My bmv 700 is showing -20 amps when the smart solar app is showing +30 amps. This is a recent development. I have repositioned the lead to the battery monitor from the battery to the shunt system terminal and there was no change in the reading.
I am not able to give you a simple drawing of the installation. I didn’t install it. It was not done correctly at the time, in that the settings on my ac charger weren’t changed properly but I’ve put in the correct numbers. I also tweaked the bmv settings on that unit(non-blue tooth) and also my smart solar app. This was about 5/6 months ago. Since then I’ve not (or rarely- twice!) seen the bmv return to 100% capacity when it reaches its zenith. The smart solar app will show battery voltage at 14.45, it will go to absorption, still putting in full amps (50+), for a while (20+ minutes). However the bmv doesn’t reset to 100%, it would show 70% full. The next day it would be lower still to eventually it would be 0% capacity and 0 hours of charge. I’d then (if not before) reset the synchronisation to 100% when it was at 14.45 volts.
There has always been a discrepancy between the app and the bmv battery voltage and the amp input from the solar panels. Recently this has jumped to huge discrepancy in the amp input.
I think it may be a faulty bmv. As I didn’t change anything before the discrepancy became apparent, it seemed to just happen by itself.
The settings for the 150/85 TR are as follows:
My bmv settings are as follows:
Battery cap 500ah
Charged voltage 14.1
Tailed current 2.0%
Charged detection time. 3 min
Peukert 1.05
Charge effiency 99%
Current threshold 0.10 amp
Time to go averaging period 03
No. There is only one wire connected to the battery minus going to the shunt.
See picture attached:
Unless the shunt is positioned upside down and thus the leads reversed?
a few options:
- All Loads and charging sources on the load side of the Shunt as described above.
- Calibration of the shunt is off, remove all loads and chargers, and re-calibrate (zero)
- the readings are correct, remember that the shunt is a NET value, (charge - load = net) so potentially there is 50A of load, 30A from the solar, and another 20A from the battery.
- the BMV cable between the Shunt and the Display is damaged. I have seen this cause issues like this.
as for your shunt not reaching 100%, the 3 settings that wil laffect this are your Tail current (default is 4%), the charged voltage (for LiFePO4 suggest 14V is plenty) and the charge detection time for those two factors to be true, then it will show 100%.
also seeing your settings for the 150/85, I can suggest that you use the Smart Lithium pre-set, and if needed, adjust the Absorbtion and Float voltages from there. You still have adaptive Absorbtion for example, which should usually be fixed for LiFePO4.
hope that helps.
I have 5 x 100 amp/hr lifepo4 batteries hence 500ah. What is 50 MV?
Btw have done a quick check of lead between shunt and bmv plus checked connections. All seemed good.
I’ve not got a smart shunt. How do I adjust shunt?
My bmv 700 doesn’t have a smart shunt. So I disconnected the negative load side of shunt and recalibrated zero on the unit (#9) and it seems to be fine now. I missed the synchronisation for 100% but will do that at a later date. I think all my problems came from a wire being wrongly joined to battery and not load side of shunt. Fingers crossed.
Thank you for all your help.