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Hoping someone here might have seen this before. My two Lithium RV batteries were very consistent up until July 1st. Then something happened on that day and the voltage spiked to 48 then dropped and the graph becomes very unstable after that and never hits the full charge. Here's a graph shot that shows the change.
Since that time the batteries never show 100% charge. Did something get shorted out or could this be a BMS problem in the battery?
The SmartShunt has a small glass fuse in an inline holder with spring contacts in the positive wire. Sometimes these get a bit loose and give a poor contact, or of you have had a voltage spike perhaps that has done some damage. When these contacts get loose the measured voltage can be lower than actual.due to the resistance. Check out your fuse and fuse holder and also the terminal where it connects to the SmartShunt.
Thank you! I will check this out tomorrow. The smart shunt is "built-into" the BMI box so I'll look for fuses and connection quality at that piece.
Final update, it seems the Future Solutions BMI box was definitely not water proof. When I took it off it was about 1/3 full of water still (it hasn't rained since May). The fuse was still working, and checking the wires didn't help so I replaced the Smart Shunt (older model) with a new one that is IP65 rated. I also drilled some small weep holes in the bottom of the box and sealed the top up with a small bit of silicon after putting everything back together.
Thank you pwfarnell for the lead as that tip led me to other threads on different sites that highlighted the water problem. Not sure why the old one would sort of work, but fixing it only took $100 and a couple hours, plus it's an upgrade to a better protected device.
@Forrest Evans Glad you got it sorted, the issue will have either been some extra resistance on the positive wire due to corrosion or the water was allowing some current from the positive feed to flow to negative, reducing the positive voltage at the point of measurement.
What else is in your system, and how is it configure/wired?
There two solar panels, solar MPPT controller, xantrax inverter, two dragonfly batteries and the smart shunt built into a shutoff switch (I think it's called a BMI box).
It is the factory install from Keystone on the Cougar travel trailers. The package is called the Solarflex 400i.
What specifiics are you looking for on the wiring. I can try to look closer at it, but I didn't do the install.
Can you post the victron connect charts for the solar chargers and any errors they are showing?
Went and checked out some more on this. The Smart Solar MPPT is reporting a different (and accurate) battery voltage of 13.62. I also used the multi-meter to check what the batteries were reporting directly at the batteries and on both sides of the BMI box. Everything reads at 13.62 and that is what the Smart Solar is showing. The Battery Shunt is reporting only 12.28.
I don't see any anomalies on the trend graphs of the Smart Solar anywhere. At that same time I see the spike in voltage at the shunt, the Smart Solar is consistent. (There are drops when I recently moved the trailer to a new storage location with a roof, so the solar panels aren't generating power anymore.). Few pictures below that may help?
Battery is connected to the BMI Box at the right side, come out on the left. At battery and both sides of the box voltage reads at 13.62.
Shot of both devices SmartSolar accurate based on multi-meter. Shunt shows 12.28, but voltage in and out of the box where it lives says otherwise.
