Has anyone successfully used Victron SmartShunts to measure individual cell voltages? We’ve got a 12V VRLA Gel lead-acid battery, made up of 6 individual cells.
Each SmartShunt has two voltage inputs: Vbatt+ and Aux. In theory, with 4 SmartShunts we could monitor everything we need.
The manual states that both the Vbatt+ (which powers the shunt) and the Aux input have a voltage range of 6.5 to 70VDC. But I’m not clear whether the Aux input actually requires a minimum of 6.5V — my testing suggests it reads down to 0V just fine.
Our idea is to connect 4 SmartShunts via a USB hub to the Cerbo GX, then use Node-RED to calculate and display the individual cell voltages.
Just wondering if anyone here has already done something similar — or found a better method?
(Apologies, but I originally posted a similar question in the Modifications section, before I considered the possibility of using standard Victron gear.)
I used 4x Shelly Uni to measure 4x 12V batteries in a 48V system and built a dashboard with Node-Red. I would disable the inverter if one battery went to 11V. The BMS used to disconnect on a single battery in 4S configuration and caused all sorts of problems. The shelly UNI can measure 0-30V and was very accurate.
@Trevor. The batteries are a few years old, and we’re trying to assess how much usable life they have left. Monitoring individual cell voltages during discharge provides an indication of battery health.
Some of these batteries are/were rated at 2000Ah, so we’re prepared to invest some effort to avoid premature replacement.
Our newer batteries are lithium.
I have a similar situation but have 8 lithium batteries I need to monitor for marine compliance purposes. I was thinking of putting a smartshunt on each battery and connecting to the Cerbo GX via bluetooth. Would this work?
`Hi Trevor - Thanks for the reply. Looks like a very tidy system but appears to only work with their batteries. I have different batteries that are amazing (8 x 1.93kw each at 48v and 22,000 cycles). The note is correct that in NZ the rules are to be able to monitor each battery at the operating station.
They are Lithium-Titanate by Zenaji. No possibility of thermal run-away so cannot catch fire. 3C - can go down to 0%. They are amazing. I currently have 8 and will put in another 8 to make 32kw which is plenty of stored power for my boat.
Just a quick follow-up in case anyone is searching for this later:
I heard back from our Victron dealer that the Aux terminal of the SmartShunt 300 will in fact measure down to 0 V, and the specification will be updated to reflect this.
Once we receive some additional SmartShunts, we may set them up as follows:
Shunt
Aux Shunt terminal
Vbatt+ Shunt terminal
1
Cell 1 negative terminal
Cell 5 negative terminal
2
Cell 2 negative terminal
Cell 6 negative terminal
3
Cell 3 negative terminal
Cell 6 negative terminal
4
Cell 4 negative terminal
Cell 6 positive terminal
(This configuration ensures that Vbatt+ remains above 6.5 V, which is required to power the SmartShunt.)
In the meantime, I built a DIY solution using a couple of Texas Instruments INA3221 ADCs connected to an ESP32-S2. The ESP32-S2 runs MicroPython and publishes the voltage measurements to the Cerbo GX via MQTT.
The INA3221 is readily available as a development board (e.g. from Adafruit or AliExpress), so there’s no need for SMD soldering. (The ADCs built into the ESP32-S2 are not very accurate, and I suggest that you use external ADCs)