| sicelo | for the purposes of linux kernel POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN for our bq27200, i'm wondering if we shouldn't report EDV1, or even EVDF? which of these do you think would be more suitable? | 16:18 |
|---|---|---|
| sicelo | currently none is reported, https://github.com/torvalds/linux/blob/master/drivers/power/supply/bq27xxx_battery.c#L2059-L2060 . i don't think it's particularly important, but I'm working on a patch (for handling CI=1 state a bit better), and wondered if working on MIN_DESIGN would also be useful. | 16:22 |
| sicelo | ah, mmm, actually i guess doing it (if i manage) is a good idea, judging by https://github.com/torvalds/linux/blob/master/drivers/power/supply/bq27xxx_battery.c#L2054-L2057 | 16:25 |
| sicelo | only i'm not sure between EDV1 and EDVF ... i fear EDVF might be too late for userspace programs that need to take action (e.g. upower), but EDV1 might be too soon for calibration purposes | 16:26 |
| sicelo | anyway, maybe i'll leave this for later. for those interested, the CI=1 patch is https://paste.debian.net/1238380/ . this opens up the possibility to *always* have a capacity value in sysfs, while making it clear that it could be inaccurate. | 16:38 |
| sicelo | in combination with https://gist.github.com/sicelo/0a0e895d81a6b73b26555d215dee296d , you can actually *always* have a better estimated capacity value than having to start from 2056mAh each time. That WRTNAC register/bit is a hidden gem on the bq27200 :-) | 16:39 |
| joerg | sicelo: what is the exact purpose or definition of POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN ? for the BQ27k CI stuff, it's EDV1 for 1 minute or 16s or somesuch | 23:07 |
| sicelo | i'd say it's just extra info. it's not particularly important for bq27. kernel docs say: "VOLTAGE_MAX_DESIGN, VOLTAGE_MIN_DESIGN - design values for maximal and | 23:09 |
| sicelo | minimal power supply voltages. Maximal/minimal means values of voltages | 23:09 |
| sicelo | when battery considered "full"/"empty" at normal conditions' | 23:09 |
| joerg | line44 >># bq27200 sense resistor is needed for calculations. On N900 it is 20 megOhms<< noooooo, it's MILLIohm :-D | 23:11 |
| sicelo | ah :-P | 23:13 |
| joerg | that definition clearly says it should be EDVF | 23:13 |
| bencoh | :) | 23:14 |
| sicelo | that's a very small resistance! i actually saw datasheeting talking about milli, but i recall some discussions on irc where it was mentioned as meg | 23:15 |
| bencoh | nah, ~10mili is common for a sense resistance | 23:15 |
| bencoh | you don't want to just burn energy in it (Ri²) | 23:16 |
| joerg | I seen a YT video yesterday where they tested a "railgun" (gaus gun, magnetic accel) with a nice handy battery they unplugged and held it to the camera >>this is the battery, it has a 3.3KILO Ampere hours<< https://youtu.be/izW1X2555Wg | 23:33 |
| joerg | ;-P | 23:33 |
| joerg | oops, this one https://youtu.be/eAHKS0nVlL4 | 23:37 |
| Vajb | 3.3KAh, well, that would be one hefty battery... I wonder what is capacity of Tesla batterypack | 23:41 |
| joerg | https://i.imgur.com/ELbPWxQ.png https://youtu.be/eAHKS0nVlL4?t=144 | 23:42 |
| joerg | only 3 magnitudes off, milli to mega is 9 magnitudes | 23:44 |
| sicelo | joerg: i seem to think someone (you?) had capacity vs. voltage curve for N900/bl-5j on the wiki, but I couldn't find it on searching | 23:50 |
| sicelo | with my bq27200 WRTNAC find, I want to fetch design capacity from rx51_battery if we have CI=1, but this represents 100%, so I want to take a sensible portion of it (based on voltage) to decide the NAC value to write to bq27200 | 23:52 |
| sicelo | i know it won't be accurate, but still nicer than being too far off with 2050mAh for example, or some other random value | 23:54 |
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