Hey there! New to the group. I just finished installing a Multiplus ii and having an issue where, when on shore power and running the AC my battery shunt/meter (not a victron brand) is showing about 1-2A of draw and a very slow drain on the batteries while the Mp2 stays in float mode. Interestingly, the VictronConnect app shows a decent amount of current actually going TO the batteries even though the meter is showing a drain. As soon as I turn off the AC (still on shore power) the battery meter switches to a + sign and about 10A of charge to the battery (probaby only 10A cuz the battery is almost fully charged). There is nothing grounded to the B- side of the shunt. Everything is on the P- side as recommended. I don’t think The AC or the shorepower are the issue. The rooftop AC unit is new and very small/efficient, and the shorepower is on a 15A house circuit with a solid 120v coming in. Plenty of juice to run a rooftop AC and not much else. I feel like it’s gotta be something in the victroncnnect settings or quite possibly a faulty meter. Also, I have calibrated the meter to 100% when the victron goes into float mode. Battery capacity is 640Ah, which I have entered into the meter as well. Any advice is appreciated. Chris

A key observation is also that when the AC is off, both VictronConnect and the wall meter show the same thing…+10A charge to the batteries. It’s only when the AC is running that there is a large discrepancy between the two readings. Again, all while on shore power.

One possibility is you have wired the Multiplus negative direct to the battery negative terminal, it should go to the shunt system terminal. If the Multiplus negative is connected directly to the battery then that current bypasses the shunt. See the FAQ. [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…

thank you for the reply. All items including the multi plus are on the correct side of the shunt. The only thing coming off of the B minus side of the shunt is the wire going to the negative battery terminal. it’s possible that there is a threshold setting that is allowing the battery to drain slightly in this situation since it’s almost fully charged. It’s just trickling down a bit and showing a minimal drain (but only when the AC is on). Battery is close to fully charged. So there might just be a threshold that keeps the charging circuit from toggling back-and-forth on that last 99%.

EDIT: I think it might just be a fluke with this meter. In VictronConnect, it is showing the battery SOC at100% and a 23A charge going to battery. On the actual meter it is showing 99% and a a 9A drain. But the readout in VictronConnect seems to be holding steady at 13.5V and 100% SOC. So according to the readouts in VictronConnect, things are working fine. I just have to ignore the meter when the AC is running. Or upgrade to a better meter?

Steige auf ein besseres System um wenn da was nicht kalibriert ist oder werden kann. Irgendwann fällt Dir das auf die Füße Zeige mal Fotos der Installation.

I’ll get some photos together soon. Right now I’m just trying to figure out if the Battery readings in VictronConnect would be the most trustworthy, which shows 13.5V and 100% SOC after two hours of running the AC. If this is accurate, then there is no issue with the system itself, outside of the (non victron) meter. Just trying to understand why the meter is showing a decreasing battery voltage (now down to 95% and 12.99V). The voltage at the battery terminals (with a multi-meter) is a steady 13.5V. Same as what is showing in the VictronConnect app.

Battery meter shows drain in float mode

DIY

pwfarnell 19 September 2026 14:47 3

One possibility is you have wired the Multiplus negative direct to the battery negative terminal, it should go to the shunt system terminal. If the Multiplus negative is connected directly to the battery then that current bypasses the shunt. See the FAQ.

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Battery meter shows drain in float mode

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