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Battery calibration - Sansa c200

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tomkiewicz:
Hi, i just bought refurbished Sansa c250 - it works well, but... when i use rockbox, it turns off when battery is about 20-30% (after that, when i try to turn it on, player only displays empty battery icon). On the other hand, player won't be fully charged - I had charging c200 under rockbox whole night, after that I started original firmware - when rockbox says, the battery was 100%, OF says it was about 70% (and after connecting cable it charges to 100%).

Is there any way to calibrate battery? I guess, that rockbox have lowered voltage range - both max and min :/. When I had mobile phone Siemens SL45i, it was quite easy - I had to fully discharge battery, then save lower limit, after that I had to raise upper limit, fully charge (phone went off, when battery protection notices overcharge) and save limit a bit lower.

saratoga:

--- Quote from: tomkiewicz on April 06, 2008, 07:03:39 AM ---Hi, i just bought refurbished Sansa c250 - it works well, but... when i use rockbox, it turns off when battery is about 20-30% (after that, when i try to turn it on, player only displays empty battery icon). On the other hand, player won't be fully charged - I had charging c200 under rockbox whole night, after that I started original firmware - when rockbox says, the battery was 100%, OF says it was about 70% (and after connecting cable it charges to 100%).

--- End quote ---

I don't think the c200 charges under rockbox, so you should use the OF.


--- Quote from: tomkiewicz on April 06, 2008, 07:03:39 AM ---Is there any way to calibrate battery? I guess, that rockbox have lowered voltage range - both max and min :/. When I had mobile phone Siemens SL45i, it was quite easy - I had to fully discharge battery, then save lower limit, after that I had to raise upper limit, fully charge (phone went off, when battery protection notices overcharge) and save limit a bit lower.

--- End quote ---

Yes, you need to provide a discharge curve for the battery.  See http://www.rockbox.org/tracker/task/8480 for an example of one taken from the e200.  Currently its also used for the c200, which is why the battery percentages are off.  

I have a standing offer to fix the c200 one as soon as someone gives me the discharge curve, but looking at the battery bench wiki page it seems someone uploaded on without telling me, so i'll try and commit that later today.

(fine i'll edit)

Edit:  I take that back, the one posted on the wiki is obviously wrong, so I still need a new one.

tomkiewicz:
OK, I'll make some battery benchmarks (including OF playtime check) - it may take me about two-three days, then I'll put these on wiki and PM you

Febs:
I'll do one as well so that we have multiple data points to work from.

saratoga:
I don't really need the OF part, but its certainly interesting enough to put on the wiki if you do measure it.

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