6S vs 4S LiPo for FPV Drones: Which Battery Voltage is Better for Efficiency and Performance

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If you are simply starting with 5-inch FPV drones, you may discover it challenging to choose whether to utilize a four or six LiPo battery. In this post, I will describe the distinctions and assist you make a notified choice.

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Further Reading: New to FPV drones? Take a look at our beginner’s guide.

Pro Tip: Betaflight has introduced a new feature that enables powering a four quad with a six LiPo battery by lowering motor output.

Here’s a list of my favourite 6S and 4S LiPo batteries

Benefits of Six Over FOUR

A six LiPo battery has a 50% greater small voltage than a four due to 2 additional cells. The optimum voltage of a six depends on 25.2 V, compared to 16.8 V for a FOUR.

The prospective enhancements from utilizing a six over a four consist of (a few of these points might be up for dispute):

  • LOWER amp draw
  • LESS voltage droop
  • LONGER flight time
  • MORE nimble and responsive efficiency

Lower Amp Draw?

One of the most substantial benefits of six over four is the lower present needed to produce the exact same power.

Power is voltage increased by present: P = V x I

For example, to produce 1000W, it takes almost 60A on four (at 16.8 V) while it’s just under 40A on SIX (at 25.2 V).

Lower amp draw leads to:

  • Less tension on the battery
  • Reduced “voltage droop” throughout the flight
  • Less energy loss in the wires due to resistance, though this is typically minimal

Check out some DVR video footage of a six quad:

Is Six Better for Your Battery?

The lower amp draw implies your batteries run cooler throughout flight, which is useful for battery durability. This likewise enables the usage of lower C score loads for the exact same power, possibly conserving expenses by choosing cheaper cells.

However, to match the weight of a four battery, we typically select lower capability batteries, which can restrict the maximum discharge current, given that battery capability is a consider optimum discharge present. Greater C score loads may still be required.

 Max Discharge Current = C Rating x Battery Capacity

Responsiveness

Due to less voltage droop under load, the motors keep constant velocity, allowing them to alter RPM more quickly and regularly. This leads to a total more nimble and responsive airplane. The faster RPM modification rate substantially impacts the handling of your quad.

Higher Efficiency?

There’s a questionable theory that a SIX FPV drone uses longer flight times than a FOUR.

This isn’t always real, as we typically choose six batteries of comparable weight or watt-hours (Wh) as four batteries. To accomplish comparable speeds on a SIX, the motors require to spin at similar RPMs, needing a comparable quantity of power. In theory, flight times must be similar to those of a Four when flying at the exact same speed.

Longer flight times with a six are possible by lowering motor power (e.g., utilizing lighter props or adjust a less aggressive flying design) or utilizing bigger battery loads with greater energy capability. Either method will undoubtedly affect airplane efficiency.

The advantage in flight time is most likely to be seen in AP (aerial photography) platforms, where motor speed is more constant, and fast RPM modifications like those in racing drones are less regular.

But why exist individuals declaring they are getting longer flight time on six than four? Possibly it’s due to the lower present in the system, which causes less get too hot and in general greater performance. This advantage may not be obvious.

Is Six Faster?

A six quadcopter, with specifically picked elements, definitely have some benefit over a FOUR (as shown by many expert racers have actually now changed from four over to 6S batteries). In drone racing, race tracks typically include many turns and gates, needing as much pilot ability as raw speed, if not more.

The lower present draw and lower voltage drop of sixes offer racers more space to explore motor and prop mixes. This versatility permits more tactical options in discovering the very best balance in between performance and efficiency based upon the particular race course. When choosing motors for a SIX FPV drone,

Choosing Motors for 6S

There are 2 sides to the argument. Some suggest lower KV motors to match the theoretical max RPM of 4S-equivalent motors, while others recommend utilizing comparable KV motors as on four to totally make use of the additional power from six batteries.

I will explore both concepts in my screening.

Lower KV Motors For a more secure and more effective setup, select a low KV motor that supplies a theoretical max RPM in the exact same variety as a comparable four setup utilizing a typical KV ranked motor. FOUR– KV FIVE– KV
SIX– KV RPM (VxKV) 2300 1840
1533 38640 2400 1920
1600 40320 2500 2000
1667 42000 2600 2080
1733 43680 2700 2160
1800 45360 2800 2240
1867 47040 2900 2320
1933 48720 3000 2400
2000 50400 3525 2382

2350

59220

With more volts in the system, you can perform the KV better. You may require even a little lower KV than computed to accomplish the exact same RPM in flight. 1600KV on Six may correspond to not 2400KV on Four, however in fact a little greater such as 2500KV.

Here are my motor recommendations As KV boosts, the torque score is stated to reduce. From my observations, voltage droop is a more prominent element, avoiding you from reaching the theoretical max RPM on Four. That may be why some individuals declare six feel “more punchy”.

With a six setup, I likewise observed the capability to swing a much heavier prop better (e.g., greater pitch props). The majority of high KV motors would not have the power to swing a heavy prop at high RPMs like on the Six setup if I were utilizing a Four LiPo.

4S motors (2350KV) on 6S batteries Running Six LiPo on Four Motors

I evaluated

.allows you to power 4S quad with 6S LiPo by setting motor output to 66% These motors are thought about ultra high KV for six, and they did supply harsh straight-line speed and remarkable cornering. The drawbacks were substantial: extreme voltage droop and awful inadequacy. The motors likewise ended up being exceptionally hot after a brief flight. Personally I would prevent utilizing four motors on six batteries, motors might quickly get harmed.

However, Betaflight uses an option to decrease motor output, which

.

How About five?

Well, the cell count and voltage of five remain in between those of four and six, so you can anticipate its efficiency to likewise be intermediate. Four and Six batteries are more extensively offered, making Five batteries fairly uncommon.3S and 4S Conclusionhttps://oscarliang.com/8s-fpv-drone-2023/

Personally, I choose six mainly for the lowered voltage droop. Apart from that, I do not feel it’s substantially various from four in other element. Oh, the number of individuals still keep in mind the conversation back in 2014/2015 when we were choosing in between

  • ? It appears we are still going up in voltage. Possibly in the future, eight or perhaps 12S will end up being typical– who understands?:-RRB- Update– Here’s a brand-new short article going over the possibility of utilizing eight Lipo in FPV drones in 2023:
  • Edit History
  • Feb 2018– short article produced

Jan 2020– included information about running six on four motors(*) Dec 2023– upgraded short article(*)

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