Does the BMV 712 control the charging behavior of the MPPT Controller and the IP22 Blue Smart AC charger, or just report on the SOC? I am asking because both my MPPT Controller and Blue Smart 12/30 AC charger are going into float mode SOMETIMES, but not always, within an hour of when I turn them on, even tnough the batteries are deeply discharged, according to the BMV. For example, yesterday the BMV reported the SOC to be 70% and -153AH. I turned on the engine and pulled up the anchor and turned on off the solar and turned on the AC charger. Within half an hour, the BMV reported a 100&% SOC and -2AH, which is physically impossible. I am trying to figure out if the batteries are bad or the BMV, AC charger or MPPT 100/30 is the problem. Charged the batteries to 100% and then disconnected them and in the morning the voltage drop is tiny, so I think they are good. I have a 440AH battery bank from 4, 6v. Lifeline, GPL 4CT Batteries. Any in sights would be appreciated.
The BMV-712 is a battery monitor only, it cannot control charge or discharge functions of your batteries, it’s just reporting what it’s seeing, in context of how you’ve programmed it for the battery bank.
Thank you. I called Lifeling to get their recommendations for correct the correct settings and input them. I wish I could figure out the cause of these erratic swings in the SOC. When 100% SOC or Float Mode occurs on either charger, 0 or very few amps are going into the batteries. I try turning the charger off and then on. Bulk is entered briefly and then they go into Absorb or Float Mode again.
The screen on the BMV was damaged and is now blank. All the information from the BMV I get from the Victron Blue tooth app. Is it possible that in addiition to the screen being blank, the unit itself could be misreporting SOC information?
Have a read of this FAQ, if you have the wrong charged voltage it can jump to 100%. You could also grab screenshots of your BMV settings and give us details of your batteries and the absorption and float voltages you use.
Your charged voltage setting is wrong. Take a look at this thread over at DIYSolarForum.com where one of the very experienced users wrote up just about everything you need to know about the settings for the (Victron) shunt.
Set your charged voltage to 14.3V (although this is not the issue here I believe) and try a tail current of 1%, I found that OK with high quality AGM.
The second issue of the chargers going into float early can occur if you have too much voltage drop in your cables from the chargers to the batteries so the chargers see a higher voltage. If the voltage drop is between the shunt and the battery that can affect synchronisation to 100%.
Finally, does your engine charge the batteries by an alternator and if it does do this, does the BMV register the amps from the alternator. If the alternator negative does not flow through the shunt then this can result in early jump to 100%. See another FAQ on shunt wiring if it does not get registered.
You are really addressing the problems I am having. Thank for the links you posted and the BMV settings you suggested. I input them into the BMV, but my MPPT is in Float mode even though the BMV says I am at 8% and minus 68.4AH. Based on the screen shots of the MPPT settings I sent you, what changes would you suggest to the MPPTn Solar SettingsI?
The settings you have in the MPPT are similar to what I have seen for lifeline, the absorption is longer than I would normally use (I had 5hr when I had Victron AGM) but those settings should not go into float early. The only reason it should go into float is if the voltage is above 14.4V and current below 2A. If this is happening early then either your batteries are badly degraded, they are fuller than you think or you have a high resistance between the MPPT and the batteries. Some diagnosis with a multimeter on equipment terminals during charging would be useful, i.e. is the battery terminal voltage the same as the MPPT terminals and BMV terminals. What does the battery voltage drop to overnight.
Thanks again for your fast response. I have been struggling with this problem for weeks. I don’t have voltage drop between my MPPT or Blue Smart 30A charger and all ground wires, including the alternator, go to the shunt. I have equalized the batteries several times and charged them fully, ( amps in or out). separated into individual 6vs and rested them overnight and measured with minimal voltage drop. Please let me know if the settings in the attached screen shot of the Blue Smart 30 AC charger are correct. Thanks for your help!!
They look OK, absorption slightly lower so the solar takes priority I guess.
As you can see in this photo, the 30A charger is pushing 5A into the batteries at 13.3v.
I sent you typo before SOC was 87%.
Just now it jumped to 100%.
Are there any settings I can change to get a full charge into these batteries?
The images above show the charger providing 5A, some of this will be supporting loads and there are 1.2A going into the battery at 14.3V so the charger is still in absorption and the battery has synchronised to 100%. The batteries are full. The charger and BMV appear to be OK.
See how things go. If the batteries are bad then the voltage drops off quicker than expected.
In VictronConnect, open the BMV-712. There is a button to resync. Use this only when you know the battery bank is at a full state of charge. It will force the shunt to restart the state of charge at 100%.
This may not be your problem. You said that all connections are going to the shunt, but if that’s not the case then the shunt will be off. It’s also critical that the wires are on the proper sides of the shunt. If it’s backwards then all charging looks like a discharge to the shunt.
Thank you for evaluating the settings. What concerns me is that the BMV reported 87% SOC and -68.4AH an hour ago. It seems like they might be bad, but when fully charged, they don’t drop much overnight.
the readings for my 4, 6v batteries I during an overnight rest test were:
6.576 - 6.509
6.63 - 6.490
6.540 - 6.490
6.64 - 6.500
The first two batteries make 12v battery and the second pair make another 12v battery.
Batteries look OK overnight.
The next thing is do is a zero current calibration on the BMV. This needs the whole electrical system shutting down, the procedure is in the manual. If the BMV has drifted out of calibration then it could be recording a higher discharge current than reality and a lower charge current causing your large offsets and jumps in SOC.
If the calibration is fine then change the BMV charge efficiency factor from 95% to 99%, I used 98-99% on my Victron AGMs. With high quality batteries you can get better recharge performance so the SOC rises faster when recharging and Lifeline are some of the best AGMs. In my experience this closes an SOC jump of a few %, not 10-15% which is why I did not note it earlier.
I have used that button about 5 times in the last weeks to resync when I see 0 amps in and 0 amps out of the BMV. The Shunt is connected correctly with Batteries Only connecting to the batterie’s terminal and Load and Charger connecting to the main shunt.
OK. I will do the 0 calibration when fully charged. Thanks so much. I have been yammering on this site for 2 weeks and talking with an ABYC electrician, but my specific issues have not been addressed succesfully. I really appreciate your expertise!
I didi the 0 calibration. How do I know it is fine? The" Current " setting on the BMV jumps around from o.20A to o.21. On my amp clamp meter it jumps from 0.17 to 0.22. I changed the charge efficiciency setting to 99% and the current threshold to 0.00A. Does that sound good? I will synchronize when the batteries are fully charged and see if the system charges and discharges as it should