Postcard RTK with portability shield: power switch added

GPS/GNSS
1

Postcard RTK with portability shield: power switch added.

Hi everyone. I added an extra switch to one of the battery cables on my Postcard with portability shield.
The idea is to leave the small sliding switch on the portability shield on to protect its lifespan.
I don’t think it has any electrical issues.

Can someone on the team confirm?

Thanks.
Regards, Angel

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Hi Angel (@amlago ),

How did you connect the extra switch? Did you cut the red wire from the battery, and connect the switch inline in the red wire?

If you did, it should work OK. But please be aware that the MAX17048 Fuel Gauge may not work as well as expected. The Fuel Gauge works best when permanently connected to the battery. If you disconnect the battery completely, the Fuel Gauge has to estimate the charge level when you reconnect. The battery charge icon on the OLED may not be completely accurate.

If we ever revise the Portability Shield, we should add some extra pads to make adding an external switch easier… Please feel free to open an issue on the GitHub repo - so we don’t forget!

Best wishes,
Paul

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Hi Paul (@PaulZC)
Cut the red (positive) wire and add the switch.
I understand what you mean about the charge indicator.
Can you think of anything else to add so the battery doesn’t completely disconnect? Maybe a diode?

Is there a large resistor in parallel with the switch line?

Electronics isn’t my strongest suit.

Thanks
Regards, Angel

4

Hi Angel,

There are more complex things you could do, like remove the small sliding switch and solder on wires for an external switch. But this would involve some delicate soldering and moving the OLED (which is stuck using double-sided foam tape).

What you have now is the easiest solution! :wink:

Best,
Paul

5

Great, Paul.
I was thinking that if I put a high-value resistor in parallel with the switch, some current would still flow and the meter would be more reliable.

Could that idea work?

Otherwise it will stay like this, and even though the load meter gives me some unreliable readings, it works.:+1:

6

Hi Angel,

I think the resistor is unlikely to work. It would almost certainly change the apparent battery voltage and confuse the fuel gauge.

Best,
Paul

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I’ll leave it at that, jajaja
Thanks for your answers.
We’ll stay in touch.
Angel