A20 on battery?

[jess]

Did anyone here use A20 on LiPo battery power supply and could confirm that it worked without ANY problems?

[PaceyIV]

Yes, my friend have used this configuration with Rev D boad.
Yesterday I try to charge the battery and the orange led was on.
This night I'll try to power the board with only the battery.

[shamada]

Yes, Rev.D board with 7"LCD booted fine from a 6600mAh battery.

And the android is still running in sleep mode for almost a week now.

Similar discussion is going on here: https://www.olimex.com/forum/index.php?topic=1687.0

[jess]

Thanks you shamada and PaceyIV - I figure these are just preliminary results and I'm glad you replied.

The reason I keep asking the same question over and over again is that there's some discrepancy in how the AXP209 handles LiPo during charging and discharging. From what I observed so far the undercharged LiPo (around 60% left) will not power Android board at all. It just blinks the screen and dies immediately. Sometime it runs and then shuts it off without any warning. When LiPo is fully charged it seems to run alright. Then again, it dies around 60% battery capacity. I used both 3000mAh and 8000mAh batteries taken from my other tablets that use the same Power Management circuit built around AXP209 chip.

I appreciate if you keep posting your observations. 

[shamada]

I only tested with battery charge level above 90%. But i will keep a look at what happens, when the charge level drops.

[PaceyIV]

How can you see charge level?

Messages like this in dmesg are normal?

Code Select Expand


[  113.182020] [AXP]Correct5:fix 99:charger->rest_vol = 100


[shamada]

I'm running android at the moment. And I guess/hope the gui display of the charge level is working.

[PaceyIV]

You also have an indication of the temperature of the processor or the board?

[shamada]

No, haven't tried to find that yet.

[mauricio]

Hello

using A20 with Debian image, sourced by a 9v ac adaptor, I'm trying to use a battery connected to jst as a UPS, principally while closing some processes and shutdown in an eventually failure of the main power

I can't figure out how to know when the board is sourced through barrel or not, is there a way to know about ?, even I don't know if A20 can switch from source to source (barrel - battery), I'm concerned about SD card integrity

started this thread https://www.olimex.com/forum/index.php?topic=2928.0

thanks in advance

[fab]

Hi Jess,

You are fully right! Using a 6600mH LIPO I got from Olimex store, My Debian R7 switch off without any reasons as soon as the battery charge goes below 40% (measured by reading /sys/class/power_supply/battery/capacity).
So for the moment, the LIPO is useless for A20 for those who want to use it standalone!

Fab

[dave-at-axon]

You are fully right! Using a 6600mH LIPO I got from Olimex store, My Debian R7 switch off without any reasons as soon as the battery charge goes below 40% (measured by reading /sys/class/power_supply/battery/capacity).
So for the moment, the LIPO is useless for A20 for those who want to use it standalone!

Hi Fab, this must be a setting in Debian that is shutting down the system as I am running Android with the A20 and a 6600mA battery and it got down to under 3% before it did a switch off.

Also check the fex file as there is a pwroff_vol setting and mine is set for 3300mV

[fab]

Thx Dave,

My pmu_pwroff_vol was also set to 3300 mv.
However there was another value pmu_battery_cap which was set to 2400 mA instead of 6600mA. I just tuned it to match my LIPO, and wait wether it is going better or not.


Fab

[fab]

I played with different values regarding pmu_para from the fex file, but got no improvement.
The A20 board is actually switching off at random time. I double checked the LIPO, and it is fully charged (around 3900 mVolts read from the voltmeter).
Something weird too, is the capacity read from /sys/class/power_supply/battery/capacity is completely different when I unplug and replug the LIPO jst connector. Again seems to be random!
The capacity read seems to be totally unrelated to the real LIPO capacity.

Any other ideas are welcome

Fab

Thx Dave,

My pmu_pwroff_vol was also set to 3300 mv.
However there was another value pmu_battery_cap which was set to 2400 mA instead of 6600mA. I just tuned it to match my LIPO, and wait wether it is going better or not.


Fab

[dave-at-axon]

Hi FAB

Do you have a debug cable you can connect to UART0?

On my Android system I get a message when the system is about to shutdown. Maybe you can track it down that way?