question

lorettaboy avatar image
lorettaboy asked

Need help with wiring

I've been having issues with my smart BMV SOC ever since the solar system was installed by my travel trailer dealership. I had a look at my battery and noticed there were two wires connected to the negative terminal: the negative battery connection from the shunt, and the negative wire running from my MPPT solar chage controller. I moved the MPPT negative down to the loads and chargers side of the shunt.

Now the smart bmv is showing my battery's SOC at 100%. But the output power reading is showing a positive value rather than a negative (the solar coming in minus the actual load). What have i done wrong?

wiring
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pwfarnell avatar image
pwfarnell answered ·

Your installer made a basic error and you have done the correct thing moving the MPPT negative to the load side of the shunt.

When the solar power is larger than the loads then you will see a positive power reading. This is perfectly normal. Wait until night time and the solar charge falling to nothing and you should once again see negative power readings.

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lorettaboy avatar image lorettaboy commented ·

Phew! Thanks for the reply.

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kevgermany avatar image kevgermany ♦♦ lorettaboy commented ·

When set up correctly, the shunt only sees the current going through the battery. This is what the shunt is for. Loads bypass the shunt when not being serviced by the battery..

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