kimch said: . . . a battery expert told me most likely the power system is made for only one 12 volt battery (with relatively low aH), not for two 6 volt wired for 230 aH.
. . . Mine [ 2x 6V ] worked fine for a couple years but now the aH - - appears to be the problem with the camper not getting enough power to run what it used to run just fine.
Does not sound like your "battery expert" is very knowledgeable. How large your battery bank capacity is in AHr has no direct relationship to the "trailer power system" beyond A] how long it takes to fully charge, and B] how long your trailer systems will run on battery only.
Also, keep in mind that the 320S and 400 have very similar overall " power systems " and the original 400 model years all came from the factory with 2 two six volt batteries.
You indicate with the older two 6-volt batteries installed "trailer power does not seem correct" while with one 12-Volt battery all is well - - - - - That sure seems like one of the 6-volt batteries is defective or the wire connections of the two 6-volt batteries have an issue.
The problem, as defined, has nothing / zero to do with your battery bank AHr capacity . . . IMHO
'18 320 S, pitched axle, 3020HE; PNW based TV: '17 Colorado V6 Z71 4x4, Tow Package, GM Brake Controller Adventures: 56Nights: 379 Towing Miles 47,220
I think your “battery expert” was referring to your trailer physically having only one battery installed. To add a second battery you’re going to have to install another battery box or additional battery tray plus wiring to hook two 6v batteries in parallel and then connect it to your electrical system. It’s doable, if you have room on your tongue or in the tongue box. As far as your trailer electrical system goes it just sees a 12 volt battery, the increased ah just lets you run your stuff longer without charging up from shore power.
2023 T@B 320s Boondock, 2013 Toyota Tacoma TRD 4x4 John, Northern California
... the camper shows full charge (on the monitor) with one 12 volt low aH (group 24) battery in full sun. The camper shows poor or fair charge only with 2 6 volt 230 aH batteries even after sitting in sunlight for a week or more with everything in the camper turned off....
A "monitor" which does not include a current-measuring shunt is rarely reliable. Merely measuring the voltage is not enough. You mention have a Victron (which is not a shunt) - Is that a solar charge controller? If so its history graphs will show how much energy is being generated by the solar panel(s). If its daily generation is more than the daily background load, the graphs should say that it enters the "Float" charge state. If not, then the solar is not keeping up with demand.
Charles & Judy, Santa Cruz, CA 2018 T@B 320 CS-S; Alde 3020; 4 cyl 2020 Subaru Outback Onyx XT
... the camper shows full charge (on the monitor) with one 12 volt low aH (group 24) battery in full sun. The camper shows poor or fair charge only with 2 6 volt 230 aH batteries even after sitting in sunlight for a week or more with everything in the camper turned off....
A "monitor" which does not include a current-measuring shunt is rarely reliable. Merely measuring the voltage is not enough. You mention have a Victron (which is not a shunt) - Is that a solar charge controller? If so its history graphs will show how much energy is being generated by the solar panel(s). If its daily generation is more than the daily background load, the graphs should say that it enters the "Float" charge state. If not, then the solar is not keeping up with demand.
I am VERY familiar with solar, having 100% off-grid homes for decades. Right--my Victron is pre-shunt by Nucamp so just a solar charge controller. I have monitored the history graph since I got this camper and since the problem began the batteries have almost always been in float mode (when I am not using the camper--which I use only a few times a year). The Victron readings match voltmeter readings which match other battery-checking devices I have. Everything points to the batteries themselves being in excellent condition, ditto the solar charging of them.
Also to clarify, for the past few weeks I've been doing various analytic experiments on the system I have kept everything except the minor draws (light on CO/smoke alarms, light on radio display, etc.) 100% off. No furnace, no water, no lights, no fan, no fridge. So nothing is draining the batteries (other than by a minuscule amount). Again, I am well aware of how solar/battery systems work.
@kimch: Okay, you’ve added some useful information there, e.g., it gets to “float”, so the voltage is getting to the “I’m as charged as I’m gonna get” level. It doesn’t mean that the batteries are loaded up with 230aH of juice, especially when they are aged or perhaps defective. Going back to the initial problem report, what do you mean by “the camper not getting enough power to run what it used to run just fine”? If the symptom is that the batteries goes from a properly configured float state, to a too-low voltage after using let’s say half of its nameplate capacity, that strongly suggests that a battery is defective.
Charles & Judy, Santa Cruz, CA 2018 T@B 320 CS-S; Alde 3020; 4 cyl 2020 Subaru Outback Onyx XT
If you swapped out the batteries for a 12v and everything worked fine, then along with everything else that you are describing you have faulty batteries.
_____________________________________________________ Ken / 2023 Tab 400 “La Bolita” (29,000+ miles) / 2024 Toyota Sequoia 2025 - 1 Trip - 25 nights - 2 National Parks
It would be helpful if you would post screenshots of the Victron Controller data from the Victron Connect app.
1. Controller settings (note that these settings must be changed each time you swap between the single 12v battery and the 2 6v batteries) 2. Status 3. History
If by "monitor" you're referring to the panel of idiot lights in the trailer, I'd caution that this is notoriously unreliable.
For example, if you look at those idiot lights when the trailer is in full sun and your solar panels are producing power, the lights might be reflecting a bogus SOC based on the power output from the panels, even if the batteries aren't being charged. You should look at those lights only when there is no power from the solar panels and even then they aren't terribly accurate.
Since you already have a Victron Solar Controller, I'd recommend that you add a Victron SmartShunt to your camper. The SmartShunt is easy to install and measures every amp of current going in/out of your battery so will be more useful in tracking down your issue than the idiot light panel. If there's something in the T@B that's drawing a lot of power, the SmartShunt will give you that info (the "Current" data will be a large negative number of amps).
One word of caution, though: the default settings for the SmartShunt automatically set the SOC to 100% when you first connect a battery. So if the battery is not fully charged when first connected, the SmartShunt SOC reading will be incorrect. But the SmartShunt will still provide other valuable information until you've sorted out the charging issue.
San Francisco Bay Area 2013 CS-S us@gi 2015 Toyota Tacoma PreRunner Double Cab
The WFCO power center absolutely controls the 12V system.
It:
Distributes 12V power to appliances (lights, fridge, Alde) via its DC fuse panel.
Converts 110V AC to 12V DC to power loads and charge the battery when on shore power.Connects to the battery, acting as a central hub for 12V power.The presence of 110V breakers and 12V fuses in the WFCO box confirms it manages both AC and DC systems.
The WFCO’s converter/charger is critical for 12V battery charging when you’re plugged into shore power.
Relationship Between WFCO and Victron The Victron solar controller charges the battery from solar panels, while the WFCO charges it from shore power.
They connect to the same battery but operate independently: When Solar is Active: The Victron’s higher voltage (e.g., 14.4V) typically overrides the WFCO’s lower voltage (e.g., 13.6V), so the Victron handles charging. This is normal, as current flows from the higher potential source. When on Shore Power: The WFCO’s converter should charge the battery if its voltage exceeds the battery’s resting voltage. However, if the Victron is active or the WFCO is misconfigured (e.g., in lead-acid mode for lithium batteries), the WFCO may not charge effectively.
Things to investigate: Mismatched charging profiles:
Victron set to lithium, WFCO in lead-acid mode?
Victron and WFCO both have lithium profiles but golf cart batteries are lead acid or lithium.
Some questions to help us help you:
The problem you are trying to fix is that the battery monitor built into the TAB panel drops to one light after the sun goes down. Is that correct?
Are you trying to use 2 6v golf cart batteries and 1 12v lithium batteries at the same time?
Are your golf cart batteries traditional lead acid, AGM, or lithium? (This relates to the correct voltage provided by the power center)
Have you disconnected your batteries when you believe it/them is/are fully charged, let it/them sit for 10-15 minutes, and then measured the voltage with a multimeter?
What voltage does the Victron Solar controller show for each battery when the sun goes down? As others have stated a screenshot of the Victron would be helpful.
Why are you using the golf cart battery setup?
2021 T@b 320 Boondock "Mattie Ross" | 2021 T@b Nights: 239 | Total nights in a T@b 455 | 2022 Jeep Grand Cherokee L Overland | T@b owner since 2014
IMO - With all the experience and resources the OP has described, it seems that some actual voltage and current measurements are long overdue. Most if not all of the suppositions and what ifs can be quickly resolved with some actual data. Nothing will be resolved without measurements.
The WFCO power center absolutely controls the 12V system.
It:
Distributes 12V power to appliances (lights, fridge, Alde) via its DC fuse panel.
Converts 110V AC to 12V DC to power loads and charge the battery when on shore power.Connects to the battery, acting as a central hub for 12V power.The presence of 110V breakers and 12V fuses in the WFCO box confirms it manages both AC and DC systems.
The WFCO’s converter/charger is critical for 12V battery charging when you’re plugged into shore power.
Relationship Between WFCO and Victron The Victron solar controller charges the battery from solar panels, while the WFCO charges it from shore power.
They connect to the same battery but operate independently: When Solar is Active: The Victron’s higher voltage (e.g., 14.4V) typically overrides the WFCO’s lower voltage (e.g., 13.6V), so the Victron handles charging. This is normal, as current flows from the higher potential source. When on Shore Power: The WFCO’s converter should charge the battery if its voltage exceeds the battery’s resting voltage. However, if the Victron is active or the WFCO is misconfigured (e.g., in lead-acid mode for lithium batteries), the WFCO may not charge effectively.
Things to investigate: Mismatched charging profiles:
Victron set to lithium, WFCO in lead-acid mode?
Victron and WFCO both have lithium profiles but golf cart batteries are lead acid or lithium.
Some questions to help us help you:
The problem you are trying to fix is that the battery monitor built into the TAB panel drops to one light after the sun goes down. Is that correct?
Are you trying to use 2 6v golf cart batteries and 1 12v lithium batteries at the same time?
Are your golf cart batteries traditional lead acid, AGM, or lithium? (This relates to the correct voltage provided by the power center)
Have you disconnected your batteries when you believe it/them is/are fully charged, let it/them sit for 10-15 minutes, and then measured the voltage with a multimeter?
What voltage does the Victron Solar controller show for each battery when the sun goes down? As others have stated a screenshot of the Victron would be helpful.
Why are you using the golf cart battery setup?
Some good information here--thank you. So for 12v, the WFCO is just distributing power, not doing anything else. I've checked and even replaced (tho all looked fine) all the possibly relevant fuses both in-line and in the WFCO, so it sounds to me like the WFCO isn't a problem based on what you said. No settings have been changed and this camper has always had lead acid batteries so unless something electronic flipped itself, nothing is set for lithium. My Victron app has no settings for me to change battery type or pretty much anything.
Remember all the power in the camper worked completely fine for over two years and nothing has changed other than time passing (and recently me trying a 12v lead acid battery to rule out the in-great-shape-as-tested 6v batteries as the issue.
Your #1 towards the end--NO. The monitor is a symptom only. The problem is the Alde furnace gives Low Battery and won't come on when the monitor has only one light.
2. NO. No lithium involved now or ever with this camper.
3. traditional lead acid (wet cell) deep cycle
4. yes, they showed full but I'll check them today (they've been sitting for several days while I've had the 12v in for testing) before I reinstall them
5. I've been monitoring via the app for weeks. Once no sun on the battery/batteries, the Victron shows 12.6, sometimes a bit more, sometimes a bit less. I.e., fully charged.
It would be helpful if you would post screenshots of the Victron Controller data from the Victron Connect app.
1. Controller settings (note that these settings must be changed each time you swap between the single 12v battery and the 2 6v batteries) 2. Status 3. History
If by "monitor" you're referring to the panel of idiot lights in the trailer, I'd caution that this is notoriously unreliable.
For example, if you look at those idiot lights when the trailer is in full sun and your solar panels are producing power, the lights might be reflecting a bogus SOC based on the power output from the panels, even if the batteries aren't being charged. You should look at those lights only when there is no power from the solar panels and even then they aren't terribly accurate.
Since you already have a Victron Solar Controller, I'd recommend that you add a Victron SmartShunt to your camper. The SmartShunt is easy to install and measures every amp of current going in/out of your battery so will be more useful in tracking down your issue than the idiot light panel. If there's something in the T@B that's drawing a lot of power, the SmartShunt will give you that info (the "Current" data will be a large negative number of amps).
One word of caution, though: the default settings for the SmartShunt automatically set the SOC to 100% when you first connect a battery. So if the battery is not fully charged when first connected, the SmartShunt SOC reading will be incorrect. But the SmartShunt will still provide other valuable information until you've sorted out the charging issue.
No settings for me to change in the Victron app I have. I've been monitoring it for weeks and the Victron shows everything is working perfectly (it thinks)--battery going to float each day with sun, only brief periods of charging and absorption. Voltage max and min show full charge always the 12 v battery never going below around 12.4, the 6v usually showing a min around 12.79.
The monitor is a SYMPTOM, not the issue here.
I read a bit about the shunt and it doesn't sound too easy since it looks like wires need to run both to the battery and inside the camper. Is it simple to run the wire(s) into the camper? And what do they connect to there (the instructions say to connect to "loads and charger")?
No settings for me to change in the Victron app I have.
This is absolutely incorrect. You need to change the settings for the Victron Controller through the Victron Connect app when you change battery types. If you fail to do so, the Victron Controller will not properly charge the battery/ies from the solar panel.
Access the solar controller settings by clicking the gearwheel icon at the top right of the Victron Connect page for your SmartSolar controller.
You can see an explanation of the settings interface by skipping to the 6:00min mark of this video.
I've been monitoring it for weeks and the Victron shows everything is working perfectly (it thinks)--battery going to float each day with sun, only brief periods of charging and absorption. Voltage max and min show full charge always the 12 v battery never going below around 12.4, the 6v usually showing a min around 12.79.
As I said earlier, it would be helpful if you'd post screenshots.
The monitor is a SYMPTOM, not the issue here.
I read a bit about the shunt and it doesn't sound too easy since it looks like wires need to run both to the battery and inside the camper. Is it simple to run the wire(s) into the camper? And what do they connect to there (the instructions say to connect to "loads and charger")?
The issue is that you're trying to solve a problem with insufficient data. I suggested the SmartShunt so that you have a means of properly measuring the power going in/out of your battery. If your battery is in the front tub, buy the IP65 version and put it somewhere in the front tub. Follow these installation directions. There's no need to run a wire through the camper. "Loads" = power going to the camper; "Charger" = your solar controller.
San Francisco Bay Area 2013 CS-S us@gi 2015 Toyota Tacoma PreRunner Double Cab
No settings for me to change in the Victron app I have.
This is absolutely incorrect. You need to change the settings for the Victron Controller through the Victron Connect app when you change battery types. If you fail to do so, the Victron Controller will not properly charge the battery/ies from the solar panel.
Access the solar controller settings by clicking the gearwheel icon at the top right of the Victron Connect page for your SmartSolar controller.
You can see an explanation of the settings interface by skipping to the 6:00min mark of this video.
I've been monitoring it for weeks and the Victron shows everything is working perfectly (it thinks)--battery going to float each day with sun, only brief periods of charging and absorption. Voltage max and min show full charge always the 12 v battery never going below around 12.4, the 6v usually showing a min around 12.79.
As I said earlier, it would be helpful if you'd post screenshots.
The monitor is a SYMPTOM, not the issue here.
I read a bit about the shunt and it doesn't sound too easy since it looks like wires need to run both to the battery and inside the camper. Is it simple to run the wire(s) into the camper? And what do they connect to there (the instructions say to connect to "loads and charger")?
The issue is that you're trying to solve a problem with insufficient data. I suggested the SmartShunt so that you have a means of properly measuring the power going in/out of your battery. If your battery is in the front tub, buy the IP65 version and put it somewhere in the front tub. Follow these installation directions. There's no need to run a wire through the camper. "Loads" = power going to the camper; "Charger" = your solar controller.
It would be nice if the app would at least show the settings (though I understand them not being changeable remotely) when not right at the Victron. The settings, however, have no options other than factory default for lead acid. None of the presets apply to my system, and again, all worked fine for over two years and the settings have never been touched.
Your link is the instructions I already had found. What in the tub qualifies as "loads and chargers"? Separate from the batteries which clearly show how to connect in the diagrams. By your definition, where do I hook cables for "power going to the camper"? Separate from the battery connections. The issue may be you are thinking the solar controller is in the tub. It is not. It is under a seat in the camper. Thus my comment about needing to run a wire into the camper.
For what it's worth, I've traveled, boondocked and camped with two 6v batteries wired in series for over 5 years
Good to know. I didn't have any issues for the first two years of my 2023. Does your 2019 have solar with a Victron, and what type of power center does it have?
The 2019 was the last year for a T@B KISS (keep it simple stupid). I simply connect my solar cells directly to my now AGM 6 volt batteries. I keep them on continuous trickle charge while the trailer isn't being used. I only need 95 watts of Zamp Solar while running my 3-way refrigerator on propane. I can stay out for days at a time and watch DVD's at night. The California sun is very reliable. The price of AGM's keep rising while the cost of lithium keeps falling - which is a good thing for those who attempt to do what I do with newer T@B's.
TV:2019 Nissan Frontier PRO-4X With an Old Man Emu lift
Trailer: 2019 T@B 320 Boondock with a Lock&Roll Coupler & Jack-e-up
For what it's worth, I've traveled, boondocked and camped with two 6v batteries wired in series for over 5 years
Good to know. I didn't have any issues for the first two years of my 2023. Does your 2019 have solar with a Victron, and what type of power center does it have?
The 2019 was the last year for a T@B KISS (keep it simple stupid). I simply connect my solar cells directly to my now AGM 6 volt batteries. I keep them on continuous trickle charge while the trailer isn't being used. I only need 95 watts of Zamp Solar while running my 3-way refrigerator on propane. I can stay out for days at a time and watch DVD's at night. The California sun is very reliable. The price of AGM's keep rising while the cost of lithium keeps falling - which is a good thing for those who attempt to do what I do with newer T@B's.
I use Zamps (and some other brands) to charge various things (including other campers) but they are useless for my travels with my T@b as I drive long days, do quick overnight stops along the way. In other words, I don't use the T@b for camping, rather for overnighting as I am moving between locations. So the only solar solution that works for me is having panels atop the camper to charge the batteries as I'm driving. Thus relying on the Victron and WFCO Power Center that came with the camper. (I also have a 2018 which is like your 2019--3 way fridge (I prefer the 2 way) and no rooftop solar.) That said, for my stationary uses, I'm a strong supporter of Zamps and other suitcase panels.
@kimch What is the amp hour of the 12v battery you are using and is it an AGM or flooded lead acid battery? And what are the amp hours of the 6v batteries? (Are these AGM or flooded lead acid?)
Since the Victron Solar charger will be connected directly to the battery, an easy way to help diagnose the problem would be to turn the battery disconnect off. Then allow the solar panels to completely charge the battery. Then you would need to disconnect the solar charger and allow the batteries to rest and then test them to determine the state of charge.
_____________________________________________________ Ken / 2023 Tab 400 “La Bolita” (29,000+ miles) / 2024 Toyota Sequoia 2025 - 1 Trip - 25 nights - 2 National Parks
@kimch What is the amp hour of the 12v battery you are using and is it an AGM or flooded lead acid battery? And what are the amp hours of the 6v batteries? (Are these AGM or flooded lead acid?)
Since the Victron Solar charger will be connected directly to the battery, an easy way to help diagnose the problem would be to turn the battery disconnect off. Then allow the solar panels to completely charge the battery. Then you would need to disconnect the solar charger and allow the batteries to rest and then test them to determine the state of charge.
For weeks I have been analyzing with power on, power off, full sun days, no sun days, etc. And more recently, the 6vs completely disconnected then tested. To your questions, the 12v is typical, probably 80-90 aH--I don't remember exactly but it's only a Group 24 so not many aH. Wet cell. The 6v wet are 230 aH (which is why I switched to them when the camper was brand new).
I think I may have fixed the issue but I am now in the process of more analysis along the same lines--sunny days, cloudy days, power on, power off.
Comments
How large your battery bank capacity is in AHr has no direct relationship to the "trailer power system" beyond A] how long it takes to fully charge, and B] how long your trailer systems will run on battery only.
Also, keep in mind that the 320S and 400 have very similar overall " power systems " and the original 400 model years all came from the factory with 2 two six volt batteries.
You indicate with the older two 6-volt batteries installed "trailer power does not seem correct"
while with one 12-Volt battery all is well - - - - - That sure seems like one of the 6-volt batteries is defective or the wire connections of the two 6-volt batteries have an issue.
The problem, as defined, has nothing / zero to do with your battery bank AHr capacity . . . IMHO
TV: '17 Colorado V6 Z71 4x4, Tow Package, GM Brake Controller
Adventures: 56 Nights: 379 Towing Miles 47,220
John, Northern California
A "monitor" which does not include a current-measuring shunt is rarely reliable. Merely measuring the voltage is not enough.
You mention have a Victron (which is not a shunt) - Is that a solar charge controller? If so its history graphs will show how much energy is being generated by the solar panel(s). If its daily generation is more than the daily background load, the graphs should say that it enters the "Float" charge state. If not, then the solar is not keeping up with demand.
2018 T@B 320 CS-S; Alde 3020; 4 cyl 2020 Subaru Outback Onyx XT
Going back to the initial problem report, what do you mean by “the camper not getting enough power to run what it used to run just fine”? If the symptom is that the batteries goes from a properly configured float state, to a too-low voltage after using let’s say half of its nameplate capacity, that strongly suggests that a battery is defective.
2018 T@B 320 CS-S; Alde 3020; 4 cyl 2020 Subaru Outback Onyx XT
Ken / 2023 Tab 400 “La Bolita” (29,000+ miles) / 2024 Toyota Sequoia
2025 - 1 Trip - 25 nights - 2 National Parks
Ken / 2023 Tab 400 “La Bolita” (29,000+ miles) / 2024 Toyota Sequoia
2025 - 1 Trip - 25 nights - 2 National Parks
2. Status
3. History
2013 CS-S us@gi
2015 Toyota Tacoma PreRunner Double Cab
The WFCO power center absolutely controls the 12V system.
It:
- Distributes 12V power to appliances (lights, fridge, Alde) via its DC fuse panel.
- Converts 110V AC to 12V DC to power loads and charge the battery when on shore power.Connects to the battery, acting as a central hub for 12V power.The presence of 110V breakers and 12V fuses in the WFCO box confirms it manages both AC and DC systems.
The WFCO’s converter/charger is critical for 12V battery charging when you’re plugged into shore power.Relationship Between WFCO and Victron
The Victron solar controller charges the battery from solar panels, while the WFCO charges it from shore power.
They connect to the same battery but operate independently:
When Solar is Active:
The Victron’s higher voltage (e.g., 14.4V) typically overrides the WFCO’s lower voltage (e.g., 13.6V), so the Victron handles charging. This is normal, as current flows from the higher potential source.
When on Shore Power:
The WFCO’s converter should charge the battery if its voltage exceeds the battery’s resting voltage. However, if the Victron is active or the WFCO is misconfigured (e.g., in lead-acid mode for lithium batteries), the WFCO may not charge effectively.
Things to investigate: Mismatched charging profiles:
Some questions to help us help you:
2021 T@b 320 Boondock "Mattie Ross" | 2021 T@b Nights: 239 | Total nights in a T@b 455 | 2022 Jeep Grand Cherokee L Overland | T@b owner since 2014
Remember all the power in the camper worked completely fine for over two years and nothing has changed other than time passing (and recently me trying a 12v lead acid battery to rule out the in-great-shape-as-tested 6v batteries as the issue.
Your #1 towards the end--NO. The monitor is a symptom only. The problem is the Alde furnace gives Low Battery and won't come on when the monitor has only one light.
2. NO. No lithium involved now or ever with this camper.
3. traditional lead acid (wet cell) deep cycle
4. yes, they showed full but I'll check them today (they've been sitting for several days while I've had the 12v in for testing) before I reinstall them
5. I've been monitoring via the app for weeks. Once no sun on the battery/batteries, the Victron shows 12.6, sometimes a bit more, sometimes a bit less. I.e., fully charged.
6. For the aH. 230 vs. only around 90 with 12v.
The monitor is a SYMPTOM, not the issue here.
I read a bit about the shunt and it doesn't sound too easy since it looks like wires need to run both to the battery and inside the camper. Is it simple to run the wire(s) into the camper? And what do they connect to there (the instructions say to connect to "loads and charger")?
2013 CS-S us@gi
2015 Toyota Tacoma PreRunner Double Cab
Your link is the instructions I already had found. What in the tub qualifies as "loads and chargers"? Separate from the batteries which clearly show how to connect in the diagrams. By your definition, where do I hook cables for "power going to the camper"? Separate from the battery connections. The issue may be you are thinking the solar controller is in the tub. It is not. It is under a seat in the camper. Thus my comment about needing to run a wire into the camper.
Since the Victron Solar charger will be connected directly to the battery, an easy way to help diagnose the problem would be to turn the battery disconnect off. Then allow the solar panels to completely charge the battery. Then you would need to disconnect the solar charger and allow the batteries to rest and then test them to determine the state of charge.
Ken / 2023 Tab 400 “La Bolita” (29,000+ miles) / 2024 Toyota Sequoia
2025 - 1 Trip - 25 nights - 2 National Parks
I think I may have fixed the issue but I am now in the process of more analysis along the same lines--sunny days, cloudy days, power on, power off.