Brushed motors approx life span

davidhk129

davidhk129

Well-Known Member
Without undue abuses by a newbie, how long will a drone with brushed motors last, in average ?
Say, about 3 times a week, 15 minutes max each time.
Thank you.
 
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davidhk129

davidhk129

Well-Known Member
wafflejock said:
https://www.getfpv.com/lumenier-rx0615-17-purple-chrome-micro-brushed-motor-set-2-cw-2-ccw.html

Think 6 hrs of on time is typical can see lifetime spec on page above.
Click to expand...

I want to make sure we are on the same page.
Most likely I have misunderstood what you said as English is my 3rd language.
Were you telling me that if I paid, say, $200 for a brushed motors drone, those motors would cease to function after logging in 6 hours of flight time, give and take ?

P.S. I had read the link you gave me.
 
wafflejock

wafflejock

Well-Known Member
Yah the brushed motors themselves go for about $20 . 6hrs of flight time if you fly 15 minutes at a time 3 times a week means 45minutes a week so it's about 8 weeks or 2 months of flying that much before they should have the brushes worn down I'd guess to the point that it's no longer able to efficiently fly. Brushless DC motors have a much higher run time since there is no friction part (shaft and bearings aside) passing power along and instead relies on more complex ESCs that can time the opening of the gates to let current flow through the correct coils to get/keep the motor spinning, brushed DC motors have the advantage of being much simpler to drive (can use an H-Bridge to control flow of current in two directions if current goes one way the motor goes one way if current goes the other way the motor goes the other way) Also with brushless motors there are the coils and the magnets that take up space so think it's hard to make them super miniature (I have some for my KingKong GT that is a big micro, 90mm I think)

If your quad cost $200 mostly that cost is probably in the VTX/camera and flight controller/receiver. Typically a FPV camera will go for somewhere around $30-100, a VTX (video transmitter) is similarly priced maybe slightly cheaper but I usually spend around $50 on them (for mini/250mm/5" quad) and usually FC is also around $40, receiver for your transmitter might be a little cheaper $20-30, on micros frames are typically plastic or very thin carbon fiber and either way pretty cheap. So yah $200 is just all the parts cost added together and would expect to replace the motors after about 6 hrs of flying but would just see them as a slightly more expensive slight more resilient consumable like props, with a BLDC motor I think you're more likely to damage the bell or knock a magnet loose or cut the enamel off the coils making a short than to run them dead.

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Follow up after some more reading (actually a thread on this forum) these small DC motors are apparently "coreless" so they don't actually use brushes from what I'm gathering but still have a commutator part near where the shaft exits the main body of the motor that I'd guess must be the part that wears over time (whatever is making contact between a fixed and rotating part) . More details at links below:

https://www.motioncontroltips.com/what-are-coreless-dc-motors/
http://quadcopterforum.com/threads/brushed-motor-lifespan.5730/
 
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wafflejock

wafflejock

Well-Known Member
Also I picked up one of these on Amazon https://www.halfchrome.com/king-kong-gt90/ first one I ordered was DOA (really bad solder connections on the 4 in 1 ESC board receiver didn't work other issues) I still decided to try a second time to see if it was a dud and in fact it was, the second one they sent me the motor wires were twisted right up to the ESC much better looking solder job and the receiver was different and working (so they sent me a different revision than the first time) same seller etc, I kept the original for parts but just saying it can be hit or miss too and can maybe get something a little cheaper with as many or more features.
 
J

Jeff Neese

Well-Known Member
wafflejock said:
---
Follow up after some more reading (actually a thread on this forum) these small DC motors are apparently "coreless" so they don't actually use brushes from what I'm gathering but still have a commutator part near where the shaft exits the main body of the motor that I'd guess must be the part that wears over time (whatever is making contact between a fixed and rotating part) . More details at links below:
Click to expand...

Coreless motors still have brushes. They're just a bit more efficient and can have higher output, but the lifespan is the same.
 
CobraJockey

CobraJockey

Member
Amen to the gentlemen above. While my more serious Quads are all Brushless, it's very hard to find super compact foldable camera brushless motor quads (Spark like) that you can take on trips for some scenery videos, that aren't in the $600 range. (I'm not cool with losing an expensive camera quad in "unknown territory") Some of these <$200 1080p Brushed camera quads are actually damn nice with excellent video quality so living with 6 to 8 hours life spans for the coreless brushed motors is something you accept and live with. So I only pick from this class of Quads that: 1) have some very good acclaim from other owners, and 2) I can buy spare motors to swap out myself. The better Brushed camera quads are Coreless, use standardized spec motors you can find easily to buy and lastly are "plug(in) and fly" (use micro connectors, not soldered in) so bringing with nothing more a set of jeweler interchangeable screw/hex bit drivers is all I need to pack.
 
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