Chassis battery. not charging on shore power/generator

[dano50]

2016 Monaco Diplomat with 2 new 12V lead acid maintenance free chassis batteries that are not charging on shore power or generator. They will fully charge with the alternator and on an external charger. House batteries are 800W lithium with solar on the roof. House batteries are charging fine both on shore power and with the solar.

I consulted with the tech at RV Custom Products that makes the Battery Control Center (F3-1440) in my coach. He said with the lithium batteries installed, the relay is bypassed because of the difference in charging requirements. He had me test the battery isolation solenoid relay and said that it was working as intended (not charging chassis batteries).

I called an RV tech out who tested the battery isolation solenoid relay and said it was bad. (I told him what the BCC manufacturer's tech said when I tested it, and he did not agree).

A replacement (Cole Hersee 24213) was ordered and installed today. The chassis batteries were at 12.55 when the new part was installed.
They are continuing to slowly discharge. Six hours later they are reading 12.51. The tech said to "give it few days to go down low enough to start charging." Just how low does it need to go to start charging? How long should I give it before I charge them externally?

Any ideas on where else to look where the problem could be? The chassis batteries have always stayed charged even when staying in one place for 5-6 months. I'm full-time and the coach has never been in storage.

[twinboat]

With the lithium conversion, the house to chassis charging is bypassed. You can't charge lead acid batteries at lithium levels.

Pick up a 120 volt battery maintainer for the chassis batteries and plug it into an outlet, powered by shore power.

[YC1]

The first tech had the proper answer.

Turn your battery bank off for the engine if possible when not using for more than a couple of days.

You could easily add a second charger to keep it up or a DC to DC charger.

[dano50]

Thank you for your responses. This is what I am just now learning. I am so confused because the lithium batteries and solar were installed in January 2017 by AM Solar in Oregon. I am confident they knew what they were doing. I'd call them to see what they did, but they have closed their doors. I heard the owner got a job offer he couldn't refuse, and that was the end of AM Solar.

Both battery banks have always worked and charged perfectly until I replaced the original chassis batteries that were 9+ years old. The only reason I did that was because something got left on while it was at a repair shop for a month late last year, for an unrelated issue. They agreed to keep it plugged in, but there was some miscommunication and both the house and chassis batteries were run completely down. That is when they advised I replace the chassis batteries. Since they were well past what should be expected of them, I had no problem replacing them.

Now, these new batteries won't charge on shore power. I just don't understand what is different now. Was I just lucky that nothing happened these past 8 years??

[YC1]

Post some pictures of your battery compartment. I suspect there may have been a trickle charger or device that has gone south.

[Persistent]

I think it has been clearly stated above. Charging lead acid batteries using a lithium charging profile will overcharge the lead acid batteries. For non-sealed lead acid, just add water to replace what the overcharging releases. For AGM and Sealed lead acid, don't do it. Batteries will be destroyed.

Get a small automotive charger to maintain the chassis lead acid batteries. Plug it into a shore power outlet. A 5 or 10 amp $20 automotive charger will do. This has been said above as well.

You can buy complicated and expensive electronics to charge the chassis from the lithium. Why?

If your unit has one of the complicated and expensive electronic devices, then it may be defective.

[dano50]

Originally Posted by Persistent

I think it has been clearly stated above. Charging lead acid batteries using a lithium charging profile will overcharge the lead acid batteries. For non-sealed lead acid, just add water to replace what the overcharging releases. For AGM and Sealed lead acid, don't do it. Batteries will be destroyed.

Get a small automotive charger to maintain the chassis lead acid batteries. Plug it into a shore power outlet. A 5 or 10 amp $20 automotive charger will do. This has been said above as well.

You can buy complicated and expensive electronics to charge the chassis from the lithium. Why?

If your unit has one of the complicated and expensive electronic devices, then it may be defective.

Thank you for your suggestions. We have an automotive charger that we have been using off and on for the past 3 weeks while we try and figure this out. We will be here for a few more weeks.

I am starting to think we already have one of the "complicated and expensive electronic devices" and it is no longer working, because this problem is new to us. I can't believe they were being charged incorrectly for 8+ years and we never had any issues with them until an RV shop completely drained all (house and chassis) of the batteries They even worked fine after that for several weeks, but we replaced them anyway so we wouldn't have a problem when we were somewhere where it would be less convenient. Maybe we were moving around enough that the alternator kept them charged during that time. I just don't know.

[dano50]

Originally Posted by YC1

Post some pictures of your battery compartment. I suspect there may have been a trickle charger or device that has gone south.

I'm not sure what you to look for, but here is some photos of both the battery compartments.

[dano50]

Originally Posted by yc1

post some pictures of your battery compartment. I suspect there may have been a trickle charger or device that has gone south.

[dano50]

Originally Posted by YC1

Post some pictures of your battery compartment. I suspect there may have been a trickle charger or device that has gone south.

I am starting to think you must be right. It must be there somewhere and is no longer functioning. Thank you!

[dano50]

Originally Posted by YC1

Post some pictures of your battery compartment. I suspect there may have been a trickle charger or device that has gone south.

[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.

[Ludo]

You might reach out to https://community.victronenergy.com/ to get some answers

[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.