Charging a battery with the portability shield

GPS/GNSS Development Boards
1

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?

2

Currently no, this is a side effect of the shield design.

3

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

4

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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5

Hello I was thinking about you post. You’re describing SparkFun’s Battery Babysitter but with a boost on the output. Am I getting that right?

6

In essence (core circuitry) - yes, but I’m rather talking about a simple device not meant for interaction with an MCU.

When you have something like a GNSS receiver module that has a USB interface for power and one of the UARTs, and you want to turn it into an autonomous device, there’s hardly any need for an MCU.

Ideally, you’d use a bulkhead USB connector, hook it up directly to the upstream connector of the battery charger module, then connect the downstream USB connector to the GPS receiver module. Then connect a battery to the charger module and one switch to Boost_EN, and you are done. All the power state information can be perfectly conveyed with LEDs.

But typically, you have to do some tricks to run USB data lines around the battery charger module, even if it has a USB upstream and/or downstream connector. And the PCB design is rarely helpful for doing that, unless you completely desolder those connectors and solder a cable instead, which defeats the entire purpose of having them to begin with.

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