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Off-board battery only? Or on-board option?

A project log for LiFePO4wered/ESP32

ESP32 IoT core board with flexible power and flexible communications

Patrick Van OosterwijckPatrick Van Oosterwijck 08/20/2019 at 16:480 Comments

Since this board is squarely aimed at professional IoT deployments, my first inclination was that this would be a bring-your-own-battery type board like the #LiFePO4wered/Solar1.  Customers will most likely deploy this in the field with a sizable LiFePO4 battery such as a 10Ah or 20Ah cell, to be able to bridge many gloomy days when solar powered.

However, some users might be able to get away with much smaller cells.  This isn't just a solar board--when powered by PoE for instance, it's more likely there will only be short power interruptions and power will be present 99% of the time.

Also, since LiFePO4 cells aren't as common in the market as consumer-level lithiums, and I hope to eventually launch this as a product on Crowd Supply, I have to consider market appeal, out-of-the-box experience and ease of development as well.  I need to lower the threshold for adoption as much as possible.

So I'm leaning toward providing an on-board battery option too.  Looking at the #wESP32 for the basic floor plan and holding an 18650 battery holder by it, this is likely going to make my life difficult. :)  Considering the location of through-hole parts such as connectors, headers and Ethernet jack, the isolated PoE power island, and mounting hole options, there's really only one place where an on-board battery holder can fit.  And it's going to put one of the battery terminals in the opposite corner of the board from where the rest of the power system will most likely live.

But, I think it will be doable.  A long battery trace isn't going to be as big a problem on this board as it would be on a #LiFePO4wered/Pi+ for instance, because we're working with lower currents.  The ESP32 isn't nearly as much a power hog as the latest Raspberry Pi's are!

What do you think?  Should I go for it?

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