Charging LiPo batteries in the field is an excellent way to let you fly for longer. I will share my field charging solution which I believe is better than buying more LiPo batteries in many aspects.
When I go flying, I can easily go though 20+ batteries in an afternoon with my 5″ mini quad. You can certainly buy as many batteries as you need for a single session. But I find charging in the field a more cost effective and practical solution. In this article I will explain how, and why.
Further Reading: How to choose LiPo batteries for Racing drone
My Field Charging Solution
- iSDT SC-200 Charger (Review)
- 6S 10000mAh LiPo battery (Buy: Amazon, Banggood, Hobbyking)
- XT90 to XT60 Adapter (Buy: Amazon, Banggood)
- Parallel Charging Board (Tutorial | Buy: GetFPV, Banggood, Amazon)
- Voltage Checker (Buy: GetFPV, Banggood)
How to Charge LiPo Batteries in the Field
Ideally you should have at least 8 batteries for this to work smoothly. You can make it work with fewer batteries, but you might have to spend more time waiting.
I prefer to parallel charge 2 batteries at a time at 2C, it should only take roughly 20 mins to complete. For example for two 4S 1500mAh batteries, I set the charge current to 6A.
It’s a good idea to leave your batteries to rest for at least a few minutes between discharging and charging . This will allow them to cool down and reduce the change of overheat.
8 Batteries Become 18!
Using this equation we can calculate the total watt-hour in a battery.
Energy (Watt-hour) = voltage x capacity
With a 6S 10000mah, you can charge roughly 10x 4S 1500mAh batteries.
25.2 x 10000 / (16.8 x 1500) = 10
So this whole setup is equivalent to having 18x 4S 1500mAh!
Okay, let me explain why I love field charging so much.
Field Charging is Cheaper
You can save money by buying fewer batteries. Using the Acehe Formula 4S 1500mAh ($36) as an example, you could save over 40%!
- 18x 4S 1500mAh batteries = $648
- 1x 6S 10000mAh batteries + 8x 4S 1500mAh = $388
Furthermore, you can make the most out of those batteries. LiPo batteries for racing drones have hundreds of cycles. Sometimes we buy so many we don’t use enough cycles to get the value back. The performance of LiPo also gets worse over time even if you don’t use them a lot (Internal resistance increase).
With field charging you will be using 2 to 3 cycles on those batteries instead of just 1 per session.
It’s not a good idea to leave LiPo batteries fully charged for too long for safety and to avoid performance degradation. It’s annoying to still have fully charged batteries left after a session because you need to discharge them if you are not flying any time soon.
Fear no more. With field charging you can “reverse charge” them back to the big battery, or any empty batteries.
You can also share your charging station with your friends. And you can charge other types of battery too such as your FPV Goggles battery.
The weight of a field charging setup is only slightly lighter than carrying the whole 18 batteries.
- The weight of 18 small batteries: 3.4Kg
- The weight of 8 small batteries + 1 big battery + charger + parallel charging board = 1512g + 1210g + 450g = 3.1Kg
The overall weight saving might not be a big deal, but it does take much less space. The 6S 10000mah LiPo is only slightly bigger than four 4S 1500mah.
Field Charging can be Safer
By keeping and charging a smaller number of Lipo batteries in the house, there is a lower chance of fire, statistically speaking.
Field charging might not be everyone’s cup of tea.
- You need a new LiPo charger, if you don’t already have one that support LiPo input
- All the arguments are based on the assumption that you fly a lot, e.g. 20 packs or more in a session. If you don’t fly enough then this might be less appealing to you
- In order to parallel charge, your batteries have to be at similar voltage level. That means you have to pay extra attention to the voltage while flying and decide when you should land. I found this is easier if you have a current sensor, and just monitor how much mAh has been consumed
Choosing a Portable Charger
First of all, you will need a portable charger that can be powered by DC. The input voltage range should be wide enough to support your choice of portable power source.
I particularly like the iSDT series (SC608, Q6, SC620) for charging LiPo batteries in the field because of their compact and light weight designs. They support 9V-32V input and come with an XT60 connector that allows LiPo batteries as power source. They are also great for everyday indoor charging.
Take a look at my LiPo battery charger recommendations.
Choosing Portable Power Supply
To power the charger without access to a wall socket and electricity, you’ll need a portable power source. Here are some common solutions:
|Name||High Capacity LiPo Batteries||Portable Generator||Deep-cycle Batteries||Solar Generator|
|Fuel||Rechargeable||Varies – Petrol/Diesel||Rechargeable||Rechargeable – Sun|
|Voltage||11.1V – 25.2V (3S-6S)||Varies – AC and DC||12V||Varies – AC and DC|
|Capacity||Low (10Ah – 16Ah+)||High||High (20Ah – 120Ah)||Medium|
|Weight||Light (1Kg – 2Kg)||Heavy||Heavy (5Kg – 35Kg)||Medium|
|Price||Cheap||Expensive||$50 – $300||Expensive|
It’s possible to use car battery for charging LiPo, but we don’t recommend it in case you kill it. We recommend using a separately deep cycle battery instead.
If you have a lot of batteries to be recharged in the field, or need to power multiple chargers, a portable generator is a good option. They are powerful and often have DC as well as AC output which is compatible with a wider range of chargers. But generators are noisier and more expensive than other options in our list.
Solar generators are another great option especially for sunny day camping/flying.
I personally prefer the simplicity of a high capacity LiPo battery which I can easily carry in my backpack.
- Jul 2017 – Article created
- Apr 2018 – Updated info about my own field charging solution and how it compares to buying extra lipo batteries