18650 Brings ESP8266 WiFi Repeater Along For The Ride

We’re truly fortunate to have so many incredible open source projects floating around on the Internet, since there’s almost always some prior art you can lean on. By combining bits and pieces from different projects, you can often save yourself a huge amount of time and effort. It’s just a matter of figuring out how all the pieces fit together, like in this clever mash-up by [bethiboothi] that takes advantage of the fact that the popular TP4056 lithium-ion battery charger module happens to be almost the exact same size of the ESP-01.

By taking a 3D printed design intended to attach a TP4056 module to the end of an 18650 cell and combining it with an ESP8266 firmware that turns the powerful microcontroller into a WiFi repeater, [bethiboothi] ended up with a portable network node that reportedly lasts up to three days on a charge. The observed range was good even with the built-in PCB antenna, but hacking on an external can get you out a little farther if you need it.

While it doesn’t appear that [bethiboothi] is using it currently, the esp_wifi_repeater firmware does have an automatic mesh mode which seems like it would be a fantastic fit for this design. Putting together an impromptu mesh WiFi network with a bunch of cheap battery powered nodes would be an excellent way to get network connectivity at an outdoor hacker camp, assuming the ESP’s CPU can keep up with the demand.

28 thoughts on “18650 Brings ESP8266 WiFi Repeater Along For The Ride

  1. If you wanted to implement this as a “throwie” to leave a breadcrumb trail of repeaters you weren’t sure you were going to get back again, you might want a cheaper battery. It came to my attention that disposable vape pens actually have Lithium rechargeable in. Ergo, you might ask around, advertise, place a drop box etc to collect dead ones and repurpose the batteries.

    In such a case, you maybe just want a stiff wire antenna cut to right length rather than the one shown also.

    1. Vape pen batteries are tiny though. ~6cm x ~7mm. You’d only get wifi for an hour or 2 before they’d die. (I used to harvest them, but they’re of limited use)

  2. This is a very interesting concept as these things are essentially $1 each! I wonder what the possible bandwidth is. Can’t be much more than a couple single digit mbits, right?

          1. How about “$30 an hour”?

            On the other hand, not everyone has the visual acuity or the fine motor skills to make those joints reliably.

            I have taken to using a wire-wrap tool to connect (reversibly) to these development modules when I’m not using a breadboard.

  3. Now this I like. Add in a solar charger, and you have a repeater to get wifi down to the end of a long garden.

    Leave a trail of these in ziplok bags (or even encapsulated in resin), and you have communications from the depths of a cave/mine – or even access to a filesystem running from the 12V battery of a car.

    The possibilities are almost endless.

  4. My most recent project is powered by a 18650 from a solar motion sensing light… You can get them on aliexpress for ~50¢ each, comes with a small solar panel, 18650, a case and a bunch of leds… Along with their board that might have a moron sensor worth harvesting…

    Add an esp01 and an antenna for a buck or so and you’ve got a ~$2 system that is capable of solar recharging…

    Build a bunch of them and add in a few magnets slap them on the back of street signs and you’ve got WiFi all down the street.

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