Solar Help required

[GlennG]

Hi All
I finally received all of the components for my Solar system
I have
2- Renogy 175 flexible panels wired in series on the Yakima tracks
1- Victron 100/30 Smart Solar Controller
1- Victron 712 Battery Monitor and temperature sensor
2- Rolls 6 Volt 275AGM Batteries

i have installed and set it all up and have been watching for the last 2 weeks with camper shut off (no load)
Can not field test as we are still in lockdown mode here.

What I'm seeing is that the SOC is slowly dropping every day and is now at 72%
The setting I'm using are from Rolls tech

BMV 712
Battery Cap 250
Charged V 14.7
Discharge Floor 50%
Tail Current 2%
Charge Det time 3mins I changed this from Rolls recommended 60 mins
Peukert 1.09
Charge Eff 80%
Current Threshold .10A

Victron 100/30 set points
Battery Preset User Defined
Expert Mode Yes
Absorb Voltage 14.7
Float Voltage 13.8
EQ Voltage 14.7
Absorb Duration Fixed
Tail Current 1 Amp
Temp Comp .02

Here is what I'm seeing this morning
BMV 712
72% SOC
Voltage 13.79
Current -0.25
Power -3W
Time since Full Charge 13 Days 19 Hours

100/30
Solar
7 W
Voltage 44.44
Current 0.1A

Battery
Voltage 13.79
Current 0.40
Temperature 17 C
State Float

Unsure why I'm not getting back up to full charge. It has to one of the setpoints I think
I see that every morning at first light it goes in to bulk charge for a short and then the rest of the day it stays in float.
Any help would be appreciated. I'm thinking of covering the solar panels and putting my Noco Genius 10 to recharge the batteries and reset and see what happens
Cheers
Glenn

 

[ri-f]

Have you tried resyncing/calibrating when the batteries are resting, at night? I'd try that before tweaking your settings. You may need to drop your charged voltage setting slightly, say 0.1 or 0.2v below your aborption voltage and see if that makes a difference. Also, what is the absorption time? You may need to increase it or decrease it to get a full charge depending on the temperature and solar exposure at different times of the year. Also, if you are not under any load, a fixed absorption time might be too much time vs a fixed absorption time under a constant load. What does your Rolls manual suggest for aborption time with your battery AH rating, with no loads, using solar (fluctuating ) charging at your current temperture? They may suggest a different setting than the averages listed in the manual. Are you also showing that you are down in amp hours consumed, as well as SOC, they are related.

 

[GlennG]

Thanks Rf-i
It appears to use about 3 AH a day which I assume is the controller and 712 but that does seem to high
Should I recharge the batteries back to full charge before resyncing at night
or that does that matter?

 

[ri-f]

If your solar is getting good sun for a few hours each day they should do the charging well enough. Just try to sync it a few hours after the sun goes down. You shouldn't be seeing any significant discharge with your system turned off. Let us know if resyncing helps. Otherwise you'll need to adjust the settings. Rich

 

[ri-f]

Glenn - also, based on your numbers, it doesn't appear as if you are not staying fully charged. 13.79 is close to your float voltage. Is the battery resting at ~13v overnight and then going up when the sun starts charging it? If so, then it would seem to me that your battery is acting as it should. Have you confirmed that after you set up the solar, the panels were putting out good amps in the sun under a load? If not, you can simply run down the battery, say to 50%, and then see what kind of current you're seeing from the panels. It should be close to 10 amps +/- in good sun with your 2 panels. Right now you're seeing very little current coming in because your batteries are floating and already topped up and your controller is preventing it from overcharging.

It would be good to test that your solar is working properly under a load. You can just run some lights or a fridge and discharge the battery in your driveway and then let the sun charge it back up. But again, the voltage seems good, so the SOC and amps/hrs appear out of sync. You'll know soon enough.

p.s. Here's something to look at: What does your Victron MPPT controller show you in the MPPT history (VictronConnnect app) for max voltage and min voltage over the last couple weeks? You should see the resting voltage (min) and the absorption voltage (max). These should be consistently close to your high of 14.7v absorbtion, and low resting voltage (~13v or so I would think). How long does it stay in absorption mode (minutes, hours?) If it never reaches close to your set point of 14.7v for the absorbtion/charged voltage stage of charging, then it isn't getting a full charge, but that isn't likely since your readings show that you are in float mode, and have completed the charging cycle for the day.

Rich

 

[GlennG]

Rich
I rested the solar panels for 24 hrs (cover up the panels) and then took a measurement with my multimeter which showed 12.89 v which is fully charged from what see. I then synchronized the Smart BMV 712.
The history on BMV 712
Charge
total charge cycles
0
Synchronisations
1
History on Smart Controller
Solar Panel
Pmax 100w to 80w thru the week
Vmax 46.31 to 46.96 thru the week
Battery
Max 14.70
Min 12.86 to 13.37

To me this looks like the Solar controller is charging the battery and keeping it charged albit there is no load.
It appears to me the BMV 712 is not doing it's thing.
Should it Sync automatically ?

I will put it under load this weekend and see what happens. We are actually supposed to get some sun.
Cheers
Glenn

 

[ri-f]

Rich
I rested the solar panels for 24 hrs (cover up the panels) and then took a measurement with my multimeter which showed 12.89 v which is fully charged from what see. I then synchronized the Smart BMV 712.
The history on BMV 712
Charge
total charge cycles
0
Synchronisations
1
History on Smart Controller
Solar Panel
Pmax 100w to 80w thru the week
Vmax 46.31 to 46.96 thru the week
Battery
Max 14.70
Min 12.86 to 13.37

To me this looks like the Solar controller is charging the battery and keeping it charged albit there is no load.
It appears to me the BMV 712 is not doing it's thing.
Should it Sync automatically ?

I will put it under load this weekend and see what happens. We are actually supposed to get some sun.
Cheers
Glenn

Hi, Glenn. Why does it appear that the BMV 712 is not doing its thing? Is it not showing a 100% SOC after a full charge cycle? Is it showing a loss of amp hours while the SOC continues to drop? All the numbers you have provided seem to point to a fully charged AGM battery resting at a good voltage, and a solar controller and panels that appear to be functioning correctly. Your multimeter also confirms a full charge in the resting state which I assume correlates with your BVM 712 . I'm also assuming that both of your new 6v batteries are showing equal voltage and that you don't have a bad cell in one of your new batteries. And, that all your negative wires to the battery are before the shunt. If they are not, then your meter will be off and your consumed amp hours and SOC won't be accurate.

So, that said, is it the meter that still isn't syncing to 0 amp hours and a 100% SOC? I still think that you need to discharge the battery properly by puting the system under a load, discharging it by, say, 30% and then fully charging it up again, either in the sun or with your Noco 10. You've had 0 discharge cycles to date and the BVM 712 might need at least one charge cycle to figure your battery out. Also, AGMs are sensitive to a good charging routine and I think that they can sometimes be difficult for the BMV 712 fo sync properly if they haven't received a full 14.7v charge for a number of continuous hours (~3-5 hrs) to top off the last 20% (I think you said your charge efficiency setting was 80%). You still may need to tweak the parameters a bit to get the system to sync accurately. Perhaps the charged time setting needs to be adjusted to accomodate, primarily, solar charging since you don't typically plug in. Also, I think the charged voltage setting should be slightly lower (maybe by -0.3v) than the absorbtion voltage, and maybe the absorption voltage itself needs to be tweaked as well. Those settings as well as the tail current (I think yours show, for some reason, two different tail currents, one of 1% and another at 2%) Hopefully, Rolls can walk you through these Victron settings, while on the phone with their tech dept.

I have heard that sometimes people with BMV syncing problems will look at the charging current on the BMV 712 and know when their batteries are full when the charge current coming in shows only 0.1v to 0.5v, when the panels are getting good solar input, at which point they are charged and will manully reset their meter.

Again, though, first things first, try discharging by 30%, then charging up again and see if it will sync up automaticallly (which it should). If it doesn't at that point, then you at least know that your system is working correctly, except for the settings that need to be tweaked for your BMV 712 to sync automatically when the battery is fully charged. Rolls should be able to walk you through those specific setting adjustments for their battery and the Victron BVM 712. You might also try Victron's tech support with your data and see what they suggest with your Rolls AGM 6v setup -- for a cross check. Let us know how it's coming along if you can, to add to the knowledge base. You're almost there. Good luck with this. Rich

p.s This is from the Victron manual:

155.3.2 Manual synchronisationThe SmartShunt can be synchronised manually if required. This can be achieved by pressing the synchronise button in the VictronConnect battery settings.A manual synchronisation can be needed in situations when the SmartShunt does not synchronise automatically.This is for example needed on first install or after the voltage supply to the SmartShunt has been interrupted. A manual synchronisation can also be needed when the battery has not been fully charged, or if the SmartShunt has not detected that the battery has been fully charged because the charged voltage, current or time have been set incorrectly. In this case review the settings and make sure the battery regularly receives a full charge.

 

[Vic Harder]

I don't know about you guys, but my BMV 712 does NOT have the automatically synchronize function turned on, by my choice.

And, if it was on, the BMV would have to be convinced that the batteries are in fact fully charged. That's based on your Charged Voltage, Tail Current and Charged detection time settings.

The Rolls Battery charging guide Rolls Battery User Manual says for 12V batteries to set the charger to 14.7 @25*C and float @ 13.8, which matches what you have on yours. I would NOT use equalization on AGM batteries.

I also note that you have the battery capacity set at 250AH, when they are 275AH batteries.
I would use the Rolls recommended Charged Time of 60 minutes.

 

[ri-f]

Yes, good point about not turning on auto sync. I've read that before and it seems to make good sense for the Rolls AGM.

I was also curious about why the 60 mins were changed to 3 mins.

As for the 275 designation on those particular 6v AGMs, the specs actually do say that it's a 250AH battery as the OP has stated.

So, Vic, glad you chimed in. Do you reset/sync your BMV 712 manually, when the full charge is reached, based on incoming current? Or what?

Rich

I don't know about you guys, but my BMV 712 does NOT have the automatically synchronize function turned on, by my choice.


And, if it was on, the BMV would have to be convinced that the batteries are in fact fully charged. That's based on your Charged Voltage, Tail Current and Charged detection time settings.

The Rolls Battery charging guide Rolls Battery User Manual says for 12V batteries to set the charger to 14.7 @25*C and float @ 13.8, which matches what you have on yours. I would NOT use equalization on AGM batteries.


I also note that you have the battery capacity set at 250AH, when they are 275AH batteries.
I would use the Rolls recommended Charged Time of 60 minutes.

 

[Vic Harder]

I reset mine manually if I have been mucking about with the system, which I do often. But once I am in "operational" mode I find I do not have to synchronize, ever. I fully charge before leaving home (shore power) and then I'm good to go for the camping season, or at least for the given trip we are on.

 

[bsharp007]

Do you have all your load wires connected to the Victron 712 shunt, INCLUDING the solar charger?
The 712 must see all the amps coming into and out of the system. When I originally installed the Victron 712 battery monitor I didn't have my solar charge controller properly connected to the shunt so it could only see the power going out of the battery.
As far as the solar charger was concerned the batteries were fully charged up each day but the Victron would show less SOC each day until I connected the two.

 

[Vic Harder]

+1 on having everything grounded via the shunt. I've made that mistake more than a few times myself. Easy to do.