Smart Shunt - state of charge

[DavidSmith]

I have installed a smart shunt on the negative terminal of four connected lithium 100ah batteries for a total of 400ah. The shunt read full charge at the start and has been draining down to now show 0% with -495ah. I did charge the batteries with a lithium battery charger to full again but the shunt doesn’t register this. Is this a manual setting?

[MikeD (Mike)]

No, most likely the current from the battery charger did not go through the shunt. SOC resets on voltage.

[pwfarnell]

If the SOC is not increasing when you charge it indicates you have not wired the shunt correctly and the charger negative is connected to the battery negative, not the shunt system negative. See the FAQ I wrote, there is also another about synchronisation settings thst you should read. Pinned topic at the top of the DIY section.

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This topic covers the reported SOC being out of sync with the actual battery voltage or state. It covers 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 and is often linked to mobile applications with small solar systems. The SOC jum…

[DavidSmith]

Thank you for the informative reply. This helps a lot as I need to move the negative of the battery charger from the battery to the shunt. My wiring was incorrect and that why it wasn’t working, I understand now. Thanks.