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Jan 01, 2020, 09:01 PM
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Mains powered test stand


Things happen quickly when they happen !

Pictured :

Adjustable voltage power supply AC to DC Lowest voltage is 15v

Then I have a DC DC adjustable Buck voltage regulator ..

As long as the incoming Voltage is higher .

Plan is to run 2s to 4s VIA Mains .. ( Forget about batteries ) The regulator should handle 20A ( advertised ) , I will be happy with 10A ...
I have already run it to 7A @ 8.33v ( going in to the test stand )

Now I can run voltage tests as well as the rest . Also make prop testing a lot easier . ( No saggy baggy batteries )

Just need to compare voltage sag , which I have not done yet ..
Just confirmed that this works . ( Thats all )
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Jan 01, 2020, 10:07 PM
If it flies, I can crash it.
rocketsled666's Avatar
Something that small is going to want a fan for 20A. Especially with the heat sink oriented that way and hidden behind the wall of the enclosure... you want air to be able to flow over and past the heatsink fins completely unobstructed (or assisted by a fan).
Last edited by rocketsled666; Jan 01, 2020 at 10:24 PM.
Jan 02, 2020, 12:34 AM
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Yeah ! Thats what I thought ...
But the AC DC power supply gets warmer than the DC Buck converter .

So far it seems to be handling the situation just fine . ( Buck Converter )

Only tested my 1306 to 4s level so far , 22 volts going into the buck converter .

Voltage SAG !!!! Before I forget

2s 2200 battery pack .. Fully charged ..
Test stand is reporting 8.48v Sagged to 8.04 volts for 6.98 Amps
Was that my 1108 motor and 3830 prop for just over 200 grams of thrust

Mains power reporting the same voltage at rest :
Sagged to 8.19 volts for 7.18 Amps at full throttle .


That 1306 motor is going to be my prop tester ... ( 1103-4-5-6 size props )
Jan 02, 2020, 12:46 AM
If it flies, I can crash it.
rocketsled666's Avatar
At less than 10-15A you're probably OK. 13xx and 11xx (and there are some 12xx motors now) aren't going to draw much more than that worst case on 3 or 4S power.

The battery is not a regulated supply, so as you load it up the voltage has to drop. The buck converter is regulated, it shouldn't show much if any voltage drop at all. The fact that it sagged that much under load suggests most of it is coming from someplace else. Shorten up the wires from the buck converter to the thrust stand and see if the sag is reduced.

I have the same test stand. I made a little adapter plate for the 11xx and smaller motors. The existing plate was only just small enough for a two screws on an 11xx, the 08s and 07s and 06s could only hang on with one screw.
Jan 02, 2020, 02:50 AM
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Hmmm , my leads are a little on the long side ..
Some voltage sag was expected .
Does not affect motor performance much , one or two grams of thrust .
Not enough to worry about .

I just realised I havent done a motor test on that 1306 ( 2700kv ) ..
Shortly a 2s to 4s test .. ( Motor is supposedly 3s and 4s but runs fine 2s as well )

2020 , plan is to do about a motor a month ( testing ) ...
Jan 02, 2020, 02:58 AM
If it flies, I can crash it.
rocketsled666's Avatar
Be mindful of the wattage you're putting in to the motor. I've burned a few out flogging them too hard...
Jan 02, 2020, 05:16 AM
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Hehehehe , killed a 1103 and a 080? ...

Yeah , small motors die fast ...

Thats why I went 1306 for testing 1103-4-5-6 props ..

I can run 16 volts , get decent RPM .. Without stressing the motor . ( well - too much ) I should probably have got a slightly higher KV motor though , 2700kv is a little hard to push for High rpm . ( 30,000+ )

Can always buy another motor


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