battery only reaches 87%


zedr0k

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Hello everyone,
with my pyra the battery is usually only charged to 87/88%. I've already tried a different battery.
Is this normal behavior? Or is it a bug that can be fixed (software / hardware)?
thanks in advance
 

elvissteinjr

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I've had my Pyra at 100% before, though I intentionally avoid getting to that point. Unless something changed in the past few months it should be possible to get there at least.
 

Magic Sam

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Hi all,

Same here, I can barely reach 80%.

And the battery widget currently tells me that I have 4 hours and 35 minutes left, with battery charged at 78%.

Cheers, Magic Sam
 

hns

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That seems unlikely. Surely the modem chip is connected to the 3V3 rail, not directly to the battery.
Modem modules are usually directly connected to the battery because 2G may draw too much energy during transmission pulses. Otherwise one would need a 3.3V regulator that can handle 2-3A pulses and still have no significant energy loss.
In the Pyra there is a 3-way switch in the charger chip. It negotiates energy flow between battery, usb power, and system (modem, omap5, display etc.).
The modem is connected to the system voltage rail which is just a little lower than battery voltage during discharge. This is important to keep the system running at low battery level.
During charge the system voltage can be up to 100mV above battery voltage (so that energy flows into the battery).
Now, for LiIon batteries charging has to stop at 4.2V.
But the Modem sends an overvoltage message at 4.25V and turns itself off.
Since it gets a 100mV higher voltage than the battery, the modem will turn off when the battery is full (or can't be turned on).
To avoid this we have to stop charging at 4.1V which is ca. 80% fuel level. And the fuel gauge chip and kernel drivers are not aware of this and report 4.1V as 80%.
So yes: the battery is not full (with some reserve for the modem not to turn off during charging). But it is as full as it can be.
Why was it designed as it is? Well, we were not aware of this 4.25V turn off point and the 100mV addition when we designed this and it was too late for a hardware modification (which would have been fundamental).
 

matzesu

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How do you want to take care that the Update dosnt harm the allready used Pyra Modems? Allthough i dont use my Modem (as its too complicaded: First i have to put my Iphone Panzer Case from the Iphone, then use something to poke in the hole to eject the SIM, and then put this in the Pyra, i think using my Iphone as Mobile Hotspot also works good enough...).. i have still the old modem..
 

levi

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will this change if the new universal modem is used ?
What makes you think it might?
Post automatically merged:

How do you want to take care that the Update dosnt harm the allready used Pyra Modems?
What update? A software update is the most obvious meaning of that word to me, and I don't see how that would affect the modem adversely outside of a regression occurring. There's also the plan to replace the modem with a new universal modem in a hardware update, but that's a different modem which won't have been using outside of an integration test when assembling the unit.
 

elvissteinjr

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To avoid this we have to stop charging at 4.1V which is ca. 80% fuel level. And the fuel gauge chip and kernel drivers are not aware of this and report 4.1V as 80%.
I assume this doesn't apply to the standard model? I just charged mine to 100%/4.2V to see if it was just my memory being wrong.
Just hope I won't charge mine to 120% in the future then.
 
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matzesu

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I meant the "Sudo apt upgrade" update, : If i remember correctly, this might also update the Power Controll Software..
But im not a professional Pyra User, i just know how to Play Tetris on it..
 

PowerGod

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I meant the "Sudo apt upgrade" update, : If i remember correctly, this might also update the Power Controll Software..
As far as I understand, even if something not patched is installed, the Modem will not be damaged, it just shuts down itself if there is overvoltage, so in the worst case it will just not work, at least until the system is patched again.
 

Letalis Sonus

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On the bright side: This charging behavior greatly increases the overall battery lifetime, as charging to 100% every time is very stressful for Li-Ion batteries. It is actually very common with electric cars to only charge up to 80% to avoid unnecessary battery wear (physically, the UI will still report 100% charge).
 
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