Hello There!!
Sooooo many time since I made my last post... I was just a kid...
I want to ask a short question:
I have connected one of those 3G USB modems to my Raspberry PI when it was turned on and the RPI shut down. I immediately thought "Oh, the RPI charger doesn't have the enough power to supply the 3G modem". But then I realease that it didn't shut down completely but it was a reset! 
. It booted normally and all that...
So... I was trying to use Sakis3G to configure and connect to the internet using the 3G modem, but the setup always failed... So I thought "Oh, this must have something to do with the current and voltages an all that crap".
So I borrowed an external USB hub from a friend to see if that could solve the problem. And it actually did, I could configure the 3G modem using Sakis3G and everything worked fine...
The thing is that reading on the web I came to the conclusion that the problem could be that the amperes of the charger I was using wasn't enough (700 mAh). When I saw the amperage of my friend's USB hub it was of 2000 mAh, so I cut the wire and connect the microUSB connector to it and connect that directly to the RPI to see if I could now use the 3G modem without the USB hub. The surprise was that I couldn't... So what the fuck?
I also noticed that connecting the USB hub to the RPI (Using a normal USB port) I don't need to use the power MicroUSB connector of the RPI... Somehow the USB hub through the USB port feeds the RPI... So the MicroUSB port is useless.
So my current conclusion is that maybe the USB hub has a capacitor (I don't know if that is the correct name) that when the 3G modem sucks too much energy the USB Hub is able to provide that energy for a short period of time while the RPI shuts down due to the low voltage of that moment...
What do you think?
Normal USB can't properly power a Raspi, especially if you're plugging regular usb devices into the usb ports (except powered usb hubs).
Your best bet is to use a 1.5A or higher AC adapter, and a powered usb hub.
I tried 1A and I cannot even have ethernet with that, nor keyboard, or anything. With 2A everything works great for me.
I was using a 0.7A charger and my ethernet connection and keyboard worked fine. I think the problem in this case is not related directly to the charger but the circuit of the RPi. I'm supplying enough energy but there must be some part of the RPi that can't provide that amount of energy that the 3G modem needs when it's connected.
I'm wonder if there is no problem to power the RPi using the normal USB port. It seems to work fine.
The real problem is the Rpi takes 700mA on its own. Adding more usb devices like a 3g modem is going to pull even MORE power. wifi and 3g modems tend to want 200-500mA on their own.
Like I said earlier, you want at least 1.5A if you're plugging additional stuff into the raspberry pi directly. You can get away with less if you're only using a powered USB hub.
Like I said earlier, you want at least 1.5A if you're plugging additional stuff into the raspberry pi directly. You can get away with less if you're only using a powered USB hub.
I also said earlier that I used a 2.0A charger and it's the same. My current theory is that even if I had a 3.0A charger I will have the same problem. I have just bought one to see if it's true. I purchased from China, though... 
Watch out for cheap chinese ac->dc adapters. They like to cause shock hazards and fires.
It is also possible that your hub is a cheap pos as well! 
You're powering it from a car? Or another 12v source?
Yhea I will be using a 12V battery.
Interesting setup. You're going to need a rather large 12v battery.
Yhea, this is a project for cars.
You're not going to surf the interwebs while you're driving, are you? 
I hope your dc->dc converter has some beefy voltage regulation. power in a vehicle is incredibly noisy.
You're not going to surf the interwebs while you're driving, are you?
Of course not............................
I hope your dc->dc converter has some beefy voltage regulation. power in a vehicle is incredibly noisy.
Yhea it has! You see, when the voltage goes down my DC to DC converter also goes down! and the same when the voltage goes up! Isn't that great!?
You see, when the voltage goes down my DC to DC converter also goes down! and the same when the voltage goes up! Isn't that great!?
Assuming I'm understanding you properly.. No, thats bad. That's exactly the opposite of good. The output voltage from a good regulator should be steady, even if the input is noisy. Of course there will be certain thresholds that the will cause the regulator to not work properly or at all (input too low or too high).
Ahhhh... Poor Thomas... Man, you're a computer. Where is your sense of humor? I told you to not program so much, do you see what happens?
I dunno, its hard to tell sometimes what's supposed to be a joke or not 
Oh BTW. All these years I have been asking you for your furnace. So tell me Thomas, is your furnace working? I want to remind you that you live in Canada a country most known by its maple syrup and its long long loooonnggg winter... Have you replaced your furnace?
Here in Spain we're at 12ยบ more or less. Not that bad so far. 
All these years I have been asking you for your furnace. So tell me Thomas, is your furnace working?
I heard the movie version comes out next year.
Oh BTW. All these years I have been asking you for your furnace. So tell me Thomas, is your furnace working? I want to remind you that you live in Canada a country most known by its maple syrup and its long long loooonnggg winter... Have you replaced your furnace?
Heh. Yeah. Over a year ago now. And boy is it nice. It's actually able to keep my bedroom warm now. Used to be when it got to -20 and below, my room would be ice cold, and I'd need like 4-6 blankets to keep warm at night. Now one is more than enough.
We hit somewhere around -40c within the past couple weeks. With windchill it was probably -50c. For that one day we were the coldest recorded place on the planet. Even colder than the Arctic or Antarctic.
I heard the movie version comes out next year.
Oh nO! What! Where!... I didn't get it...
Heh. Yeah. Over a year ago now. And boy is it nice.
Good to hear that.
Used to be when it got to -20 and below, my room would be ice cold, and I'd need like 4-6 blankets to keep warm at night.
Not good at all to hear that ... MAN!
With windchill it was probably -50c. For that one day we were the coldest recorded place on the planet. Even colder than the Arctic or Antarctic.
Man, I didn't know Canada could be so cold. Compared to that here it's summer all year long.
Used to be when it got to -20 and below, my room would be ice cold, and I'd need like 4-6 blankets to keep warm at night.
I've ruined computers by storing them in a room that may have gotten as low as +7 C (+45 deg F).
High humidity?