Chassis battery. not charging on shore power/generator

[dano50]

Originally Posted by YC1

Interesting you seem to have two solar power regulators. One has more output capability than the other based on a quick search.

Have you changed where you keep the RV? That is, was it in the sun all those years and now you are in the shade?

I do not see any after market looking chargers in the pictures. Although I do not recognize the little blue modules in the first pictures.

Another thought is that something is draining those batteries that was not draining them in the past. Storage bay lights for example left on will hammer batteries in a few days.

Thank you for looking everything over. There is a lot.

We initially had some solar panels installed to charge the original house batteries. About 6 months later we went with the lithium and more solar panels were added. About 4 years later we swapped out the Magnum inverter for 2 Victron Multiplus inverters, and a few more solar panels were added at that time. That might explain why there are 2 solar power regulators.

We have lived in the coach full time since it was new. We are in full sun now and that is not much different than how it has always been. We have had a few long stays before for medical or family reasons, so we know something is different now. Honestly, we never even check the status of the chassis batteries. The coach has always started up just fine, and we had no reason to monitor them.

I will look more closely at what might be draining them. After looking back, we think it took about a month for the batteries to drain, all while on shore power I didn't want to make my initial post any longer than it already was, and I wasn't sure it was relevant, but there is another thing that might help figure this out. A few months ago, I noticed the vacuflush toilets were pumping back up slower and slower over several weeks. I decided to do the annual maintenance on them thinking that might help. Of course, there were complications and I had to order an additional part. It took about a week to get everything back together. When I tested the toilets, they were pumping back up even slower than before, and then the system just died. No lights. My house batteries were at 100%, but I eventually learned that the chassis batteries had died. I was able to use the battery boost to start the engine and get a charge back on them. Later I got my battery charger out of my kid's garage and got them fully charged again. I have been putting the charger on them about once a week to fully charge them back up after they drain down to about 12.6. I've let them go lower to test if something will charge them, but no luck there.

They drain very slowly, about .09% per day. We have checked, and noticed that flushing the toilet does cause the chassis battery voltage to drop about .05% and then it goes back up to where it was within about 10 minutes. I have received the schematics for the coach from REV, but I can't find the vacuflush on them anywhere or a connection between the chassis batteries and the vacuflush. Any ideas on what is going on with this? Could this be the problem?

[dano50]

Originally Posted by Persistent

I do not see any device that I recognize that would charge the chassis battery from the house batteries.

You have a high quality Victron power management system. The parts I can see are:
Two solar controllers
A Lynx Distribution
Two smaller blue boxes I can't make out the model numbers.
Two 12 volt disconnect switches
Two high capacity solenoid disconnect switches on the back wall

The solenoid with the larger cables may be the connection between the chassis batteries and the house batteries. It has a small wire that is probably connected to an ignition circuit. That solenoid probably closes when the chassis ignition is "ON". It is probably open when the ignition is "OFF". It charges the house batteries from the chassis battery. I would expect a battery to battery charger in this circuit somewhere to manage the charging differences, but I don't recognize one.

There may be a Victron Multiplus II inverter/charger and a Cerbo communication device located somewhere else.

If you have a Cerbo somewhere, a licensed Victron dealer may be able to connect to it remotely and better understand your system. If not, make an appointment at a Victron dealer. They can help you with all the details.

I think the two smaller blue boxes you see are the battery protects.

Yes, the solenoid with the larger cables is the battery boost for help with starting the engine.

Yes, there are two Victron Multiplex inverters located in another bay. There is a Cerbo communication device with a color display inside the coach.

We have a Victron rep that we consult with. He has connected to our system remotely before. He hasn't yet for this issue because neither of us quite understand what we are looking for. It might end up being an unusual, new drain on the batteries. Thank you for your input. I really appreciate it.

[YC1]

A month for the engine batteries to hold up without a charger is quite amazing actually. There are usually so many sneaky leaks that they will last only days or a couple of weeks. My manual discusses disconnecting them during non use over just a few days.

Your activities may have allowed the alternator to keep them up and perhaps your lifestyle has changed.

Installing a simple low amp full time charger is just fine. It has been done on coaches for years that did not come with bi-directional charging systems.

[dano50]

Originally Posted by YC1

A month for the engine batteries to hold up without a charger is quite amazing actually. There are usually so many sneaky leaks that they will last only days or a couple of weeks. My manual discusses disconnecting them during non use over just a few days.

Your activities may have allowed the alternator to keep them up and perhaps your lifestyle has changed.

Installing a simple low amp full time charger is just fine. It has been done on coaches for years that did not come with bi-directional charging systems.

Yes, I'm starting to figure out that they must have always been charged via the alternator only. But I'm having a hard time believing they have lasted 6 months at times without charging any other way. We've never turned them off while parked for an extended time, charged them externally or had dead batteries before this. If anything, we are moving a little more often now, than we were between 2020-2023. I will still be searching to find an answer. Until I do, I'll be watching and keeping them charged up one way or another. When I figure it out, I will update my post. Thank you for all of your comments and suggestions. They are much appreciated.

[YC1]

A 2016 Diplomat would have come with some sort of bi-directional charger. Read the owners manual. If you can get a digital copy, please post it.

[Persistent]

Originally Posted by dano50

A few months ago, I noticed the vacuflush toilets were pumping back up slower and slower over several weeks. I decided to do the annual maintenance on them thinking that might help. Of course, there were complications and I had to order an additional part. It took about a week to get everything back together. When I tested the toilets, they were pumping back up even slower than before, and then the system just died. No lights. My house batteries were at 100%, but I eventually learned that the chassis batteries had died. I was able to use the battery boost to start the engine and get a charge back on them. Later I got my battery charger out of my kid's garage and got them fully charged again. I have been putting the charger on them about once a week to fully charge them back up after they drain down to about 12.6. I've let them go lower to test if something will charge them, but no luck there.

They drain very slowly, about .09% per day. We have checked, and noticed that flushing the toilet does cause the chassis battery voltage to drop about .05% and then it goes back up to where it was within about 10 minutes. I have received the schematics for the coach from REV, but I can't find the vacuflush on them anywhere or a connection between the chassis batteries and the vacuflush. Any ideas on what is going on with this? Could this be the problem?

House appliances appear to be running off the chassis battery. That should not happen. They should be connected to the house battery system.

What other house appliances are connected to the chassis batteries? Many modern 12 volt appliances have a standby power draw. This would pull the chassis batteries down slowly. Perhaps the wiring has been accidentally changed. Maybe a 12 volt wire previously connected to the house batteries is now connected to the chassis batteries.

[dano50]

Originally Posted by Persistent

House appliances appear to be running off the chassis battery. That should not happen. They should be connected to the house battery system.

What other house appliances are connected to the chassis batteries? Many modern 12 volt appliances have a standby power draw. This would pull the chassis batteries down slowly. Perhaps the wiring has been accidentally changed. Maybe a 12 volt wire previously connected to the house batteries is now connected to the chassis batteries.

I agree with you. Something has definitely changed and I want to find out what it is and fix it. I could just set it up so they stay charged with a charger and move on, but I am more interested in finding out what happened and put it back the way it was.

Since late October 2024, several different techs have worked on it and there were multiple issues involving the electrical system. That is why I believe something did get changed, as you suggested.

We had just returned to California from a 5 month, 6,000+ mile trip where we had not experienced any issues with the electrical system or the batteries staying charged. We were stationary at a couple of the places for 4-6 weeks, so plenty of time for the batteries to drain or get low. I can't remember a time we have ever even needed to use the battery boost to start the engine.

At the end of October 2024, we went on a 33 day cruise and left the coach with an RV repair shop to get some minor body work fixed. They agreed to keep the coach while we were gone and keep it outside to recharge daily with the solar or keep it plugged in if it was kept inside the garage. We didn't even care which. It has plenty of solar, and can recharge the house batteries to 100% everyday when just sitting.

We are able to check the status of the house batteries remotely. The morning after we left it at the RV shop, we checked and the house batteries were around 20%. Something was not right. We figured out one of the floor heaters had probably accidentally gotten left on. The floor heater displays are low down inside the cabinet and hard to see. They often click back on or off when turning them off or on. One of us didn't triple check that it had clicked off and stayed off. I called the RV shop and explained to them what probably happened and asked them to make sure the floor heater got turned off. (When I returned to pick it up, I found that they had only clicked it down to the lowest setting, 60 degrees, not actually turned it off, so it was left turned on the entire time.)

A week or two into the cruise, I texted to check in on the progress and learned that they were having all sorts of electrical issues with it that they could not diagnose. A battery protect had burned marks on it and needed to be replaced. They could find no reason for this to have happened. After convincing them that it wouldn't have happened for no reason, they eventually found a 50amp breaker had tripped that had been added when the new inverters were installed, about 2 years prior. They could not find a reason that had tripped either. They also could not get the house batteries to charge on shore power most of the time. This turned out to be 20 amp service used by the whole shop, which they did not mention when they offered to keep it plugged in. Since the lithium batteries were so low/shutdown, and they didn't know to reset the input current limit for 20 amps, their breaker kept tripping. So basically, they had run down all the batteries (both house and chassis) and did not have a way to get them recharged and stay charged. They used the generator sometimes, but sometimes that wouldn't charge them either. (In the end, they did use an external charger on the chassis batteries so it would start to move it out of the shop.)

Several weeks later when we returned from our trip, they still had found nothing to explain why it wouldn't take a charge, why the breaker had tripped, or why the battery protect burned. After looking around myself, I found a loose wire on the 50amp breaker that had tripped. That was corrected and we thought all was good. They suggested we should get new chassis batteries, but said we could make it to wherever we going next, which we did.

We have been at our present location since 1/17. During the next few weeks we experienced 3 or 4 short term electrical outages that were attributed to outages at the park. A couple of times we received an email with an explanation from the park and a couple of times we didn't. So I am not sure exactly what was happening with those. Some may have been only an issue with our coach. We only had to reset the GX Color Control. On 2/15-16 we took out the old chassis batteries and brought back identical Alliance starting batteries to replace them. While replacing them, something caused ALL of the power to go off and the battery protect burned up again.

We called out an RV tech who was also an electrician. He got things up and running temporarily. The vacuflush was still not working so he ran a temporary jump with a fuse so it would work. (This might be a clue. I have since removed it, and the battery is still draining.) It took him many hours during several trips, but he eventually found the issue was a loose cable (AB) near the chassis batteries. The other end was near the battery protect in the bay with the house batteries, so that made sense. I am not sure if that was part of the original problem at the RV shop or it became loose more recently.

We didn't really think about the timing of all of this until now. After that was when we started noticing the vacuflush pumping slower and then eventually draining the chassis batteries.

After doing some checking and researching, I contacted RV Custom Products who manufactured the BCC in the coach. He was very helpful and explained about the bypass of the isolation solenoid when there are lithium batteries, etc.

Then we called another RV tech to see why the chassis batteries weren't staying charged on shore power. (The first tech/electrician has left the area). He checked and decided right away it was a bad isolation solenoid and had me order a new one. He came back and put it on, and nothing changed. I had told him about it being bypassed because of the lithium batteries and what the RVCP engineer had explained. He didn't believe it. He does now. He's trying to figure it out before he comes back again this week.

If you have made it this far, thank you for your efforts to help. It's long and complicated and I was hoping someone would be able to help without all of this detail. Hopefully some bit of information here will help someone help me figure this out.

[dano50]

Originally Posted by YC1

A 2016 Diplomat would have come with some sort of bi-directional charger. Read the owners manual. If you can get a digital copy, please post it.

I do have a bi-directional charger. It was disabled via the BCC when the lithium batteries were installed in 2017, because charging AGM batteries with lithium batteries will ruin them.

[YC1]

Originally Posted by dano50

I do have a bi-directional charger. It was disabled via the BCC when the lithium batteries were installed in 2017, because charging AGM batteries with lithium batteries will ruin them.

So the bi-directional charging was disabled and I understand why. But how were you keeping the coach batteries charged with that disabled?

Was something installed such as a DC to DC converter? Surely the folks that installed the lithiums knew this would be an issue.

Your solar may be what has been charging the coach batteries and perhaps they are not working properly or the controllers are not.

What is your voltage on the coach batteries, and what is the voltage on the output of your controllers, and where are they connected?

[dano50]

Originally Posted by YC1

So the bi-directional charging was disabled and I understand why. But how were you keeping the coach batteries charged with that disabled?

Was something installed such as a DC to DC converter? Surely the folks that installed the lithiums knew this would be an issue.

Your solar may be what has been charging the coach batteries and perhaps they are not working properly or the controllers are not.

What is your voltage on the coach batteries, and what is the voltage on the output of your controllers, and where are they connected?

Other than the alternator charging the chassis batteries while traveling, I really never gave it a thought about how they were being charged. Whatever uses them has just always worked. I believe what was modified in the BCC only keeps the batteries from connecting to each other. Anything else it did, it still does.

The coach batteries are charged with solar power, alternator when traveling, shore power, and from the generator when necessary. After all of the research I've been doing, I'm learning that charging lithium from the alternator may not be a good idea, but we haven't had any problems so far. It may be because the alternator is heavy duty, the batteries are usually on float when we are traveling and when combined with the solar input, there is not a heavy draw on the alternator.

I don't believe there is a DC to DC charger anywhere. No one saw one in the photos I posted. The Victron rep I consulted with about this issue, and who is familiar with my coach only mentioned what DC to DC converters were available. He also did not mention that the solar should be charging the chassis batteries, so I don't believe it does.

AM Solar in Springfield, Oregon, installed most of the solar, the Victron products and the lithium batteries. When they were in business, they were very reputable. It was a 3-4 month wait for an appointment. If they were still around, I'd be contacting them. Apparently the owner closed down the business with little notice last year to accept a dream job he had been offered.

After going through the sequence of events over and over, I'm starting to concentrate on finding where something was not wired back correctly, as Persistent suggested. If the chassis batteries shouldn't be running any house appliances, I'm looking into why the vacuflush is connected to them. I'm going to give the electrician/tech a call tomorrow and see if he can remember what he did. It looks like he may have replaced a fuse where the vacuflush is connected, and that might be where the issue is.

I was thinking about the use the chassis batteries get and any reason why they stay charged so well. All I could think of was that almost everything they control, i.e. the slides, jacks, headlights, etc. are used with the engine running. It seems like, for the most part, they are being recharged from the alternator whenever they are being used, so that would keep them charged. I've never been aware of any parasitic drain on them. I'm still digging.

[YC1]

Time to get the voltmeter out.

Trace the solar charge lines. Simple enough. You say it is charging on shoreline? Prove it.

Simple enough to take measurements when you connect shoreline, run generator, or the alternator. You need a note pad and write the readings down. You will not remember them three steps in.

You may need to cover your solar panels to discover which ones drive which controllers.

Find out what is being charged and under what circumstances.

[dano50]

Originally Posted by YC1

Time to get the voltmeter out.

Trace the solar charge lines. Simple enough. You say it is charging on shoreline? Prove it.

Simple enough to take measurements when you connect shoreline, run generator, or the alternator. You need a note pad and write the readings down. You will not remember them three steps in.

You may need to cover your solar panels to discover which ones drive which controllers.

Find out what is being charged and under what circumstances.

I am a little confused why I should do this. To me the coach batteries are the auxiliary or house batteries and the chassis batteries are the main or starting batteries.

I know the shore power is charging the coach batteries because I'm running the air conditioners most of the time and the coach batteries are showing 99-100% charged day and night. The batteries could not do this on their own.

I have the color display that continuously shows the watts being used on L1 and L2 from shore power, the amount of AC and DC being used, the excess watts and amps charging and discharging, current battery voltage, watts of solar power charging the coach batteries, and a lot of other information. That is how I know the shore power is working with the coach batteries.

I tested the generator and alternator as well. With the color display, it is easy to tell when they are charging the coach batteries by the information provided on the color display. I was able to charge the chassis batteries up with the engine running, but a test using only the generator did not show any increase in voltage on them.

I don't know if the shore power or generator EVER charged my batteries, once the lithium batteries were installed. All I know is it has been 8 years with no issues and somehow they were always charged when I needed them to be.

[YC1]

Originally Posted by dano50

I am a little confused why I should do this. That is how I know the shore power is working with the coach batteries.
All I know is it has been 8 years with no issues and somehow they were always charged when I needed them to be.

Because you don't know the "somehow".

Gauges and lights do not tell you the story. They may be happy as a clam, but if that actual voltage does not get to the battery posts, you are just guessing.

[dano50]

Originally Posted by YC1

Because you don't know the "somehow".

Gauges and lights do not tell you the story. They may be happy as a clam, but if that actual voltage does not get to the battery posts, you are just guessing.

I think we must have different concerns. The gauges and lights are for batteries that there are no issues with. They are charging and powering just fine. If they weren't, I'd be getting alarms, and I'm not.

That charging system is separate from the chassis batteries and does not charge them. There is no solar or a charge controller connected to the chassis batteries. Testing all of that would not help me. I was not aware before, but after researching and consulting with others on the subject, I know a lot more than I did before.