How to add charging to a project using the Zero Lipo shim

#1

I have a project that’s using a Zero Lipo shim to power a Pi Zero (picture attached). It works beautifully, but it’s been rather inconvenient to unplug the battery from the shim every time I need to charge it. Is there a way I could wire in something like an Adafruit Micro Lipo battery charger, and if so, how would I do that?

I’m already using the GND and EN pins to connect an on/off switch.

Thanks in advance!
pete

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#2

Using an Adafruit Powerboost “charger” instead of the LIPO Shim would be one option.
https://shop.pimoroni.com/?q=powerboost
It also has the enable pin. No having to unplug the battery to recharge it. I’m using them in several of my projects. Rovers mostly. You don’t have to use the Micro USB port on the powerboost to recharge the battery. There are solder contacts you can use to feed the +5V in. I’m using a barrel connector for some of my builds. It’s a lot easier to plug in , IMHO.

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#3

If you want to go the other route I think you’d end up wiring the battery to a switch to switch its contacts back and forth between the Charger and shim. You’d only really need to switch the red wire. The back could be wired to both the charger and shim. You could also switch both with a double pole double throw switch. I wouldn’t try to connecting the charger and the LIPO Shim to the battery at the same time.

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#4

Yeah, I should’ve thought about that to begin with, but I was excited to use the shim with the inkyPHAT (for my badge project). Unfortunately, I don’t have the skills to de-solder the shim at this point; I actually tried that once and wound up ruining a shim and a Pi Zero.

pete

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#5

I don’t need it to run and charge at the same time; it’s hanging from my shirt (with magnets) when it’s running, and off when it would need to charge.

What would the circuit diagram look like?

pete

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#6

A double pole double throw switch will have 6 contacts. Something like this looking at the back side.
1 . 4
2 . 5
3 . 6
!, 2 and 3 are one switch and 4, 5 and 6 the other. They are isolated from each other but both switched by the one handle
In one position 1 and 2 are connected together, and 4 and 5 are connected together
In the other position 2 and 3 are connected and 5 and 6 are connected.
Wire the battery + (red) to 2 and - (black) to 5
LIPO shim + to 1 and - to 4
Charger + to 3 and - to 6
You want the + all on one switch and the - all on the other.

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#7

Gotcha! You’re a life saver! Thanks.

pete

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#8

I fixed a typo so if you clip and pasted it to save it do it again. ;)

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#9

A couple of these may save you from having to cut the battery cable. And make hookup easier.

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#10

I should also mention, my pin numbering of the switch was completely arbitrary. Each manufacturer could number their switch different, or not use numbers at all. They may tag them as NC C NO etc. The physical location of the pin is what to go by.

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