Rockbox General > Rockbox General Discussion
Iaudio X5l/M5L battery life estimates.
GSV3MiaC:
I'm enjoying my Rockbox'd Cowon/iAudio M5L, but the battery life estimation is way off. I mean WAY WAY off .. factor of 2-3 pessimistic. The software won't let me opt for any battery larger than 2250mAHr (which is what I actually have), so I can't fake it out that way - is there any other user adjustment(s) to tell it that it needs to multiply by a bigger number? Or does it calibrate itself over time and get better?
I guess I could put a battery_bench.txt file in for analysis, but the current error is rather more gross than 'fine tuning' IMO. Also I tend to actually use it rather than leave it playing one album in a loop. fwiw I'm playing .ogg at Q=1, into Sennheiser PX100s, no effects, no equalizers, volume = -30 (why '-' ??).
nls:
The reason it is off is that no one has calibrated it (yet), simple as that, this is tru for most rockbox targets currently. (All except archoses and iriver h100)
It does not calibrate itself over time.
Why negative volume?
Because the volume in rockbox is a reference to the recording volume, 0dB means it should be at the same level as it was recorded/mastered, a negative volume is lower and a positive (where possible) is louder. We had an arbitary scale of 0-100 (iirc) long ago but since it doesn't really mean anything and a volume of say 50 would not be the same on different models it was dropped for the dB scale
GSV3MiaC:
Ok, Guess I better turn in a battery_bench log after all then, even if it means deliberately leaving the M5l to sit and run down. So far I observe (from a limited run):-
a) The battery starts at 4.2v. Rockbox seems to be hardwired to believe the max is 4.1v, so we stay at 100% for the first 3-4 hours until it gets down to 4.1v.
b) from there the voltage and %age track down together (as you'd expect), however the hours left (gradient) is off by somewhere between 2x and 3x. 8 hours in, my battery life estimate has dropped from 15+ to 13+, although, as I said, it didn't move at all for the first 3 hours.
Looks to me as if I should eventually get 25-30 hours, which is pretty good .. original firmware quotes 35, which is normally a bit optimistic.
Thanks for the explanation of volume. Makes sense, but it is sort of counter-intuitive to have smaller numbers equate to larger volume (the '-' is easy to overlook in some fonts). I can't imagine getting into positive number territory without massive distortion and aural destruction.
nls:
Then it seems like the voltagepercent conversion isn't entirely correct either...
IIRC amiconn (who made the m5 port) got something like 50 hours in a mp3 runtime test on an m5l.
pixelma:
--- Quote from: nls on May 15, 2007, 01:31:15 PM ---IIRC amiconn (who made the m5 port) got something like 50 hours in a mp3 runtime test on an m5l.
--- End quote ---
Yes, but that was a battery_bench test with backlight turned off... plus it was a brand new device and as usual for a bench: no browsing etc. He also did a "backlight always on" test under the same - otherwise perfect - conditions which lasted for 36h 14 min.
Anyways - the battery level percentage was calibrated using these test results and it seems to be quite good on mine (well that's the one used for calibrating ;D). If your result is way off and maybe others' as well I think that gathering a few benches in the wiki, like it's been done for other targets, could possibly help to find an average that suits better. It would be best to agree on a certain bitrate and codec and/or other average settings so that the results are comparable - the "standard" that was used is 192kbps mp3s which worked out well for calibrating battery percentage on other targets in the past.
The runtime estimates on the other hand weren't calibrated at all which would have meant additional work in the powermanagement code - a part that needs a severe cleanup as some developers (including amiconn) say. At least I believe that was the reason given (not a 100% sure though).
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