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3s vs. 6s setup? Jollymotor upgrade..

Old 02-18-2010, 12:02 PM
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Pekka L
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Default 3s vs. 6s setup? Jollymotor upgrade..

I'm planning to upgrade my JollyMotor boat with a 2856 or 2868 sized brushless inrunner motor. Original setup is 2836 sized outrunner with 2185kV. Runs with 3s batteries like this: http://www.youtube.com/watch?v=WWoKQ...=http%3A%2F%2F 40x1.2 Graupner prop.

What is the main difference if I use 3s or 6s setup?
As a electric engineer I understand the relations between voltage, current and power, but is there some other thing to keep in mind?

So why people still use 2-3s setups if you can get the same power with 6s/22,2V setup with less current and smalller ESCs?
Or am I missing something?

So should I get a motor with 3000kV or 1500kV if I aim to the ~30krpm range?
I have few 3s lipos, so should I use them parallel or in series? My Seaking 60A ESC should handle both.


Br.
Pekka from the land of snow and ice (at the moment..).
Old 02-18-2010, 12:11 PM
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srt10
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Default RE: 3s vs. 6s setup? Jollymotor upgrade..

correct!
you are on the right path, going 6s with 1/2 the kv of the stock motor you will longer runtimes and a cooler running system.
but if you run 6s on the stock motor, that would be to much rpm and cause lots of heat and damage
Old 02-18-2010, 12:19 PM
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srt10
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Default RE: 3s vs. 6s setup? Jollymotor upgrade..

so lower kv motors of the same size can, pull less amps
lets say
2200kv motors on 3s pulls 35amps that = 389 watts
1100kv motor on 6s pulls 18amps that = 400watts
not exact but it gives an idea.
longer runtimes with lower kv motors on higher volts, and also cooler running gear
Old 02-18-2010, 12:35 PM
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Pekka L
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Default RE: 3s vs. 6s setup? Jollymotor upgrade..


ORIGINAL: srt10
longer runtimes with lower kv motors on higher volts, and also cooler running gear
Is the motor and esc effeciency much better with higher voltage? High current will increase power loss with internal resistances, but is that difference big?

If you have 5000mAh 3s/11.1V battery it will give you ~55Wh of power/energy.
If you have 2500mAh 6s/22.2V battery it will give you the same amount of energy to use and the battery size (weight and dimensions) are very similar.
So in that case only effeciency of the motor esc combo matters.
But yes higher voltage means less current usually and that means less power loss caused by resistanses inside components and wires etc... That's why we use 230VAC here in Finland for our home apliances

The information I am looking for is that, are there some significant difference in motor charecteristics between 1500kV with 22.2V and 3000kV motor with 11.1V? Torque on half throtlle, effeciency on full load etc.?

Old 02-18-2010, 12:45 PM
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srt10
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Default RE: 3s vs. 6s setup? Jollymotor upgrade..

I wish we had the higher volts here in the US for home use!
it sounds like you have great knowledge behind you that is helping you decide on a system upgrade
no real difference between motors going higher volts with lower kv, just much more effincient running system

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