Is using 6s Lipos on 4s motors using motor_output_limit a good idea? Bench Tested!
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- เผยแพร่เมื่อ 26 ก.ค. 2020
- After seeing a lot of people talk about running 6s batteries on 4s motors, I was curious enough to do a couple of bench tests specifically designed to test the benefits or disadvantages of running this setup. Join me in bench testing the efficiency and response of both 4s and 6s batteries on 4s motors.
- วิทยาศาสตร์และเทคโนโลยี
I've completed testing doing a direct head to head testing of 6s vs 4s motors for anyone interested: th-cam.com/video/Vy_JMJNG31Y/w-d-xo.html
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This is the data and tests we need in this hobby! I would love to see the comparison of equivalent 4s/6s motors. Thanks for the great video!
This is still a hot topic. I'd love to see low kV with 6S LiPo compared to high kV with 6S LiPo and reduced motor output. Great video btw 👌
Good to see you upload something again! Very informative and entertaining! Thank you!
If you posted regular content you would be so successful. Hey that landscape looks like my cottage!
Yo this guy deserves so many more views.
Please make more content! I love this stuff!
Entertaining, informative, and funny as hell bro! Great job!
Came here for the comparison between 4s and 6s motors, this was a brilliant part 1!!!
Your humour is underrated. You should have more subs.
Great video!
Great video. Yes run the comparison between the 4S and 6S motors that you mentioned at the end
This is a awesome video!!!!
Great Video! Thanks alot
thanks for the vid sir!
Amazing work. I wanted to by a 6S drone but it’s sold out so I’m thinking of getting the 4S version and putting 66%output limit and use 6S battery. But after watching this, I think I won’t. It’ll be less efficient and maybe destroy engine sooner due to increased heat. Ty for doing this work, you da man!
It would also be interesting to compare 4S with 5'' prop vs. 6S with 4'' props, with the same pitch and same motor kv.
For finding out, what combination leads to the highest top speed of the drone
Super informative. Thanks. Will I build a 4s build and still run 6s, heck yes😆
Great to see actual data on this rather than just opinion!
I'm in the market for new batteries - and will make the jump to 6S eventually - so now I'm wondering if it might be worth stealing a march and buying 6S for my next batch ...
Great video and exactly what I needed right now. I´m deciding if to buy or not to buy a set of new motors with 6S KV for one of two quads while I still run 4S batteries until they are worn out. After seeing this, it looks like dedicated 6S and 4S quads right now.
Surely I´m also interested to see the difference in "pure" 4S/6S setups in your testing equipment!
Just subbed!!!
Great test, although tbh I find very little difference in performance in flight using the motor output limit on higher kv motors...
This is a really great video! Thank you for this great comparison with equivalent conditions! And it was surprising for me and I still don't understand why 6s makes motor warmer. We have less amps for 6s so less heating was expected (according to P=U*I formula). Maybe it is because transient process (start and stop) ? Do you think if you run 5 min on 4s and 5 min on 6s - it would be the same temperature difference (more hot 6s) ?
Output limit works great flr me on 2550kv 6s , I can recommend it
Hmmm what if you under size the prop for special applications
Very informative tests. In real life though part of energy will get lost by voltage sag. So motors will be only ~15% warmer. No reason to deliberately build 4S quads for use with 6S batteries, that is correct. However many of us like me, have builds with 4S motors and a ton of spare motors. No reason to throw them out - better let crash and fry them with fun :D I will fly the rest of my 4S on 6S till they crumble.
Prop that you're using, is very noisy indeed. Used such props in my first quads 7 years ago - they was awfully loud.
There was still voltage sag in the tests. Any heat from the wiring/motors would sag the voltage. I agree on not throwing out motors though.
Excellent testing, Recursion! Would reversing the order of testing (e.g. 6s first) change the results because the 6s test starts off cooler? Followup study: would 4s achieve higher efficiency on low kv motors (designed for 6s)?
Great questions. You're right in that heat would taint the results since heat would add resistance to the motor. I made sure the motors were cooled to room temperature between tests. I also redid tests off camera afterwards to double-check results to make sure I didn't miss something, and they were the roughly the same. If I throw those on the bench I could always put 4s voltages in to see if they are more efficiency (they should be), but you'd definitely lose top end thrust.
@@RecursionLabs Brilliant. Thanks a lot for running this test and welcome back to making videos on TH-cam. I recently saw an ESC filtration test from 2016 and just realized that it was also made by you. PLEASE CONTINUE MAKING CONTENT!!!
Do you have a hypothesis for why 6s has a lower efficiency (and generates more heat)? I'm not a physicist or engineer and am befuddled by why wattage at the same RPM is different... in the ideal world, it would reason that since 4s is 2/3 of 6s in voltage, 4s should draw 3/2 the amps of 6s, but that's experimentally proven to not be the case.
Looking forward to seeing your 4s vs 6s respective motor comparison :D
Philip Lee Maybe the ESC can’t control the output as precisely as on 4s due to the higher voltage? Or the motor efficiency has shifted in the torque/speed plane due to the higher voltage?
@@brechtfpv7480 Yeah, interesting points. Now we gotta find a physicist who can explain the PDEs that govern motor output!
yes please
My 4s 5 inch quad is unflyable on 6s batteries. Motor output limit is correct. The weight is the same. It just overshoots and bounces back to the point of being unflyable and dangerous.
OMG, that is awesome testing rig/setup you have. On 4s motor like a 2507 1800KV motor, if you used the motor_output_limit, to bring the kv down to something like 1500; what would be the expectation of flight time?
motor_output_limit doesn't bring the kv of the motor down, it just limits the throttle % to the ESC that it will send, so 1-100% of throttle to the FC would be like 1-60% to the ESC if you limit it to 60%. The top end is the least efficient, so cutting it off when it's not needed would help (and increase your throttle resolution).
Make more videos 👍
Im not sure how exactly motor output Limit and the ESC's work. But if my understanding is correct:
an esc controlls the voltage given to the motors. An ESC does not control the RPM over Amps. The motors draw the amps they need at a certain voltage. U:R=I (volt/motor internal resistance= Current draw)
I'm thinking the motor output Limit on 6S set down to equivalant 4S should tell the ESC's to only output maximum ~14.8V.
Maybe the ESC's are less efficient reducing the power supplied by the LIPo. Okay. But in real flight the motors will have more constant thrust on 6S than on 4S with motor output Limit.
Why?: because of the voltage sag from the current draw. A 4S on full throttle and lets say 1V voltage sag per cell will only have 12.8V running the motors and give less max thrust.
Whereas on 6S there should be constant 14.8V on the motors.
Why?: because even under voltage sag on 6S there will still be 16.2V as reserve in the lipo. (Also assuming 1v sag per cell)
There was a guy testing this on his 4S quad and you could clearly see and hear there was more Power on 6S with motor output Limit.
Just one downside: the lipo will be heavier with same mAh capacity rating. If you go down to a lighter 6s lipo, then the voltage sag on the 6s lipo will be more, because for example 100C rating on 750mah are 75A and 100C on 550mah are 55A max current draw.
A good idea for a light weight 6S lipo are making your own 6S out of two tattu r line 550mah 3S lipos. Perfect on 1800kv 2004 motors.
By the way: 2004 motors or larger motors in general spinning small props have no benefit in thrust and just add extra weight. Unless you find that motor om really high kv and need larger lipos to handle the current draw. But there are no large motors available woth high kv for small props. It just doesnt make sence.
Thanks for the tests. Try some 1804 3500kv motors on 3~4 inch. They are great.
Or 1207 on 2~2.5 inch. Not efficient, but powerful.
I have a video with 1408 motors on 3", and they did produce a significant amount of additional thrust. Motor output limit just tells the flight controller to cap the throttle at a specific point then make 0-100% fall into that range. The top end takes the most current and where you'd burn them out if you went over the wattage limit for the motor. It does not reduce the voltage. If it did, then the tests would have been identical.
No fresh videos? Does this mean tu our hearing didn't come back? 🤔
I hope not! I've subbed!
I just finished doing some tests actually which I'll need to edit together. I only test when I have something I want to know that I can't find a good answer for instead of just duplicating other peoples work. The 6s/4s tests were completed but after questioning the results I found out the emax 1306 motors on 4s were ALL were lower kv than rated (3400kv instead of 4000kv marked), which invalidated the results (though, I did find them interesting). I got new brotherhobby motors for both 4s and 6s, but the 4s kv are completely understated (they boosted the kv to make them seem like they have more thrust). If the 6s did the same I might test them, but I've been testing different 3" motors to see which are better for a new build I'm working on (bought a couple different brands/kvs).
in a few years we will all be converting to 8s
Define a unhealthy amount of batteries. 30+?
Enough that people give you an odd look when you open up the bag full of them on the field.