17MKE Battery & Charging question

[jkwilson]

I agree 100 percent and apparently so does GD. The 2023's are being shipped from the factory with a Furrion shunt type battery monitor. The OP can correct me if I'm wrong, but I expect his 2023 17MKE has the same Furrion FBM08A10C shunt battery monitor that is in my 2023 22MLE.

Does that shunt have the ability to compensate for charging efficiency of different battery types? A lead-acid battery needs about 2AH input to regain 1AH of charge, while lithium are very close to 1:1.

[Harvestmoon]

HarvestMoon,
(For a laugh, try Googling "Doris Day Harvest Moon")
As it happens, I do have that Furrion "component manual" and I did read the procedure given there. And I thought at the time that it was really bad to discharge (and damage) the battery at 0 VDC in order to "set up" the system. But you have indicated that "when the battery stops taking charge, then it is fully charged." But the MPPT 25A Solar Charging Controller is a three stage charger. And it is my understanding that one has to set it up so it knows when to switch from the fast "bulk" charge to the "absorption" charge (80%?) and finally to the "maintenance" or trickle charge (95%?). I have not done the steps in the Battery Indicator manual to set it up. Do I need to do that to get the correct readings on the indicator. If so, one part of the setup is to max out the charge and then "teach" the indicator at that point. And I have not really gotten close to the 128 AHrs, if that is even possible, although it was still charging today when I last looked. But it is insanely slow, and this is with shore (house) power. I just would like to know the best way to fully charge the batteries. I've even considered hooking up my 6A/2A automobile charger to give it a boost. Would that be bad?
Craig

For purpose of running the calibration procedure, I would charge from the converter (i.e., plug into shore power) for ~24 hours. If you apply an external charger, this will charge the battery but will not show up at increased amp-hours on the battery monitor, because the external charger current is not flowing through the battery monitor shunt.

I have not physically verified in on my on 22MLE, since it is buried someplace I have not found yet, but assuming GD did it right, the negative battery lead will go directly to the battery monitor shunt. All of the current flowing into and out of the battery flows through the shunt and is tallied by the battery monitor. So whether the charge is coming from the solar controller or the converter does not matter. However, any charge or load attached directly to the battery posts will not pass through the shunt and would throw off the SOC shown by the monitor. The same would be true if you pulled the batteries off the camper and did something else to charge or discharge them.

Cliff notes of the monitor calibration procedure:
1) Discharge the battery to whatever minimum state of charge you decide. The manual says not less than 10.5V. The 11.6V suggested by @SolarPoweredRV is probably a good mark.
2) Calibrate the monitor to 0 percent SOC
3) Bump the Ah capacity value up to something greater than your expected capacity (does not matter at this point as long as it's more than the usable capacity)
4) Charge the battery until it stops taking charge (again, I'd suggest charging from shore power ~24 hours)
5) Calibrate the monitor to 100 percent SOC and set the Ah capacity value to whatever Ah it took to fully charge

The calibration procedure itself is going to empirically tell you how much usable capacity you have. Do not get too hung up on what the manufacturer or anyone else tells you the capacity "should" be. From discharged to charged is what you have. This may change as the batteries age. Repeating the calibration procedure would keep the monitor accurate and reveal the overall health of the batteries as they age.

[Harvestmoon]

Does that shunt have the ability to compensate for charging efficiency of different battery types? A lead-acid battery needs about 2AH input to regain 1AH of charge, while lithium are very close to 1:1.

That is a great question and the user manual does not explicitly state. The Furrion monitor has no provision to select battery type, so that implies it does not. The manual simply states, "This product works with 8V-30V battery pack, such as the most common RV deep cycle: wet cell, AGM, and lithium batteries." I have one of these Furrion monitors in my 22MLE, but I have not used it in practice because I moved my batteries, resulting in the factory shunt being in the wrong place electrically. So with my new battery setup I installed a new Victron shunt.

[tptNbone]

I agree 100 percent and apparently so does GD. The 2023's are being shipped from the factory with a Furrion shunt type battery monitor. The OP can correct me if I'm wrong, but I expect his 2023 17MKE has the same Furrion FBM08A10C shunt battery monitor that is in my 2023 22MLE.

Correct. I have read my literature, and my 17MKE should have a shunt in it already. I guess my issue is that watching the charging rate and AHrs, that rate gets exceedingly slow at around 75 AHrs, and further increases are slower than I expect and never reach 128 AHrs. My best guess is that I may need to reset(?) the high end of my AHr range in my Furrion Battery Indicator. I think I do that by holding down the "SET" button for 3 seconds, and then pressing the "%/>" button until I reach 128 AHr, and then pressing the "SET" button again to set the top end for my two 64 AHr batteries. Then I expect that my charging may proceed at a faster rate and achieve a higher value sooner. But I am a neophyte trying to figure things out. I suspect that the settings in the Furrion Battery Indicator tell the MPPT at what point to slow the charging down. Does any of what I've said make sense?
(And thanks for the feedback from everyone!)
Craig

P.S. - And althought the Furrioin Battery Monitor doesn't set the battery type, the MPPT in my 17MKE does in fact provide settings for the different batteries, incl LiPo, AGM, and my Flood Lead Acid (not sealed). So my system does have some control of that.

[SolarPoweredRV]

Correct. I have read my literature, and my 17MKE should have a shunt in it already. I guess my issue is that watching the charging rate and AHrs, that rate gets exceedingly slow at around 75 AHrs, and further increases are slower than I expect and never reach 128 AHrs. My best guess is that I may need to reset(?) the high end of my AHr range in my Furrion Battery Indicator. I think I do that by holding down the "SET" button for 3 seconds, and then pressing the "%/>" button until I reach 128 AHr, and then pressing the "SET" button again to set the top end for my two 64 AHr batteries. Then I expect that my charging may proceed at a faster rate and achieve a higher value sooner. But I am a neophyte trying to figure things out. I suspect that the settings in the Furrion Battery Indicator tell the MPPT at what point to slow the charging down. Does any of what I've said make sense?
(And thanks for the feedback from everyone!)
Craig

P.S. - And althought the Furrioin Battery Monitor doesn't set the battery type, the MPPT in my 17MKE does in fact provide settings for the different batteries, incl LiPo, AGM, and my Flood Lead Acid (not sealed). So my system does have some control of that.

What you are experiencing is the charge rate of Lead Acid batteries. They will charge up to 80% fairly quick, however, 80% to 100% is agonizingly slow. It can take 10 to 24 hours to fully charge a Lead Acid battery. Fast charging is one of the many advantages of switching to Lithium (LiFePo4) batteries.

[Harvestmoon]

I have not done the steps in the Battery Indicator manual to set it up. Do I need to do that to get the correct readings on the indicator. If so, one part of the setup is to max out the charge and then "teach" the indicator at that point. And I have not really gotten close to the 128 AHrs, if that is even possible, although it was still charging today when I last looked.

I'll refer back to this post. Yes, you need to run the full calibration procedure from start to end in order (ref my prior post #12 ). It is likely that the dealer did NOT run the calibration procedure when they installed your batteries. Therefore whatever is now showing on your battery monitor for amp-hours / SOC is meaningless. You are correct that you need to "teach" the monitor the max SOC, but that is the LAST step in the Furrion calibration procedure. The Furrion procedure is bottom up. Start from the minimum SOC, set to zero, then charge to full.

[tptNbone]

I'll refer back to this post. Yes, you need to run the full calibration procedure from start to end in order (ref my prior post #12 ). It is likely that the dealer did NOT run the calibration procedure when they installed your batteries. Therefore whatever is now showing on your battery monitor for amp-hours / SOC is meaningless. You are correct that you need to "teach" the monitor the max SOC, but that is the LAST step in the Furrion calibration procedure. The Furrion procedure is bottom up. Start from the minimum SOC, set to zero, then charge to full.

HarvestMoon,
First many thanks for your patience.
Second, I have read so many times that discharging my not-sealed flood lead acid battery to Zero charge (0%) could kill or damage the battery. That has scared me away from the discharge-it-to-zero step. Should I not be afraid of a full discharge? Sulphation? But I do want the system to be working correctly, and I suspect it is not doing that now. And if my 2023 model is among the first to have updated MPPT controller and Battery Indicator changes (with a shunt), then maybe the dealer didn't go through the steps. My 'novice' thought on my battery is that, if its max has not been set up correctly, then the MPPT controller probaby starts the trickle charge too soon (at 75 AHrs), such that it will almost never get to the full charge. If I can reset the top limit to 128 AHrs, then maybe the charge would go faster until it reached 96 or 102 AHrs (75 or 80%), at which point it could start trickle charging. Does that make any sense?
Craig

[Capt Bob]

HarvestMoon,
First many thanks for your patience.
Second, I have read so many times that discharging my not-sealed flood lead acid battery to Zero charge (0%) could kill or damage the battery. That has scared me away from the discharge-it-to-zero step. Should I not be afraid of a full discharge? Sulphation? But I do want the system to be working correctly, and I suspect it is not doing that now. And if my 2023 model is among the first to have updated MPPT controller and Battery Indicator changes (with a shunt), then maybe the dealer didn't go through the steps. My 'novice' thought on my battery is that, if its max has not been set up correctly, then the MPPT controller probaby starts the trickle charge too soon (at 75 AHrs), such that it will almost never get to the full charge. If I can reset the top limit to 128 AHrs, then maybe the charge would go faster until it reached 96 or 102 AHrs (75 or 80%), at which point it could start trickle charging. Does that make any sense?
Craig

Late to the party but I would ask this. Does the battery indicator actually control the MPPT controller/battery charger as it relates to the charging cycle (or for that matter, anything)? For a moment, pretend you didn't have (as many don't) a battery indicator. With a correct charger, the charging algorithms are contained in the charger itself. You need to set the battery indicator to what you tell it (as stated above) because it's just reading what you stated your battery(s) are rated at.

I have a Renergy Monitor. I fully charged my 100AH battery and after connection, programmed the monitor to read 100% charge at 100AH. The indicator voltage and amps show on the monitor but the % charge and the amp hrs. are more of a guideline that you set yourself. This is the way my system works so I may be entirely wrong with your setup but I'm guessing if you fully charge both your batteries and THEN set your indicator, you'll see usage (charge and discharge) closer to what you really have going on.

Good luck.

[Harvestmoon]

HarvestMoon,
First many thanks for your patience.
Second, I have read so many times that discharging my not-sealed flood lead acid battery to Zero charge (0%) could kill or damage the battery. That has scared me away from the discharge-it-to-zero step. Should I not be afraid of a full discharge? Sulphation? But I do want the system to be working correctly, and I suspect it is not doing that now. And if my 2023 model is among the first to have updated MPPT controller and Battery Indicator changes (with a shunt), then maybe the dealer didn't go through the steps. My 'novice' thought on my battery is that, if its max has not been set up correctly, then the MPPT controller probaby starts the trickle charge too soon (at 75 AHrs), such that it will almost never get to the full charge. If I can reset the top limit to 128 AHrs, then maybe the charge would go faster until it reached 96 or 102 AHrs (75 or 80%), at which point it could start trickle charging. Does that make any sense?
Craig

As @Capt Bob stated, the solar charge controller works completely independently from the battery monitor. As long as you have the battery type set correctly as lead-acid (which it sounds like you do), it will apply the correct charge profile. As the voltage comes up and the charge current goes down, that is the battery's way of saying "I'm full".

For calibration of the minimum charge state, don't confuse 0 percent charge with 0 volts. You can pick whatever low state of charge you that you feel comfortable where your battery will provide good service life. Probably somewhere between 11.6-12.0 volts. The trade off is less depth of discharge gives you longer life but less capacity. As you know, that's the deal you have to make with lead-acid batteries. I'm not knocking lead-acid, because I used them for many years myself and they can work just fine, like anything else, within their limitations.

[SolarPoweredRV]

HarvestMoon,
First many thanks for your patience.
Second, I have read so many times that discharging my not-sealed flood lead acid battery to Zero charge (0%) could kill or damage the battery. That has scared me away from the discharge-it-to-zero step. Should I not be afraid of a full discharge? Sulphation? But I do want the system to be working correctly, and I suspect it is not doing that now. And if my 2023 model is among the first to have updated MPPT controller and Battery Indicator changes (with a shunt), then maybe the dealer didn't go through the steps. My 'novice' thought on my battery is that, if its max has not been set up correctly, then the MPPT controller probaby starts the trickle charge too soon (at 75 AHrs), such that it will almost never get to the full charge. If I can reset the top limit to 128 AHrs, then maybe the charge would go faster until it reached 96 or 102 AHrs (75 or 80%), at which point it could start trickle charging. Does that make any sense?
Craig

You are correct to not drain your battery to zero, just to set the battery monitor.

You only need to know your "usable" amp hours and not what the battery is theoretically capable of delivering. Consequently, you only need to drain your battery to 12 volts [50% SOC] (after 1 hour rest) and then fully charge your battery for 24 hours without any other loads on the battery. This will be your "usable" amp hours of energy storage.

Your monitor may show 64 amp hours of battery capacity, or it might show slightly more capacity (most likely scenario) because the battery performance will decrease over time to the manufacturer's stated 64ah level. Lead Acid batteries loose capacity over time, so, the manufacturers stated capacity is lower than what the battery is capable when new. This way, the battery will still perform above specifications when the warranty eventually expires. If they specified the "real" new battery performance, then they would get a lot of warranty claims to replace perfectly good batteries.

One additional piece of advice: If you are monitoring your batteries too closely, you are not having fun camping. If you are constantly draining your batteries to 50% SOC you do not have enough batteries.

I suspect that you will quickly find that 64ah of usable battery is not enough energy storage for your camper, especially if you have a 12v or residential refrigerator, or if you need to run your furnace without Shore Power.

You probably need to start thinking about upgrading to Lithium batteries, they make camping so much easier, you won't know how you survived the Lead Acid era.

Here is a post that will help you understand the advantages of Solar and Lithium batteries:

Affordable-Solar-How-To-Design-and-Install-an-Affordable-Solar-System

Note: be sure to follow all the links in the above thread for more detailed information.