Not long ago we found that the Victron Smart Shunts have a software glitch. When power is disconnected and reconnected, the Consumed Ah figure can randomly change. It can go higher or lower, by up to a few percent. This means the figure is useless to our testing, but it also has implications for other situations.
Victron may or may not acknowledge this, I have alerted them to it and it’ll be great if they find the bug and release a software update to fix it. But for now we have quickly put a solution in place.
We purchased a bunch of cheap and simple Low Voltage Disconnect PCB’s and installed them to our test rigs. With the right settings these now stop the DC-DC discharge of the battery on test, before it triggers the BMS to disconnect. Due to this the Smart Shunt no longer shuts down and that means its figure is accurate… Done!
This accurate figure is what we’re after. Because it’s from a popular and respected commercially available shunt, it should be easily replicated in customer situations.
So we’re back on track until the next test rig upgrade, which will hopefully not need to be soon. We’ve made huge improvements recently and it’s boosting the quality of measurements. But making too many changes also has traceability implications so we’re keen to keep this going as is for a while again.
