5 replies to this topic

[Ultrasonic2]

Here Is my test bed. As you can see i have my stryfe setup to an adjustable PSU so i can adjust the voltage to common battery voltages and with the crhono i know what FPS im getting.

Actually it seems i can't attach images so i can't show you.

Here are the results

100% stock Stryfe

4.8v (4x1.2) = 52.5 fps
6.0v (4x1.5) = 63.4 fps
9.0v (1x9v) = 85.7 fps

Now with the locks and resistors removed but stock motors

4.8v (4x1.2) = 56.5 fps
6.0v (4x1.5) = 69.3 fps
9.0v (1x9v) = 90.4 fps
11.1v (3x3.7)= 99.7 fps
14.8v (4x3.7)= 96.8 fps


The interesting thing is the reduction at 14.8 the rounds just vary so much on a vertical plain that it was impossible to get one through the chrono without it hitting it.
Also based on the range test i could only get 1 out of a lot of shots to travel further than at 11.1v. It's possible that all of this would be "better" if an extended barrel was added.

I presume the fundamental problem is that at this voltage the motors are unable to keep their RPMs anywhere near the same to ensure a consistent vertical plain.

At this point i would go with three 3.7 14500 batteries (11.1v) and one spacer OR the "Safer" option of possibly using four 14500 lifepo4 3.2v (12.8v) but i didn't test that voltage.


I will now be replacing the motors with high performance 130 Atomic ball bearing motors. This should at least drastically reduce the noise the gun makes.

Edited by Ultrasonic2, 26 January 2015 - 04:26 AM.

[ravetrooper]

Nice info. Good for people without chronographs.

Phoenix66 posted a tutorial for uploading pictures here:
http://nerfhaven.com...showtopic=23345

[Love777]

As someone who doesn't know too much about batteries this seems to suggest that mAh plays a big part in FPS performance. I say that only because we measured my friends stryfe (rewired on a 9.6v 2000 mAh nimh pack) and he was consistently getting 110 FPS.

[meishel]

As someone who doesn't know too much about batteries this seems to suggest that mAh plays a big part in FPS performance. I say that only because we measured my friends stryfe (rewired on a 9.6v 2000 mAh nimh pack) and he was consistently getting 110 FPS.

Yes and no. Voltage determines how fast the motors spin, but mAh is part of how the current is determined. If a battery has too low of a discharge rate ©, and a low mAh, it will have too low of current (Amps) to adequately spin up the motors, and can even damage the battery. Motors can draw a LOT of amperage. a set of 180's hit 40+ amps at stall I believe. To determine discharge rate of your battery pack, take the C rating and multiply by the Ah (mAh convetered to Ah, ex: 2000 mAh = 2 Ah) of the battery, this gives you the max amps that the battery can safely output.

Take this battery: http://www.hobbyking..._Lipo_Pack.html 25c * 2.2Ah = 55amps. However, it has a burst rating of 35c, so it's max burst amps is 77amps.

[T3kn0Hazard]

Thanks again for sharing! Crazy that with the 4x3.7s it all goes to hell.
This chart is very very helpful!
We all use different stuff, its nice to know how it all stacks up.

[Love777]

Yes and no. Voltage determines how fast the motors spin, but mAh is part of how the current is determined. If a battery has too low of a discharge rate ©, and a low mAh, it will have too low of current (Amps) to adequately spin up the motors, and can even damage the battery. Motors can draw a LOT of amperage. a set of 180's hit 40+ amps at stall I believe. To determine discharge rate of your battery pack, take the C rating and multiply by the Ah (mAh convetered to Ah, ex: 2000 mAh = 2 Ah) of the battery, this gives you the max amps that the battery can safely output.

Take this battery: http://www.hobbyking..._Lipo_Pack.html 25c * 2.2Ah = 55amps. However, it has a burst rating of 35c, so it's max burst amps is 77amps.

Thanks for the clarification and explanation on that. I had heard how it was related to rev time and drop between shots but this makes more sense now. Still curious as to why the disparity exists with the above data and what I did the other day. Possibly just flywheel build-up but I would be surprised if that alone accounts for a 15-20 fps difference when voltage is even lower than the above data