Raspberry Pi + Pico Projector on a Lipo Battery?

When you say the projector doesn't work do you mean that it turns on but doesn't show a picture or it doesn't even turn on?  Have you tried to unplug the Pi and Power hub and just run the projector?

The projector turns on and begins it startup process, but then shuts down. So I assume it's from a lack of power. If I unplug the Pi and the USB hub, it does seem to work in that case. And, of course, the projector also works when it's running off its own AC adapter.

My alternate solution was to use the battery in the projector itself. I had assumed that even though there may not be enough amps to run the projector, there might have been enough for it to charge the battery. However, it seems that the projector won't even charge the battery when it's running off my Lipo battery.

You are correct in that it doesnt have enough amps to support all the devices.  What is the charging voltage for the battery?

For the projector battery? I'm not sure exactly. It's a 3.3v battery, but the AC adapter for the projector that charges the battery is 5v at 2 amps

If the battery on the projector is lets say  3.3v but you are trying to charge the lipo battery back thats 11.1v the voltages are different.  It would act like water and the charge would move from the higher voltage(Lipo) to the lower voltage(projector) which is opposite of what you want.  Hope this helps.

Thanks for the reply, although I'm not sure that makes any sense to me. The 11.1v battery is running through a 5v switching BEC circuit, so it seems to me that this would create the same conditions that the projector would run off if it were simply plugged into a 5v AC adapter like it is normally.

Even in terms of amps it seems to be the same to me. The SBEC circuit allows a maximum of 5 amps, approximately 2 of which are needed to run (or charge) the projector. The remaining amps seem more than enough to power the Pi.

I know I'm missing something obvious here, but I'm just not seeing it.

And just to clarify, the internal battery for the projector is 3.3v, but the AC adapter to charge or operate the projector is 5v.

let me make sure i understand what you are doing correctly.  So you are trying to charge the lipo battery with the battery from the projector correct?  if that is the case like you stated above the lipo battery is 11.1v the max output on the projector battery is 3.3v.  Since the projector battery is 3.3v which is less than 11.1v  then the flow would go the opposite way of what you want.

No, it's the other way around. Sorry, I know it's confusing. Let me summarize:

I have a 11.1v LiPo battery with a 5v 5amp SBEC circuit. I wanted to run the projector off this battery along with the Raspberry Pi, so I tried two things:

1. Take the internal 3.3v Lithium ion battery out of the projector and run it off a wired power connection to the LiPo battery, essentially replacing the projector's 5v power supply with my LiPo battery. This did not work, probably because it was drawing too much current.

2. Keep the 3.3v internal battery inside the projector, and when the projector isn't on, connect the 11.1v Lipo battery (again, regulated at 5v) to the projector in hopes that it would charge the battery enough to run it for short intervals when the projector was switched on. However, then I connect the LiPo battery to the projector with the goal of charging the 3.3v Lithium ion battery inside the projector itself, it doesn't actually charge the battery at all.

Hopefully that clears things up. I only tried option 2 because I couldn't get option 1 to work, even though it seems to me like it should have.

You probably are getting a little charge but eventually the batteries are coming to a balance and no charge is being passed.  I don't know if charging a battery with another is good for them.  As I haven't really tested this I couldn't tell you.