# Question about ESC and amps in mission planner

Hi everyone.

I have what I hope is not to silly a question. But I have the following motors on my APM 2.6 quad.

They suggest 18 amp speed controllers and I have 4 20 AMP ESC. What I don’t understand is on DroidPlanner 2 and mission planer it is telling me the amp usage at any given time is 11 amps (no gimbal and gopro) to 18 fully loaded.

What I don’t understand is would the amp draw show on the apm software not be the total but just per motor? Or am I only putting 4.5 to 5 amps through each motor for a total of 18 amps ?

you don’t add up the total of the esc, it doesn;t work that way.

The value on the esc is the max rated current, so normal hover current should be way under that.

[quote=“RabbitStu”]you don’t add up the total of the esc, it doesn;t work that way.

The value on the esc is the max rated current, so normal hover current should be way under that.[/quote]

So if I had a hex copter and used the same motors my amp draw would go to say 25 to 30 so I would have to upgrade all ECS from 20a to 30a?

Not sure how you came up with that question based on what I said

I suggest you play with ecalc.ch with as close to the specs/values as you have/or are intending to have and see what the effects of more motors. more weight etc. its only a model, but hover current in ecalc is usually close enough. the max current is absolute wort case and may never occur in real life in my experience.

I can’t answer in a simple way, but a hex of the same weight would PROBABLY need less current per motor/esc all else being equal.

I am clearly missing something obvious. Just trying to connect the dots and maybe not explaining myself properly. I am trying to understand the ESC rating compared to the real world draw when hovering.

So you are saying you don’t add the esc together. So for example on a quad with 4 esc at 20 apms you cant draw 80 amps total from the battery when hovering. Your total drew cant exceed 20 amps across all for esc total?

Where I am getting lost is how many amps is each individual motor pulling and how will that relate to the ESC rating and the total amp draw from the battery.

Sorry if this is frustrating but I want to understand the concepts.

The required current from the battery or for each motor is basically/crudely related to how heavily the motors are loaded. At hover the motors/esc shouldn’t be that heavily loaded, else you have an undersized system

[quote=“ssbn506”]

So you are saying you don’t add the esc together. So for example on a quad with 4 esc at 20 apms you cant draw 80 amps total from the battery when hovering.[/quote]

If your hover need all of the current capacity of the esc yo would have no reserve…and probably fried escs.

I didn’t say that. It could. My big octa quad uses 20A (if rather conservatively rated) escs, but requires approx 50A from the battery, so current into each is esc is 1/8 of that.

play with ecalc and see what happens It breaks down esc and total for hover and max power in its estimates. the esc should be sized for max not hover.

Not frustrating for me…just trying to nip over simplification/false conclusions in the bud

ecalc is worth a look in aiding your understanding.

Ok I think you answered my question with this. So if I draw 18 amps from the battery hovering I am drawing 4.5a per motor on a quad using 4 20 amp esc. At that amp rate I am using 1/4 or so or each ESC rated capacity?

Yeah in simple terms that is correct. But check when doing hard manoeuvres what your peak current is too as a rough indicator.

sent from my phone so apologies for any typos