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BMV712 battery capacity percentage

Just installed a BMV 712 on a ”house bank” of 2 deep cycle AGM Firefly’s in parallel. Just learning how to use the system but it appears that the “battery percentage” indication doesn’t go down as power is used. The Bluetooth app shows the number of amps being used...it also shows a negative value when I turn on the battery charger. But after disconnecting from shore power and leaving my fridge and water heater running the battery percentage is still at 100%. Could anyone help out with an idea as to why this might be. Much appreciated. Thanx.....

battery capacity
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seahawk avatar image seahawk commented ·

I have a further question. In my setup, I presently have a large 1-ought cable at the battery negative going to ships ground. Also on the neg terminal of the battery I have a cable connected to the other house battery putting the two of them in parallel. Theres also a third negative, smaller gauge wire which I believe goes to the battery charger. So to wire the BMV712 correctly .....I'll disconnect all the existing negative cables from the battery. I'll connect the 1-0 cable that goes to ships ground to the "LOAD CHARGER' side of the shunt. I'll connect another 1-0 jumper....one end from the "BATTERY' side of the shunt and the other end to the neg battery terminal. Is this correct so far. If it is then this is where I get confused. Now, where do I connect that third negative cable that I think connects to the charger. And,....from this point forward, where would I connect any negative cables for other equipment. I know it cant go to the "BATTERY" side of the shunt,.....so would it go to the other end of the shunt,???....or to the battery negative terminal directly. Thanks again for any help. I know theres something obvious that I seem to be missing here. This isn't really difficult but I seem to be making it so.......... :-)

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3 Answers
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trip-tracks answered ·

Sounds like you have shunt around the wrong way.
When there is a load (and no charging), the current should read negative; when charging, it should read positive.

Make sure you have the battery negative terminals (and ONLY the battery negative terminals) connected to the "battery" side of the shunt.
All other connections should be connected to the "load" side of the shunt - loads, chargers, inverters and any chassis negative connection.


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seahawk answered ·

Thanksfor that. I appreciate That.

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seahawk answered ·

I have a further question. In my setup, I presently have a large 1-ought cable at the battery negative going to ships ground. Also on the neg terminal of the battery I have a cable connected to the other house battery putting the two of them in parallel. Theres also a third negative, smaller gauge wire which I believe goes to the battery charger. So to wire the BMV712 correctly .....I'll disconnect all the existing negative cables from the battery. I'll connect the 1-0 cable that goes to ships ground to the "LOAD CHARGER' side of the shunt. I'll connect another 1-0 jumper....one end from the "BATTERY' side of the shunt and the other end to the neg battery terminal. Is this correct so far. If it is then this is where I get confused. Now, where do I connect that third negative cable that I think connects to the charger. And,....from this point forward, where would I connect any negative cables for other equipment. I know it cant go to the "BATTERY" side of the shunt,.....so would it go to the other end of the shunt,???....or to the battery negative terminal directly. Thanks again for any help. I know theres something obvious that I seem to be missing here. This isn't really difficult but I seem to be making it so.......... :-)


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