Portable Pi Power Problems

hi

if your in the us you might want to try this

http://www.amazon.com/MURATA-POWER-SOLUTIONS-SWITCHING-REGULATOR/dp/B005T571NK/ref=sr_1_1?ie=UTF8&qid=1375980373&sr=8-1&keywords=78SRH-5%2F2-C+muRata

but if your in the uk this should work but you might want to check first

http://uk.rs-online.com/web/p/linear-voltage-regulators/0463650/

hope that helped

You can indeed use a linear or switching regulator to do this, linear regulators are more wasteful so a switching is preferred, look up Rohm BP5275-50.

Another option is using a single cell, or multiple parallel cells so you boost to 5V, then you can use something like this

https://www.sparkfun.com/products/11231

Which has the buck/charging circuit for a Lipo and then the boost to 5V all on one board.

The first problem I am running into is the Li-Po pack I've found that I think should work is 7.4v which is a bit much for the pi so the first requirement for the power supply is that it steps the voltage down to 5v at least.

I would also like to beable to use everything while its charging, that way I can hook it up to a display and use it as a compute as well, if it can charge while active and plugged in thats great.

i dont know about that but the first one is the one ben used

If you are using the same screen as Ben, we've successfully tied off the 5V line inside of the LCD to power the Pi, and that's how we'll do it on the improved version of the portable.  Just bring the 7.4V into the 12V input on the screen, then tack a wire out of the 5V output and take it to the Pi.

The downside to this setup is that the regulator cuts out about 6.4ish volts, so you are losing capacity there.  With the new Pi with the boost convertor, we should be able to use the batteries down to a lower level definitely increasing the run time.

it would probably be easier to just buy a cellphone backup battery because celphones run on 5v and it will already be set up to charge correctly.

There is a capacitor on the screen. It acts as a 5 volt regulator.

Rhyse Thompson wrote:

 

There is a capacitor on the screen. It acts as a 5 volt regulator.

No, that isn't correct. There is buck converter on the screen which acts as the 5V regulator.  The capacitor and inductor of a buck converter help smooth out the peaks to give you an ideally flat output.

I think I've found what I'm looking for,

http://microcontrollershop.com/product_info.php?products_id=5934 for the charging and power

with https://www.bananarobotics.com/shop/Pololu-5V-Step-Up-Down-Voltage-Regulator?gclid=COG89_SF8bgCFchaMgod2HsATA to get it down to where it needs to be for the pi

for the display I am looking at either

http://www.robotshop.com/24-raspberry-pi-touch-lcd-display-starter-kit.html (touch screen)

or http://www.adafruit.com/products/912 (no touch)