As Li-Ion cells have higher energy density than LiPo (more capacity mAh at the same weight), they make great battery for long range flying, in this post I will show you how I built a 4S 18650 Li-Ion battery.
Disclaimer: Soldering on battery is dangerous, if you decide to follow instructions in this post, do so at your own risk.
You can also buy this pre-made I believe, I will try to test some and see if they are worth recommending. For now I am making one with the cells that I trust :)
The Pros and Cons of Li-Ion Battery for Flying
Li-Ion battery has a higher capacity than LiPo for a given weight. The 4S 18650 3400mAh I built, only weighs 203g, while a 4S 1600mAh LiPo weighs nearly the same. On paper you should get double the flight time!
However, the maximum discharge rate of Li-Ion battery is not great compared to LiPo, that’s why it’s not a popular battery choice for FPV drones.
For long range aircraft which don’t require a lot of current, with an efficient power system, Li-Ion cells are totally fine.
In fact, Li-Ion battery is popular in wings as they only has one motor. It’s also possible to use on highly efficient quadcopters. I am currently testing a long range quad which weighs under 250g. With the 4S 18650 Li-Ion battery I built, i am able to get nearly half an hour of flight time :) It’s incredible!
The following photo is the wiring diagram of the Li-Ion cells, XT60 and balance connector. If you can understand this diagram, you should have an IQ in the top 2 percent :)
You can use other Li-Ion cells, but 18650 is the most common size and widely available online.
Sony VTC5A (US18650VTC5A) and VTC6 (US18650VTC6) are the popular choice and rated for 2600mAh and 3000mAh respectively. I think VTC5A has higher discharge rate but slightly less flight time. I am using Panasonic NCR18650B in this build log as I have some spare, and they do work like a charm for my setup.
Buy 18650 Batteries Here:
You will also need some wires (I am using 16AWG for the discharge lead and 20AWG for balance lead), as well as 5-pin balance connector and a XT30 or XT60 connector. XT30 should be fine, but XT60 might be more convenient if that’s what you use on the drone.
Buy XT30 Connectors Here:
Buy 16 AWG Wires Here:
Buy Balance Connector Here
Buy Heatshrink Here
- Transparent Heatshrink (get the 86mm)
How I Built 4S 18650 Battery
Solder wires to the connectors, I use longer wires than I need, and I can just trim them to the length I want later.
Soldering wires to the 18650 cells according to my wiring diagram. You should definitely check out my tutorial on how to solder 18650 batteries safely.
Here’s the top side.
Here’s the bottom side.
Cover all solder joints with electrical tape then finally wrap it in heatshrink. And yes, you can probably use a shorter discharge lead to save a couple of grams, I made it longer on purpose.
Even smaller than my 4S 1500mAh LiPo pack.
The 4S 18650 battery weights 203g, and I get about 30 mins of flight time from it on the Flywoo Explorer LR 4″: https://oscarliang.com/flywoo-explorer-lr/