That logic is sound, and I agree a conservative estimate is safer. You are saying more than 30% SoC loss per month this way. But I think, based on my observations on my bike, the pack is not losing charge that fast. I think the BMS continuous draw is closer to 0.15W rather than to 5W. If that lower figure is close to correct, it would result in about 1% loss of charge per month on an 11kW pack. While I don't know what the exact loss % per month is, on my bike it seems to be closer to 1% per month than to 30% - there is barely any change in SoC reported on the app over several months unplugged...
I've been checking my bike every few weeks and the reported SoC has not budged one bit. If anything it rises a few percent in the hours/days after the bike is shut-off after last use, and then stays constant for the next few weeks. I'll report here again the next time I check my SoC - last night it was 53%, 4-5mV imbalance.
Is anyone seeing faster decline in SoC when unplugged?
I went to go fix that section and realized I shuffled some notes into the wrong section and fixed that.
I did make a back-of-the-napkin calculation, though: if the BMS continuously drew 5W, a 2016 11.4kWh nominal battery would draw down 100% SoC to 0% in about three months.
So, 10% per week is a reasonable figure if conservative; kind of a worst case way to know when to go check on the bike just in case.