In this post I will test various 18650 Li-Ion batteries and decide which one is the best 18650 battery for low current application. For example, powering equipment in drone racing and FPV, such as your FPV Goggles and radio transmitters.
Since I will only be using these 18650 batteries for low amp applications, I am not too concerned with max discharge current. Anything that can supply a steady 5A current would be more than enough.
I will focus on verifying the actual usable capacity of the batteries. And I will also try to test at least two different samples for each battery to get a more objective overview of the quality.
Further Reading: What’s the best battery for FPV goggles?
What’s the Best 18650 Battery
Please note the testing was to find the best 18650 batteries FOR MY OWN USE, I am only sharing my experience and results as I thought some of you might find it useful.
Here are some other great 18650 for long range flying:
Panasonic NCR18650B 3400mAh:
- Amazon: https://amzn.to/2W93Uwp
- GetFPV: https://oscarliang.com/product-h1sg
Molicel P26A/P28A 18650:
- RDQ: https://oscarliang.com/product-1np7
- GetFPV: https://oscarliang.com/product-ghz0
- Amazon: https://amzn.to/3A99ocl
Sony VTC6 18650:
- Amazon: https://amzn.to/3zMZfSm
- GetFPV: https://oscarliang.com/product-rlio
Table of Contents
Test Candidates
I have selected these batteries because of their high capacity and good reviews. I will surely test some other batteries in the future, please let me know what you want to see tested in the comment.
| Image | Name | Seller | Price | Weight |
 | Panasonic NCR18650B 3400mAh | Amazon | $7 | 45.8g |
 | LG MJ1 3500mAh | Amazon | $7 | 46.2g |
 | Samsung 30Q 3000mAh | Amazon GetFPV | $6.5 | 46.1g |
Test Method
I will charge these batteries to 4.1V, then discharged them down to 3.1V with a constant 2.3-2.4A current. Data is recorded every 3 minutes, including the voltage and “mAh drawn”.
Why 4.1V and 3.1V?
You get much more cycles from 18650 cells if you use them between 4.1V and 3.1V. By charging them up to 4.1V you get roughly 2000 cycles, and that number drops to about 500 if you charge them to 4.2V.
This is what my iSDT SC620 charger does, it only charges Li-Ion batteries to maximum 4.1V. And 3.1V is the recommended “safe minimum” voltage for Li-Ion cells.
Results and Findings
I seemed to get more charge out of the Panasonic than the LG despite the lower rated capacity. And as expected, the Samsung 30Q provides the least usable capacity.
Note that we are not getting the advertised capacity because we are not charging and discharging the cells to their maximum and minimum voltages.
The Panasonic lasted the longest until the voltage reached 3.1V.
| Rated Capacity | mAh bet. 3.1V-4.1V | Duration | |
| Panasonic NCR18650B | 3400mAh | 2447mAh (72.0%) | 64mins |
| LG MJ1 | 3500mAh | 2377mAh (67.9%) | 62mins |
| Samsung 30Q | 3000mAh | 2212mAh (73.7%) | 58mins |
Interestingly, the cells with higher capacity appeared to have the worse voltage sag during discharge, i.e. lower C-Rating. (Maybe that’s why 18650 batteries with high discharge current are usually lower in capacity?)
Conclusion
The weights and prices are very similar between these batteries I tested so far. Purely base on the result of this test, the Panasonic NCR18650B seems to be the best 18650 battery for low current application in FPV. They are the lightest yet they have the highest usable capacity. The LG MJ1 is not bad either, given the higher “C Rating”.
Beware of Fake 18650 Batteries
Some batteries can have exaggerated capacity, it’s rare to find batteries with capacity over 4000mAh. If you find a battery that claims to provide 10000mAh, it’s mostly likely to be fake (in some cases these turn out to be only 500mAh :) )
- Buy from reputable sellers, check out reviews before purchasing
- Fake 18650 batteries generally weighs less! The good ones I have come across all weighs around 40-50 grams while the fake ones weigh only half of that at around 25 grams
Charging 18650 Batteries
It’s recommended to charge your 18650 Li-Ion batteries with a dedicated Li-ion battery charger, like the iSDT C4 charger.
However you can also charge them with a LiPo charger if they support Li-Ion battery. In order to do that, you can connects the cells in series, this will allow you to charge multiple batteries at the same time – just less hassle and faster.
Solder Wires Directly to Batteries
I don’t recommend soldering directly on the battery’s terminals, because overheating batteries can result in fire and explosion. But if you must, here are some of my safety advice how I personally do it.
Build a DIY Case
Instead, get a battery holder and solder the connectors to it.
For example, here is how to make a case to connect 2 individual cells in series, and turn them into one single 2-cell battery. Parts list:
- 2-cell 18650 battery holder: Amazon | Banggood
- XT60: Amazon | Banggood | GetFPV
- JST: Amazon | Banggood
- 5.5mm Barrel for FPV Goggles: Amazon | Banggood | GetFPV
- 2S Balance Lead: Amazon | Banggood
Pick whatever discharge connector you prefer, but you must connect the balance lead for charging. You can actually use this case to power your goggles!
You can use larger cell holder and build a 3S or even 4S case, it’s all up to you.
When charger, remember to…
- Change battery type to “Li-ion” before charging
- Only charge at 0.5C or lower to minimize the risk of fire
21 comments
Hi Oscar,
What’s your recommendation for using 18650 batteries with the DJI Goggles v2? I have the DJI Goggles v2 with the BDI Analog adapter and wanted to know if using 18650 batteries would be a good option, since I have a couple laying around. Do you still recommend 18650 batteries for someone starting out or do you recommend a cable that can regulate the voltage?
Thanks!
I made a 4S 18650 pack to power it: https://oscarliang.com/li-ion-battery-long-range/
Thank you, very useful. I have some experience with the “Panasonic”. I wonder “how” you charge. My charger do it up to about 4.2v, batt will be soon only 4.1v. 3.1v is close to zero. I want also find the balance between used capacity and lifetime. The complete discharge I fear more then the upper end. Get some Panasonic with real 3200, 3300 usable C. Drain moderate, around 0.3 C. Sample nominal 12v LED tube lamp 60cm. “Mystyle” emergency lamps. (3 batt, 3 hours. More power failure? Click next batt pack in.)
To all the naysayers….soldering directly to lion cells is possible and can be done safely. It’s takes the combination of soldering experience and the right equipment. I would never recommend it to anybody with little soldering experience. Soldering is something that can be taught but there aren’t many classes that teach soldering. Most learn from experience, over time you will realize what works and what doesn’t. My biggest ah ha soldering moments were discovering rosin flux, makes a huge difference. Another was buying a proper temp regulated soldering iron. I now recommend the TS 100 for general soldering. For soldering 18650/27000 cells I recommend a large soldering iron. The thermal mass and high temperatures of an iron starting at something like 80W will make the time spent soldering the cell very fast. Less time on the cell = less potentially damaging heat transferred into the cell. With skill/experience and a proper tools a perfect solder connection can be achieved in under a second. Personally, I feel a properly soldered connection will be superior and have less resistance to the spot welding that seems to be the standard probably because it’s easier to automate and is faster and safer when done manually by semiskilled assembly line workers.
I’ve run into something strange with 18650s and FPV equipment. In my case I ordered some Skyzone Cobra box goggles, but the 18650’s I ordered from amazon didn’t fit into the battery bay. It appears there are different lengths of 18650s out there, and the skyzones require the smaller variant.
I wasn’t able to use the batteries, and I finally found a set that fit in size (Sony VTC4), but the process was frustrating.
Have you run into much equipment which requires the smaller / larger configurations exclusively? I’m curious if there’s an easy way to tell which variation is required, or how to spot the difference when shopping online.
I think what you got is the “protected” version of 18650, aka “button top”. You should always get the “unprotected” ones aka “flat top” which is slightly shorter, and these are actually more common.
Just check the product pictures, if they have extruded terminal (the positive end), and they should also mention “protected” in the description, these are the type you should avoid.
I’m in the process of getting all the parts for my first fpv racing quadcopter and I’m getting the taranis x lite pro transmitter which takes the 18650B but my question is do I get protected or unprotected? I’ve read that protected can just cut out from spikes but they where being used in a plane not a transmitter so I’m only assuming that a transmitter wouldnt get a spike and just turn off . Also I’ll be getting fatshark goggles which also takes them but do both protected and unprotected fit in the case?
Hi Oscar,
i’m new to lion cells and need your suggestion here. Does it make sense to buy lion cell with protection pcb’s installed or do you prefer ones without that built in protection? I will use my isdt or hota d6 charger in combination with a charger tray and a balancer connector as you described already in your article.
Regards Thomas
Without protection is easier to work with, and more commonly used in the hobby. All 18650 cells i personally use are without protection.
Great article.
If someone can not calculate the pack or want to make it easier :)
I suggest install the Android app: “Battery pack calculator” (calculates: voltage, capacity, energy, discharge current, etc.) up to 9999s 9999p packs. Built-in database of 37 popular, branded batteries and the ability to define your own battery cells. play.google.com/store/apps/details?id=pl.freshdata.batterypackagecalculator
I use a 2s pack of 18650 sony vtc6 3120mAh to fly with a 5″. (the auw is 270gr, the battery 100gr). Motors 1306. About more than 20 min of soft flight. In Last flight the max power from all motor was 15a. Below 5.5v you must land or the quad “land” for you.
And i use a 2s pack 18650 panasonic 3400 for the glasses. And another for the transmitter (Taranis q7x), but in this case i need to do more tests for if there are effects in power transmitted .
Don´t like lipos, and thanks to electrical-smokers, there are powerfull 18650 models today.
You stated a constant 2.3A draw in your method. Is this comparable to real world use with goggles & receiver?
The time of 64mins seems low, im sure I use my goggles for several hours in an afternoon flying. So Im wondering if the amp draw in the test is higher than general use?
FPV goggles draw far less current than 2.3A, under 1A I would say.
For NCR18650B, the website says unprotected. What is the meaning and the risk of having unprotected li ion (use for fatshark battery)?
Once again – great article here! I started to use 18650 cells in fatshark battery cage. first ones I got were horrible (only around 1000mah instead of 3000mah.
The new ones I bought are Samsungs – and they are around 2500mah wich is fine.
I will show this in a video soon since I tested the isdt C4 – which is a great charger for cells!
Soldering to battery will generate a lot of hot. Especially if you don’t know what you are doing. Heat is bad for the battery. In addition, it will cause the battery to puff. Unlike the Lipo we use that is encase in slightly expendable wrap, Li-io is encased in a hard case. It can explode or cause fire.
That is why manufacturers do not solder packs together. They use spot welding.
Can you go into detail why one should not solder directly on the battery?
Placing a lot of heat on the battery is not good.
I don’t think there is anything that needs to be changed. The whole purpose of this test is to find the battery that can give me the longest battery life for powering my FPV goggles, and it did.
Meaningless? Please read my post again, there is so much info you can extract from those graphs.
This test was meant to determine the best battery for my own use, I am only sharing my result because I thought someone might find it useful. Take it as a grain of salt if you don’t think it’s good enough for you.
You don’t need to set the charger to li-ion, regular lipo setting works fine on 18650’s, they can handle 4.2v max no problem
I haven’t verified this myself, but I read somewhere you get more discharge cycles out of the battery if you charge them up to lower voltage such as 4.1V vs 4.2V… The difference is 800 cycles vs 400 cycles.