When I started this hobby the thing that shocked me the most was how short flight times were.
5 minutes??? Sometimes more. Sometimes less.
To make matters worse, most people drive to a park or a field where they don’t have access to electricity to recharge their batteries.
Yes, you can buy a couple dozen batteries so you can get a couple hours of flying in. But what many people do is they make portable charging stations so they can stay out in the field.
A lot of DC input lipo chargers will work at 12 V. For example, the SKYRC iMAX B6AC V2 has an input voltage range of 11 V to 18 V.
This means you can use a lead acid car battery to power you lipo charger.
And because a lot of us drive our cars to get to where we want to fly, this has become a popular solution for charging in the field.
There are a couple options here.
- You can literally use your car battery.
- You can buy a separate car battery that you only use for charging lipos.
Option 1 is cheap. The only thing you have to worry about is killing your battery. By charging your lipos with your car battery you are, of course, discharging your car battery. Discharge it too much and your car might not start.
Option 2 involves buying another car battery, which can cost a lot. They are also heavy to move around. And if you are going to be regularly discharging it you are going to need a battery charger to charge it back up.
There’s one more problem with using a car battery for this.
Car batteries were meant to start your car’s engine. This means it needs a whole lot of current for a short period of time. Starting your car only discharges about 3% of your battery. This is the opposite of what you need when charging lipos … a little bit of current for a long time.
More on this in the next section.
Deep Cycle / Marine Batteries
As I mentioned above, car batteries aren’t designed to be discharged all the way and then charged back up.
Because of this a better solution would be to use a deep cycle batteries. Deep cycle batteries are designed with thicker lead plates that allow it to be fully discharged and fully charged for many cycles. This is ideal for field charging lipo batteries.
These are sometimes called marine batteries because they are used for things like trolling motors.
High Capacity Lipo Batteries
Deep-cycle lead acid batteries aren’t the only type of batteries that are made to repeatedly go through a charge-discharge cycle. Lipo batteries like we use on quadcopters are designed to do that, too.
This means they would be perfect for charging in the field.
The 2 things you need to keep in mind if you go this route would be 1) input voltage and 2) capacity. If you need a refresher on what those terms mean, check out my lipo battery guide here.
For input voltage, I would recommend using a 4s lipo for most DC chargers. The nominal voltage of a 4s battery is 14.8 V and this puts you right in the middle of the voltage input range for most chargers.
For lipo capacity, I would recommend the biggest you can afford. The higher the capacity, the more times you are going to be able to use it to charge in the field. This battery is 16,000 mAh.
The great thing about this solution is that you don’t have to buy an extra charger like you do with a lead acid battery. You can use the same charger that you would use for your quad batteries.
(One caveat with this … Some of these bigger batteries use XT90 connectors while smaller capacity batteries usually use a smaller connector, like an XT60. Again.)
There are a number of advantages to using a generator.
- You don’t need to worry about capacity. Most generators will be able to provide more than enough energy to parallel charge multiple lipos.
- Most generators have both an standard AC output and a 12 V DC output. This means you have more options for what charger you can use.
- You don’t have to worry about charging up yet another battery. All you have to do is fill it up with gas.
- Generators can be used for all sorts of other things: in emergencies if your electricity goes out, if you go camping and want to be able to do things like make coffee in the morning, etc.
There are some disadvantages, of course. They will be noisier than the other options (although not as noisy as you would expect) and they will be more costly. But other than that, they are a good option.
Find a field with electricity
The last option is maybe the best option if it is available. Find a place to fly that has electricity available. Some RC clubs may have fields that have electricity available. Or try to find a park that has publicly available outlets.
I’m sure there are other options that people have come up with for charging your lipos in the field. It’s a pretty common problem. Let me know in the comments if you’ve tried anything else.