I am trying to power Photon with a 3.6V rechargeable battery.
To charge the battery I am using
TP4056 module http://lygte-info.dk/review/Review%20Charger%20TP4056%20UK.html
Am planning to connect the Bat+ and Bat- of TP4056 module to the battery + and - terminals and also to 3V3 and GND of Photon. I am trying to power the Photon with battery and also directly from TP4056 module if and when it is plugged in.
Do you think this would work or am I going to blow up my dear Photon?
@shregz, you cannot connect the battery directly to 3V3 of the Photon as you will exceed the maximum voltage allowed. You will need to connect the battery to Vin of the Photon, possibly using a boost converter (up to 5V) or to 3V3 via a buck converter (down to 3V3). 
Ohh bummer!! Thanks Peekay … and what about TP4056 module? Can I connect its output terminals to power up photon? And can you suggest a boost converter?
Also be careful feeding the Photon low input voltages. It has been reported that when a battery gets close to empty and the voltage starts dropping that this can cause the Photon to fail and not recover. It will show a dim lit blue LED on PIN 7 and that’s it. Some people can recover from this and I have also and sometimes the Photon will not recover which just happened to me the other day.
I’m not sure what causes the failure other than the low voltage input.
@shregz these two units from Adafruit do both charging AND boosting:
Hello,
I am also trying to use the TP4056 module to power my photon with a chargeble portable 3.7V 1S Li-Po battery.
Differently from @shregz, I wish to directly connect the out of the TP4056 module to the VIN and Ground of my Photon. Which will allow me to power the Photon and charge the battery when connected with a 5V 1000 mAh adapter and to run off the battery when the TP4056 is not connected to a power source.
I was able to power the photon with the TP4056 both plugged and running of a Li-Po battery. However, I noticed when running of the battery the V OUT started at 4.2 V and was dropping near 3.7V where as it should be stable 4.2 V. I disconnected the battery when the voltage drop to 3.7V to not damage the Photon.
My concern is the compatibility and would like to get your opinion @peekay123.
I checked the adafruit chargers you have shared but they are a bit inaccessible where I am currently due to no local supplier.
@cem.nura the TP4056 is not a good choice as it only provides 4.2v and is designed to charge a battery and not drive a load simultaneously. You need a circuit that can charge a battery and output 5v for the Photon. Which suppliers to you have access to (Aliexpress? Digikey? Others?)
Thanks @peekay123 great to know that the TP4056 is not a good choice.
I will try to obtain a adafruit charger you recommended.
In the meantime I found a SparkFun Photon Battery Shield and will prototype (perhaps use) for my project.
Also, I might be consider to upgrade to a GEN 3 Argon which has a bult-in Integrated Li-Po charging and battery connector. Which would be very convenient.