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New Hobbyking A-10 75mm A-10 on 4s?

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New Hobbyking A-10 75mm A-10 on 4s?

Old 03-30-2011, 02:16 PM
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mobaddawg
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Default New Hobbyking A-10 75mm A-10 on 4s?

I have a HK A-10 with twin 75mm ducted fans here are the specs-
*Twin 20 A ESC's
*Twin 3900 KV brushless out runners
*3s Batterys currently on it-Sky Lipo 2200 mah 3s 25c 11.1v
*4s battery to be put on it-Blue lipo, or Black lipo 4s 2200mah 20c 14.8v.
Would this be a safe configuration for the motors and esc's?
I hope and think it should because 14.8~2=7.4v x2 Motors/esc, so thats 7.4v to each motor and esc. I have ran a single 20a esc and a 11.1 v and it worked fine.
Old 03-30-2011, 07:43 PM
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gary41
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Default RE: New Hobbyking A-10 75mm A-10 on 4s?

The voltage to EACH motor/esc will be whatever the voltage is of the LIPO used. (16.6v for most fully charged, 4S LIPO's at the initial phase of operation).

If your ESC'c AND motors are rated 3 to 4S, you will be fine.
Old 03-30-2011, 08:21 PM
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Hokie Flyer
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Default RE: New Hobbyking A-10 75mm A-10 on 4s?

I don't think going to 4S with this motor/fan/esc combination is going to work.  In my opinion, a kv of 3900 is a little too high for 4S, especially since these are not premium quality motors.  Also, these motors are going to try and draw alot more than 20 amps on 4S.  My HET F-20 which has a Wemotec Minifan (69mm), HET 2W-20 motor (approx 3000kv) draws 48 amps in 4 cells (3700 20C battery).  For further discussion, let's use 48 amps as the minimum we can expect a fan on 4S to pull.  A 3900 kv motor will pull even more amps in the same fan.  I'm not familiar with the HK fan, but most 75mm fans are a larger load than a 69mm fan, so again, more amps.

Also, your math of 7.4 volts to each fan does't compute for me.  Voltage only divides if the esc's motors are wired in series, and I've never seen a series brishless motor set-up.  If they're wired in parallel, each fan will see 14.8 volts, and each fan will will try to pull something over 48 amps each.  If you're running two 4S batteries, you will be overtaxing them a as a 20C battery maxes out at 44 amps.  If you're going to run a single 4S 2200 20C battery, with both fans trying to pull over 96 amps combined, voltage depression will drive the esc's to LVCO before you reach full throttle.  And, you may damage the battery in the process.

Hope this helps.


Rob
Old 03-31-2011, 02:41 AM
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ACES&8s
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Default RE: New Hobbyking A-10 75mm A-10 on 4s?

the motors will burn out with sustained 4 cell operation
Old 03-31-2011, 06:00 AM
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Default RE: New Hobbyking A-10 75mm A-10 on 4s?


ORIGINAL: ACES&8s

the motors will burn out with sustained 4 cell operation
It appears that those motors are NOT designed for 4S operation with their KV that high. I totally agree with Rob ans Aces&8, that you will smoke'em!

Besides, the full scale A-10's are NOT designed for speed; agility at lower speed is their forte'.

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