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I'm using a BMV-712, a Victron MPPT smart controller, with 2 x 100ah Battle Born lithum batteries wired in parallel. The 712 was configured as instructed by Battle Born and everything seems okay except for the time remaining estimate. With an amp draw of 1.89 amps and 25 watts the estimated time remaining is less than 24 hours. This is with a full charge. Please see pics for setting confirmation. Any guidance is greatly appreciated!
This maybe the cause. please check
Under the setting options there is a relay mode this I think is currently set to 50% change this to zero.
as the time to go is based on the time to get to that setting
Hey Paul,
Thank you for taking the time to reply. Unfortunately I've been down that path with no luck. I first set the relay to 0% and allowed the day to pass and later simply turned it off with no change. I feel like I could be missing something in these calculations but they do seem straight forward.
I allowed my dual maxxair fans to run all night at 50% speed. Almost 12 hours later the stats are as follows:
Deepest discharge: -23Ah
Cumulative Ah drawn: -30Ah
Time since last full charge: 11h 23m
Voltage: 13.27V
Current (battery output): -1.73A
Power (battery output): 23W
Consumed Ah: -23.3Ah
Time remaining: 5h 55m
After running in this way for 1 hour last night the Time Remaining was 4h 16m so clearly the time remaining calculation isn't working as designed because running for an additional 11 hours it's saying remaining is just under 6 hours.
So if I did only draw 30Ah that should leave me 170Ah or 75% remaining but the BMV says I only have 30% remaining. It's as if it thinks I only have 1 battery- although the math doesn't really match up on that either.
What in the world am I missing. My main interest in understanding this is to determine if I need to increase my capacity for cloudy days or get a DC to DC charger.
You might want to change the "Charged Voltage" value to 14.0 volts (BMV) if you are following BB recommended charging voltages (mppt).
Accurate SOC and proper synchronization are more important than "time to go figures" for now.
I've been digging all morning and did do that after going in circles. It's interesting the variability on recommended baseline settings for BB lithium batteries where Ah size isn't a factor. Seems every "authority" on the subject has slightly different takes on the proper setting. Anyway, thank's so much for replying. At least I have that set and we'll see how today goes. Hope you have a good weekend. :)
If the "charged voltage" setting is set too low, the BMV can "syncronize" (reset to 100% SOC) too soon. BB recommended 14.2 for the charged voltage (with a Multiplus). Try this, and after your batteries come off their absorption charge, and then settle at their float charge, make sure the SOC says 100% and not something lower. If the problem still exists, make sure than when there is zero loads the current reading is zero (if not, disconnect the load side negative cable on the shunt and "reset" the zero amps calibration).
I'll up it from 14v to 14.2v and will see. Thanks for the reply! I did notice on my solar controller's history tab that my absorption cycle only lasts 1 minute before going to float. This is after it being in bulk for a while. Since last night was my deepest discharge to date I'll see what happens there as well. Battle Born programmed my MPPT before shipping so I assume it's setup as it should be.
