So I found a bug. Hank is probably pretty unhappy with me for not finding it sooner, but it’s pretty easy to miss. It requires a few independent moving parts to activate:
- It seems that adding LVP in sleep mode made it do temperature measurements too, and thermal events. Like, in sleep mode. That’s not a problem by itself though; should be harmless.
- It also seems that, after 15 minutes, if the cell is partially drained, temperature measurements while asleep are suddenly waaaay off. But again, that shouldn’t be a problem by itself, since the “off” and “lockout” and “momentary” modes all ignore thermal events.
- However, muggle mode wasn’t ignoring thermal events while it was off.
So muggle mode has some really weird and not-good behavior. After being off for 15 minutes, on a cell which isn’t full, it gets spurious overheat warnings and tries to step down… but stepping down from 0 causes it to wrap around and turn on again, and then it goes back to sleep, then gets another warning, then goes back to sleep, etc. This makes it blink while off, but only in muggle mode, and only after being off for more than 15 minutes.
I sent Hank an update which fixes this, but it’s something to be aware of for the D4v2 lights which have already been shipped. With these early units, I wouldn’t recommend relying on muggle mode.
No other lights are affected.
If anyone has a pogo pin adapter for firmware updates, a fixed version is available.