voltage question

[Beta-guy]

I have a USB changer that gives 2 Amps at 5.3 volts, I know too much amps won't damage the the device as the device will use only what it needs, but my question is can the Raspberry pi handle 5.3 volts? I'm trying to get USB chager that give 2 amps, and 5 volts, but this is the best one I got, other wise I'm stuck with 5 volts 1 amp...

[jbeale]

I can't comment on the RasPi specifically, but it seems a bit naughty to produce such a device, given that the USB spec is 5.25 V maximum.  I assume your device was built just for battery charging, and/or they count on a certain amount of drop through the cable.

5V 1A should be more than enough for the RasPi by itself, it has a 700 mA maximum rating. Any power-hungry USB devices like hard drives, should connect through a separately powered USB hub.

[max1zzz]

I see no reason it should cause a problem, the psu i'm going to use for my Pi puts out 5.5v (label states 5v)and although i haven't tried a Pi on it yet (as i don't have one yet) it is charging my iPhone just fine

[Gert van Loo]

Juts curious: is it specified on the supply as 5.3V or have you measured it? If the latter: you can safely use it. Idle supplies are 95% of the time above their nominal voltage. If specified you should be carefull as a lot of supplies are +/-10% so 5.3+10%=5.83V which is rather high.

[rurwin]

The maximum specified voltage is 5.25V. If the charger really puts out 5.3V then the difference is miniscule, but be aware that you  would be testimg the top end of the permitted range and you willl find any problems with the RaspPi or any of the USB devices you attach to it.

[Beta-guy]

Gert said:


Juts curious: is it specified on the supply as 5.3V or have you measured it? If the latter: you can safely use it. Idle supplies are 95% of the time above their nominal voltage. If specified you should be carefull as a lot of supplies are +/-10% so 5.3+10%=5.83V which is rather high.


I just read it on the power adapter (It's a HP Touchpad Power adapter if that helps)

just used a cheap multimeter and it read 5.17 ~ 5.20V I feel safe now thanks for your help.

[GrahamC]

Many USB cables use 24 AWG wires for the two power conductors (0.0842 ohms/metre) so you are going to lose around 0.17 to 0.2 volts of drop on a 2 metre lead. So a little bit of over voltage is probably quite a good thing anyway.

[bredman]

Initial reports from real users say that the RPi will tolerate an overvoltage for a short time. Excess voltage is burnt off by the linear regulator.

However, this causes excess current through the polyfuse which may trip within 30 seconds.

The main 5v line is also shared with the USB peripherals. They may not be so tolerant of an overvoltage.

So in summary, a slight overvoltage will not damage the RPi but it may shut down without notice. You risk damaging your USB peripherals.