Is there a rule of thumb for working out motor amp draw

[pinkpanda3310]

I had a look through Brian's calculator but didn't find what I'm looking for.

From what I can work out in a good brushless setup-the batteries have an amp rating at or above the esc rating and the esc above the motor draw(which is subject to the setup).

If I'm wrong on that then obviously I need some direction
So do I need an eagletree to know what's going on or is there a rough and untrustworthy method used for guessing if my motor is likely to draw to much other than temperature?

[Arct1k]

A rough guide:

Motor is X amps
Batteries should be X * 1.25 amps
ESC should be X * 1.5 amps

Best thing to do is post your setup and guys wih equivalent setups can help guide your selections / provide eagletree results from comparative setups.

Rgds

[pinkpanda3310]

Set up is-
e-maxx 3905
mmmv3
medusa 36-80-1600
neuenergy 4300 25c 6s
Integy 40 series sq pattern

Gearing is subject to change if im out front of my house then it bearly does 30mph on 4s (and bearly warms up) but I like to bash it in sand and occasionally do hill climbs and I prefer a bit more speed, 23/58 is the tallest gearing i have but am reluctant to use that anywhere but on the flat. I probably have a bit up my sleive but don't want to push it in the hot dry dirt of oz.

Thanks for your reply Arkt1c, I'll have to start jotting down points like that to make up a bible for myself.

[lincpimp]

As Arct1k said.

Please give us some info about your setup. You will also have to factor in that some batt mfgs overrate their packs, and a few other variables.

I can usually guess the necessary pack by the vehicle setup and tire size. Something like a monster truck with 6" tal tires and a properly sized motor that will turn around 35k rpm geared for 40-45mph will need around 2200 watts worth of battery power.

[pinkpanda3310]

I thought I did it all wrong for a second then realised I got in just before you Lincpimp

Originally Posted by pinkpanda3310

I had a look through Brian's calculator but didn't find what I'm looking for.

From what I can work out in a good brushless setup-the batteries have an amp rating at or above the esc rating and the esc above the motor draw(which is subject to the setup).

If I'm wrong on that then obviously I need some direction
So do I need an eagletree to know what's going on or is there a rough and untrustworthy method used for guessing if my motor is likely to draw to much other than temperature?

I have a basic Power Calculator program. It is mainly for estimating power required for Speed Runs, but it can apply to any setup. It will get you in the ballpark for how many amps you will need.

[BrianG]

B4: If you get good feedback on that program, and it is fairly accurate, I can port it to use at my site if you want. Of course, you'll get credit (posted at the top of the page). If not, no biggie.

Originally Posted by BrianG

B4: If you get good feedback on that program, and it is fairly accurate, I can port it to use at my site if you want. Of course, you'll get credit (posted at the top of the page). If not, no biggie.

Thats a good idea. I haven't gotten any feedback yet, but it gives me the same results I got with my Excel spreadsheet.

Its nice to have all this stuff in one place, lol.

[BrianG]

Well, we can work out the details via PM. I would just need the formulas and such. And maybe any specifics on layout, otherwise, I'd use the same theme the rest of the pages use. No matter what, it would be a little while before it is ready. I'm current working on 2 freelance projects (one definite, one to start soon).

[pinkpanda3310]

Thanks B4maz, and like you said it will be handy to have that calc in with Brians.