One of the first things people notice when they start the hobby is that quadcopters or “drones” don’t have a very long battery life! The reasonable question of how to increase flight time comes up and that is what we are exploring today. There are some obvious factors that contribute to your flight time. We will be exploring these, as well as some others that you may not have considered, in a effort to increase your flight time.
So, how can you improve your drone flight time?
The easiest way to increase your flight time is changing the way you fly. Just like when driving, if you accelerate rapidly and frequently or generally fly with high throttle, you will burn through your battery pack faster. So by flying gently, with slow forward motion and soft turns, or sticking to hovering, you can increase your flight time! The trouble with this is that unless you are capturing an atmospheric aerial shot, it’s not much fun! So what other options are there?
Changing your drone/quadcopter battery to improve flight time
Since our drones use battery packs with a finite capacity, once this is used up we have to land. To fly longer, there are two main things we can change in relation to the battery:
Size – this is the most obvious as the more capacity your battery has, the more time you have in the air, to a point! Going too large will make your miniquad difficult to handle and you will have to hold a higher throttle point just to hover. This is because with increased capacity comes increased battery weight. However, getting your battery size just right will mean you have more time in the air, without making the drone too slow or sluggish. A common change on a racing drone is to swap from a 1,300 mAh battery to an 1,800 mAh battery (a good option is the Infinity 1,800 mAh 4S).
Peak discharge capacity – An alternative option to using a larger battery is to use a battery with a higher “C” rating (read more about that and batteries in general here, in my LiPo guide), as this will cause the battery to maintain its voltage for longer during punch outs. This is only worth considering if you do lots of punch outs or find yourself landing because the voltage sag in your battery is the reason you are landing. A good example is if your battery alarm is going off, but after landing your packs regularly go back up to 3.8V or more. Batteries with a higher C rating are typically very slightly heavier than their lower C counterparts (when dealing with the same capacity), but the difference is so small it is unlikely you will notice any difference because of the weight. A higher C rated battery will still cause a low voltage alarm to go off when put under a high load, but is less likely to do this if there is still plenty of capacity. By using higher C rated packs, you can use more of the pack and so have longer flight times.
Changes to your drone/quadcopter that increase flight time
As well as changing the battery size and C rating, there are quite a few other influences when it comes to increasing flight times.
Weight – one of the best ways to increase your flight time is to reduce the weight of your quadcopter. By reducing the weight, less force is required to hover or accelerate and so less battery power is drained. Whether hovering or racing, reducing the weight will have a positive impact on your battery life. When racing around a track with a lighter drone it is easier to turn around corners and you can accelerate to top speed quicker. When flying forward you can consider there to be two elements of force acting on your quad. Vertical and horizontal. Vertically, the down force from your props mast match the gravitational force pulling your drone down. Horizontally, your props overcome air resistance acting against the body of your drone. With a lighter drone the vertical element is reduced, meaning you can tilt further forward without dropping. This means a larger percentage of your power goes into forward motion and you can fly/race faster for longer.
Props – the more blades your prop has and the higher its pitch, the less efficient it will be for most situations. Each prop blade tip creates trailing vortices when it moves through the air, wasting energy. The more blades your prop has, the more wasted energy. Props with two blades/bi-blades are considered the most efficient readily available option. Looking at the prop pitch, this should be selected based on how fast you are flying and may take some trial and error to get right. The flatter/lower pitch the prop, the less air it has to push out of its way when moving slowly or hovering. A good example here is a 5051 prop, which would be no good for hovering. Since it is working hard to push air out of the way, as well as down for thrust, a large amount of energy is wasted. In this case a lower pitched prop such as a 5030 or 5040 would be a better option. Where the 5051 option would be better is for fast forward flight. Here, the angle of the prop blade means that it carves through the air, generating thrust without the air getting in the way too much.
Motors – for efficient flight it is generally accepted that lower kV motors rated at higher voltages provide a better option. They are better suited to swing larger props and by being compatible with higher voltage battery packs, can benefit from these too. Running at a lower kV rating means that you have more control around the low throttle range, making control easier too. Motors can vary in price significantly, depending on their quality. Generally higher quality motors will not only last longer, but are more efficient. When selecting motors for increased flight time, it is worth considering both their weight and efficiency. You can read more in my FPV Racing Drone Motor Comparison.
Other smaller consumers – not so much. These draw such small amounts of power, that reducing their consumption would make little difference. However, depending on their age and size, there may be significantly lighter new versions available. Typically these will also offer increased functionality as well, so there are other benefits to upgrading. A good example here is the Eachine VTX03, which is a very small, lightweight transmitter. With adjustable power output and one button channel changing (rather than awkward dip switches) and an incredibly low price, it is a great option for anyone who hasn’t upgraded in the past year.
Closing thoughts
I hope that this has provided some ideas for your own drone customisation. Obviously there are lots of different ways you can increase your flight time and each one in isolation may not have a significant impact. However, when you make lots of small changes, you benefit from them all. So when you next build a quad, consider the props, motors and weight as well as battery size as all complementing each other.
If you have any improvements that haven’t been mentioned or want to ask questions about your own build, make sure you leave a comment or get in tough via the Contact us page.