Hi Fairphoners.
My FP1 does not charge any more. I measured the voltage of the battery and it was 3.55v while the charging contacts had a voltage of 3,58v. That seems rather low to me.
It seems to me that these contacts should be something over 5v.
I looked at cables, charger etc. and they seem to be OK.
Ik measured the voltage outcome of another phone charger and it was 8,3v or something. So it takes well far over 3,7v (nominal voltage of the lithium battery) to charge the battery
What to do?
I am out of options.
Bob Horjus
Is the USB port stable? I mean is it still firmly attached in its original place or is it loose?
A USB phone chargers nominal voltage is 5V. This is the USB charging standard.
The battery outputs between 3,5 and 4V, I’d say. Voltage decreases when the charging percentage gets lower. My battery with 19% has about 3,6V output at the moment:
Please refer to the forum’s #batteryguide for further information.
The USB port looks stable to me…
Could it explain why the contacts have only 3.55v?
I would think if the USB does not make contact I would measure zero volt,
Thank you. Is the info from an app? Nice! I shall try it once my fairphone is working again.
This info is from the extended battery tile feature of Gravity Box. There are other apps that can display the current battery voltage.
Have you checked out the #batteryguide ? I think that your battery is simply undercharged and you should try a battery reset (which is explained in the guide).
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Thank you for the advise. I did not know a battery reset existed, but i (not on purpuse) already did this.
Not having a good result. Anyway I’ll try it again but now with an intention added to it. Who knows…
I will look into that batteryguide link when I have my phone working. That gravity box looks interesting.
Follow up:
Battery full, 4090mV
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Too bad, nothing happened.
Does anyone know whether ther is an alternative way to charge the battery?
You could try an external charger. There are some examples mentioned in this topic:
Hi everyone,
I managed to charge the battery. Thanks to diy video’s on Youtube. The battery now measures 4,02volts. Too bad it does not make the FP work. I can press the power button as much and as long as i want, but nothing happens. About a half year ago i remember i had the same problem and FP gave me another motherboard. I remember they sait that there was a problem with the power switch. I hope this is not the same problem. Has anyone an advise?
Power button problems are common with older FP1s. Please use the forum search (click on the little magnifying glass above) to find many topics about fixing power button issues. 
Can you tell me how I can be sure that it really is a power button issue?
No, unfortunately not… 
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You can measure it.
You will need a Multimeter to measure the resistance of the button.
The resistance is around 60kOhm when its not pushed.
When pushing the button the resistance should be close to zero ohms.
Greetings
Patrick
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