I need to power a Pi 5 and a Waveshare 10" touchscreen display from a LiIon battery pack, but those two devices are thirsty buggers. The Pi wants 27 watts, and the touchscreen wants 4 watts or 750ma. With a bit of elbow room included, I think I need about 40 watts or 8 amps of power delivery, all from a module that can charge and draw from a battery pack, too.
The solution might require switching to an 11 volt battery and using a buck converter, it would just be wonderful if there was an equivalent to the Amigo Pro that could handle it. Are there existing modules that could be combined to get the same effect?
The Amigo Pro isn’t a good choice for your application. It only delivers the battery voltage. That’s fine if its powering a Pico. The Pi is going to want a stable +5V.
I usually use a Power Boost for my battery powered Pi builds. It outputs +5V and can charge a battery.
PowerBoost 1000 Charger - Rechargeable 5V Lipo USB Boost @ 1A - 1000C (pimoroni.com)
It’s no where near the current your wanting though. :(
Do you need a Pi 5? What is said Pi going to be doing?
Also keep in mind that the Pi 5 may not need all of those 27 watts. The power supply is rated for a maximum of 27 watts. The actual current drawn depends on the load. How hard the Pi is working and what else is connected to it determines how much current (power) it needs from the power supply.
The touchscreen is designed to mount a Pi 4 or 5, and its job will be to run multiple terminals and Remote Desktop sessions, with maybe some local apps and a game. I picked a Pi 5 because I might as well use the latest. At least one use will be remote camera viewing for a digital microscope and a robot. I also want the fastest switching speed for jumping between sessions.
The peripherals would be two e-Ink displays (tiny current usage) and the standard cooling fan for the Pi.
I have two setups with Pi 4B’s and the Pi 7 inch touch screen. They mostly get used to view camera feeds. No battery power on these. The more powerful the model Pi used, the more problematic it gets trying to power it via a battery. I have a couple of Pi Zero’s I can run on battery, and some Pi Pico’s.
I’m thinking your going to have to use a buck converter and big beefy battery. Is your device going to be portable?
Before you start, you should measure the power consumption. I have used a Pi4 with those screens and all in all they don’t use that much current. I really had a hard time to drive this to 1.5A. But of course this really depends on what your multiple remote terminals and desktop sessions really do (terminals and desktop sessions themselves actually do very little).
Pi5 will of course be higher than Pi4, but people typically look at these 27W without ever thinking about what they need to attach and run to really get there.
I would be more worried about a stable voltage than about current. And I would go for a 12V battery and a 12V-5V converter that has beefy caps. And nothing cheap, or you will have problems with voltage stability.