Battery-powered Pi?

mgt6910 over 13 years ago

I would like to use my Pi on a robotic platform, for which an onboard power supply will be

necessary. I have a rechargeable 6-volt battery. How can I regulate this down to 5V ?

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morgaine over 13 years ago

Over on http://www.raspberrymod.com/viewtopic.php?f=60&t=640&sid=b006909c691d78e07788ff03dbf8526c I wrote a little piece about Lithium-Polymer batteries and the rising trend to integrate Li-Po chargers on microcontroller boards.

This doesn't help at all with Malcolm's question of course, but I'd like to ask a supplementary question in case someone here knows the answer. Is there a 2-cell Li-Po charger module (2 x 3.7V = 7.4V) available from anywhere, suitable for integration into 5V-powered equipment?
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fustini over 13 years ago in reply to morgaine

Interesting idea of putting them in series. I had been wondering how the Duracell Li-ion battery-powered USB chargers I have work. I suppose it could either have cells in series and then regulate down to 5V or have a boost converter which brings a single cell up to 5V. I wonder which method, in general, is more efficient.
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fustini over 13 years ago in reply to morgaine

Interesting idea of putting them in series. I had been wondering how the Duracell Li-ion battery-powered USB chargers I have work. I suppose it could either have cells in series and then regulate down to 5V or have a boost converter which brings a single cell up to 5V. I wonder which method, in general, is more efficient.
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morgaine over 13 years ago in reply to fustini

Alternatively we could ply Pete with crates of beer until he submits and makes future Pi board operable standalone from 3.7V.
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fustini over 13 years ago in reply to morgaine

Sounds good I can't remember exactly what post but I recall from RPi forum either Pete or Gert saying that the Pi not designed with battery operation in mind at all (understandably given their goal). The impression I had is the way it handles power is not super efficient, but it doesn't matter as much when plugged into wall and not trying to squeeze out battery life.

But yeah, I just started using 3.3V 8MHz Arduino Pro from SparkFun and I'm digging it for LiPo operation. The main embedded project I have in mind for the Pi would unfortunately be battery powered, so I'll be interested in figuring out an efficient solution once Pi's are available in quantities.
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Former Member over 13 years ago in reply to fustini

By the way there are significant differences between switching power supply modules, if you care about efficiency. I tested two small ones shown below (much smaller than what you need to power a R-Pi). They aren't directly comparable but I found the efficiency of the Pololu one to be higher at *every* output current than the Sparkfun design. And the output noise was also lower. (and the Pololu one was actually cheaper!)
https://picasaweb.google.com/lh/photo/PzArmv5OEmDtBuyC2cBFQ9MTjNZETYmyPJy0liipFm0?feat=directlink
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