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4 100mh BB's. Set up per victron 712 instructions. 14.4 charged, discharge floor 5%, tail 4% peukert 1.05, charge efficency @99% batt starts synch, On shore the SOC goes down. Consumed ah are at -210 although on shore for 30 hours. Multi Plus Inverter shows on storage at 13.22v. SO, why they heck does bat show 49% and why not fully charged given on shore for 30 hours? Why any discharge forgetting whether soc is calculated correctly?
Sounds like the 712 smart shunt may not be wired to spec. Be sure the only neg connection is from the neg side of the BBs. All other loads, including the shore power battery charger go on the load of the shunt. Better way is to have a bus bar with all positive and neg loads connected to it, then only one wire connection from the load side of the shunt to that bus bar. I have 2 BB 100AH in parallel on my boat’s house bank. Here’s my schematic
If the system is set up as ESS this might be expected. Otherwise, the Multi should be able to keep up with existing loads and your SOC should always be close to 100%.
The BMV-712 won't control charging. This is all managed in the Multi. And without a Venus device, the Multi won't use info from the battery monitor, so make sure its battery monitor is enabled and its parameters are set properly also.
Check to make sure the Multi's charger is enabled and its charging parameters are set properly: Lithium batteries on, 14.4 absorption, 13.6 float, equalization disabled or 14.4. Absorption time should be set to 30 minutes per battery so 2 hours. These numbers are from Battle Born.
The Multi can also operate in Inverter Only mode in which case it will not charge the batteries and the loads will run off the battery bank. Check to make sure the Multi is either in the On or Charger Only mode.
There are virtual switch modes or assistants that can disable charging so check for those.
According to Victron, the 712's "charged" voltage should be set to 13.2. This value and the tail current are used to trigger 100% SOC sync.
Thanks. With SOC steadily declining and now at 7%, but v showing 14.2 I'm convinced it is wired wrong. 712 shows consumed as -369 when it seems to me that should be a positive number. All this is above my pay grade. Switched multi panel to on, left inverter at charging and bam the v went up. Gotta be wired wrong as suggested.
Sounds like the shunt is backwards: battery vs system connections
