there is a consensus among this forum and others that my system is not set correctly and that I need to set the correct SOC in my BMV 712 settings.
In order to set the SOC at 100% I need to know that my batteries are actually fully charged.
How would I know that?
If I leave SOC at 100% as it is now, then the batteries won't charge, right?
Should I lower to a small number to make sure they fully charge?
I haven't been following your posts but what makes you think your battery charger is not fully charging the batteries? Very few (if any) modern battery chargers will stop charging when the battery is fully charged and indicate when that happens, provided of course the battery charger was set appropriately for the type of battery being charged.
I should also add the BMV is a battery monitor but needs to be setup properly to report accurately. That information can be found in the user manual.
The components of the system should get to the target voltage set on them for charging. Even with a BMV.saying it is 100%.
So is the battery getting to the target voltages set?
How you know your battery is fully charged..
1. Battery it at target absorption voltage
2. Battery is now drawing very little to no current (depends on chemistry) this is known as tail current. Technically the battery is fully charged at this point.
3. Battery should then drop down to float voltage (if you have set it lower) and is considered all the way through the charge cycle.
The basic stages are bulk - absorption - float.
Bulk (same target voltage as absorption) bigger amps voltage rising up to target.
Absorption. No voltage rise lower amps. (Technically cell balancing happens here) at this point the battery is fully charged - chemistry as fully reversed as it can be.
float - small discharge down to this level maybe maintained there until there is not charge source such as solar.
my batteries are at 100% at night and down to 20% in the morning (10h non-solar power).
I have 200W constantly drawing at night.
12V system on a boat. 2x 200Ah Dakota lithium.
Ok. Well what are your settings?
I know it is not linear but roughly....
400ah x 12v is 2.4kWh
200w over 10 hours is 2kWh
2 kWh of 2.4Kwh is 83% DOD. So 17% SOC in the morning. Or about there. Assuming you started at 100%
NB. There is no need to reset the SOC manually. When the smartshunt is correctly set up, it will set itself correctly.
We need to see your battery settings in the smartshunt, and your charger settings, as well as the battery charging requirements.
It's also worth checking that only the smartshunt is connected to battery negative. Nothing else. If there is anything connected direct to battery negative it must be moved to the load/system side of the shunt.
Sorry, mixed up smartshunt from your other post with BMV here.
Your charged voltage is set too high. This can prevent the BMV from synchronising when the battery is full. What you need to do is tune the settings to match your system.
For solar charging you need a charged voltage setting that's a little below the absorption voltage. Try starting at 14.2V.
The other settings that affect the synchronisation are charge detection time and tail current. These look ok to start with. If there are longish cloudy periods where you live, good idea to increase charge detection time. Might need to lower the tail current setting for this as well, but it also depends on your batteries.
BMV will synch to 100%.when the 3 parameters are all met. I.e. battery voltage at 14.2V and tail current at/below 2% for the detection period. This does not affect the charger behaviour. After synching the SOC is calculated for current until the next synch event.
