I have a 330w panel on my boat, we have 6x105LA batterys, the system has been working for 2 years but I have never believed the SOC. Its always higher than I think it should be. We have 12.2v in the morning but the soc is saying 91%?
All settings are as recommended from victron with CV at 14.1v TC at 4% PE at 1.25
The battery charges to 14.1v and hits 100% but never goes lower than 90 so it doesn't synchronize.
All wires are through shunt.
Can anyone help its driving me mad.
It will only synchronise if the detection voltage it met and the tail current condition is met.
Charge detection is 0.2 or 0.3v under float and tail current can usually be left at 4A% but with older lead acids it can be higher.
So it synchronises when higher not lower.... On charge voltage and lower than tail current after the charge detection time is met.
I cant imagine that you have managed to keep the bank charges with one small panel on such a large bank.
Aldo peukerts is adjusted depending on the load on the bank. So if you have a very time draw the peukerts will be very different . What is your usual loads in watts?
For solar charging, Victron indicates the charge detection should be 0.2V under ABSORPTION. Due to the potential inconsistency of solar power input, false syncs to 100% are common if float voltage is the charged basis.
In this case, shunt should be set for 13.9V and 5% to ensure false syncs are minimized and the sync occurs very nearly at true full charge.
Is the shunt sharing voltage/current data with the MPPT in a VE.Smart network or with GX DVCC? If not, you should.
Loading a battery pulls the voltage down, so the voltage in an active system is a very unreliable indication of SoC. I know these are different from your battery, but Rolls Surrette publishes voltage vs. SoC at various time periods:
This says that a battery at about 90% charge should be at about 12.36V 1 hour after the load is removed and the battery has been completely at rest.
If you truly want to establish a shunt to voltage correlation, you'll need to disconnect the battery from loads/charges completely for 1 hour and see what the voltage does. If it rebounds into the 12.3V+ range, ~90% SoC should be believed.
The trouble with SOC is that it's calculated, and how it's calculated is determined by the settings. The defaults might 'work' for all batteries, but need tuning if you want accuracy on your particular batteries. Two major things..
Peukert Exponent.. Victron offer 1.25 for Pb batts, and while that might be technically correct, most of us draw down the batts at far less than C20 (hour) rate. Your usage suggests somewhere in the C50 to C100 range. And using a (high) 1.25 may give an excessive 'credit' to your batts' SOC, which is likely why you've developed suspicions. If your battery maker provides a range of 'C' specs, grab Victron's Peukert Calculator from the website and run the C20 and (say) C100 specs for a more accurate PE. And even this is a bit rough, as there's other factors like Temp and batt aging that can impinge. My own Pb's bobbed with 1.16, then I reduced it to 1.10 and found I gained more reproducible SOC results from day to day. And it's on the safe side of the calculation, so I stuck with it.
Charge Efficiency. The default 95% is way too high for me. Pb's aren't very efficient charging at the top end of the range, so a lower value is needed. I'm using only 88% CE now as I'm not drawing down much more than 90% SOC. The aim here is to have the SOC rise back up to the !00% SOC naturally at the same time as you think it should sync anyway.
Your sync settings probably need work too, but look first at the PE and CE.
