ESP8266 nodeMCU external power source

I am currently using the ESP8266 nodeMCU wifi module for my thesis project but I'm currently struggling to find an appropriate battery source for it. I will be using it for a wearable fall-detection device and was planning on a rechargeable coin cell battery but there are non available here in the Philippines. My last resort is a 9v battery, but that would need a voltage regulator, making the board very big and bulky and not advisable for wearable devices. Hoping for any suggestions regarding this matter.

Li-ion or li-po or LiFePO4 batteries?

With li-ion and li-po, the voltage when fully charged is 4.2V, which is too high for the esp chip, so a voltage regulator will be needed. To maximise battery life, this should be a low-dropout regulator. Unfortunately, the regulator on the nodeMCU boards is not a low-dropout, so you would need to bypass it. A Wemos mini would have been a better choice, because it's regulator is low-dropout.

With LiFePO4, the fully charged voltage is around 3.6V, so this can power the esp chip directly (bypassing on-board regulator) with no regulator.

Look for one of these. Cheap, simple, can charge from a laptop or phone charger.

5v Battery Pack

PaulRB: Li-ion or li-po or LiFePO4 batteries?

With li-ion and li-po, the voltage when fully charged is 4.2V, which is too high for the esp chip, so a voltage regulator will be needed. To maximise battery life, this should be a low-dropout regulator. Unfortunately, the regulator on the nodeMCU boards is not a low-dropout, so you would need to bypass it. A Wemos mini would have been a better choice, because it's regulator is low-dropout.

With LiFePO4, the fully charged voltage is around 3.6V, so this can power the esp chip directly (bypassing on-board regulator) with no regulator.

Li-ion battery since it is the most available here.

I looked up the LifePO4 battery available here but there are only "4S 30A 12.8V W/Balance LiFePo4 LiFe 18650 Battery Cell BMS Protection PCB Board" kinds of LiFePO4 batteries. Would this be sufficient?

No, the LiFePO4 batteries I am suggesting have a maximum voltage of 3.6V. Any voltage higher than that would have to be regulated and that would waste most of the energy.

LiFePO4 without 3.3volt regulator would be fine for a bare ESP-8266 module,
but OP is using a NodeMCU (with onboard voltage regulation).

Then a more commonly available (and probably cheaper) LiPo battery would make more sense.
Connect a LiPo to the V-in pin. (a LiFePO4 could be connected to 3.3volt directly).
Leo…

Wawa, I disagree with your advice about LiPO and I think you are missing my point about LiFePO4.

LiFePO4 batteries have a maximum voltage that is within the allowed range of the esp chp. The OP could power the chip directly with this battery via 3.3V pin, bypassing the on-board regulator. Regulators inevitably waste power, so avoiding their use can extend battery life.

With Li-ion or LiPo, the maximum voltage is above the limit for the esp chip, so a regulator is needed. However, the voltage drop of the nodeMCU's on-board AMS1117 regulator is at least 1.1V (and they have the cheek to call it "low drop-out"!) so these batteries won't have enough voltage to run the esp chip via the Vin pin.

My alternative suggestion to LiFePO4 was to use Li-ion or LiPo but using an external truly low drop out regulator such as mcp1700 (drop out around 0.2V). Or use a Wemos mini instead of the nodeMCU, because the Wemos' on-board regulator is low drop-out.

No, I didn't miss the point Paul, and I do agree that the LiFePO4 is power-wise an economic solution. But LiFePO4, and the charger for it, might be harder to get where you live.

The NodeMCU uses AFAIK an SPX3819 low dropout regulator (~0.2volt at the current of a NodeMCU). So LiPo on V-in shouldn't be a problem.

For a bare ESP8266 module I would definately look at LiFePO4. Then you don't need to bother about voltage regulation. Leo..

NodeMCU does indeed have a regulator onboard, hence why I suggested the small 5volt pack. It's about the size of half a cigar. I use them all the time, with sleep mode they run for a day or so easily.

It has a mini usb socket and regular usb on it. Comes with a short usb power cable that connects directly to the nodeMCU. Easily disconnected and charged.

Wawa: The NodeMCU uses AFAIK an SPX3819 low dropout regulator (~0.2volt at the current of a NodeMCU). So LiPo on V-in shouldn't be a problem.

Leo, I sincerely apologize. The schematics I can find do indeed show SPX3819, not ams1117. I was certain it used ams1117. Perhaps some versions from some manufacturers do. I can find some references to replacing the ams1117 on nodeMCU with other regulators, and pictures that show ams1117 being removed from the board. Oh well.

I agree, with a SPX3819 regulator, the OP can power the board using Li-ion or Li-Po.