Hi, I have a discrepancy on the state of charge for by house battery. I have an auxillary lithium battery set-up in my 4wd vehicle. This is charged through a victron DC to DC charger. But when I check the my SmartBMV states the charge is 42%, whereas the blue connection directly to the battery states 97%. Recently charged my battery using a Victron charger, since it was low due to not using the vehicle. Any idea why there is such a difference. [Screenshot_20251031_110311_Original] [Screenshot_20251031_110325_ABC-BMS_Original]

In most cases the reason is wrong installation or wrong settings of the shunt. [image] Shunt / battery monitor not reading the correct SOC/ Amps, missing solar, decreasing daily or other misreading problems DIY This topic covers the SOC / Amps reported by BMV battery monitors, SmartShunts, Lynx BMSs and Lynx Shunts and will just be called shunt below. It is also assumed that the shunt is monitoring the domestic / house / cabin battery bank and not engine start / bow thruster / winch / caravan mover battery banks. The problems may be one or more of the following The SOC decreases daily despite the solar charger or other charger(s) working. The SOC increasing when discharging and falling when charging…

Welcome to the forum! From my experience it could be due to difference of sensitivity to low currents: many battery BMS ignore small discharges (or charges). Victron BMV or Smart Shunt units are way more precise in such situations, so their SOC percentage reading is closer to real. So, in case of long “sleep”, the battery could think there is no discharge at all, but Victron BMV will register system’s small self consumption, lowering SOC accordingly. If possible, place light load (say 0.2-0.5 A) on the system and take a look at both readings - one from battery by bluetooth, second from Victron BMV - You could be surprised.

Battery charge indication

Q&A and troubleshooting

M_Lange (Matthias Lange - DE) 31 October 2025 04:06 2

In most cases the reason is wrong installation or wrong settings of the shunt.

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Battery charge indication

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