Crazy Battery Charging Threshold behavior - Help

[yvonnejim]

I am trying to set low and high threshold charging levels on my new X120e.

If I set the low end at 40% and the upper level at 80%, for example, and the current charge happens to be at 51% at the time, the battery charge
somehow manages to stay at 51% indefinitely. The charging icon says it is not charging, and the battery icon indeed says that "Charging will start
when below 40% and stop at 80%.

Any combination of numbers results in the same behavior. The existing charge that is on the battery currently, will remain there … FOREVER!! So
the charger has to be charging the battery just enough to maintain the level it happens to be at.

Been thru this with Lenovo, they says something wrong inside. I was able to return to vendor for brand new one. The new one behaves exactly the same.

Any ideas? I think everyone is missing something, including me.

Again, if I let my battery drain down to 60%, for example, and set low charging level to 20% and high level to 90%, the battery charge will remain at 60%.
If I use the computer for a week, and check the battery level every minute, it will always read 60%.

Thanks, Jim

[mariol90]

This sounds normal to me. so if you have it set to charge when below 40% and stop at 80%, if you discharge the battery to 39% and plug it in, it will charge to 80%. if you discharge to 40% and plug in, it won't charge since it's not below 40% like you set it to.

[yvonnejim]

Like I said before, if the charge happens to be at 51% for example, it DOES NOT charge to 80%. It stays at 51%. It does not discharge, it does not charge ( at least according to the computer ) , but
obviously it must be charging intermittently to maintain a 51% charge. Why doesn't it charge back up to 80%, or conversely, why isn't the battery allowed to discharge down to 40%, and then charge back up to 80%

That is the issue.

[dr_st]

Sounds like you just don't understand how this feature is supposed to work.

You set the battery to start charging when its <40% and to stop charging when it's at 80%, right?

Therefore if the current charge is anywhere between 40% and 80%, and it's connected to AC, it will stay there. The battery won't charge and won't discharge, the computer will use AC power.

Once you use the battery and it goes down below 40%, it will start charging the next time you connect to AC. And it will stop at 80%.

I don't see any issue here.

[yvonnejim]

That simply is not true. I don't make statements lightly. I do my research. The Full Charge Capacity of my battery is 58.55 Wh. When I don't use the Custom charge threshold, the battery discharges at a rate of about 0.01 Wh per hour - maybe closer to 1% every 2 1/2 days. This is just a shelf-life issue, as all batteries discharge ever so slightly over time. I set up a video camera that allowed me to record the Remaining Capacity over a 24 hour period, and record the current level at the same time.

When the threshold option is used, I could see the current level go from 0.00 to a couple amps for a few minutes, basically trickle charging the battery to keep it exactly at it's current Wh level. It only happens every few hours, but the only way to capture it was to replay the video ( at fast speed, of course )

So the battery does discharge without the Threshold option, but stays exactly the same with the Threshold option.

That is what I was getting at.

Jim

[dr_st]

That's an interesting observation and it shows that one of the statements I made is apparently not true, but it still does not mean that the general battery behavior you observe is anything but normal.

[yvonnejim]

Still not sure what you mean. The laptop is not supposed to start charging until the battery discharges to 40%, but it keeps charging it every few hours to maintain
the current setting ( in this case, 51% ) It should take about 3 to 4 weeks to discharge this amount.

[yvonnejim]

The general battery behavior was never an issue. I never thought the battery was behaving in an unusual manner. It was purely the behavior of the Threshold option.
The battery just does what it's told to do, either the laptop is charging it or it is not.

[dr_st]

Okay, I think I _finally_ understand what you mean...

Yes, come to think of it, it is a bit different from what I'm used to. Usually my thresholds are 94% and 98% and even though I do find the battery at 97% most of the time, eventually it does seem to drop below 94% and charge back to 98%. Like you said, it can take a really long time.

Not sure why one would care though. If the goal is to reduce battery charging cycles, then you get just as much by charging a little bit every once in a while to maintain a fix level, as you do by letting it run down below the low threshold and then charging all the way to the high threshold in a single session.