Can I put 6 volts on the 5 volt input?

[equivalents]

I was looking for a datasheet that listed the tolorence of the 5v rail on the RaspPi.
Basically what I want to do is power the pi from 4 D batteries I have. They are rated at 1.5 volts, so If I use 4 that is 6 volts. So I'm wondering if I can put 6 volts on the 5 volt input, I've used only 3 batteries and ran it at 4.5 volts but there where some problems.

[joan]

When I bothered to measure the voltage between TP1 and 2 on the Pi I got readings of approximately 5.8 volts (supply via micro USB cable).

There is no evidence this harmed the Pi, although I suppose some components lifetimes may have been shortened.

People seem to be more concerned that the voltage might harm components connected to the USB. Hasn't done my wireless dongle any harm.

Can you measure the voltage between TP1 and 2?

[rpdom]

I was looking for a datasheet that listed the tolorence of the 5v rail on the RaspPi.
Basically what I want to do is power the pi from 4 D batteries I have. They are rated at 1.5 volts, so If I use 4 that is 6 volts. So I'm wondering if I can put 6 volts on the 5 volt input, I've used only 3 batteries and ran it at 4.5 volts but there where some problems.

The official recommended voltage range is 4.75V to 5.25V. Outside this range could damage your Pi, will invalidate the warrantee and may damage anything plugged into the USB ports.

[WillCK]

Don't risk it. At the very least get a +5V linear voltage regulator and wire from the battery pack to the voltage regulator ..then out to the micro USB of the Pi. They are $2 at radio shack....you will lose some battery life as the VR will dissipate the extra energy by heating up...but it's much better to spend $2 for a VR than to damage a USB device that costs much more by overvolting your Pi.

[poing]

If you use NiMH rechargeables their voltage depleted is 1.2V and charged 1.4V. This makes the voltage run from 4x1.4=5.2 to 4x1.2=4.8 which is within spec.

[feverish]

Could I ask you experts where this affects the raspi-config setting for overclocking which indicates that 7-v seems unlikely to damage the raspi, but can speed things up considerably? Is it therefore likely to damage usb stuff but not the raspi itself?

[rpdom]

Could I ask you experts where this affects the raspi-config setting for overclocking which indicates that 7-v seems unlikely to damage the raspi, but can speed things up considerably? Is it therefore likely to damage usb stuff but not the raspi itself?

The "overvolt" setting for overclocking has nothing to do with the 5V supply line. What it does is adjust the internal chip voltage by small fractions of a volt from the default 1.2V. An overvolt setting of 2 will change that to 1.25V. The maximum +8 will make the innards of the main chip run at 1.4V. The main supply still needs to be between 4.75V and 5.25V.

[joan]

Could I ask you experts where this affects the raspi-config setting for overclocking which indicates that 7-v seems unlikely to damage the raspi, but can speed things up considerably? Is it therefore likely to damage usb stuff but not the raspi itself?

I'd like to know how it would harm the Pi. It would be nice to know which part of the Pi is going to blow up first if the voltage rises above 5.25V (especially because mine don't) and at what voltage this will happen.

[gordon77]

Could I ask you experts where this affects the raspi-config setting for overclocking which indicates that 7-v seems unlikely to damage the raspi, but can speed things up considerably? Is it therefore likely to damage usb stuff but not the raspi itself?

I'd like to know how it would harm the Pi. It would be nice to know which part of the Pi is going to blow up first if the voltage rises above 5.25V (especially because mine don't) and at what voltage this will happen.

Looking at the schematics it appears most if not all the chips run on 3v3 from a regulator, rated with a max input of 20v, The 5v only seems to go the USB ? I maybe wrong so don't risk it !!

NOTE l am wrong and 5v goes to the BCM chip !!!

Gordon

[ShiftPlusOne]

Isn't there a TVS diode (D17) to clamp the output to 5V? I think the breakdown voltage of it is about 9v, but I have never used them, so I am not sure how they work. I know they work well for transients, just not sure how they would cope with a constant DC component.

[FTrevorGowen]

...
I'd like to know how it would harm the Pi. It would be nice to know which part of the Pi is going to blow up first if the voltage rises above 5.25V (especially because mine don't) and at what voltage this will happen.

Hi Joan,
Without looking at the Pi's schematics in detail (IIRC they may be found in the wiki) I can only comment on what I can see on the board. The earliest components in the power chain are the filter capacitor and 3.3V regulator adjacent to the micro-usb power input socket. Having looked at the specs. for t.i.'s version of the "17-33G" 3.3V LDO, whilst that does have thermal overload protection and may be "fed" from voltages higher than 5.25V, there is minimal heatsinking and were the Pi + attached USB/GPIO devices to draw the full 1000mA of recommended PSU's it would be having to dissipate nearly 2W at 5.25V. Also it has been suggested in other posts elsewhere on the forum that the Pi has (what I would call) a "crowbar" device to protect against "overvoltage spikes". At what voltage threshold that may act I don't know. However, if I understand matters correctly, the 5.25V "limit" is also specified to ensure that other connected devices/i.c.'s (USB/GPIO) are not subject to "fatal stresses". I'm sure other forum members could elaborate further. W.r.t. the capacitor I haven't checked its specs but my Pibow model A case carries a "magic blue smoke" warning around it .
Trev.

[joan]

That chimes with my reading of the schematics. All the internal voltages (3V3, 2V8, 1V5) seem to be supplied via regulators rated at up to 20V inputs.

From the point of view of testing a nominally 5V PSU I'd disconnect the peripherals and then feed in the voltage checking TP1/TP2.

[mramos]

Why not use the 6volt pack with a low cost power silicon diode to drop a little over 1/2 a volt? That will get you close. But the 5VDC regulator is the safest bet. Or the 1.2V re-charge type cells.