# p4 motors kw??

#### xrider

hello there
im in search of specs in p4 motors.. need to know about kw

ive seen a post in dji forum talking about 800kw motors.. dont know if thats correct..

xrider

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#### Phantomwolf

hello there
im in search of specs in p4 motors.. need to know about kw

ive seen a post in dji forum talking about 800kw motors.. dont know if thats correct..

xrider
There has to be a mistake. 800 kw is 800,000 watts. On a 12 volt system that's 66,666 amperes. No possible way from a P4 drone battery.

• xrider

#### xrider

..
There has to be a mistake. 800 kw is 800,000 watts. On a 12 volt system that's 66,666 amperes. No possible way from a P4 drone battery.
youre so right.. it was a mispelling from me.. he didnt say kw.. he said kv..
so 800rpm/v
there is another one thread here talking about 920 and another 960.. on a p3 .. how about a p4 or p4p (i think same motors) .. im trying to complete a form here and dont know the specs..

#### xrider

@Phantomwolf found that is 800rpm/v ..
so.. how do i calculate the power consumption assuming there are 800 rmp * 4 motors?? or what ill get will be the watts (power in idle) ?? do i have to divide it per 15volts?? i calculated the max thats 800*15 if i divide the 11.300 by 4 * 15 will i get the total watts under load??
im not so good in maths 🙄

#### Phantomwolf

@Phantomwolf found that is 800rpm/v ..
so.. how do i calculate the power consumption assuming there are 800 rmp * 4 motors?? or what ill get will be the watts (power in idle) ?? do i have to divide it per 15volts?? i calculated the max thats 800*15 if i divide the 11.300 by 4 * 15 will i get the total watts under load??
im not so good in maths 🙄
I'm afraid my knowledge of the calculations needed leaves a lot to be desired. From what I have read, and I prefer someone who truly knows, to correct me if I am wrong. Here goes... the motor is rated at 800 (your number) rpm per volt applied. So if 10 volts is applied, the rpm will be 8,000. The amount of work required to maneuver the craft will depend on several factors including the weight of the drone with all accessories that may be attached, and how windy it is. I would think that the attached propellers would also affect the results of the calculation.

What I am saying is you will need to have more information (the unknowns) to be able to determine how much work is being done at any particular instant before you can determine what the power consumption (amount of work) the motor is doing. This may be impossible to calculate without a controlled environment. I would think this topic would be more for a design engineer who is designing a system.

I am curious, if you care to share... what is the purpose of this exercise?

#### Phantomwolf

@Phantomwolf found that is 800rpm/v ..
so.. how do i calculate the power consumption assuming there are 800 rmp * 4 motors?? or what ill get will be the watts (power in idle) ?? do i have to divide it per 15volts?? i calculated the max thats 800*15 if i divide the 11.300 by 4 * 15 will i get the total watts under load??
im not so good in maths 🙄
You can do a basic power consumption of the whole system. The battery is 5,350 mAh. It is 15.2 volts. Watts = volts x amps so 5.35 x 15.2 = 81.32 Watts per hour. The battery flight time rating is 28 minutes. That means the consumption is 81.32 x 2 = 162.64 watts per hour. If we guess at what the rest of the electronics is using, say 12.64 watts (for easier calculations) that leaves 150 watts for the motors. Divide 150 by 4 motors you get 37.5 watts per motor. Don't forget this is just an idea of the what might be. No doubt the motors are going to be unequal in the amount of work they are doing.

I hope this gives a rough idea and I hope I haven't been too far out to lunch on it. There are many factors that affect how much work each motor does so it is next to impossible to know for sure without an extensive experiment set up in a strictly controlled environment.

If I am wrong, I welcome any and all constructive corrections. I am always willing to learn when I am wrong so I can be right. (LOL).

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• xrider

#### xrider

I would think this topic would be more for a design engineer who is designing a system.

I am curious, if you care to share... what is the purpose of this exercise?
exactly this.. im making calculations (or try to make) for better understanding of how the craft behaves.. filling a form about power consumption in idle.. average load and max load.. without any payloads.. im very interested about the values in a log (taking some time as i want no wind to mild wind contitions.. 4 logs to compare the efficiency at each time) in power columns that motors consuming from start to end..

so if there is 8000 rpm and i divide it by four (makes it 2000rpm per motor in hover.. no wind) and then divide the value to 30 minutes of flighttime (i know thats not absolute but lets say that it hovers in no wind) that makes us 67 (its 66.66 and i rounded it up for ease) of 100 of the total power consumpion in hover..

in the scenario that there could be wind and say that message about max motor speed reached.. ive seen that in smode (no wind) it triggers the message in about 80% of total power.. know already that it weights about 3lbs (to calculate the drag) and here im stuck as i dont know the watts that its adressing per minute from the 15v battery to make the calulation about power consumption in 30 minutes..

yes i know there are no absolute values.. but im trying to calculate for better understanding the efficiency of the whole system

edit.. now i see how it goes (was typing with you at the same time 😁).. definetly was wrong in some calculations as i didnt put in the scenario the rest of electronics.. only the ppms i was looking.. oops 😁

edit2. where does the 2 value comes from when you did the multiply in watts?? think ive got a bit confused.. its 28 minutes right?? im a bit confused @Phantomwolf

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#### Phantomwolf

exactly this.. im making calculations (or try to make) for better understanding of how the craft behaves.. filling a form about power consumption in idle.. average load and max load.. without any payloads.. im very interested about the values in a log (taking some time as i want no wind to mild wind contitions.. 4 logs to compare the efficiency at each time) in power columns that motors consuming from start to end..

so if there is 8000 rpm and i divide it by four (makes it 2000rpm per motor in hover.. no wind) and then divide the value to 30 minutes of flighttime (i know thats not absolute but lets say that it hovers in no wind) that makes us 67 (its 66.66 and i rounded it up for ease) of 100 of the total power consumpion in hover..

in the scenario that there could be wind and say that message about max motor speed reached.. ive seen that in smode (no wind) it triggers the message in about 80% of total power.. know already that it weights about 3lbs (to calculate the drag) and here im stuck as i dont know the watts that its adressing per minute from the 15v battery to make the calulation about power consumption in 30 minutes..

yes i know there are no absolute values.. but im trying to calculate for better understanding the efficiency of the whole system

edit.. now i see how it goes (was typing with you at the same time 😁).. definetly was wrong in some calculations as i didnt put in the scenario the rest of electronics.. only the ppms i was looking.. oops 😁

edit2. where does the 2 value comes from when you did the multiply in watts?? think ive got a bit confused.. its 28 minutes right?? im a bit confused @Phantomwolf
OK. I am not sure why you would divide the 8,000 rpm by 4. If the motor is rated to spin at 800 rpm per volt applied, then applying 10 volts would result in 8,000 rpm. If all four motors were placed across 10 volts then all four should be spinning at 8,000 rpm.

Wattage is a "per hour" measurement so if you want the "per minute" value, divide the wattage by 60. Again, we have to assume everything else remains constant.

For what you are doing, you need to know what the idle rpm is. Then you can calculate what the voltage is being applied to the motors. You would also need to know what the input voltage is to the ESCs (electronic speed controls) and how much power is consumed by them in controlling the voltage applied across the relative motor.

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#### xrider

Wattage is a "per hour" measurement so if you want the "per minute" value, divide the wattage by 60. Again, we have to assume everything else remains constant.
im doing the calculations in minutes as its more clear to me..
did you rounded up the 28 mins to 30 that makes us the 2 value (when you said "81.32 x 2" ) ?? if so thats why i made the mistake trying to figure power consumption without the rest of electronics..

did 81.32 / 60 / 4 .. makes a 0.338.. whitch doesnt make any sense🤦
lets try x 2 (your way)
81.32 x 2 / 4 .. it makes us 40.66 .. so 40.66 is the consumption per motor at 8000 rpm
is that solution correct or am i missing something?? 🙄

ps. give it a try to see how many v needed from gimbal.. camera (the whole assembly if i remember correct is happy at 12v).. 3in1.. cooling system (5v there) .. fc (5v here).. escs (from what i had read mosfets work at 3.6v and there are also sensors there.. 4.something in v.. make it 5 at each side) etc modules all around the unit in mV.. considering all these i dont think is only 12.64 watts.. 🤔

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#### Phantomwolf

im doing the calculations in minutes as its more clear to me..
did you rounded up the 28 mins to 30 that makes us the 2 value (when you said "81.32 x 2" ) ?? if so thats why i made the mistake trying to figure power consumption without the rest of electronics..

did 81.32 / 60 / 4 .. makes a 0.338.. whitch doesnt make any sense🤦
lets try x 2 (your way)
81.32 x 2 / 4 .. it makes us 40.66 .. so 40.66 is the consumption per motor at 8000 rpm
is that solution correct or am i missing something?? 🙄

ps. give it a try to see how many v needed from gimbal.. camera (the whole assembly if i remember correct is happy at 12v).. 3in1.. cooling system (5v there) .. fc (5v here).. escs (from what i had read mosfets work at 3.6v and there are also sensors there.. 4.something in v.. make it 5 at each side) etc modules all around the unit in mV.. considering all these i dont think is only 12.64 watts.. 🤔
Sorry, no can do. I have given you a rough estimate of what may be used by the motors. If you really need the rest of the information I would suggest, if you have the knowledge, take a drone apart, connect a meter that measures amperes with a storage capability and run the drone through it's paces with the ammeter connected to the different circuits that you wish to measure the current draw. You will also need the voltage readings so you can calculate the power consumption. Have fun doing that. All I need to know is whether my battery is fully charged before take-off and when I need to land before the battery dies. The rest I leave up to the engineers who designed the product.

• xrider

#### xrider

Sorry, no can do. I have given you a rough estimate of what may be used by the motors.
nevermind.. you helped A LOT and thank you SO MUTCH for your precious help!! 👍
have a nice day!!