Bugzilla – Bug 14161
Battery icon display scheme -- % full, battery empty
Last modified: 2019-01-25 10:38:53 UTC
Bug 13761 has a discussion about providing some warning before a battery-only Baby turns itself off. This bug talks about correlating battery voltage levels to user-visible battery charge icons. Currently the % battery charged icon has weak correlation to the battery charge itself. The following numbers were derived using firmware r7664, a PVT2 Baby, and battery voltage readings from the Power screen of the Diagnostics menu: - Battery voltage after 9-10 hours charging: 13735 (or 13.735 volts) - Battery voltage when Baby refuses to stay on with volume = 100: 11456 - Battery voltage when Baby refuses to stay on with volume = 0: 10950 With battery voltage of 11537, I was able to keep Baby on with volume = 10 or 20 for about 15 minutes (possibly less, since that's when I noticed Baby was off). After that, I could not keep Baby on at all with voltage = 10950. (Would turn itself off while I was reading battery screen). With battery voltage of 11537, I didn't find out how long Baby would have continued playing if volume = 75 or 50. However, it would not be greater than 15 minutes. My proposal is to display these states: - 100%, 75%, 50%, 25%, 0% charge - Blink or red icon - Please charge me screen Given the empirical values on this one unit, I propose the above states to correspond to these battery voltages. I divided the range between 11683 and 13735 into 5 equal chunks (I couldn't see a reason for non-equal chunks): - 100%: Greater than 13324 - 75%: Between 12914 and 13224 - 50%: Between 12504 and 12914 - 25%: Between 12094 and 12504 - 0%: Between 11683 and 12094 - Blink/red battery icon: Between 11450 and 11683 - Please charge me screen: Below 11450 My data showed that it will take 18 minutes to go from voltage 11557 to 11456, or 7 minutes from 1537 to 11456 with volume = 100. Blinking at 11683 will give the user possibly 22 minutes at volume = 100.
We do need to improve the batter states, but voltage actually is *almost* meaningless to determine state of charge. 10V really is dead, but other than that, it's hard to tell. That's why we do the coloumetry. But.... It's not well calibrated yet.
We'll need to release Baby with some way that the user can look at an icon on the screen and determine battery charge %. Right now, 25% and 50% seem somewhat random. Any suggestions if battery voltage is not the right thing to use? Let's discuss this at tomorrow's meeting. We need to have a plan ASAP to provide something useful for the user.
The current scheme works okay, once you have gone through a full change/discharge cycle (and don't run into the other charge-related problems you've seen before).
cc'ing Ross for possible battery experimentation.
Pat, Mickey, Matt, Caleb to have a meeting to discuss this issue.
I had by PVT2 battery-only unit with firmware r7679 go into low battery state overnight. Not sure how I turned it off this time. This is what happened: - Hold down Power button for 20 seconds to get unit to turn ON - 3 items only on main menu. Wireless icon was red. Scrolling sluggish - Battery icon on screen displayed 50% - On Diagnostic screen, battery voltage was 11.012V - Before I could read other values, Please Charge Me screen appeared - Unit turned itself OFF after approximately 1 minute - Unit turned ON after momentary press of Power button after waiting a few minutes - When ON, wireless icon is white, battery icon is 25%, main menu has all listings - Please Charge Me screen appears while I'm typing this (10 seconds) - Screen goes blank after about 1 minute
Mickey, As of yesterday's firmware, if you're in power off state, Off-means-off. Your battery was DEAD. you are not supposed to hold the button down for 20 seconds. If it doesn't power up, plug in AC. What you are describing is *correct* behavior. 11 V is *dead*. By pressing and holding for 20 seconds, you're resetting the micro-controller and depleting the battery, which is a bad thing for battery life. For now on, the 20-second trick is only to be used if it fails to power on when AC is installed, in which case a bug should be reported. I agree that there should be a better warning of impending low battery, but that's not going to be a 7.4 fix.
*** Bug 14071 has been marked as a duplicate of this bug. ***
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