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+--- Thread: Power supply vs battery (/showthread.php?tid=16874)
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Power supply vs battery - albafrati - 06-20-2022
Hello
I'm I new owner of a Pinephone. After a few tests I decided to install Mobian Phosh.
To save battery life during the first tests I connected the phone to a power supply (0-30V, 0-5A).
I used a resistence to simulate the battery thermistor.
My power supply is regulated to 4.1V as measured from original battery.
The phone behaviour is very strange to me. Sometimes seem booting but is stuck with black screen, green led in the upper left corner lit and a current drain of 0,4A.
Sometimes it boots and seem to work correctly but if SIM is installed the phone turns off after a few minutes.
Anybody had related experiences or can give me any advice to make it work reliably as with battery?
Thanks and regards
RE: Power supply vs battery - Zebulon Walton - 06-21-2022
I don't know what's causing those problem, but even if you got the phone to boot running off a power supply you would not be able to do much with it because the modem and wifi are connected directly to the battery and will not work without it.
The battery won't run down if the phone is connected to a suitable USB power supply while the phone is on. Charge level will just fluctuate a few percent due to the components that draw power directly from the battery.
RE: Power supply vs battery - albafrati - 06-21-2022
I don't like using battery because even with charger always connected battery life is affected.
When the phone starts without SIM inserted the behaviour is almost correct. Wifi woks, modem accepts AT commands and the voltage reading done with AT+CBC is correct. The power supply is connected to battery contacts so the phone should make no difference if the voltage comes from a battery or not. Before it turns off with SIM inserted phone can sometimes receive and make calls.
Thanks
RE: Power supply vs battery - fxc - 06-21-2022
(06-21-2022, 06:38 AM)albafrati Wrote: I don't like using battery because even with charger always connected battery life is affected.
When the phone starts without SIM inserted the behaviour is almost correct. Wifi woks, modem accepts AT commands and the voltage reading done with AT+CBC is correct. The power supply is connected to battery contacts so the phone should make no difference if the voltage comes from a battery or not. Before it turns off with SIM inserted phone can sometimes receive and make calls.
Thanks
WiFi and Modem are wired directly to the battery due to technical reasons if I remember correctly.
RE: Power supply vs battery - albafrati - 06-21-2022
I don't understand what you mean by that. Connected directly or not every piece of hardware is powered by the battery, if I substitute it with a power supply the phone should work.
On my phone battery has contacts that touches when is installed, removing it and connecting a power supply to those contacts powers the phone.
The modem is visible... removing the cover... and at this moment powered by the power supply. Now I connected also an oscilloscope to measure possible voltage fluctuations but at the moment SIM is installed, everything's working (wifi, ssh, mobile network, etc.) and I'm waiting for the phone to turn off suddenly.
RE: Power supply vs battery - Zebulon Walton - 06-21-2022
I didn't realize you were connecting directly to the phone's battery contacts, thought you were using the USB connection which would not have powered everything up without the battery.
RE: Power supply vs battery - wibble - 06-21-2022
What's the current limit on your supply set to? The reason the wifi and modem have direct connections is because they sometimes draw high current when transmitting. I don't know how much but it's probably in the datasheets (see the wiki). If current peaks trip the current limit and cause the voltage to drop odd things will happen.
RE: Power supply vs battery - albafrati - 06-21-2022
After hours of trial and error I choose 2.3A of max current though I've never seen it raising over 1.3A.
At the moment slightly increasing voltage to 4.2V I reached decent stability.
The only thing I still cannot solve is that powering on the phone it stucks booting, as I described in the first post, 2, 3 or 4 times before starting correctly.
RE: Power supply vs battery - wibble - 06-22-2022
The bootloader should show something via the serial console on the headphone port that may help narrow down what's going wrong. Can't help with the details as I've never had reason to try it.
RE: Power supply vs battery - albafrati - 06-22-2022
I should have a broken headphone... as soon as I find it I'll cut the cable, give it a try. and let you know.
Thank you