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This might be a stupid question

Old 04-06-2020, 10:59 AM
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mtc777
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Default This might be a stupid question

What is the difference between lets say 2000 kV motor powered with 6S lipo and 4000 kV motor powered with 3S lipo? The only difference I see is the current consumption, is there anything else ?
Old 04-18-2020, 05:06 PM
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Chrisg81983
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Overall efficiency.... the 3s setup will be more stress on electronics. I use Lehner motors and have the choice to run in delta or wye. On my motors in wye configurations is say around 1010 KV and in delta is 1750. These KV values are under load not free spinning like most manufactures are. I run 2 of these in a boat on 11s 1p each. If i ran this setup in delta on 6s for around same rpm i would fry the electronics. The batteries could not handle it as well even if ran as 6s2p.

Last edited by Chrisg81983; 04-18-2020 at 05:14 PM.
Old 05-24-2020, 11:19 AM
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funcentric
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My specialty. I have more data in my spreadsheet than I care to admit. I gathered all this when designing my own power system for some RC cars. To answer your question:

1. Your getting slightly higher RPM with the smaller battery and larger KV motor combo from your example. RPM is calculated as KV x voltage. Using our example.
2000kv x 22.2v = 44,400RPM
vs
4000kv x 11.2v = 44,800RPM

2. The stress level on the battery has to do with the amps. The more amps your battery can tolerate over the motor's rating, the less stress it will be. Amperage of the battery is calculated using Mah and the C rating. A higher Mah battery will need a lower C rating to achieve the same amperage as a lower Mah battery with higher C rating.
Mah x 0.001 x C rating = amps it can handle. You didn't provide Mah nor C rating of your battery comparison so I can't say exactly how this applies to your example. A higher C rated battery generally costs more, so you may want to keep that in mind. A larger Mah rated battery will generally be physically larger in size so that's something to consider as well. 6S lipo is a fairly large battery. Consider safety when charging. Also the larger the battery gets, the less efficient it becomes. The performance of the battery needs to be at least as much as the drawback of the added weight.

3. People think that a lower KV motor has more torque, but that's only true if the voltage is the same. In your case, your voltage is increased with a lower KV motor.

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