Is it safe to power a raspberry pi from battery's?

Tristan,

it's perfectly possible. The easiest is to use a USB power pack, look for instance at my Raspberry Pi Slow Scan Television (SSTV) Camera .

You will see the power pack below the raspberry pi on the first photo.

best,

Gerrit.

In 2013 I thoroughly tested the first rPi 256MB with four NiMH AA rechargeables.  Finding was that "5V" input won't boot at 5.1V, which is inside USB specification, but after running down the batteries a bit it would boot if 4.9 to 5.0 Volts was supplied.

Suggestion is to buy a buck dc-dc converter, wind its screw until it supplies 4.98 Volts to your test resistor, and then solder to the power rails near to the micro-usb power connector on your rPi.  A pwm buck will accept anything from 6x AA or 2x Li or 6V Pb battery and by regulating that down to 4.98V it won't care when the battery has gone down, and nor will it break your pi when recharging.

Dear D2113F,

Many, many PIs have been running just fine on 5.10V or 5.25V. So even though your experiment shows that in your case your PI had a problem with "5.1V", that is not the case in general. Officially the pi will take up to 5.5V, in practice I've tested it down to 2.8V (for the pi2), and it kept on working, but I am not willing to "sacrifice" a pi to see where it will break if I increase the voltage. I don't expect this to happen at less than 6V, but I could be wrong.

When I was testing the lowest-possible-voltage, it became clear that part of the required voltage is to have a little margin to allow for voltage dips. If the CPU is idle and then gets an interrupt and suddenly starts to process again, the current consumption can rise so quickly that the powersupply (what/whereever it is) cannot provide the additional current quickly enough. A buffer (capacitor) close to the pi will help getting enough power to the pi on short notice. So, maybe the effect you were seeing was related to "dynamic effects".

Gerrit's suggestion to use a powerbank holds up: those provide the right voltage at enough current to allow a pi to function perfectly without odd stuff like having to "drain the batteries first before you start using them". The come with an included boost converter to provide a stable 5V (usually a little more).

The Pi power supply has changed since then as I recall. Maybe time to retry on newer models.

Clem

Yes!! however you havent specified which batteries you intend to use. Remember that a USB power pack is merely a battery at it's heart.

As several have alluded to  you can run directly off the batteries and now the RPI2 has a switch mode regulator it's less fussy than before but still all 5V powered sections of the RPI would be at risk of damage at excessive voltages say much more than5.25/5.5V or just not working at low voltages.

You will in practice require 5Volts from some where  in the case of batteries this could be 6V(4 AA bateries for example) or more into a decent switchmode regulator.

We would need to know your intentions for the device including what batteries you intend using to make more specific suggestions.

Personally I would use a USB battery pack as they are cheap and powerful as well as been simple to use

Yes Clem it's totally changed sind "the old days" of the RPI 1

Hello, I'm currently working on an Instructable and element14 article about making a Raspberry Pi PowerHAT. It will let you power your Raspberry Pi with batteries, safely. I'll share the links here, once I complete them.

First of all, by using the 5V GPIO pin you are bypassing the input fuse that is on the RPi. This means you have no protection in case of a short circuit, or reverse voltage. If you do make an error, a lot of current (depending on how much you power supply can provide) can flow through your Pi and can damage it. You are also bypassing a high-efficiency diode circuit, so you are basically without any protection. I've included a schematic of the power management circuit for a Raspberry Pi Model B+, below.

Despite all these cons, it's still possible to power the Pi through the pins, with a simple circuit. First off, a regulated 5V power source has to be inputted to the 5V and ground GPIO pins. Most power adapters won't output a regulated voltage (unless stated otherwise on them) so you would also need to use some voltage regulator circuit. Lastly, there are a few capacitors used to smooth the voltage, which makes power more stable.

To power the Pi, you will need to have a regulation circuit, or use a regulated power supply. Then, just add a schottky diode on the input, and maybe a resettable fuse. I hope this helps, and I'll try to provide a schematic of said described circuit.

Absolutely! I Like using these on my Pi's. :-)

https://www.piborg.org/battborg

Dylan, I am also working to a project to power the Pi with a battery. And your suggestion is very good. I was just planning to adopt a solution like this. In your scheme the power is connected to the USB connector, but IMHO with this kind of power control it is the case to use the direct GPIO power connection leaving the USB connector free for the wall mount power supply as an alternative to the battery support.

Enrico

Consider power as water, current as speed of flowing water and battery as a container...

What we really need to power anything is amount of the water(voltage) and throttle of the water(current)...

If the water container(battery) is not providing enough amount of water(voltage), add more containers(batteries) in series...

If the container(battery) is not providing enough throttle of water(current), add more containers(batteries) in parallel...

So, yes we can power anything with this logic