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I bought the display along with the camera board v2 a couple of months ago to work on some projects with my Raspberry Pi 2 but only recently found the time to actively experiment. Now unlike the camera board where there is actual official entry in the FAQ for the Raspberry Pi (see here) I seem to be unable to find any for the official 7" display especially in terms of power consumption though there are plenty of blog posts that discuss the topic.

My power supply (5V/2A...hopefully) is not the official one. It came with the Raspberry Pi kit I bought (plus casing, fan, heat sinks, SD card (a very crappy one from Intenso; had to buy a new one since it got corrupted pretty fast) etc.). I have noticed the following:

  • Active Ethernet connection (a single SSH session running between by notebook and Raspbian) + attached display (power goes through it to the Pi) - I sometimes get the colourful square depending on what I do software-wise which indicates power issues. Touch on the screen works
  • Active Ethernet connection (same as above) + attached display (same as above) + attached camera board - same thing with the square but in this case the touch doesn't work.

I would like to combine both the display, Ethernet connection and the camera board and I would like to know what the power consumption would be in such a scenario. Any ideas?

The Pi 2 requires approx. 1.8A, the camera on the other hand requires 250mA which would make the 5V/2A power supply enough for the two to run without any issues. If I take the data provided by the blog post I have linked above the display requires around 460mA. So for the three together I would need around the 2.5A mark. Is this a correct assumption? Or should I use two power supplies (one at 5V /0.5A for the display and one 5V/2A for the pi) separately?

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The Pi 2 requires approx. 1.8A

This is a misreading of the linked information. That's not what it requires. It is the "recommended PSU capacity". PSU = power supply unit. I am pretty sure there is a hard limit of 2A on how much can actually be drawn through the microUSB jack (only the 3 is higher); after that you risk triggering a polyfuse (which if you aren't going over much will just mean the board shuts off and won't go back on for a little bit, but probably most likely: A drop in voltage that shuts the board off first).

The "typical bare-board active current consumption" from that chart -- 330 mA -- is a (minimal) figure for how much the Pi 2 itself will use, and that seems reasonable enough. Round it up to 0.5 A, then start considering your peripherals. You should have enough for the camera (250 mA), the display (0.5 A), a USB keyboard (<150 mA) and normal size wifi dongle (<250 mA) and/or ethernet link, and with some headroom left over.

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You do not need to use separate power supplies. You can just use one bigger power supply and split the power cables out. In general it is a good idea to not overload the Pi. So that means if you can power the LCD using the seperate power cables, just by pass the Pi and wire it directly to the power supply!

You should invest in a a slightly higher quality power supply. Forgot these cheap USB things. I am talking about power efficient switching power supplies that only use as much power as you need AND provides clean DC power.

You do not have to break the bank, you can get these of ebay or dx.com for about a fiver for a 3A and under a tenner for 5A.

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Sure, they not exactly these nice wall plug solutions but high quality power supplies solve 90% of the problems with long term use of the Pi. Just saying. You do not have to get on of these but I keep repeating this so people understand that the wall plug USB power supplies are like going fishing in stormy weather.

You should endevaour to split as much away from the Pi as possible. Like using USB HUBs, which again, can be powered by 1 good power supply, bypassing the Pi.

As long as the total Amperes of peak does not excees 90% you will be OK!

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Removing the LCD power supply coming out of a Pi USB socket will unfortunately remove the touch data going into the Pi. So the (slightly) tricky part is to open up the LCD power lead and cut the red and black power leads, and I do mean snip them and bring them out to connect to the additional power supply that will be used for the LCD display. So the USB plug still attaches to the Pi to enable the touch data. This sounds simple to me and would be easy to implement but I understand that some non electrically minded folk might assume this is way too complicated a task. Maybe someone here could draw a simple diagram to show how this will work. I do hope this tip can be used by a keen enthusiast or two but it may be that a powered hub may be a better option. Ozzie Phil

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  • Ozzie Phil said, "Maybe someone here could draw a simple diagram to show how this will work." ... Maybe that someone could be you! Here's how to add a schematic. I am sure you have a good answer here, but I fear that many will not understand it. A schematic would add tremendous clarity to your answer. Please consider making the effort; if you have questions post them in "meta"
    – Seamus
    Aug 30, 2018 at 11:53

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