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685eric avatar image

MPPT 100/50 Charge Controller Reading Wrong Voltage


I am having an issue with my MPPT 100/50 charge controller reading the wrong voltage, which in turn does not fully charge my battery bank. The charge controller is networked with a SmartBMV battery monitor. The charger controller receives battery voltage and temperature from the battery monitor through VE smart networking.
For example, my battery monitor is reading 26.45v. This is the correct reading, verified by a volt meter and consistent with the state of charge. When I log into the charge controller, the voltage is reading 27.26v. This is WAY high!! This stops my batteries from fully charging. If I sit there in the app and watch the battery voltage for a while, it will sometime dip down to ~26.8v and then jump right back to ~27.2v. When this happens, EVERYTHING is off. No charging or discharging. Battery monitor voltage does not move and stays right around 26.45v.

I thought maybe the battery monitor was sending the charge controller the wrong voltage, so I removed the VE smart networking between the two devices. So now the charge controller is reading the voltage for itself. The charge controller was still reading around 27.2v. Nothing changed. Reconnected the network, charge controller was receiving the correct battery temperature, but the voltage was again high, around 27.2v. Do I have a bad charge controller? It is less than a year old. I am not a novice at this as I have an undergrad in mechanical engineering and a master’s in industrial engineering. My day job is mostly electrical engineering. This issue is starting to drive me nuts. Am I missing something? Is this a known issue? Firmware on both devices are up to date. Battery monitor v4.03, charge controller v1.46.

MPPT - Solar Charge ControllerBMV Battery Monitor
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1 Answer
685eric avatar image

After reading a lot of questions on here, I think it is a connection issues. I think the wire I have is thick strand wire. I will get some new wire and see what happens.

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