How do Watts come into the equation of powering a 1000 watt 36 volt motor with 3.7 volt Li-Ion Batteries?

Question

I just used these 3.7 volt Li-Ions as an example but how could you figure the amount of power supplied? I know the bats have different Amp Hours let's say 1200 how does this work into the equation.. I just don't understand this and i want too.

Answer 1

Voltage of the battery x amphours of the battery = kilowatthours

1200 will most likely mean 1.2 ah or 1200mah. a 1200 ah battery would be huge.

If you use 10 3.7v batteries in series the voltage is added current stays unchanged. You must use batteries with the same ah.

so if you hooked up the batteries to the motor you would get 37vX1.2ah which + 44wh or .044kwh. That is the output of the battery bank.

The motor consumes 1000 watts which in 1 hour would be 1kwh. So your motor would run .044/1= .044 of an hour or 2.64 minutes.

This all assumes 100% efficiency and 100% loading.

Now that you know a single bank of ten batteries in series gives you 2.64 minutes of run time you can continue adding banks of batteries in parallel. Each new parallel bank will give you 2.64 minutes more run time.

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+   <ten batteries in series ( a bank)

-=+  \

-=+   |

-=+   |

-=+   |

-=+   ||

-=+   ||  10 batteries in parallel.

-=+   |

-=+   |

-=+   |

-=+  /

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+   \

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |      -=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |\

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |/   10 banks in parallel -=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+    |

-=+-=+-=+-=+-=+-=+-=+-=+-=+-=+   /

Answer 2

" but how could you figure the amount of power supplied?"

The first part of your question states that you have a 1000W motor.  That is the 'amount of' (sic) power supplied.  There's no figuring out to do.  

You would do well to Google for "Ohm's law" and read up the basics.  The maths is very simple.  

Answer 3

watts is amps (or flow rate or number of electrons) time volts (the press sureor force those electrons have) = watts the energy.  So 3 3.7 volt batteries in sseries will have 3 times 3.7 or 11.1 volts.  The motor is a dc motor, the more volts you apply, the faster it will turn, so this set up will have the motor turning 11.1/36 or 1/3 third its max speed.

The motor is rated at  1000 watts at 36 volts or 1000/36 = 29 amps. This doesn't mean the motor always uses 1000 watts or 29 amps, it means tthat'sthe most it can do without damage.  The actual use is a function of what amount of energy the motor needs to supply to whatever its tied to.  So, we know that the may watts the motor can use with three batteries is 29 * 11.1 or 350 watts.

Now the battery can supply 1200 amps for 1 hour, or 600 for 2 hours or 1 amp for 1200 hours.  SO, the maximum amps is 29 therefore 1200/29 is about 40 hour, tthat'show long it will last.  If the motor only uses 15 amps, the mbatterywill last 80 hours.

BUT, a 1200 watt battery is huge, are you sure it isn't 1200 mA or milliamps. just checking.

Answer 4

are you asking how many 3.7volt batteries you need to run the motor?

watts are a measurement of power

watts = volts * amps

so if your motor pulls around 25amps @ 36 volts then you would be using 1000 watts of power

now 25 amps is a lot for instance if you were to connect 10 of those 3.7v li-ion batteries in series to approximately 37volts necessary to run that motor, my guess is that those batteries would lose their charge in about 10 min tops.