Using Solar to trickle charge series batteries in parallel

[JohnnyCLE]

At the risk of violating the rule of "better to remain silent and appear ignorant than speak and remove all doubt!" I have a question which begs more experienced discussion.

It appears that batteries generally prefer to be charged and used in parallel but practical compromises are made to use them in series resulting in relatively minor but increasing differences in cell charge states. These charge state differences over time reduce cell life and / or require remediation efforts.

It also appears that solar produces dribs and drabs of current which is generally underutilized because other sources produce energy in such larger quantities.

It seems like a great use of solar would be to correct the minor charge differences between individual cells which result from being used or charged in series.

In a wonderful, imaginary world one could leave one's RV out in the sun for a few days to "top off" individual cells to an ideal state.

Is this possible? What would be needed to accomplish it? Has it been done?

[booster]

Originally Posted by JohnnyCLE

At the risk of violating the rule of "better to remain silent and appear ignorant than speak and remove all doubt!" I have a question which begs more experienced discussion.

It appears that batteries generally prefer to be charged and used in parallel but practical compromises are made to use them in series resulting in relatively minor but increasing differences in cell charge states. These charge state differences over time reduce cell life and / or require remediation efforts.

It also appears that solar produces dribs and drabs of current which is generally underutilized because other sources produce energy in such larger quantities.

It seems like a great use of solar would be to correct the minor charge differences between individual cells which result from being used or charged in series.

In a wonderful, imaginary world one could leave one's RV out in the sun for a few days to "top off" individual cells to an ideal state.

Is this possible? What would be needed to accomplish it? Has it been done?

It isn't what I have seen happen in our batteries as long as you get the batteries full on the charging cycle, which in the real world of RV's seldom happens, IMO, and when it does there is often an overcharging.


Tow six volt batteries in series are really no different than one twelve volt battery for number of cells, as both setups have six cells in a row. You just can't check the 12v battery in the middle to see if there is a variation at that point. The argument can be made that the six in the 12v battery may match better, but I wonder about that if the six volts are from the same batch, and due to the fact that most 12v wet cells use more water in the end cells.


IMO, if you have wet cells in series or parallel, you should separate and at least charge them separately and to true full occasionally, and if there is cell imbalance equalize them separately. You can't check the individual cells on AGMs so you can only do the charging part separately unless the manufacturer allows equalizing and you have lost some compacity.


Again IMO, based on what we see in watching our AGM bank and past wet cells, the best way to get batteries full is by using the float transition (tail, return, ending also used terms) amps. The manufacturers nearly all will give you this spec. You charge at full absorption voltage until amps go below the spec, and then go to float. We have tested going beyond that point and the amps do keep dropping, but it takes many hours so may not be a good thing to go that far and why the spec is where it is. After a full charge our Lifeline AGMs will then show the charge amps slowly decrease at float for up to three days then stabilize, so there certainly is an indication that the lower, nearly trickle level, charging is doing something but can't tell if it is evening indvidual cells out. We have series then parallel setup with 4 six volt batteries and don't see the balance between batteries change during the time at float right after full charging. If the charging were stopped earlier like is very common with RV chargers, I don't know if they would get to the same end point or not with certainty. The best guess is that they wouldn't because it would take too long and allow the unrecovered charge to get non recoverable before it gets charged.


Solar is good for floating batteries continuously and lots of folks do it in storage where no power is available and it does appear to do a good job of taking care of batteries as it can recover the tiny losses overnight pretty easily and before the can't be recovered. You do need to make sure the solar controller doesn't do a full voltage charge every day, though, as that will harm the battery quickly. Some controllers do that and some don't.

[JohnnyCLE]

Thanks! Many good considerations. Let me restate what I gleaned from your comments to make sure I understood the key points.

1) In practice today that is not how solar is applied to the batteries. - Totally agree, hence my frustration to come home with small differences between cells and see solar being thrown away each day vs applied to fix these small differences. If nothing is able to do this today, it puts everything else into a theoretical discussion.

2) Some batteries have internal series construction so that it may never be possible to put these into a fully "happy" state. - Understood, if these are used in series then one must end up with series strands off of a series string further complicating getting to an optimal state.

3) Proper charging has to be done carefully, a more rapid charge to a slightly overcharged state followed by a trickle holding charge slightly below maximum. - Solar likely would not have the current to rapid recharge the whole bank at one time and this would need to be accomplished by shore power or engine generator on the drive home. Or Solar would need to do this one battery at a time.

4) Most RV chargers stop short of fully charging. - I guess this is understandable given the penalty for overcharging on the road is higher than undercharging.

5) You totally lost me at the " because it would take too long and allow the unrecovered charge to get non recoverable before it gets charged " I will need to work on that one, sorry!

It appears my solar sits there and contributes little because I generally arrive home with as fully charged batteries as my RV allows. Short of pulling each battery out and bringing it to an optimal state on my workbench using house current (which I probably won't do) it seems like the state of the industry does not allow the coach to optimize at rest. Sad. It would seem that balancers are allowing some parallel current cross flow in a series setting and that this should be a solvable problem. Perhaps it becomes easier with more intelligent batteries which have individual BMS intelligence and we can look forward to a more hopeful future!

[booster]

Re number 5. This relates to what you probably have heard stated before. It is commonly repeated that it is important to recharge a battery as soon as possible after the discharge to prevent sulphation and capacity loss. What is missing from that is that you need to COMPLETELY recharge the battery because the part that doesn't get recharged quickly will have the same issues that whole battery would have if not recharged right way. If you get charged to 85% and then trickle the rest it could be long time to get the batteries full so some of the material is not recharged promptly.


I think you can put a balancer on two six volt batteries. It would equalize the state of charge, but couldn't balance any inherent cell to cell or group of cells variations. All cells are not equal even in a single battery and may not come to the exact same voltage and/or capacity.


There is charging equipment available that will do the very good charging, stopping the absorption charge at just the right amperage that the manufacturer of the battery recommends, and then going to float charge. They use a battery monitor type setup to know when to stop without overcharging and do a very good, automatic, full charge every time, including with temperature compensation. Both shore and solar chargers are available with this capability, but especially for shore power, are not inexpensive items. We routinely use the shunt controlled solar controller to top off 440ah of AGMs so there is enough capacity to do that part of it. On our AGMs, the transition to float is only 2 amps of charging current. If our van sat outside we probably would not plug it in for long term sitting, as the solar would take very good care of it. I think Avanti has done that exact thing for many years without issue.

[JohnnyCLE]

Thanks and an apology. I carelessly used the word "cell" in my original post when I should have used the word "battery" and it turned it into a question different than I intended.

My main frustration is that the solar charging is done through the 24v RV charger with it's compromises and precautions against overcharging vs the small amount of current which might be needed to improve the balance of each battery and having a "harness" to do this. The equivalent of attaching a "float" tender to each battery. I am skeptical that my solar controller is attune to the needs of each battery.

[booster]

Originally Posted by JohnnyCLE

Thanks and an apology. I carelessly used the word "cell" in my original post when I should have used the word "battery" and it turned it into a question different than I intended.

My main frustration is that the solar charging is done through the 24v RV charger with it's compromises and precautions against overcharging vs the small amount of current which might be needed to improve the balance of each battery and having a "harness" to do this. The equivalent of attaching a "float" tender to each battery. I am skeptical that my solar controller is attune to the needs of each battery.

I assume you have an 8 AGM battery etrek? Lots of information on them on the forum and how to improve the wiring, charging, etc. Searching out and reading a few of them may be interesting to you. Number one on the list is a balancer for the two twelve volt halves of the system. Without it, battery failures appear to be very common. The long cables and hot conditions at the front two batteries is also an issue as it gives the setup very unever cable lengths which makes for uneven charging.

[JohnnyCLE]

Yes, I do. I spent the better part of three days reading through all 17 pages of threads which referenced an E-Trek. It was a walk through time.

Purchased the E-Trek in Apr 2015 as my first RV and in May had an email exchange with Roadtrek support personnel about the electrical system. Being new to the RV world I was unaware of this forum. I was given some limited disinformation which I found disappointing, but not being the litigious type I chalked it up to one of life's many disappointments and concluded that perhaps it was because I needed to learn to live with the system better.

My major issue was that AC time was incredibly shorter than advertised and we had two dear pups we were trying to keep cool while my wife and I might shop or lunch. Fortunately I never totally trusted the system so it did not create a bad situation because I checked on them frequently.

We have frequently used the E-Trek, usually on short trips of 7-10 days, and have had a minimum of complaints other than the battery life. I was unaware of the balancer change because the disappointment of AC run time was not critical enough to demand that I find a solution and simple math pointed out that I was a fool for buying into their promises to begin with. I guess I wanted to be a believer and never checked out the math ahead of time.

Roadtrek's misinformation attributed the short battery life to cleanly "split" battery banks. At that time I read the SmartGauge article on why not to "split" battery banks but concluded that the 12v functions like detectors, water pumps, and in my case a cold beer out of the fridge, warranted life support category and that I would not want to risk running down all batteries for the sake of a little more AC. My concern is that the balancer may eliminate this benefit of a "split" battery bank.

It is now five years on, our pups have grown old and passed away, and battery technology has changed so the questions are different now. I would lean to the solution you have advocated of a single bank of batteries in the back. Because we are snowbirds I have to ask AGM or Lithium - temperature lows are not an issue. Unless something breaks, I don't have an urgency to do something so I am trying to fully understand what I have, and the tradeoffs for different options.

[booster]

Originally Posted by JohnnyCLE

Yes, I do. I spent the better part of three days reading through all 17 pages of threads which referenced an E-Trek. It was a walk through time.

Purchased the E-Trek in Apr 2015 as my first RV and in May had an email exchange with Roadtrek support personnel about the electrical system. Being new to the RV world I was unaware of this forum. I was given some limited disinformation which I found disappointing, but not being the litigious type I chalked it up to one of life's many disappointments and concluded that perhaps it was because I needed to learn to live with the system better.

My major issue was that AC time was incredibly shorter than advertised and we had two dear pups we were trying to keep cool while my wife and I might shop or lunch. Fortunately I never totally trusted the system so it did not create a bad situation because I checked on them frequently.

We have frequently used the E-Trek, usually on short trips of 7-10 days, and have had a minimum of complaints other than the battery life. I was unaware of the balancer change because the disappointment of AC run time was not critical enough to demand that I find a solution.

Roadtrek's misinformation attributed the short battery life to cleanly "split" battery banks. At that time I read the SmartGauge article on why not to "split" battery banks but concluded that the 12v functions like detectors, and in my case a cold beer out of the fridge, warranted life support category and that I would not want to risk running down all batteries for the sake of a little more AC. My concern is that the balancer may eliminate this benefit of a "split" battery bank.

It is now five years on, our pups have grown old and passed away, and battery technology has changed so the questions are different now. I would lean to the solution you have advocated of a single bank of batteries in the back. Because we are snowbirds I have to ask AGM or Lithium - temperature lows are not an issue. Unless something breaks, I don't have an urgency to do something so I am trying to fully understand what I have, and the tradeoffs for different options.

Sounds like a plan, and a history that is all to familiar with those models and Roadtrek support of them. What you do is probably somewhat related to how much you would be willing to spend to update the systems. Personally, if I could spare the 25% of capacity I would go to the 24v pure 24 battery system to get rid of the 12v center tap and the long cables to the too hot front batteries. Magnum makes a good 24v shore charger that runs on a shunt and they have an add on solar controller, IIRC, but it may be overly large for you. If it is a 24v Blue Sky controller would also run on shunt control. 12v power to the coach from a 24 to 12v converter. If I recall correctly, I think it was 6 eight volt Trojan GC style AGM batteries that fit in the existing box. Good lithium systems would be much more expensive, and again personally, I am not sure the drop ins are ready for prime time.


Your patience and tolerance with Roadtrek has to be admired, and rare, I think.

[Bud]

Originally Posted by JohnnyCLE

Yes, I do. I spent the better part of three days reading through all 17 pages of threads which referenced an E-Trek. It was a walk through time.

Purchased the E-Trek in Apr 2015 as my first RV and in May had an email exchange with Roadtrek support personnel about the electrical system. Being new to the RV world I was unaware of this forum. I was given some limited disinformation which I found disappointing, but not being the litigious type I chalked it up to one of life's many disappointments and concluded that perhaps it was because I needed to learn to live with the system better.

My major issue was that AC time was incredibly shorter than advertised and we had two dear pups we were trying to keep cool while my wife and I might shop or lunch. Fortunately I never totally trusted the system so it did not create a bad situation because I checked on them frequently.

We have frequently used the E-Trek, usually on short trips of 7-10 days, and have had a minimum of complaints other than the battery life. I was unaware of the balancer change because the disappointment of AC run time was not critical enough to demand that I find a solution and simple math pointed out that I was a fool for buying into their promises to begin with. I guess I wanted to be a believer and never checked out the math ahead of time.

Roadtrek's misinformation attributed the short battery life to cleanly "split" battery banks. At that time I read the SmartGauge article on why not to "split" battery banks but concluded that the 12v functions like detectors, and in my case a cold beer out of the fridge, warranted life support category and that I would not want to risk running down all batteries for the sake of a little more AC. My concern is that the balancer may eliminate this benefit of a "split" battery bank.

It is now five years on, our pups have grown old and passed away, and battery technology has changed so the questions are different now. I would lean to the solution you have advocated of a single bank of batteries in the back. Because we are snowbirds I have to ask AGM or Lithium - temperature lows are not an issue. Unless something breaks, I don't have an urgency to do something so I am trying to fully understand what I have, and the tradeoffs for different options.

Curious, were the primary ambassadors, Roadtreker with utubes have any influence concerning your purchase?

Bud

[JohnnyCLE]

Thanks! I will look those products up. Parallel in back appeals to me to eliminate the one bad link taking out the whole chain issue. I guess max batteries for a Class B sprinter might be six 24v lithium batteries in back, one additional somewhere in the coach, if the weather gets too cold for the ones in back to operate, and two AGMs up front charged by the chassis alternator!

If my calculations are correct this would store about 8,000 watt-hours of usable capacity. Only about 2 hours driving time!

My starting post was somewhat triggered from my MC touring where I would abuse my body, bike, and bike's battery for 4-6 weeks and all limp home in some state of disrepair. Once home, after plugging in to a float tender, the battery at least was back to spec overnight! It would be nice to do that for my RV batteries.

[booster]

Originally Posted by JohnnyCLE

Thanks! I will look those products up. Parallel in back appeals to me to eliminate the one bad link taking out the whole chain issue. I guess max batteries for a Class B sprinter might be six 24v lithium batteries in back, one additional somewhere in the coach, if the weather gets too cold for the ones in back to operate, and two AGMs up front charged by the chassis alternator!

If my calculations are correct this would store about 8,000 watt-hours of usable capacity. Only about 2 hours driving time!

My starting post was somewhat triggered from my MC touring where I would abuse my body, bike, and bike's battery for 4-6 weeks and all limp home in some state of disrepair. Once home, after plugging in to a float tender, the battery at least was back to spec overnight! It would be nice to do that for my RV batteries.

Have you checked the full output over time amps/watts out of the 24v alternator? That would be very interesting to know, as we have never seen that data in the past IIRC. The 12v units will net out at under 2000 watt hours per hour per hour as they will hot cycle the output and average around 165 amps.



Do remember that the voltage a battery is at doesn't necessarily determine it's condition. I have had batteries at 12.6v after charging that had hardly any capacity left, but the little the had was charged full and showed good voltage. Capacity test is best to do, load test not as good but better than nothing.

[JohnnyCLE]

Bud, Ah yes, the wonderful wandering pair, the Wendlands described specifically how there was plenty of AC to keep their dog comfortable while they were out and about. I have forgotten it's name - I think it was Beau - but it also has grown old and passed on. They should have known better.

[JohnnyCLE]

No, I haven't measured the output. Our use case is usually a rich mix of driving to stopping so charging time has never been an issue. I was just using the rated numbers for discussion.

Yes, the ability to achieve a charge vs hold a charge. I haven't been too scientific about it. When my batteries can no longer hold the charge I need for a reasonable time I replace them. I run the refrigerator off of 12v and only turn on 110v breakers as needed. If I start getting less than 4 days on 12v off of shore power I will probably replace them.

I ruined one set of batteries because of haste. I needed to get our Sprinter down to Arizona for the winter and then fly back to Ohio to tend to my wife who was going through cancer treatment. I left the battery connect switch "on" rushing for an Uber and several months later came back to blistered batteries. The inverter has a low battery protect but not the 12v circuits. Other than that things have been serviceable.

Perhaps all inverters are the same, but the LW5000 seems designed for the split bank battery system which Roadtrek used. When plugged in to shore power the display shows the level of the 12v bank and when off shore power the 24v readings are displayed. This is always a little awkward because you have to unplug shore power to see what level one is charged to.

The battery remote only shows a reading for the 12v bank. So the battery remote might show a full battery reading and the display on the inverter might be showing a low battery error because the AC has depleted the 24v bank. This was the reason for my first email to Roadtrek.

It may be that Roadtrek was sold the battery / inverter design by ZLPower and never fully understood it themselves. The do not appear to have had real depth in battery system design. This might explain some of their statements from ignorance vs deceit.

[Bud]

Originally Posted by JohnnyCLE

Bud, Ah yes, the wonderful wandering pair, the Wendlands described specifically how there was plenty of AC to keep their dog comfortable while they were out and about. I have forgotten it's name - I think it was Beau - but it also has grown old and passed on. They should have known better.

They knew plenty. I'm very sorry about your being . I better not say it with any f word, or avanti, Janet will censor me. Bummer, very sorry.

Bud

[booster]

Originally Posted by JohnnyCLE

No, I haven't measured the output. Our use case is usually a rich mix of driving to stopping so charging time has never been an issue. I was just using the rated numbers for discussion.

Yes, the ability to achieve a charge vs hold a charge. I haven't been too scientific about it. When my batteries can no longer hold the charge I need for a reasonable time I replace them. I run the refrigerator off of 12v and only turn on 110v breakers as needed. If I start getting less than 4 days on 12v off of shore power I will probably replace them.

I ruined one set of batteries because of haste. I needed to get our Sprinter down to Arizona for the winter and then fly back to Ohio to tend to my wife who was going through cancer treatment. I left the battery connect switch "on" rushing for an Uber and several months later came back to blistered batteries. The inverter has a low battery protect but not the 12v circuits. Other than that things have been serviceable.

Perhaps all inverters are the same, but the LW5000 seems designed for the split bank battery system which Roadtrek used. When plugged in to shore power the display shows the level of the 12v bank and when off shore power the 24v readings are displayed. This is always a little awkward because you have to unplug shore power to see what level one is charged to.

The battery remote only shows a reading for the 12v bank. So the battery remote might show a full battery reading and the display on the inverter might be showing a low battery error because the AC has depleted the 24v bank. This was the reason for my first email to Roadtrek.

It may be that Roadtrek was sold the battery / inverter design by ZLPower and never fully understood it themselves. The do not appear to have had real depth in battery system design. This might explain some of their statements from ignorance vs deceit.

I think there is a bit of confusion on how the 12 and 24v power is achieved. If yours is like the other etreks we have heard about , there would two strings of four 6v batteries, so in essence two 24v batteries wired parallel. That gives a ground on one end of the strings and 24v on the other end. The 24v charger, the 24v alternator, the 24v solar, and the 24v output to the inverter would all be attached to the 24v end of the strings.


The 12v power would be achieved by connecting to center of the two strings of batteries which in a 4 battery string is 12v to ground. All they are doing is use 1/2 of the batteries for 12v power and letting the other half sit. Those batteries supplying the 12v are also used for the 24v power, so any 12v power used makes the 12v side of the bank discharge while leaving the other half of the batteries charged. This mismatch is really bad for the batteries and makes recharging well virtually impossible. The battery balancer that most users have added basically recharges the batteries in the string that are used for 12v power from the batteries that are only used for 24v power, so they all wind up the same state of charge for the recharge cycle or further discharges.


So there is really only one 24v battery bank, with a center tap, which is a horrible setup without a balancer. Roadtrek insisted for a long time that the system was fine and the failures were user caused, even denying warranty and threatening the users with legal action if they posted complaints online, so not their finest hour.

[JohnnyCLE]

My batteries appear to be connected the same as the wiring diagrams which were included in prior threads. The misinformation I got from Roadtrek was that there were two banks of 4 6v batteries, one in series for 24v and the other in series & parallel for 12v. While this might be considered the case for discharging the batteries, it is definitely not the case for charging them.

Total agree with all of points raised about how this approach taken violates all accepted sources of good design. Some people seem to go further and say that the approach of slamming 24v into one end of a series of 6v batteries is itself poor and will not optimize battery life and performance. As a neophyte it never occurred to me that one could do this. I always assumed the simplistic charge in parallel and discharge in series if you must. Everything in between seems to be trying to remediate weaknesses. Thus my question about something to be able to "true up" individual batteries at the end of each trip. The most charitable thing that can be said about it is no design is worthless, if nothing else it can be used as a bad example! But, I am a layman here just wanting something simple which works!

I certainly don't support or defend any of the corporate messaging or positions Roadtrek took as they realized they were in way over their head. I just find it interesting that the ZLPower inverter seems to support the poor battery bank choices made by how they display state of charge of both virtual banks. It would seem unlikely that ZLPower designed their product around Roadtrek's bad design vs more likely that they may have influenced Roadtrek with a "cheaper" product and design and Roadtrek might not have taken the time to fully understand the implications until it was too late. Unfortunately a lot of innocent employees and customers got hurt, which always seems to be the case.

The ZLPower inverter is the one component I feel most exposed on. If it fails I suddenly have a burning platform and the timeframe to do something becomes immediate. I am hoping to baby it along for another couple of years!

[booster]

That sounds about right from all that I remember about those discussions. I think one question that was open was if both, or just one of the 4 battery, 24v, strings of batteries were center tapped for the 12v. A case can be made for both ways, I think.


From what was said in those discussions, and what some reading has done, the 24v, 4 GC battery strings have been common in boats for decades and pretty well understood in those applications, and that understanding is that there has to be a balancer in to handle a center tap.


Personally, I have not got an issue with 4 battery strings, as the issues of having more potential cells to fail is small compared to the advantages of 24v system voltage. Of course, if you have the right space for them you do the same 24v with less cells if you had space for big capacity batteries like 4D or such and eliminate a string. Looking back, I think I might have seriously considered going to 24v when I did our upgraded system a number of years ago, even though it would have cost a bit more space for the 24 to 12v converter.


The converter shouldn't really have an issue with the setup, as all it does it put voltage and current out and doesn't really know where it goes or if it does a good job once it gets there.



If you are concerned about if a balancer can be put on just one bank if the banks are not tied at the center, you may want to look up the balancer install manuals and see what they say, or contact the manufacturer. I don't think it is a problem to do just one, but not certain. Without a balancer, you probably will continue to have expensive battery failures, I fear.

[JohnnyCLE]

This discussion has been invaluable to help think through some alternatives. I think I am starting to see a path forward which optimizes what I have and allows for incremental change.

I should consider making the misinformation I got from Roadtrek about having split battery banks true by eliminating the cross wiring and charging the 12v bank via a converter or off of the chassis alternator. I'm not getting more that 400 usable AH into 110v inversion anyway so just cut the Gordian knot.

It appears the 12v feed to the coach fuse box comes off of the two front batteries. This would isolate my 12v "life support" batteries from ever being depleted by my 110v "comfort" circuits.

I could then have a battery monitor dedicated to the 12v 2 series pair in parallel and have the fail soft redundancy of parallel on these "life support" systems. If I find that two AGM's in the front are adequate for my use I could then us the back as 6 8v in parallel strands of three on the inverter. This could happen when battery upgrade time comes or I get an uncontrollable urge.

The more I get to know about the LW5000 the less I like about it. It seems to be a jack of all trades and master of none. Noisy and not a great bypass when plugged into shore power. Not a great battery tender when idle. Solar gets terminated there and becomes difficult to access as well the solar controller has to deal with all of the confusion in the current battery wiring. If I could limit it's use to quietly charging up the 24v batteries and having a better bypass on shore power I am imagining life would be better.

If I could have access to the output of my solar so that I could direct it to charging the 12v bank or running a smaller inverter it would gain me flexibility. It would seem that flexibility would be a good thing vs dumping a trickle of solar into a big pool of batteries never to be seen again.

If I do these things I become less exposed to the Charger / Inverter in the back, perhaps extend it's life, and have more replacement options if it blows.

Related to my original post, I am casting a jealous eye at products from this company

https://no.co/gb50

and wonder if I had direct access to my solar, the right wiring harness, batteries mostly filled by the drive home, and plenty of sunshine, that maybe, just maybe . . .

[Sehc]

Lead acid chemistry only. A good charge controller will have an equalization charge applied maybe once a month. Should be done at least twice a year. That mixes the stuff and will help keep the cells in balance. Go to the battery manufacturer to find the right voltage and time.

[JohnnyCLE]

Thanks, I understand your statement as meaning that the NOCO products only apply to Lead Acid batteries despite, what I read as, their claims otherwise?

I read through the Technical Manual for the Lifeline AGM deep cycle and understood their care recommendations. It doesn't seem reasonable to expect that an RV electrical system automatically provides this given that they are designed for other priorities and seem to have precautions for over and undercharge built in.

I am increasingly skeptical that the "plug it in to shore power when you get home and you'll be good" is optimal. At the same time, I probably can't be counted on pulling the batteries and tuning them up on a bench once a month. Nor do I plan to store them like a expensive bottle of wine when not in use.

I get better life out of my other vehicle batteries by keeping them on tenders when not in use. I am trying to understand if there is the equivalent which will do a better job than the onboard RV systems short of pulling the batteries. If the answer is no, it would be a disappointment. If the RV systems automatically provide this it would be a happy surprise.