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BrianG · 02:49 PM

That motor is not a good choice IMO. 11A no load current @ 20v is rather high, which means 220w of power loss due to inefficiencies.

As said, you will need one heck of a good power source to spin 33" of blade to cut grass. Even your 3.5HP is 2600w, which is probably a lightly loaded constant figure. I too think ~7HP is more reasonable value for such a large blade. To keep current draw down as low as possible, you'd have to use the full 70v on that linked motor, gear it down, and even then you it's gonna draw 75A constantly (for 7HP). I don't know the size of the area to mow, but that current will require over 1250mAh per minute of battery capacity, and that's not counting efficiency losses. So, to mow a lawn that takes 20 minutes, you'll need a 70v (19s) 25Ah battery.

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BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	03.02.2011, 02:47 PM That motor is not a good choice IMO. 11A no load current @ 20v is rather high, which means 220w of power loss due to inefficiencies. As said, you will need one heck of a good power source to spin 33" of blade to cut grass. Even your 3.5HP is 2600w, which is probably a lightly loaded constant figure. I too think ~7HP is more reasonable value for such a large blade. To keep current draw down as low as possible, you'd have to use the full 70v on that linked motor, gear it down, and even then you it's gonna draw 75A constantly (for 7HP). I don't know the size of the area to mow, but that current will require over 1250mAh per minute of battery capacity, and that's not counting efficiency losses. So, to mow a lawn that takes 20 minutes, you'll need a 70v (19s) 25Ah battery. Last edited by BrianG; 03.02.2011 at 02:49 PM.