RC-Monster Forums - View Single Post

lincpimp · 05.16.2009, 01:09 PM

Watts is pretty easy, it is just volts x amps. Watts are a good indicator of total power available.

You can figure that a vehicle of a certain size and weight will draw X number of watts. Main issue is figuring what wattage you need to get the job done. It is usually best just to post up the setup you plan to run and the desired result. The the rest of us who had done something similar can offer insight.

More example:

say you want 2000 watts, and plan to run 4s - 2000/14.8 = 135.13 amps. If you figure that is what you need at the tires, and the motor is 85% efficient, you will need about 2353 watts from the battery to get the job done - 2000/.85 = 2352.94, or you can take the 135.13 amps/.85 and get 158.97 amps needed from the battery at 4s.

So as you can see, to get 2000 watts at the tires with and 85% efficient motors you will have to have a 4s pack capable of 150 amps, so a 5000mah 30c lipo should do the trick (as long as the specs are true to the pack's performance...).

Tire weight and vehicle weight play the biggest part in figuring the amp draw a system will determine. You have to move the chassis weight around with the motor, so it stands to reason that lighter is better. Wheel weight is also a big factor, as a heavier wheel/tire will need alot more power to get moving that a smaller lighter tire. That is why we can get away with smaller lower torque motors in buggies, while truggies/MT need a big torque motor to get those big tires moving.

	(#7)
lincpimp Check out my huge box! Offline Posts: 11,935 Join Date: Aug 2007 Location: Slidell, LA	05.16.2009, 01:09 PM Watts is pretty easy, it is just volts x amps. Watts are a good indicator of total power available. You can figure that a vehicle of a certain size and weight will draw X number of watts. Main issue is figuring what wattage you need to get the job done. It is usually best just to post up the setup you plan to run and the desired result. The the rest of us who had done something similar can offer insight. More example: say you want 2000 watts, and plan to run 4s - 2000/14.8 = 135.13 amps. If you figure that is what you need at the tires, and the motor is 85% efficient, you will need about 2353 watts from the battery to get the job done - 2000/.85 = 2352.94, or you can take the 135.13 amps/.85 and get 158.97 amps needed from the battery at 4s. So as you can see, to get 2000 watts at the tires with and 85% efficient motors you will have to have a 4s pack capable of 150 amps, so a 5000mah 30c lipo should do the trick (as long as the specs are true to the pack's performance...). Tire weight and vehicle weight play the biggest part in figuring the amp draw a system will determine. You have to move the chassis weight around with the motor, so it stands to reason that lighter is better. Wheel weight is also a big factor, as a heavier wheel/tire will need alot more power to get moving that a smaller lighter tire. That is why we can get away with smaller lower torque motors in buggies, while truggies/MT need a big torque motor to get those big tires moving. Alot of Savage parts for sale!!!