Updated: 3/30/2017 – Updated some text, including recommendations regarding LiHV batteries.
Updated: 10/15/2018 – Simplified the guide a bit, updated recommendations for 2018.
In the latest edition of our miniquad component buyers guide series, we’d like to talk about batteries. Specifically, what types of batteries you should be buying, what you should steer clear of, and how you should go about picking your flight batteries.
What does the LiPo battery I choose affect?
Two things – power and weight. The LiPo battery is the power bottleneck in the miniquad realm. This is because there is no sub-1500mAh LiPo battery on the market that can supply the electrical current required by today’s high-end motors. This shouldn’t be surprising – on high end quads we regularly pull 80-120A at full power, which isn’t much more than most full-size car starters. This load is put continuously on an incredibly small and light battery. This is asking a lot.
One problem with the battery world is that the manufacturers lie. All of them. They advertise discharge ratings that near the realm of “physically impossible”. If you were to expose your batteries to these types of loads they would at best fail early, but would be more likely to puff and eventually turn your quadcopter into an airborne fireball. The good news is that as long as you stick to a power system that has proven itself and buy mid to high-end batteries, you are going to be fine. The problem remains that, in the current world of LiPo battery marketing, it will be impossible to select the “best” battery without seeking out independent research.
One other thing to keep in mind is the equation for electrical power: P= I x V, (P) is power in Watts, (I) is current in amps and (V) is voltage applied. This is important for quadcopters because our batteries are current-limited devices. If you can use a higher voltage battery with your quadcopter, it will have access to more power and run more efficiently. Manufacturers cannot lie about voltage.
Weight is the other factor when choosing a LiPo battery. All things being equal, a heavier battery will deliver more power. This is because a bigger battery capacity-wise can be designed to deliver more current or because the act of adding more voltage means you add more cells to your battery. Both, obviously, add weight. If your miniquad is too heavy, however, your ability to make sharp turns or accelerate quickly will suffer. As with many things in life, this is all about finding a balance.
Energy Density vs Power Density
There are two LiPo battery performance figures that are always at odds when you are concerned about weight: capacity (or energy density) and the ability to deliver power (power density). Designers of LiPo batteries are given the option to design for high current deliver capability, high capacity, or anywhere in between at a given weight. Lithium batteries like those found in cell phones, cameras and laptops are generally the low power-density types. These devices do not draw a lot of current but seek to have long run times between charging. It is a very rare occurrence for one of these batteries to see >1 amp of load, and when they do, they often fail. On the other hand, miniquad batteries are designed to let go of their electrons as quickly as possible so that you can get that impressive “punch-out”.
What does this mean for you? Basically – there is no “free lunch”. Take, for example, the Turnigy Graphene batteries. While they can deliver a fantastic amount of current without breaking a sweat, they weigh in at a whopping 15% heavier than comparable batteries. Are the performance gains seen on these batteries enough to justify this weight difference? Probably not – unless you are on the bleeding edge. The point is that if you really want to min/max your quadcopter, you really need to take capacity, power delivery and weight all into account when comparing battery performance.
What makes a good LiPo battery?
- Battery Voltage or “S” – LiPo batteries are built by sandwiching several 3.7V cells in series — each one adding to the total voltage of the battery. The way to get increased voltage is to add additional cells. How many cells you have is specified by the “S” value of the battery. Here is the voltage lineup popular in our hobby:
- 3.7V (1S)
- 7.4V (2S)
- 11.1V (3S)
- 14.8V (4S)
- 19.5V (5S)
- 22.2V (6S)
When dealing with miniquads, you will mostly be using 4S batteries. This construction hits a sweet spot between size and weight that is hard to beat for our aircraft. It also matches the requirements put forth by most spec classes. Even if you want the more docile feel of a 3S battery, it would be better to go 4S and tune your quadcopter to behave more slowly. Many high end pilots fly with 5S or 6S batteries. Why fly with more volts? Increasing voltage is the preferred way to increase power. There is a reason why the electrical grid runs on hundreds of volts and not hundreds of amps – delivering power by using a high voltage is simply more efficient. Why then, are we not all running 6S batteries (or more) on our miniquads? A few reasons: (a) Because the form factor of most 6S batteries is atrocious (most resemble a cube). (b) Adding more cells adds more complexity and things that can break. (c) The ESCs and voltage regulators on our miniquads are often not rated for 22+V.
- “LiHV” LiPo – This is a type of LiPo who has had the cells conditioned such that they can take extra charge, resulting in an extra .3V per cell. This means on a 4S battery, you will have 1.2V more volts from a battery that is otherwise the same size as any other 4S. It means you get not only about 8% more power, you also technically get 8% more capacity as well. The biggest downside to these batteries is that they require a special charger. Charging a normal LiPo battery in LiHV mode can cause it to explode. For this reason, if you want to use LiHV batteries, we recommend you only use them. The same goes for standard LiPos. The other downsides of LiHV batteries is that they weigh slightly more, cost more, and seem to wear out faster on average.
- Capacity or “mAh” – This number tells you how long you can expect your battery to last. “mAh” stands for “milli-Amp hours”, or how many milli-Amps you can pull from the battery such that it will last for one hour. To determine how long your miniquad will fly with a given battery, divide mAh by your average current draw in Amps then divide again by 1000. This will let you make a rough guess of how many hours your battery will last – assuming you know how many amps your miniquad pulls on average.
When flying mini-quads, you will be using batteries between 1000mAh and 1800mAh generally. 1300mAh is the most common size used and offers a great balance between power capability and weight.
The “hidden secret” of Capacity is it also determines how much Amps your battery can produce as well as how long your battery will last. This is because the discharge rating is based on your capacity, see below.
- Discharge Rating or “C” – This is the batteries’ so-called ‘C’ rating. What it is supposed to tell you is how much current the battery can continuously discharge without damaging itself. In reality, though, these figures are almost always unrealistic. What this figure is is a good measurement of is quality among a manufacturer’s own line. E.g. if you are buying a battery from brand X, and 45C and 65C batteries are offered – the 65C batteries are the ones made from the cells most-able to handle high discharge rates like those seen in miniquad racing.
- Weight – Simply, how much your battery weighs. This is an important, often-overlooked factor to batteries. Many times batteries with the same capacity and C rating weigh much more than comparable batteries from another manufacturer. When you are talking about the single heaviest component of your miniquad, this is important to pay attention to. See “Energy Density vs Power Density” above for more details on weight.
- Price – An obvious factor albeit an extremely important one. You will be buying many batteries – more than any other part other than props. Finding a set of cheap batteries that work for you is really important. One piece of advice I have for those getting into the hobby is to buy just a couple of batteries to start with, then wait for a sale on one of the brands below to pick up the rest of your batteries. If you subscribe to the newsletters of any of the vendors that sell these batteries, you will see at least one on sale every month. That is when you should pounce, and pick up 4-6. This way, you can save $10-$40.
- Internal Resistance – A figure that is not often advertised by sellers. This is the underlying number which helps determine a LiPo battery’s “C” rating. It is determined by the chemical formulation of the battery as well as the overall quality of the manufacturing. Lower resistance is much, much better.
- Form Factor – Long, thin batteries are not ideal for most miniquads. Most miniquad frames are designed around batteries that are boxy and short in length.
- Connectors – Most mini-quad pilots use XT-60 connectors to connect their batteries to their miniquad. It helps a lot when the batteries come with these connectors already installed.
Should I buy discount batteries?
“Discount” batteries generally come in two forms: those with less “C” rating, and those that are unbranded or purchased from dubious sources.
The former, batteries with low “C” ratings, are generally OK to purchase for beginners. You probably won’t be doing any sick gravity flips or high powered climbouts in your first couple of months of flying, so it’s unlikely you will ever need the exra power afforded by a high quality 65/70C battery. That being said, you will eventually grow out of your beginner phase and want more power. Like many purchases in this hobby – the choice here will be dependent on how you intend to fly, how fast you intend to learn, etc.
Unbranded batteries are a little bit more of a wild card. Here you will have to do your own research. Search for the battery on RCGroups or your favorite social media and see if anyone has any experience with the battery you intend to buy. We actually recommend a few batteries that we would place in this bin below.
How many batteries do I need?
It depends on what you want to do:
I’m a total beginner: You should probably just get 1 or 2 batteries to start with, in case you don’t like what you picked. If you have the need for flight, consider picking up a couple of different types of batteries so you can try them all out and figure out what suits you best.
Fly for an hour or so at lunch every day: 3-5 batteries will probably satisfy your needs.
Attend fly-ins and race: A lot of time at races is spent waiting around for your chance to fly. As a result, you don’t actually need a ton of batteries. 3 at a minimum is a good rule of thumb, then go up from their depending on how much you fly at your field.
Fly all day long: This actually isn’t impossible. Consider than each LiPo battery will give you a 3-5 minute flight on a miniquad. Add another 2-3 minutes of ground time to swap the LiPo out after a flight and check everything out. If you have a multi-battery charger and a generator, you just need to have enough LiPos to make sure you don’t use them all within the hour time it takes to cycle a battery fully through a charger. So, conservatively you’ll want 10 batteries, but realistically taking into account crashes and breaks you will probably take, 6-8 will be sufficient to keep you going all day long.
Great LiPo battery brands to consider
So you know what to look for now, who do you buy from. We’ve picked out a variety of different battery brands that we have used or am familiar with and listed them below. We also have listed a comparison table at the bottom of the post if you are interested in specs. If you see any missing, feel free to drop a comment below.
HobbyKing is one of the best sources for batteries because they keep such a huge stock of them. Unlike other retailers, they will generally have a good stock of some variety of battery you need. They also come out with innovative batteries from time to time that are ahead of other manufacturers.
HobbyKing keeps a huge stock of batteries from numerous vendors. For miniquad pilots, we highly recommend the Graphene line-up. We’ve been using “Graphene” labeled batteries for years now. Despite being pretty heavy, these batteries can really take a beating and last considerably longer than any other battery we have ever used.
A brand sold out of the website DinogyLipos.com. These LiPo batteries are the only high-end batteries on the market to come with G-10 fiberglass plates on the top, bottom and sides of the battery. These plates not only protect the battery, but also reportedly improve performance and resist puffing. They don’t even come at a weight penalty – the latest Dinogy “graphene” batteries are among the lightest in their weight class.
Propwashed Best Value Pick
The Infinity brand seems to be a house brand for Banggood. As with most items you can purchase from this site, the prices here are a real bargain, especially for our international readers. We were a bit skeptical at first but determined in the end that the Infinity 70C Graphene LiPos perform just as well as other “Graphene” labeled packs – at a very low price, and without the weight penalty of the Turnigy Graphenes. For this reason, this battery is our new Propwashed Best Value pick for those looking for a bargain.
RaceDayQuads, or RDQ, sells some fantastic discount LiPos out of the US. These are probably the best deals you are going to get on high quality LiPos if you live in the US, and may even be a good deal for some of our international readers. We have had good experiences with both the “CNHL” and “RDQ” branded batteries found here.
GetFPV.com offers house-branded LiPos under their Lumenier label. Bench tests we have seen seems to indicate these packs are of average quality, though we have not tested them personally.
Rebel is a relative newcomer to the miniquad world, perhaps best known for their appearance in a dedicated Rotor Riot episode. Like SMC, they claim to give a “true rating” for their batteries and thus do not compare well with other manufacturers by reported numbers alone. They also have really catchy packaging!
Another brand that has a following in the community from other models – in this case RC helicopters. I have actually been generally pretty pleased with my Tattu batteries. They do not offer stellar discharge capabilities but they are consistent and last for a long time. My oldest 4S 1300 LiPo is a Tattu – and it has more than 100 cycles with no loss in capacity. I generally pick these up when they are on sale.
A famous “old school” brand in the RC community. These batteries are extremely expensive, have an inconvenient form factor, and have pretty dubious performance at best (3/3 of the batteries I recently received from Thunderpower during a recent winter sale had an un-matched cells). In my own experience, they are some of the worst batteries on the market. However, there are many out there who swear by them. Try them if you like.
Special Batteries – (TX/FPV Headset/Etc)
LiPos are not just used to power your miniquad, they are also used to power all your gear as well. When it comes to your gear, though, cheaper is always better. You get absolutely no performance gains from high quality LiPos when used in your radio transmitter or FPV goggles, so find the cheapest battery with the correct connector and voltage.
As I mentioned earlier, the only way to truly know that you are getting a good deal on a LiPo is to rely on third party reviewers. Much of my knowledge of how various LiPo battery brands compare with one another come from the fantastic battery tests done by RCDevotee. This post is aging but his conclusions and test methodology is still very relevant. I urge you to read over his mini-quad battery review part 1 and part 2 to get an idea of how these batteries stack up with each other.
Joshua Bardwell has also become a powerhouse in doing independent testing for LiPo batteries. He is funded through Patreon and patrons will generally send him batteries for testing, so he is generally quite un-biased. To get the most up to date comparisons, I recommend you check out his channel here.
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