soldering battery pack

[damaru]

Hi there,

I would like to solder a battery pack the the pi, Could I use the TP2 and TP1 to connect ? I would prefer to stay away from the solder joint at the micro usb connection - but if it the best choice, which of the 4 connection should I use of the + and - of the battery connection ?

EDIT - I realized that the micro usb connections are made on the top of the board, which makes it even less of an alternative.

[Gert van Loo]

I suggest you connect it to the GPIO connector 5V pins.
If you buy a fitting connector and solder to that, you don't have to solder to the board.
Especially with a battery pack : add a fuse. Some of those packs can deliver a huge amount of current (>10A).

[damaru]

So the GPIO 5v is for voltage coming in to feed the pi ?

I was under the impression that the 5v pin was to feed some other device attached to the pi -

But if that's the case it would be really simple to attach the power pack to this board!

[abishur]

So the GPIO 5v is for voltage coming in to feed the pi ?

I was under the impression that the 5v pin was to feed some other device attached to the pi -

But if that's the case it would be really simple to attach the power pack to this board!

It goes both ways. The pins are source/sink which means they can push power out or take power in

[damaru]

do I need to program anything to tell the gpio to receive 5 volt from the pin ? My mind has a hard time comprehending how a pin could accept or give you 5v -

[abishur]

do I need to program anything to tell the gpio to receive 5 volt from the pin ? My mind has a hard time comprehending how a pin could accept or give you 5v -

Nope there's no programming that needs to be done.

If it helps, I find thinking about electricity as water to be very illustrative.

Imagine you have a faucet. Now a faucet doesn't have anything that says water has to flow a certain direction. It's just a valve and as you open it water flows through that valve. Most people use a faucet to send water from a city supply line into their yard or flower bed. It's a water source, this would be people who use the usb power port to send 5 volt wherever it's needed (like out the pins in the GPIO strip).

On the other hand you have a plumber whose trying to find a leak in your pipes. He disconnects the water from the city and uses your faucet to pressurize the system with water and listen for where the water is leaking out. The faucet still doesn't care which way the water is going, but this time water is flowing into it rather than out of it. This is called a "sink" (so many puns, so little time). On the pi this is the group of people who wants to use their own voltage protection (or worse, no voltage protection) and feed it into the pins on the GPIO strip.

This is what is going on with the 5v pins in the GPIO strip. It's just a bunch of metal so it doesn't care where the power comes from, once there is power on the line, it powers the whole shebang. So you can either give it power on the micro usb power port and send power out of the GPIO pins or you can send power directly into the pins, what does metal care?

[rew]

The "best" way to do this, IMHO would be to wire the battery to a micro USB plug. Buy a cable, cut it and connect to the red and black wires there.

This leaves the fuse on the "pi" in the loop. i.e. you don't have to mess with a fuse.

Do take into account that you'll have to regulate the power. Say 4* NiMh would deliver 6V when freshly charged. Too much. Pi goes pooof!. Quickly there will only be 4.8V, but power will sag to below 4.4V before the batteries are depleted, causing the pi to stop working.

It would be better to make say 6-9V with 6 NiMh batteries, and then regulate it down with a cheap switching regulator from Ebay. http://www.ebay.com/itm/LM2596-DC-Step- ... 416655eb3b
(about half what I paid 2 months ago).

This adapter is PI-proven: My pi is currently powered by one of these!

[damaru]

Thanks abishur for the explanation! Yeah connecting to the 5volts pins work ok, but when connecting network or another device to the pi it seems to reboot... I have to do more test for that.

I am using a battery pack
http://www.nuelectronics.com/estore/ind ... ucts_id=17

that seems to have some sort of regulator on it... anyhow - more to be tested!

[psycho_moggie]

The specification for the battery pack shows a maximum output current of 500mA, if it goes into current limit mode a bit higher that may be the reason for your reboot.

[trikidiki]

..........................................Imagine you have a faucet. Now a faucet doesn't have anything that says water has to flow a certain direction. It's just a valve and as you open it water flows through that valve. Most people use a faucet to send water from a city supply line into their yard or flower bed. It's a water source, this would be people who use the usb power port to send 5 volt wherever it's needed (like out the pins in the GPIO strip).

On the other hand you have a plumber whose trying to find a leak in your pipes. He disconnects the water from the city and uses your faucet to pressurize the system with water and listen for where the water is leaking out. The faucet still doesn't care which way the water is going, but this time water is flowing into it rather than out of it. This is called a "sink" (so many puns, so little time). On the pi this is the group of people who wants to use their own voltage protection (or worse, no voltage protection) and feed it into the pins on the GPIO strip.
....................................

Just to throw a spanner in the works, all outside taps (faucets) in the UK should be fitted with a non-return valve which would leave your plumber scratching his head.

[waygood]

Any chance REW can post some pics of what the Pi looks like with the battery pack and everything installed, as I've just bought an identical regulator from Ebay.

I was also thinking of adding a solar battery charger I bought a while ago from Clas Ohlson (to charge my iPhone) http://www.clasohlson.co.uk/Product/Pro ... =164692039
Is there anything I need to consider before I just plug it in, like putting a regulator between them too?

[hcunningham]

here's another option for connecting your batteries to the Pi, just launched on Kickstarter:

https://www.kickstarter.com/projects/ha ... spberry-pi

hth, best

h