Powering Raspberry Pi 2 and TFT screen at once via battery?

[wermy]

This page lists a bunch of specs for what looks to be the board you have:
https://translate.google.com/translate? ... rev=search

It mentions the max output current as being 500mA. So that looks to be your issue right there: 500mA just isn't enough to drive both the Pi 2 and a screen, from what I've seen. I think you'll need a different board.

Alright, thank you!

So it shouldn't be the battery in any case? How many mA do you think do these two devices need? Is there a simple way to find it out?

The mA rating on the battery has more to do with how long the battery will last on a single charge than anything (though that's not to say that the capacity and max current it can output are not related). If you've got a few minutes, I highly recommend reading through this:

https://learn.adafruit.com/all-about-batteries/overview

And for some li-ion and lipoly-specific info:

https://learn.adafruit.com/li-ion-and-l ... s/overview

[Exceen]

Uhm... somehow this doesn't make sense to me actually.

What happens when I connect the Adafruit board via USB to another power source? My MacBook for example. In that case everything works fine, but the step-up board still outputs only 500mA maximum, right? So isn't the problem caused by the battery then?
Or does the external power source (anything but not the battery) skip something on the step-up board which is the reason why it works?

[wermy]

Uhm... somehow this doesn't make sense to me actually.

What happens when I connect the Adafruit board via USB to another power source? My MacBook for example. In that case everything works fine, but the step-up board still outputs only 500mA maximum, right? So isn't the problem caused by the battery then?
Or does the external power source (anything but not the battery) skip something on the step-up board which is the reason why it works?

The mA rating on the battery is the capacity -- how much it can hold. How fast you can take it out, though, is a different story. It looks like the step-up board you are using can only "take out" 500mA of current from the battery at any given time. Your setup with a Pi 2 + screen probably requires more than that.

Edit: It might also be helpful to note that the rating on the battery is mAh (mA-hour) and not just a current rating (mA).

[Exceen]

It looks like the step-up board you are using can only "take out" 500mA of current from the battery at any given time.

So when I connect the board via USB to my notebook it skips this whole conversion thingy and I get more than 500mA?

I just looked for a board that provides more than 500mA but I couldn't find one. Could you suggest anything please?

[wermy]

It looks like the step-up board you are using can only "take out" 500mA of current from the battery at any given time.

So when I connect the board via USB to my notebook it skips this whole conversion thingy and I get more than 500mA?

I just looked for a board that provides more than 500mA but I couldn't find one. Could you suggest anything please?

When you say "connect the board via USB" do you mean connect the pi/screen? Or the boost board?

I recommend the Adafruit PowerBoost. It's a little more expensive but it is top-notch quality, and you know exactly what you are getting. Plus in the product description they mention they had no problem drawing 2.0A+ (provided your battery can handle it).

[Exceen]

When you say "connect the board via USB" do you mean connect the pi/screen? Or the boost board?

As you can see on the picture I posted before I connected the Adafruit board to this boost board. What I meant before is the connection between the Adafruit board and my notebook.

So it's basically like htat:
notebook ---usb-cable---> adafruit board ---> boost/step-up/whatever-board ---> raspberry pi ---GPIO-pins---> screen

In this particular case everything works fine. As soon as I disconnect everything from my notebook (external power source), it doesn't work anymore and the result is what you can see in the video I posted before as well.

I recommend the Adafruit PowerBoost. It's a little more expensive but it is top-notch quality, and you know exactly what you are getting. Plus in the product description they mention they had no problem drawing 2.0A+ (provided your battery can handle it).

So that would be this one, right?
https://www.adafruit.com/product/1944

[wermy]

When you say "connect the board via USB" do you mean connect the pi/screen? Or the boost board?

As you can see on the picture I posted before I connected the Adafruit board to this boost board. What I meant before is the connection between the Adafruit board and my notebook.

So it's basically like htat:
notebook ---usb-cable---> adafruit board ---> boost/step-up/whatever-board ---> raspberry pi ---GPIO-pins---> screen

In this particular case everything works fine. As soon as I disconnect everything from my notebook (external power source), it doesn't work anymore and the result is what you can see in the video I posted before as well.

I recommend the Adafruit PowerBoost. It's a little more expensive but it is top-notch quality, and you know exactly what you are getting. Plus in the product description they mention they had no problem drawing 2.0A+ (provided your battery can handle it).

So that would be this one, right?
https://www.adafruit.com/product/1944

I'm not sure, but it sounds like maybe when you have it plugged in it is bypassing the battery altogether and just connecting you straight to the USB power source.

And yes that Adafruit one should work (they mention in the description it can supply upwards of 1A which should be enough). For a few more bucks, though I'd recommend the set up from that (the Powerboost 1000C). It will supply enough charging current (1A or 1000mA, which is where the 1000 comes from) so that you can play and charge at the same time (great for plugged into the TV), where as the 500 only charges at a rate of 500mA. So if your battery went dead with that one, you wouldn't be able to charge and play at the same time, likely, and would probably have issues similar to the ones you're having now.

[Exceen]

And yes that Adafruit one should work (they mention in the description it can supply upwards of 1A which should be enough). For a few more bucks, though I'd recommend the set up from that (the Powerboost 1000C). It will supply enough charging current (1A or 1000mA, which is where the 1000 comes from) so that you can play and charge at the same time (great for plugged into the TV), where as the 500 only charges at a rate of 500mA. So if your battery went dead with that one, you wouldn't be able to charge and play at the same time, likely, and would probably have issues similar to the ones you're having now.

I just checked out adafruit.com and noticed that the 1000c booster is out of stock. The other one is there, although the shipping is priced a little bit higher than the product itself, which is quite expensive in the end.

I checked out Amazon and Ebay as well and there's almost nothing that's cheaper than 40 Euros. Compared to the 3 Euros for my current board that's extremely expensive, so are there any alternatives? Or sites that ship cheap to Europe?

[wermy]

And yes that Adafruit one should work (they mention in the description it can supply upwards of 1A which should be enough). For a few more bucks, though I'd recommend the set up from that (the Powerboost 1000C). It will supply enough charging current (1A or 1000mA, which is where the 1000 comes from) so that you can play and charge at the same time (great for plugged into the TV), where as the 500 only charges at a rate of 500mA. So if your battery went dead with that one, you wouldn't be able to charge and play at the same time, likely, and would probably have issues similar to the ones you're having now.

I just checked out adafruit.com and noticed that the 1000c booster is out of stock. The other one is there, although the shipping is priced a little bit higher than the product itself, which is quite expensive in the end.

I checked out Amazon and Ebay as well and there's almost nothing that's cheaper than 40 Euros. Compared to the 3 Euros for my current board that's extremely expensive, so are there any alternatives? Or sites that ship cheap to Europe?

Looks like @Sander added this as an alternative in the wiki:
http://www.banggood.com/37V-Liion-Batte ... 37201311DI

Source:
http://sudomod.com/wiki/index.php?title ... wer_Supply

[Exceen]

Looks like @Sander added this as an alternative in the wiki:
http://www.banggood.com/37V-Liion-Batte ... 37201311DI

Source:
http://sudomod.com/wiki/index.php?title ... wer_Supply

So if I use this, I can easily charge it via micro USB. The battery is connected at the B- and B+ poles and the power output is the USB 2.0 port, right?

The thing is that I don't really want a USB 2.0 port there, so is it possible or hard to remove it? I'd like to solder the USB cable on the board which you can see here (blue and brown wires):