Smartsolar 150/70 underreading battery voltage

Jis Okes. Hope all is well.

I recently ran into a problem and would like to know if someone else maybe a similar issue.

Since Oct 22 I started getting random “Etower high voltage” errors on my Victron console. i started monitoring and checking the batteries and it seemed battery #2, cell #13 had an increased voltage (up to 0.5V more than the rest) and was causing the error. I logged the fault with FreedomWon and after a remote diagnosis session we realized that the Multiplus DC bus and etower’s voltage sits at about 56.2 Volts while the Smartsolar reads 55.8, where it’s set to charge.

What could be the cause of this underreading of Voltage by the MPPT? I’ve checked all connections and cables and all seems fine. The system has been working fine since December 2021 and now this started all of a sudden. I’ve restarted the MPPT, GX device and inverters with no change. All Firmwares have been updated to the latest last week but this problem started before that.
I’ve adjusted the DVCC to 55.3Volts to compensate and keep the battery voltage around 55.8V but I want to get this sorted asap.

Any advice?

Could be a difference in calibration. 0.4V is on the high end, but not unheard of. If the battery is 0.2V high and the MPPT 0.2V low, both within acceptable limits, something like may well happen.

I would start with a good multimeter to check which one is off the furthest. I’ve seen the Multi being off by a little, and I’ve seen CAN-BMS batteries off by A LOT, but rarely have I seen an MPPT being off by that much.

Although, in an ESS system the MPPTs are synced with the Multi, so if the Multi is calibrated low the MPPTs will follow.

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Okay. It seems to have been an easy fix. Not sure what exactly the cause was but here’s what I did…
I’ve got 2 48/3000/50 Multiplus’s set up in parrallel. The voltage sense wires was connected to the master inverter and has been like that for almost 2 years. Last night I sat down and firstly checked voltages on all components with a borrowed Fluke meter to confirm the voltages and then configured both inverters to standalone mode first and ran each of them, isolated offcourse, for around 5 mins. I then re-configured them to Parrallel mode but swapped the master and slave configuration, re-installed the settings file and switched the system on. This means that the voltage sense is connected to the slave unit now (still connected to the same inverter but now only setup as slave). Seeing that we had our share of darkness at 20:00 last night I set ESS to optimized (without batterylife), set the SOC limit to 20% and let it be. It was quite hot last night so I had my bedroom aircon (12000btu fixed speed) on 24deg and the kids had fans running in 3 more bedrooms. When I woke up this morning at 6 the SOC was on 49% and all voltages within 0.1V difference. Seeing that it was cloudy early morning the batteries reached 100% SOC by about 10:43 and after checking the biggest cell voltage difference on the eTowers reached 0.08V and the biggest voltage difference between readings on the eTower, Smartshunt, Multiplus and MPPT was 0.11V. Battery voltage is stable at 55.8V (±0.05V at 100%SOC) and all cells seem to be balanced within 0.03V range.

What started this problem boggles my mind seeing that it suddenly started on the 22nd of October if I look at the stats and logs and worsened from there untill I received a bunch of errors everytime the batteries came close to 100% SOC.

I guess these things happens and if I ignored the warnings I would’ve screwed at least one of the R28k eTowers.

I must acknowledge that FreedomWon again stood up to their reputation and was logged in to my diagnose my batteries within a few hours from reporting the problem to them and that Zwile Mbaso were absolute proffessional during the whole process. Yet again so happy with my choice of batteries and offcourse the blue stuff.

So long story short guys, assumption is the greatest f@ck up. I assumed the battery was at fault while it was a complete different gremlin that creeped in from nowhere. Diagnosis is key and with all the stats on hand with VRM I could have realized this earlier…

Have a nice one…I’m sure I’ll become stalker again after my system is now running like clockwork again :rofl:

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Thanks @plonkster,

“Although, in an ESS system the MPPTs are synced with the Multi, so if the Multi is calibrated low the MPPTs will follow.”

This made me think about the voltage sense on the MP that might be corrupt. It helped a lot. Many thanks!!

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