CSD Tool assumes there are no batteries with capacity higher than original

@simo so if I buy a Polarcell battery and continue my habit of charging to 85% I should be allright?

By this chart comparison, it seems Jolla might report the charging level exactly as same between 7% - 85%, and accurate enough even between 3% - 97%. Should be all right yes, but I just can't be 100% sure before data from Jolla.

@simo As a logical question: if the Jolla charges the battery with its built in parameters and comes to an "official" end at 100% with slow flashing led, shouldn't that be a guarantee that it's NOT overcharging? If the battery itself would stop the charging by using its safety circuit, Jolla should show less than 100% and shouldn't stop? So, if I see the led flashing in the morning, I can be sure not to overcharge the battery, can't I? (I'm using the polarcell continuously since the first post here and always do an overnight charge.)

@Robomike Your longer term testing is promising for the safety, great job there, but without more information about the official battery I really can't answer to you... Jolla's 100% is set to a point where Jolla official battery reaches 2100mAh, so it's not a quarantee for any other batteries (until proven 100% compatible, which I'm somehow trying to reach...) By the way, you can get some more battery information during different stages of charging via terminal, using command upower --monitor-detail in your testing. And thanks for joining us here :)

@simo Thanks for your answer. But, from a technical viewpoint, for the device it's impossible to know how much energy is stored, unless the battery wasn't completely empty once - which is very dangerous for Li-Ion-batteries and should be avoided in any case. Theoretically you may replace batteries with different charge state anytime, and the device shouldn't kill itself by overcharging. The only parameters the device can see are current, voltage and temperature. The end-of-charge voltage is fixed and has nothing to do with the nominal (imprinted) voltage. The device _may_ use the coded curve (the img above) to make a guess about the charging state, and if it's well programmed, it may learn something about the battery's condition by comparing the voltage/current-position with some saved values. But it will never know the exact charge. (Btw: the curve plot in your initial answer uses an odd ordinate identifier. It should be "voltage", not "current". We should try to minimize confusion :) )

The "capacity" of 102.21% (>100) is most probably the reason that makes the test fails. But indeed only because the app thinks (in a hard-coded way) that 100% <=> Official Jolla battery capacity. By the way, isn't the CSD tool available a FOSS? Isn't it capable of running on community port on different devices? Someone should have noticed this bug already I think :X (as this tool would be great to see if you drivers work while you port the system to a new target)

@Elioty It reaches a capacity of 102.21% cause it calculates with the hardcoded value "Design maximum" instead of the one provided by the battery itself "Maximum".

According to https://wiki.merproject.org/wiki/SailfishOSS it's not.

//EDIT: Also it's not the capacity value failing. When "Value" falls below "Design Capacity" (caused by discharging the battery) the test passes while "Capacity" still shows 102.21%.

//EDIT2: @simo Still it shouldn't fail for non technical reasons. "Value" > "Design maximum" isn't technical. We need an answer from a sailor here.

//EDIT3: Even if for some weird reason the statement from EDIT2 would be technical the test should fail if the reported "Maximum" > "Design maximum" but that's not the case. So no matter how you look at it; there's a bug. ;)

Capacity is (and should be) calculated from the Design maximum value, which is set into the system by Jolla, no settings offered to change it (hence a feature: Jolla is a phone for 7.98Wh batteries (3.8V*2.100Ah) by design)

There is a workaround to manually change this value using dbus command, writing a new DesignFull value by what's expected from the battery, but before using such workaround I'd wait for information if the battery is safe to use in the first place.

But it's not about "Capacity" but "Value" (see also latest screenshot).

So either this is a bug or you just found the real root and this is just a symphtom. Bug no matter how you look at it... ;)

You didn't get it. Battery is seen as overcharged if the Value (current charge) > Design maximum (max accepted charge). Test SHOULD fail in this case.