battery bar + battery profiles + battery calibration

[DJ2LS]

This work in progress (WIP) PR adds some more battery monitoring, a battery bar, a small ability of calibrate battery discharge voltage and hopefully a more accurate battery discharge profile .

I opened this PR already, as it needs some more time of testing and I want to avoid things getting broken. Also git commits are not 100% clear, @defidude , as explained on Discord. Contribution and feedback are very welcome, as I'm not an electronical engineer, for sure there are some battery gurus and calibration wizards out there :-)

new battery settings:

• Battery Display: Switch between Percent and Bar
• Discharge Curve: Switch between LiPo and Linear
• Charge Above: Voltage threshold, when indicating we are charging the device
• Full Battery: Voltage threshold, when we start draining the battery after charging
• Voltage: Tap to get current battery voltage for calibrating "Full Battery"
• Charge: Actual charge level.

Lipo discharge curve:

I tried to simulate discharging better, used this one as reference:
https://www.researchgate.net/figure/Li-ion-battery-discharge-voltage-curve_fig5_363575973

At least I tried to manually interpret it, interpolated values between:

static const VoltPct LIPO_CURVE[] = {
    {4.20f, 100}, // manual chart reading
    {4.00f,  95},
    {3.80f,  90}, // manual chart reading
    {3.78f,  85},
    {3.75f,  80}, // manual chart reading
    {3.74f,  75},
    {3.73f,  70},
    {3.71f,  65},
    {3.70f,  60}, // manual chart reading
    {3.69f,  55},
    {3.68f,  50},
    {3.66f,  45},
    {3.65f,  40}, // manual chart reading
    {3.64f,  35},
    {3.63f,  30},
    {3.61f,  25},
    {3.60f,  20}, // manual chart reading
    {3.55f,  15},
    {3.50f,  10}, // manual chart reading
    {3.25f,   5}, // manual chart reading
    {3.00f,   0}, // manual chart reading
};

Those values need to be tested in real world. That's the real "work in progress" part. Challenge is to find the best tradeoff regarding the voltage plateau.

battery calibration instructions:

• plug in charging cable
• charge until you think its full, at least several hours
• keep charging cable plugged in
• go to battery settings, tap on Voltage for getting current charging voltage
• set "Charge Above" to a save value, e.g. 4.1V if we have a Voltage of e.g. 4.2V
• unplug charge cable
• tap on Voltage again, value should be now at 3.8V or so
• set Full Battery to the Voltage level

how to help:

Calibrate battery, discharge until device dies and inspect battery levels so we can see if we found a good interpretation of discharge curve.

[DJ2LS]

okay, the actual discharge table isn't working reliable. Time for using a battery logger and see how power levels really drop.

[DJ2LS]

While charging, battery level drops down to 4.05V, so "Charge Above = 4.00" might make sense

[DJ2LS]

So, this is a plot of a real discharge process. I will adjust the discharge table according to given data

[DJ2LS]

percentage suggestion:

{
    {3.90f, 100}, {3.80f, 90}, {3.72f, 80}, {3.65f, 70},
    {3.59f, 60},  {3.53f, 50}, {3.48f, 40}, {3.44f, 30},
    {3.40f, 20},  {3.36f, 15}, {3.30f, 10}, {3.15f, 5},
    {3.00f, 0},
};

Lets see if we can get this working

[DJ2LS]

Okay, it seems we're closer to our goal now. Battery bar becomes green when charging, yellow at 20% remaining, red at 10% ... only Charge level has a small offset related bug, lets fix it...

[DJ2LS]

Latest tests looking good to me. Battery curve seems to be more realistic now. Looking forward to some testers results

[DJ2LS]

@defidude , I merged latest changes into this PR, everything seems to be working so far. So from my side, you can review and merge it if you want.