Zero W: Cut USB power lines?

Question

I understand that the Zero W USB port has just the power lines connected to all the power on the board (+5V and GND). I also understand that you can use something like Adafruit PowerBoost 1000C to power by connecting to those rails (e.g. using PP1 for +5V and PP6 for GND).

In that case, the PowerBoost would have a lipo battery, and you'd plug your power cable into its USB port (not the Zero W's USB port), and power would be intelligently distributed between the battery and the Pi.

The problem with that approach is instead of using the Pi's USB power port, I have to use the PowerBoost's power USB port. My desire is, because the Pi has all its jacks secure in a row, I'd like to use them as is.

My thought is:

1. CUT the connection between the Pi's USB power port and its power rails.
2. INSTEAD re-route the Pi's USB power port to input to the PowerBoost.
3. Connect the PowerBoost output to the Pi's PP1/PP6 (fairly typical).

My question is whether this is possible and the best way to go about it.

I think in the worst case, the USB power jack could be removed from the Pi and reconnected so it's not touching the solder pads, then +5V wired from it to the PowerBoost. Would it be a problem if the GND is shared though?

Or, are there some traces I can cut to remove the Pi's power from USB power jack, without desoldering the USB power jack? Is there anywhere I can get a board layout of the traces to see where they go?

Finally, has anyone done something like this before? I know it's easier to just use the PowerBoost separately, but I'd really like to re-use the Pi's power jack if at all possible, as it's a cleaner solution if it can be achieved.

Answer 1

Hmm, honestly, your question is a little difficult to understand (there are a lot of "bits", but I'm thinking:

You want to use your power supply plugged into the Pi0 power connector, without actually powering the Pi, but powering the 1000c instead. In other words, you want to plug the power supply into the Pi0's power connector, but use the UPS.

I'm not sure how your plan is "cleaner"?

Yes, the 0V can be common, definately!

Looking at my Pi0, there are no accessible tracks on the top or botton layer of the PCB.

BTW, I once unintentionally powered up my Pi0 via the USB host port.

          ******* HIGHLY NOT (!) RECOMMENDED *******

But... As you mentioned, you could desolder the micro-USB Power socket, run a 5V wire from the socket to the UPS (1000C - I want one!) and run a wire from the UPS's 5V2 output to the Pi0's 5V input power connector pad.

Put a tiny piece of electrical tape (Kapton tape or a thin piece of plastic would be better) between the connector and the solder pads.

Sort out the 0V somehow.

Solder and/or glue the connector shield back on.

But why do you want to use that single position on the Pi0 to power the UPS so desperately???

It is too risky, IMO. PLEASE don't attemp it!!!

          ******* HIGHLY NOT (!) RECOMMENDED *******