AK2M4 / XT Brushless Motors

[ak2m4]

4. However Chihai is using UH grade magnets which I think is rated for 180 Celsius, compared to normal grade (?) of 80 Celsius, which should make it more reliable and stable in game, although this may be a moot point (if there is a mosfet there will be some current protection to prevent overheating in the first place)

XT one uses UH grade magnet as well, my guess is they all do and it's nothing to get hung up on.  I like the toggle switch of CH though, less for the customer to fuck up!

 

[Lozart]

It is a PTS grip.

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That's the same as mine except black!

@Colin Allen It's subtlety different from yours but I'm going to get one of these next pay day...

https://www.ptssyndicate.com/product-page/pts-ep-series-enhanced-polymer-m4-grip-epg-for-aeg-erg-olive-drab

... as the base plate online looks like it may not foul up on the motors end bell, but we'll see (either way it's nicer than that on my DE M908A, as long as it doesn't put the motor at an unusual angle).

I've just had a look at one of my spare EPG-C grips, the flanges either side of the height adjuster may still need cutting down a bit, the end bearing on the XT motor is shallower than a regular motor, plus you don't have all the empty space around it where the tabs mount on a brushed motor.

Plus they do usually put the motor a touch too steep for me. Not so bad that it shags the motor but not the best meshing!

 

[Sewdhull]

Uh magnets seem overkill for a 150w motor, but the specs look all but the same.

https://m.airsoftmotor.com/airsoft-motor/long-shaft-aeg-motor/high-speed-39k-cnc-brushless-airsoft-motor.html

 

[Leo Greer]

I should note, if you’re getting a brushless to overheat or even heat up in any capacity, you’re likely doing something wrong…

 

[ak2m4]

@Leo Greer yep, should not be generating too much heat.  25-40C ideal battery .  I read an post about a guy who used a 75/160C drone battery and it melted the PCB traces on the controller, understandable as that battery will kick out a huge amount of power.  As soon as things calm down I'm going to get myself some more batteries and do some heat tests on some different builds.  Just slammed with work at the moment

 

[Sewdhull]

The current that flows is regulated by the resistance of the circuit so any reduction in resistance increases the current flowing. It's motor load that raises the current predominantly because as you can see from motor stats, with no load you're seeing around 2A. Increase load and you raise the current to around 20A.

It's possible to keep raising that current by loading the motor even if it's a 30C lipo, making it's revs drop.

My cheap 11.1v 25C 2Ah lipos have an IR of about 30mOhms. Short it out and potentially you have 370A for a little while at least, so it's unlikely your battery will be a source for destroying things, but loading the motor.

 

[ak2m4]

@Sewdhull check out coconut airsoft on FB, interesting stuff he did with a 45k motor

 

[Leo Greer]

Interestingly and anecdotally, I most often use a 25C 2200 Mah Kypom LiPo with my T238s, but I also use a Turnigy Nanotech 70-140C 5K Mah brick, which is capable of more than enough output to fry everything in that motor whether shorted or not. I haven't had any issues yet, but I'll let folks know if I do.

 

[Pseudotectonic]

Yeah the battery rated output is a maximum (and often incorrect, only way to know is testing), the actual current is determined by how much load the motor is under.

If there is no load (i.e. motor is outside of the gearbox by itself) it will draw a few amps. Even a battery with 9000000 C will only output a few amps in this situation.

If there is infinite load (e.g. clamped in a vice so the motor cannot turn) it will draw infinite amp (or shorted), figuratively speaking. A 1000 mAh battery with 10 C will be able to theoretically output 10 A and all of which is turned into pure heat in the motor and very quickly overheat.

 

[Sewdhull]

@Sewdhull check out coconut airsoft on FB, interesting stuff he did with a 45k motor

Looks like he's finding ways to fry MOSFETs

 

[dlusted]

Mine arrived, and I've gone to install it in the ARP9 and it's a similar issue with the baseplate. Seems that G&G needs adding to the list for modification

I need to square off due to it being shaped to hold the brushed motor in.

Need to give it to someone who's got a grinder to do it and I'll revert back when its tested

 

[ak2m4]

@dlusted added, many thanks

 

[dlusted]

I've done the modification.

Motor can now be adjusted. Hole in gearbox a little tight for the tower compared to the stock G&G motor tower, nothing a quick dermel grind won't sort though.

Super happy with the motor, a lot more snappy compared to the G&G.

My Titan 3000mAh battery I had zero issues.

Will be even better when I redo the gearbox with new gears and shim.

I'm not a Tech as only just started Airsoft so my opinion may be invalid, I'm just an eager hobbiest

Looking forward to using the other parts I've ordered from @ak2m4 to aftermarket my ARP9.

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[ak2m4]

@dlusted fantastic mate

 

[Fatboy40]

@ak2m4Finally got around to sorting out my semi-boneyard CMYA MP5K, needed a v3 spring guide from you as I disassembled the gearbox last weekend and the ball bearing cage just fell apart

So, running your brushless motor along with a GATE Titan v3, and I've now a nice little nippy SMG ?

AB is set to manual and zero percent, but anything else you recommend for GATE Titan users with your motor?

 

[ak2m4]

@Fatboy40 glad you got it all sorted, if ever you need a thrust bearing just shout, got plenty of them.

I'm not a GATE user so don't have a whole deal of experience with them sadly.  

 

[Sewdhull]

For pretty much all Brushless motors don't use active braking or rate of fire reduction, including smart trigger. Some motors might work with these but its a bad idea anyway.

 

[ak2m4]

Chatting with the factory for the next batch, what's the ideal speed that people want to see?  I was thinking around 23,000 rpm +/- 10%

Factory did say they can fit a speed controller dial but I'm not really convinced as it could increase the price more.

 

[Pseudotectonic]

23,000 rpm +/- 10%

I concur

With 13:1 this will get you to just under the PME ceiling which is optimal

Btw I was thinking those x ms delays in brushless may be related to the software denouncing method, and there is a way to completely remove this delay if they change the code to "register immediately upon voltage detection and ignore input for the next x ms" rather than the usual "wait x ms for the voltage to stabilise before registering"

 

[ak2m4]

@Pseudotectonic thanks, I'll mention the ms delay thing to the factory and see what they say.