Jam2 2019: Another charging issue?

[pegnose]

My battery was on 2 bars when I plugged it in for charging. I use a wall socket adapter with a timer, as I charge in my rather remote basement compartment. I charged the bike for just 1h as I didn't know when I would use it again. When I revisited the bike ~1 week later, the battery was completely empty, the bike wouldn't even start. I don't really know what happened, only that the wall socket adapter apparently worked as intended. It was off, i.e.

Anyone with a similar experience? This is my "new" 4.0 A replacement charger.

 

[Eckythump]

Suspect the charger has drained the bike battery after the timer cut the AC supply to it.
Hopefully the BMS cut in and saved your battery from exceeding the battery low voltage threshold.
Have you managed to charge it back up OK since?

 

[pegnose]

I hope so too. How this can happen is a miracle to me. The charger should protect against back drain.

I managed to power up the bike after a couple of minutes of charging. Then I dialed in another 4h into the wall plug. I'll see in ~30 minutes what is what.

 

[Eckythump]

I really would not use a timer for this purpose. Removing the power from the charger while it is still plugged into a battery is a bad idea. Any protection circuitry is disabled with the supply removed.
You would be far better off leaving the power on, it is less hazardous.
I’m far from a safety nazi however it is probably a good place for a reminder about not charging lithium batteries unattended......

 

[pegnose]

So the battery still charges, it seems. The range indicator initially was rather low, but seemed to recover during the ride. I'll probably do a full charging cycle in the new future.

Thanks for the wise words, @Eckythump !

 

[pegnose]

Addendum: Focus replied that they did not test my particular charging scenario. The timed wall plug might actually only disconnect one phase of the wall power and therefore the battery getting sucked dry might even depend on the relative orientation of the plug.

In addition, I suspect, it might as well depend on whether power got interrupted during charging or after the charging cycle completed. It might leave the charger in different states.

Together these points might explain why I have noticed this issues for the first time now after having used my charging solution for a while.

 

[aarfeldt]

I'm using a Hue Smart Plug that sits just before the charger.
Then I can use cheap power to charge the bike.
It turns on at 02 at the night and shuts down at 05....3 hours of charge is enough in my situation.
It works very well.