I recently had a leg 1 overload error on my multiplus ii. After that the smart shunt SoC seemed to be low, overnight it seemed to correct itself to 100%. Now I think the SoC is showing an inaccurate value. I assume a zero calibration procedure is needed but wanted to come here to poll the audience on whether or not there are other things I need to do.
My system is based off an Explorist Life diagram, has MPPT coming into lynx distributor, a multiplus ii, 400 AH of batteries. I have programmed the multiplus and shunt previously and they ran accurately without issue up until the error about a week ago. Now it just seems like the SoC of dropping faster than normal compared to usage.
I’m curious if dividing the current battery voltage reading into the full voltage value would give me an accurate percent? If that is a valid equation then I’d feel more confident I just need to recalibrate and that I don’t have any other issues in my system.
I assume the SOC jump you refer to is from the shunt? What batteries do you have?
You possibly had an early synchronisation to get the jump.
What is your setting for soc on reset?
Thanks for replying, let me know if this information is helpful.
Yes, the reading is off the shunt and that is on the negative side of the battery bank, nothing else to/from it. I’m using 4x 100ah power queen batteries, they’re budget so I’m assuming the BMS is rather basic and not doing too much.
Batter SoC on reset = set to 100%
charged voltage - 13.4 (manufacturer spec)
Still need some clarification. A 12v system?
It is possible they tripped under the overload, the shunt reset.
Are they daisy chain connected?
13.4 is too low for the charged voltage setting in the SmartShunt, and is causing the BMV to set itself to 100% far too early. “Charged Voltage” in the SmartShunt should typically be set to a few tenths below absorption voltage when working with an LFP battery bank; since Bulk/Absorb is usually 14.4v on an average 12vNom system, the BMV “charged voltage” should usually be set to between 14.0 and 14.2v.
Agreed, the 13.4v seems closer to float for most batteries. This would point to chronic undercharged and unbalanced cells.
Well the shunt isn’t affecting the actual charging, so it’s possible the batteries have been being charged just fine, just the SmartShunt is registering 100% far sooner than is actually the case.
If the shunt is not quite correct, what other settings have been copied across to other components?
@gbikery what are your other settings on the inverter, mppt etc?
I’ll try to pull the other settings today.
Yesterday it did hit 100% and seemed to correct itself a bit, something I haven’t seen while not on shore power since the error occurred. So, that was encouraging but I still want to run through all the things and get it configured properly again.
More to come
The Multiplus ii settings are of course more difficult to get to. I don’t have the connector hooked up and would have to remove the cover in a very tight space to get to it.
Did you set the inverter the same as the MPPT though? I am sure you did.
Peukerts is closer to 1.05 for lithium.
66% is close to 152ah of 400.
Your battery soc on reset is the reason it jumped to 100%. Try use keep last SOC instead
@lxonline , I’ll go back and check the inverter vs. MPPT settings soon. Thanks for the confirmation on all of this. I’m thinking of doing a zero and 100% calibration too, I assume those would be good steps right now. Just need to find the time to do it all.
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