I don't know how the battery percentage and the runtime estimate are coupled code wise. If it is not a simple conversion, where the calculations for percentages and runtimes (which are percentages of the max runtime) are based on the same algorithm, then it would make sense to me to keep the more accurate algorithm and convert the other display value from that.
With most battery level displays (e.g. in mobile phones etc.) the percentage drops faster when the battery is lower. To get from 100% to 50% takes much more time than from 50% to 0%. I can learn how much time I have left with 40% battery, sure. But this doesn't tell me anything I can rely on about my battery at 20% charge (and I don't want to keep a discharge curve in my head, rockbox can do that better for me) If the current runtime calculation is better than a simple linear voltage conversion, then I think we should keep it and use it for the percentage display, too. On my iRiver, the estimate is quite good, I suppose it can work equally good on portalplayer targets when the current power issues are fixed. I can learn how much time I have left with 40% battery, sure. But this doesn't tell me anything I can rely on about my battery at 20% charge. -- Simon (Rincewind)