pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

powering my model a

Tue Oct 22, 2013 2:39 am

Hi everyone
I want to have a battery power my raspberry pi model A through the USB port. Planning on getting a 9V battery connected to a UBEC to convert to 5V and connect that to the USB port. The thing is that I also have a wifi adapter I need to use with the USB port. Im wondering if I can get one of those split USB adapters so that I can use my wifi adapter and power the pi through the USB port without any problems. I have read about back power but Im wondering if that only pertains to hubs that receive their own power.

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Hove
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Location: Cotswolds, UK
Contact: Website

Re: powering my model a

Tue Oct 22, 2013 10:53 am

Why not power it through the normal micro USB power connector? Is there a good reason? Doing it that way would open up the single type A USB port for your dongle.
www.pistuffing.co.uk - Raspberry Pi and other stuffing!

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Tue Oct 22, 2013 2:01 pm

You know what, my bad, I havent gotten my hands on the pi yet, I was taking care of the power supply for a project and I guess misread the pi A's features. Sorry guys

lazarus78
Posts: 236
Joined: Thu Jul 25, 2013 5:16 pm

Re: powering my model a

Tue Oct 22, 2013 5:48 pm

pistons4550 wrote:You know what, my bad, I havent gotten my hands on the pi yet, I was taking care of the power supply for a project and I guess misread the pi A's features. Sorry guys
If you havnt gotten yours yet, then I suggest getting a model B instead.

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Tue Oct 22, 2013 7:31 pm

Thanks for the suggestion but its a group project for school and the choice was made by a different member

lazarus78
Posts: 236
Joined: Thu Jul 25, 2013 5:16 pm

Re: powering my model a

Tue Oct 22, 2013 8:18 pm

pistons4550 wrote:Thanks for the suggestion but its a group project for school and the choice was made by a different member
Well get a model B for yourself to mess with! XD

Good luck with whatever your project it. Pis are fun to play with.

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Tue Oct 22, 2013 9:32 pm

Lol well this whole thing has got me hankering for some of my own side projects so I probably will

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Wed Oct 23, 2013 4:47 am

Ok well I think I have a legitimate question this time. I need a power supply that will power the model a pi, motors on an RC car, and my custom PCB that takes in 3V. I have all the things I need to step down the voltage so that my stuff doesn't fry but im wondering if you guys could give me an opinion on using this
http://www.adafruit.com/products/248

since I already have a charger for AA batteries that would save me some trouble

karlkiste
Posts: 189
Joined: Tue Jan 22, 2013 8:50 am
Location: berlin, germany

Re: powering my model a

Wed Oct 23, 2013 5:21 am

Go on, seems OK.

I'd like to give a little warning on Model A's USB port: I had trouble connecting USB pendrives. They lost connection after some minutes. Plugging a USB hub in between helps, even if it is an unpowered one. Don't know how WIFI works, though.

I've recently been powering a Model A like this: I took a powered USB hub, and shorted the diode which prevented the input to be powered. So, the hub gives power to the pi through the USB port. It's not a recommended way of powering the pi, but it's possible.

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Wed Oct 23, 2013 3:15 pm

karlkiste wrote:Go on, seems OK.

I'd like to give a little warning on Model A's USB port: I had trouble connecting USB pendrives. They lost connection after some minutes. Plugging a USB hub in between helps, even if it is an unpowered one. Don't know how WIFI works, though.

I've recently been powering a Model A like this: I took a powered USB hub, and shorted the diode which prevented the input to be powered. So, the hub gives power to the pi through the USB port. It's not a recommended way of powering the pi, but it's possible.
Sounds like a cool thing to try out, but with my grade riding on this thing I wanna try the approach with the least amount of risk

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Wed Oct 30, 2013 2:34 am

Ok so I got my parts in the mail and I tested my ubec with a 9V battery and didnt get out 5 volts, instead I got 5.25V. Is that extra .25 gonna be a problem?

Edit: the third one I tested is outputting 5.3 volts

ame
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Location: Korea

Re: powering my model a

Wed Oct 30, 2013 4:16 am

pistons4550 wrote:Ok so I got my parts in the mail and I tested my ubec with a 9V battery and didnt get out 5 volts, instead I got 5.25V. Is that extra .25 gonna be a problem?
Unlikely. Wikipedia states the USB 5V supply line to have a range of +/- 0.25V. The voltage may drop a little bit with a load anyway.

karlkiste
Posts: 189
Joined: Tue Jan 22, 2013 8:50 am
Location: berlin, germany

Re: powering my model a

Wed Oct 30, 2013 5:07 am

Most electronics states 5.5V or 6V as the upper working limit, and no damage is guaranteed up to 7V.

And: If you're measuring 5.3V... What does that mean? What's the accuracy of your meter? Some other (more expensive) meter would maybe display 4.983V. Accuracy "5%+1" digit means, that a real Voltage of 5.000V may be display a value of up to (5*1.05)=5,25V. If there's only one digit after the point, this may be rounded to 5.3V. Then, there's the "+1 digit", so a real voltage of 5.000V can even be displayed as 5.4V!

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Wed Oct 30, 2013 1:03 pm

Alright sweet, thanks guys

pistons4550
Posts: 9
Joined: Tue Oct 22, 2013 2:30 am

Re: powering my model a

Thu Oct 31, 2013 8:17 pm

Has anyone experienced problems using cheap micro usb cables to power their pi. I was gonna buy a 2 dollar one and cut it open to use the positive and negative wires to solder to my ubec

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