomorrow, feel free to give me a call after 0900 PDT. CF (415) 264 0800.

[booster]

The whole thing does get complicated with isolator in there. The big black wire certainly would be the wire connected to the battery, but it is on the separator, so it the diode fails it doesn't see the battery. The smaller 12v wire from the ignition may or may not be the field positive, but likely is not and is most likely to start the alternator. Regulation on the ground wire as has been mentioned by all.

Someone who has dealt with one of the Dodges may chime in, but I seem to remember reading several times on the Yahoo Roadtrek board that there was a need to move one of the wires when going to a different isolator or separator, depending on style. I am pretty sure they said it was from the ignition circuit so probably the smaller 12v wire that has been mentioned.

The document that Cruising shows from allbattery looks to be the Waytek one that appear a lot of places, but I do wonder about it's accuracy for the Dodges, as they say to use diagram number one, which seems to show an internally regulated alternator with no external excitation for starting. What we seem to be talking about looks more like the diagram a ways below the first one, with external regulator and excitation.

With the procedure you have, you should be able to determine if the isolator is good, and be able to see if you have the 3 wires on the alternator that we guess you have, and be able to check for voltage there, so you should have some idea of what is up.

If you get a chance, if we had the model number of the separator, we could look up an actual wiring diagram for it.

[gksmith]

I will begin testing soon. But in the mean time, here are a couple pictures of the isolator documentation that I have, giving the wiring diagram. The model number is on the documentation.

https://1drv.ms/f/s!AtjihSWJj8H2gq0_iiZqCVtXAs7GfQ

It is very simple--even I can figure it out! The three cables going to and from the isolator are heavy cables, with the one going to the coach batteries being heavier than the others. Currently the cable from the alternator and the cable from the battery are disconnected from the isolator and tied together, with the coach battery cable still attached to the isolator.

The alternator seems to be working fine--just need to get juice safely back to the coach batteries. Now for the testing. As always, thanks!

[cruising7388]

Originally Posted by booster

The document that Cruising shows from allbattery looks to be the Waytek one that appear a lot of places, but I do wonder about it's accuracy for the Dodges, as they say to use diagram number one, which seems to show an internally regulated alternator with no external excitation for starting. What we seem to be talking about looks more like the diagram a ways below the first one, with external regulator and excitation.

The pictorial for group 1 doesn't show how the alternator is regulated, but the opening description for group 1 for Chrysler cites all models, all years, including Nippon Denso externally regulated alternators which covers his installation and is consistent with the three terminal isolator diagram he has supplied.

[cruising7388]

Originally Posted by gksmith

The alternator seems to be working fine--just need to get juice safely back to the coach batteries. Now for the testing. As always, thanks!

Alternator voltage is temperature dependent but typically is in the whereabouts of 14 volts. In your case, if the computer is detecting the typical .7 volt drop across the isolator diodes, alternator voltage may be a a bit higher.

While you're at it, do an alternator diode AC ripple check to rule out any alternator diode failures. Using the AC mode on your digital meter, measure across the alternator output lead and chassis ground. AC ripple should be less than 100 millivolts and ideally less than 50 millivolts.

[gksmith]

Here is the latest. I disconnected the coach batteries (they have been charging on shore power overnight) and tested them. One shows 13.3 volts and the other shows 13.2 volts. The charging eye on one is green and on the other it is red. Do these eyes really mean anything? But when I opened the packaging for the hydrometer, I discovered the internal float tube is broken, so I could not test the cells. Is it necessary to do so when the voltage of the batteries is up? Another problem is that the battery tray does not slide out far enough to easily access the interior cells to use the hydrometer. So, I would have to unmounts the batteries to test them. What a pain!

My biggest find is that when testing the isolator with the digital multimeter, I do not get a resistance reading between the alternator post and the engine battery post either way. The testing procedure in the documentation indicates that I should get a resistance reading one way and when reversing the leads, it should be the opposite. This DOES happen between the alternator post and the coach battery posts. So, according to this, the problem must be in the separator. Agreed?

I have also read that load testing should not be done with deep cycle batteries as they are not designed for heavy momentary loads. Since that is what was done at the original garage, and one battery failed, that is what led me thinking the batteries were the culprit. But maybe not. In addition to replacing the isolator with a separator, should I still test the batteries with a hydrometer?

Thanks!

[cruising7388]

Originally Posted by gksmith

Here is the latest. I disconnected the coach batteries (they have been charging on shore power overnight) and tested them. One shows 13.3 volts and the other shows 13.2 volts. The charging eye on one is green and on the other it is red. Do these eyes really mean anything? But when I opened the packaging for the hydrometer, I discovered the internal float tube is broken, so I could not test the cells. Is it necessary to do so when the voltage of the batteries is up? Another problem is that the battery tray does not slide out far enough to easily access the interior cells to use the hydrometer. So, I would have to unmounts the batteries to test them. What a pain!

Not to worry. There is a special place in hell set aside for builders that design battery trays that way.

Which battery has the red state of charge eye? Leaving the shore power charger off, see if after a little while this battery terminal voltage drops down significantly compared to the other battery.

[gksmith]

Originally Posted by cruising7388

Alternator voltage is temperature dependent but typically is in the whereabouts of 14 volts. In your case, if the computer is detecting the typical .7 volt drop across the isolator diodes, alternator voltage may be a a bit higher.

While you're at it, do an alternator diode AC ripple check to rule out any alternator diode failures. Using the AC mode on your digital meter, measure across the alternator output lead and chassis ground. AC ripple should be less than 100 millivolts and ideally less than 50 millivolts.

The lowest voltage setting on my multimeter (a cheap one) is 200 volts. Will that work? According to what I read on the web, I should set it to 2 volts. It is hard to get to the alternator--can I check at the battery posts since the cables go straight from the alternator to the positive battery post and ground to negative post? Or perhaps I am missing something. As you can tell, I am learning a lot with this situation!

[cruising7388]

Originally Posted by gksmith

My biggest find is that when testing the isolator with the digital multimeter, I do not get a resistance reading between the alternator post and the engine battery post either way. The testing procedure in the documentation indicates that I should get a resistance reading one way and when reversing the leads, it should be the opposite. This DOES happen between the alternator post and the coach battery posts. So, according to this, the problem must be in the separator. Agreed? Thanks!

This is a little perplexing because you haven't indicated any problems with the vehicle just starting and running. If the diode in question has shorted, while there would no longer be any isolation from the coach battery, the engine battery would still be connected to and charged by the alternator. But if this diode has gone open as you describe, there is no charging path whatsoever to the engine battery and the lighting and ignition loads connected to it would discharge it to the point that the engine would lose ignition and shut down. You're sure that the defective diode is directed at the engine battery?

[cruising7388]

Originally Posted by gksmith

I have also read that load testing should not be done with deep cycle batteries as they are not designed for heavy momentary loads. Since that is what was done at the original garage, and one battery failed, that is what led me thinking the batteries were the culprit. But maybe not. In addition to replacing the isolator with a separator, should I still test the batteries with a hydrometer? Thanks!

There is no problem with using deep cycle batteries for starting use. You just have to account for the 15 - 20% Cold Cranking Amperage (CCA) differential, size for size. For example, a larger size 27 or 31 deep cycle battery will adequately replace a smaller size 24 starting battery.

One way of resolving the access issue in the battery compartment is to replace that inacessible flooded cell battery with a sealed AGM unit and wiring it to address the house loads.

[gksmith]

Originally Posted by cruising7388

This is a little perplexing because you haven't indicated any problems with the vehicle just starting and running. If the diode in question has shorted, while there would no longer be any isolation from the coach battery, the engine battery would still be connected to and charged by the alternator. But if this diode has gone open as you describe, there is no charging path whatsoever to the engine battery and the lighting and ignition loads connected to it would discharge it to the point that the engine would lose ignition and shut down. You're sure that the defective diode is directed at the engine battery?

Yes, I am positive. But, remember that I have the alternator and engine battery leads disconnected from the separator and tied together. The vehicle runs just fine this way, but of course there is no charging to the coach batteries.

[gksmith]

Originally Posted by cruising7388

One way of resolving the access issue in the battery compartment is to replace that inacessible flooded cell battery with a sealed AGM unit and wiring it to address the house loads.

I had considered that. Perhaps I read too much and act too little, but I read that AGM batteries need a special charger to maintain them. I know that my coach came with wet cell batteries (according to documentation with the coach), so I am concerned whether the converter in the coach would properly charge AGM batteries. Is that a real concern?

[booster]

I think we need to know what "no resistance" means. If it is truly zero ohms as in shorted, the engine should have run and charged, I would think. If it means no resistance reading because it is infinity, then the symptoms would be more in line, and the diode would be open so no starting battery connection to the alternator. If the circuit is such that the alternator activated, it could go high, as was mentioned.

Now that you have the isolator bypassed, what running voltage are you getting on engine on? If it is OK, I would just let it go at this point until you get home. To protect the coach batteries, if you need to from overcharge, you could just go to the parts store and get a cheap battery disconnect switch and put it on at the coach to alternator connection.

Don't believe the eyes or the voltage as was mentioned earlier. 13.2v is with surface charge, so they either need to sit a while or have a decent load on them for a few minutes to get accurate voltage, but that voltage can still be a poor indicator of battery condition as a bad battery can show full voltage and a good battery can be low on voltage if it needs equalizing.

Call around and see if you can find a hydrometer called EZred. They are plastic, very accurate, and very easy to use, and almost indestructible.

[gksmith]

Originally Posted by cruising7388

Which battery has the red state of charge eye? Leaving the shore power charger off, see if after a little while this battery terminal voltage drops down significantly compared to the other battery.

OK. I just tested again. The batteries have been completely disconnected from each other and from shore power for about four hours. One battery reads 11.9 volts and the other reads 13.05 volts. So I definitely have a problem with one battery. BUT, this is what is perplexing--the battery with the higher voltage is the one with the RED eye, and the one with the lower voltage (which is also the one that failed a load test) has the GREEN eye! So perhaps the higher voltage battery is bad, too. Is this where a battery hydrometer comes into play? I have not replaced the broken one yet.

And the latest is that I have taken BOOSTERS suggestion and ordered a Blue Sea 7622 ACR. I am having it shipped overnight, so hopefully I will have it Monday or Tuesday. It may be overkill (500 amps capacity vs 150 amp need), but it should solve the battery separation part of the problem. I hope I can handle the installation, though. Next, to solve the situation with the batteries themselves.

I spent ten weeks travelling 6,000 miles in California & Arizona the first of the year with essentially no problems. But this 860 mile trip is causing me all kinds of grief. I guess my luck ran out! But, once I get these bugs worked out, it should be smoother sailing.

[booster]

You really won't know on the batteries until you get a hydometer, as the eyes are not very good in most cases. It may also be a mute point because normally you would want to replace the batteries together, so the match identically. Many new batteries have been hurt by being paired with old ones. Wet cells are pretty inexpensive so if you go that way not too exepensive.

The BS ACR will wire in very easily itself. Input from the alternator and output to the coach. The alternator wiring itself will stay exactly stock except to add the connection to the ACR. That includes the stock connection from the alternator to starting battery. The remote switch will take more time, as you have to fish wires through to the dash and wire 12v power and ground to it.

Is the van running OK currently, and at the right voltage? (mid 14s) with the isolator out of the circuit?

[cruising7388]

Originally Posted by gksmith

I had considered that. Perhaps I read too much and act too little, but I read that AGM batteries need a special charger to maintain them. I know that my coach came with wet cell batteries (according to documentation with the coach), so I am concerned whether the converter in the coach would properly charge AGM batteries. Is that a real concern?

What make and amp rating charger is in your coach?

[booster]

Originally Posted by cruising7388

What make and amp rating charger is in your coach?

Or even better, the brand and model, so we can see an actual charge profile, if we can find one.

[gksmith]

Originally Posted by booster

You really won't know on the batteries until you get a hydometer, as the eyes are not very good in most cases. It may also be a mute point because normally you would want to replace the batteries together, so the match identically. Many new batteries have been hurt by being paired with old ones. Wet cells are pretty inexpensive so if you go that way not too expensive.

Is the van running OK currently, and at the right voltage? (mid 14s) with the isolator out of the circuit?

I could not find an ezRed hydrometer like I expected. I could only find a mini-hydrometer with floating balls. It is better than nothing, but not as good as I want. I will order one online. But I agree that a pair of new batteries is probably in the cards. However, I would like to keep on of the old batteries to use on a popup camper I have if it seems practical. Now the question is wet cell or AGM for the new batteries.

The van is running fine. I checked the voltage with the multi-meter and the battery tests at 12. 8 with the van off and 14.2 with the van running.

[gksmith]

Originally Posted by booster

Or even better, the brand and model, so we can see an actual charge profile, if we can find one.

The converter or "Power Center" as the documentation calls it is:
Parallax Power Components Model 7345.

Unfortunately the documentation gives no specifications. The closest is the statement "Your Parallax 7300 series power converter is capable of delivering its full rated output to the battery(s) if needed, but will taper off to a few hundred milliamps when the battery(s) are at full charge."