OnOff Shim + PowerBoost 1000C


#1

Hi has anyone had any luck getting the Pimoroni OnOff Shim and the Adafruit PowerBoost 1000c (or 500c) working together?

I would like to use the Powerboost to work as a battery backup or just the primary power since my device is a little handheld device. It’s great because it offers a built in charger for the LiPo and pass-thru charging.

I would like to use the OnOff Shim to handle safe shutdowns.

So I have the power from the wall going to the powerboost.

The powerboost then powers the on/off shim (from battery and/or wall power).

The on/off shim is then connected to the Pi.

Everything works, except when the On/Off shim shuts down, the powerboost still is supplying power (LEDs are still on). Not a huge deal when plugged in, but if it’s portable, it’s drawing SOME power from the battery (not sure how much). Plus it’s just annoying to have the power LEDs still on from the Powerboost.

Is there a way to remedy this, so the Shim switches off the Powerboost when it turns off?

The Powerboost does have an EN (enabled) pin that could normally have a push switch attached…

Thanks


#2

You would have to pull the EN pin to ground to turn off the up converter. That will turn off the up converter and turn off the blue LED. The battery charger is still on (enabled) though. I have a portable project run from the PowerBoost 1000c. I use a switch to turn it off.
A relay powered by the On Off shim would likely work. Use the normally closed contacts to pull the EN pin to ground when the relay is de energised. Start up gets tricky though. The relay has to be energised to be able to start the power boost to energise the relay. Wiring in a small switch may be a lot easier.