Custom Lipo-LiFePO4 RAK3172 node

Hi all,

this is to share our latest batch of custom boards.
As we test it further we’ll share our progress.


Hello @pico

Nice project. Thanks for sharing!

Just curious, did you need an additional super-cap to backup the battery during consumption peaks?
I have no experience with this battery type.

Hi @beegee,

After some empirical tests with official rak boards and the custom design, I suspect there is no need for a supercar. I also monitored the 3V3 rail with an oscilloscope and I haven’t noticed alarming drops in voltage to the module.
Do you have further suggestions on how to test for this possible requirement?

Very nice and thanks for the share :slight_smile: Do you plan to offer boards for sales later ? what are the specs of the board ?

Hi @pico

What LoRaWAN regions did you check. I guess worst scenario for sudden power consumption when transmitting is US915 and set to max TX power of 22dB.

Hi Vincen,

Currently, there is no such a plan, it is only for our custom needs, though things might change.

These are some specs of the board:

  • dual chemistry solar charger (solder jumper)
  • 18650 cell clips or SH battery connector
  • buck-boost converter with power-good on PA9
  • protected GPIOs
  • 2x interrupts/IO
  • 2x ADC channels up to 16-bit
  • 2x UARTs
  • TC2030-style serial wire debug (SWD)
  • 4 mounting holes and small footprint (69 x 38 mm)

I have tested it for EU868, so far so good :+1:

Thanks for the share and yep quite interesting as your board looks very well designed and built, love quality it shows up on your pictures. I guess it would be an all win situation if you sell also the board by itself for geeks interested so long your customer is ok with it :wink:

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Great share to the community @pico . This neat work deserves some hearts :purple_heart:

Is the charger controller designed for either LiPo or LiFePO4 and changing profile can be switch? Or some feedback resistor still needs to change? It will be interesting to see the overall current consumption once you optimize it.

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Hi @carlrowan ,

the battery chemistry can be configured for lipo/lifepo4 by connecting a solder jumper, but probably it can be done via GPIO letting the pin to GND.
As for the consumption, I have measured diffrent boards and setup getting readings between 350 and 450uA. Actually the buck-boost is not a specifically low-power one, but this might be upgraded soon.

As a comparison I have tested the RAK3172 evaluation board mounted on RAK19003 and running the RUI3 “System_Powersave” example. This combo resulted in about 250uA. Can it be optimized any further? or maybe I missed something :upside_down_face:

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