fly boy3 Posted October 31, 2013 Share Posted October 31, 2013 Hi all, my OD foamie requires a brushless 100 watt motor. The motor I have selected 15000kv max 9 amps. Is it possible to achieve this with a 2cell lipo.rather a 3cell ? I am trying to keep the weight down and I am assuming 2cells are lighter than 3 cells. As a newbie to electrics I could be all wrong anyway LoL. Cheers Quote Link to comment Share on other sites More sharing options...
Shaunie Posted October 31, 2013 Share Posted October 31, 2013 Current is the killer on brushless motors. 9 amps at 2 cells, nominally 7.4V, only equates to 66.6W so if you want 100W then it must be 3 cells I'm afraid, actually 99.9W at 3.7 V per cell. Don't assume anything with LiPos, you can get just about any combination of mAh and cell count you would realistically want. You wouldn't save any weight anyway if you had a lower cell count each of the other cells would need to be bigger to carry the same amount of energy! Shaunie. Quote Link to comment Share on other sites More sharing options...
PatMc Posted October 31, 2013 Share Posted October 31, 2013 If you used 2 cell with a max current of 9A you would only be able to get 67W from the motor (9A x 7.4V). To get 100W you'd need to increase the current to 13.5A, use a higher current rated motor & possibly bigger ESC. If you you used 2 cells in place of 3 you would have to raise the capacity by 50% to get the same duration at the same power. e.g. a 2s 1500mAH would be needed to replaced a 3s 1000mAH. The weights would be similar. Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted October 31, 2013 Author Share Posted October 31, 2013 Thanks both, and very well explained, think I would go for the 3cell. Cheers Quote Link to comment Share on other sites More sharing options...
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