Lenovo Custom Charge Threshold

I've been round and round with this topic, and just never resolved it yet. I get same behavior on X120e and X220.

I set boundaries at 30% and 80% for example. If the battery happens to be charged to 75% when I'm out and about and plug in the AC charger, the battery will stay charged at 75% indefinitely. Same if it was at 70%.

Also, I get the same behavior whether the upper and lower limits are changed to anything that surrounds the 75% for example. Like lower limit 20% and upper limit 90% - battery stays at 75%.

Hope you are following me so far.

My understanding has always been that the AC would stop charging the battery until it ran down to the lower limit. Then start charging until it got to the upper limit. That's the whole purpose of this feature - to allow
the battery to cycle up and down for longer life.

Actually in the above scenarios, the AC charger is trickle charging the battery to maintain it at whatever level it was at when I plugged in the AC charger. I pulled up the screen that shows the Current and Voltage that is
currently going to the battery. It almost always reads "0". I recorded a video of the Current settting over about an hour, and lo and behold, I saw the Current jump from "0" to a positive amp reading for second or two.
This was the only way to catch it.

Anyway, I wish I could figure this out.

Another scenario. If the AC is plugged in, and I activate the Threshold charging, it will charge up to the upper limit and stay there. Like if set at 30 and 80%, it will charge up to 80%. Again, the Current reads "0" most
of the time, but then for a second or two goes positive to maintain the 80%. It will stay there for a month...a year. If I change it to 85%, same thing. The lower limit affects nothing.