3.7V Li-ion Battery Mini USB To USB A Power Supply Module

[SidSilver]

The switch should be between the battery and the power supply imho.

[vnman]

@valfar

The wiring you suggested is one way of connecting to this power boost. You cut the power to the pi, screen, etc.. and still able to charge the battery.

You can also buy the 3 way switch and have the switch in the OFF position that cut both the battery & power strip; another position ("charge") to only connect the +5V of the battery such that you can charge the battery without turn on other things. and the last position that I called "play" that supply power to the power strip.

[Pumpytums]

Hi everyone,
just a quick message to say mine arrived yesterday (Thanks Banggood ) I have only tried 1 and it worked great.

When first connecting you have to connect a charger briefly even if the battery is charged. Once this is done providing the battery stays connected (I believe the circuit pulls a tiny amount of current micro amps) you don't have to do it again unless you remove the battery.

The circuit looks like it comes out of a power bank which is fine as it costs £2 not £15 it also has undervolt protection, I believe the Adafruit 1000C does not I tried to get confirmation without success. My pack has a undervolt PCB on as well for double security.

Thanks

[RxBrad]

Hi everyone,
When first connecting you have to connect a charger briefly even if the battery is charged. Once this is done providing the battery stays connected (I believe the circuit pulls a tiny amount of current micro amps) you don't have to do it again unless you remove the battery.

Hmm... I wonder if that would cause issues with the graceful shutdown switch @Camble is working on...

[Camble]

When first connecting you have to connect a charger briefly even if the battery is charged. Once this is done providing the battery stays connected (I believe the circuit pulls a tiny amount of current micro amps) you don't have to do it again unless you remove the battery.

Can you elaborate on what you mean by this, and why?

[Pumpytums]

Hi,
when I first connected the battery and load (pi zero) to the board nothing happened. Then I remembered someone on the Bangood site mentioning on first set up or battery connection you must connect a charger. I connected the charger for a few seconds and the zero worked I then disconnected the charger and it carried on working. I then disconnected the zero and reconnected it and it worked perfectly.

The battery a 18650 (protected) was fully charged.

I think it may be some sort of safety circuit built into the PCB that if the battery goes below a certain voltage or i it completely disables it. It will only come to life again once a charger is connected.

I can also confirm that you can charge and use the zero at the same time hope that helps.

[Pumpytums]

I think you leave the battery connected permanently. You wont be able to put a switch between the battery and the PCB without repriming it.

Can anyone confirm about the Adafruit one does it have a low voltage cutoff or just a low voltage light?

[Zero]

I think you leave the battery connected permanently. You wont be able to put a switch between the battery and the PCB without repriming it.

That's annoying, but thanks for the info. I was trying to hook up a low power led board the other day via this power board and I couldn't get it to work, but now you've mentioned this I think it's probably the reason. I'm surprised no one else has said this before as there are a few builds on this forum using this power board and none have mentioned this. I wonder how their switches and low power leds are wired up.

[Pumpytums]

Hi,
I think you could put the switch on the zero/ screen side I think there is a image at the start of this thread (post 2). I'm going to put the Amp on one set of pins and the screen/zero on the other to split the current rather than put it through one set of pins. I have a six pin switch.

I think you can add leds from the pads on the board not sure which one goes to which led though, I think you need to unsolder the other leds though from a message on the Banggood product page comments.

[Zero]

I don't think the leds on the board show a low power status. Two are for charging status (red for charging and green for fully charged), and the other blue one is for power. I think the holes on the board for leds are there in case you just want to extend the existing leds instead of having to desolder them.

Yes I could put the switch on the output, but I wanted the switch to turn on/off the power led board too, and that has to be connected to the 3.7v battery and can't be on the 5v output. If the switch is on the output then this means the low power leds will be powered all the time, and drain the battery when the pi is off. I still need to think of a way to deal with this.