I’ve been looking at drone battery warming bags charged by USB, on Amazon, and was wondering are they worth it, and if so, which one is best?
I had an experience this week where 2 batteries were charged to the same level, but the flight time of the first one was only around 24 minutes, and the second one around 30 minutes. The difference between the two was that the first battery was cold but the second had been in the pocket of my heated body warmer for around 30 minutes before the flight. Both batteries are less than 4 months old.
Thats a big drop in flight time. I think the flight itself would have more influence than the temperature, it doesnt take long for batteries to warm up when flying. How fast or agressively you fly and how much video shot etc… would have more influence. If you use air data you can dig into it a bit more and see your overall battery health and rates of discharge before you decide if its worth warming your batteries
The old Inspire used to have dedicated DJI battery heaters:
If you’re travelling by car to your flying location, keep the drone case in the footwell of the car with the heater on as you go. Only take the batteries out of the case when needed. And then keep them in your pocket
I think you might be paying a gimmicky price for a gimmicky heated drone battery case.
Use a DIY method as others have suggested, a regular Thermos sandwich bag will keep the heat in nicely, along with the hand warmer suggestion if you need to keep them warm for hours on end.
Yes, they work. I have an ISDT K2 Air charger for Lipo batts for my model RC aircraft, and the Internal Resistance (measured in milliohms) decreases when the batts warm up. Less resistance = better performance…as the folks on here racing drones will attest. The bags are a cheap solution to a problem - but check out the bags for the rc model plane hobby too as they’re defo not gimmicky and heated using Lipo’s
My rechargeable trimmer in our cold bathroom starts of low speed and after less than 20 seconds of use it suddenly speeds up.
This effect is also seen in electric cars… however some cars use their own battery to generate heat to protect the batteries… Ironically from the charge that has just been put in.
I dint think of but a heater for batteries specifically unless a good brand. I don’t like the thought of another source of electrical
stick them in your pocket 
