I bought one of the $30 AiLi battery monitors off of Amazon and am hooking it up in my RV. I have 200w of Renogy Solar with a 20a charge controller and a 700w inverter all hooked to a 100ah LiPO4 battery. The P- side of the shunt is hooked to my negative cable from the inverter and my negative to the solar controller. The B- is hooked up to the battery negative terminal. I have the monitor shunt hooked up so it can read amps in from the solar and out of the inverter (I did not wire my inverter into the RV system). My question pertains to how the monitor figures out the AH remaining measurement. Does it just mathematically calculate from the measured amps out and subtract from your full battery setting value or does it actually know the AH remaining through a measurement. I am asking because I would like to know if this set up will actually tell me AH remaining if it is not hooked up to my RV system beyond being connected to the battery. When I ran the interior lights and the slide it didn't seem to change the AMP reading on the monitor so I am now assuming my AH measurement may not be worth anything and I just wasted my time setting this up. Should I also add the negative cable from the RV and instead of going to the battery go to the P- side of the shunt? Not sure I can fit another terminal on the shunt but I could try.