I recently installed a 24/5000 multi on a none Victron LiFePo4 pack, 300AH by the spec.
6 Ultramax 100Ah at 12.8V Nominal in 3 strings.
I added a SmartShunt connected to the Cerbo Via VE.Direct.
The Smart shunt is set up as the Battery monitor, charging is only via the Multi, the Cerbo and my WiFi/Ethernet network kit is a DC load. Nothing, other than the shunt is connected to Bat -.
Currents and voltages look reasonable.
I have two issues. (And little idea what to ask)
1) The console seems to report erratic DC load as max as +50% and -100W. The network power requirement will be fluctuating but the power meter on the buck converter that supplies it never gets anywhere near 200W peaks I see on the console.
There is never a DC charge current that isn't coming from the Multi, so I am assuming DC load should never be negative, is that right?
2) My system has shut down a couple of times with the battery capacity showing a little over 50%
The shut down is due to the batteries internal BMS protection tripping, at 9.5V!! Although I could mitigate that with a low voltage disconnect setting/logic it isn't going to help with the capacity meter error. The multi is set to disconnect at 21V, which I am about to lift, but at 21V the DC load still pulls the battery down quickly when the inverter is off.
I have 90A Bulk to 28.8V Absorb and then 27.6 Float set in the Multi, 'Charged Voltage' was originally a little low, its now 27.4, but the tail current was set to 3%,so 3A, which the pack is always well under by the time the 1Hr Absorb time has passed.
Looking at the history, the deepest DOD was 88% which if it accurate suggests my batteries are not matching the spec. Possible I guess. However it doesn't explain the low voltages and internal BMS disconnects at above 50%, metered.
What I need to know is if I am missing something? Because if I am not then the only other explanation is that my batteries are only holding about 55% of the rated capacity which is an argument I ma not looking forward to having with the supplier.
I am unsure how to proceed here. It would be great if someone pointed out how silly I am being and which settings I have wrong. Failing that some a advice on the best way to run a capacity test would be good.
Currently I have the battery monitor in the Multi disabled, assuming the Smart Shunt was a better option. However I am questioning that decision and now wonder if I am missing some fundamental point. Looking at the documentation again I am not even sure now if 'Has DC' should be on or if it will work as I thought.
I have attached a Lash Hour screen cap from VRM showing the negative DC load reading and what the rest of the system was doing at the time.
Happy to look silly here folks but need some help.