Quote:
Originally Posted by John
if I have time I might add the math to back it up
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Here's some quick rough calculations using some simple numbers to illustrate a point.
Say you have a CIM with 10.4 volts applied and loaded with 206.1 oz*in of torque. It will be spinning at 1416 RPM, drawing
80.5 amps, generating 215.8 mechanical output watts, and running at 25.8% efficiency.
Now add a 3x speed reduction gearbox. For sake of simplicity for this simple calculation, ignore gearbox losses. To produce the same output speed and torque as above, the CIM needs to produce 68.7 oz*in torque at 4248 RPM. To generate that torque at that RPM, the CIM will need 12 volts applied. It will draw
28.8 amps and be operating at 62.5% efficiency.
That's why you want to operate in low gear when
possible appropriate.
Code:
Motor Calculator build MCALC_2014d 2/3/2014 1255pm
Select motor:
1)CIM 6)FP0673 d)FP2719 f)FP9012 g)FP9015 h)FP9013 j)MiniCIM
a)am-0912 b)am-0914 7)DensoL 8)DensoR c)Denso0160 k)BAG u)UserDefined
2)RS395 3)RS540 4)RS550 e)RS775-12 5)RS775-18 m)RS555 n)am-0915
r)am-2193 s)am-2235 t)RS390 v)RS545 p)am-2161&2194
w)VEX2177hi z)VEX2177std 1
CIM FR801 001, AM802 001A @ 12.00 volts:
@ free (no load):
oz-in Nm rpm rpm% amps watts out watts heat eff%
0.0 0.000 5310 100.0 2.7 0.0 32.4 0.0
@ stall:
oz-in Nm rpm rpm% amps watts out watts heat eff%
343.4 2.425 0 0.0 133.0 0.0 1596.0 0.0
@ max power:
oz-in Nm rpm rpm% amps watts out watts heat eff%
171.7 1.212 2655 50.0 67.8 337.1 477.1 41.4
@ max efficiency:
oz-in Nm rpm rpm% amps watts out watts heat eff%
42.8 0.302 4648 87.5 18.9 147.1 80.2 64.7
Select input:
1)oz-in 7)watts_in 3)rpm 5)amps b)rpm&s 8)eff%
2)Nm 6)watts_out 4)rpm% 9)volts a)rpm&ozin m)main menu x)exit a
Enter motor rpm & ozin, and the program will calculate the motor voltage
required to produce the specified ozin at the specified rpm.
Enter rpm and ozin, separated by a space: 1416 206.1
CIM FR801 001, AM802 001A @ 10.40 volts:
@ free (no load):
oz-in Nm rpm rpm% amps watts out watts heat eff%
0.0 0.000 4603 100.0 2.3 0.0 24.3 0.0
@ stall:
oz-in Nm rpm rpm% amps watts out watts heat eff%
297.7 2.102 0 0.0 115.3 0.0 1199.3 0.0
@ max power:
oz-in Nm rpm rpm% amps watts out watts heat eff%
148.8 1.051 2301 50.0 58.8 253.3 358.5 41.4
@ max efficiency:
oz-in Nm rpm rpm% amps watts out watts heat eff%
37.1 0.262 4029 87.5 16.4 110.6 60.3 64.7
CIM FR801 001, AM802 001A @ 10.40 volts:
oz-in Nm rpm rpm% amps watts out watts heat eff%
206.1 1.455 1416 30.8 80.5 215.8 622.0 25.8
Select input:
1)oz-in 7)watts_in 3)rpm 5)amps b)rpm&s 8)eff%
2)Nm 6)watts_out 4)rpm% 9)volts a)rpm&ozin m)main menu x)exit a
Enter motor rpm & ozin, and the program will calculate the motor voltage
required to produce the specified ozin at the specified rpm.
Enter rpm and ozin, separated by a space: 4248 68.7
CIM FR801 001, AM802 001A @ 12.00 volts:
@ free (no load):
oz-in Nm rpm rpm% amps watts out watts heat eff%
0.0 0.000 5310 100.0 2.7 0.0 32.4 0.0
@ stall:
oz-in Nm rpm rpm% amps watts out watts heat eff%
343.4 2.425 0 0.0 133.0 0.0 1596.2 0.0
@ max power:
oz-in Nm rpm rpm% amps watts out watts heat eff%
171.7 1.213 2655 50.0 67.9 337.1 477.2 41.4
@ max efficiency:
oz-in Nm rpm rpm% amps watts out watts heat eff%
42.8 0.302 4648 87.5 18.9 147.2 80.2 64.7
CIM FR801 001, AM802 001A @ 12.00 volts:
oz-in Nm rpm rpm% amps watts out watts heat eff%
68.7 0.485 4248 80.0 28.8 215.8 129.4 62.5