I have the portability shield attached to the postcard with the battery sandwiched in between. When I plug the USB cable into the postcard it powers up as well as the portability shield (with the charge light on). Is there a way to charge the battery without having the unit power up?
Currently no, this is a side effect of the shield design.
As an addendum: if you’d like a standalone charger (if you plan on getting multiples to rotate or if your setup has the battery/leads readily accessible) you can grab something like this https://www.sparkfun.com/sparkfun-lipo-charger-plus.html
It might not be specifically related to GPS, but I did some analysis of existing battery charger modules with boost converters powered from USB and/or solar source, and found that devices with all these features are nearly non-existent:
- USB pass-through (with or without an actual USB connector to connect the target device)
- Boost enable/disable pin that doesn’t require additional resistors in series with a switch
- Pins for external indication (5V Out On, Charge/Full, or a battery gauge with 3-4 LEDs)
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