# Esk8 Calculator

Thanks! Still have to scroll though

3 columns here we go

Perfect!! A cooler background would just be an added plus! NIce work!

Here is a testimate to how accurate this is mind blown (science tends to do that to me)

I think that if you would be able to fine tune the ‘weighted’ speed you could get it dead on. Maybe add another field where you can input your own weight, and add like 4 pounds for the electronics. Anyway great work!

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Great job @makevoid thank you for this!

I’d like to make another request if you can accommodate With Toddy’s calc I can input decimals into the ‘s’ count on the battery cell section. This was useful because I can simulate what my speed would be under full charge or various voltages in between.

I’d like it if I could either also put decimals for the ‘s’ count on this calculator or if I could put voltage manually instead. This would make me completely convert to this calculator!

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And thanks for not making the background black … To many dark colored backgrounds out there

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I would just prefer manual voltages. Or just for lipos do 4.2V as a max speed and 3.7V as min speed.

I think it could be done by adding more battery voltage presets:

Li-ion Full (4,1 V) Li-ion Nominal (3,6 V) Lipo Full (4,2 V) Lipo Nominal (3,7 V)

Note: values mais be wrong but I think this is it.

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liion and lipo area both full at 4.2v

What about adding a slider ranging from 0v to 4.2v this way you can simulate every possible voltage

eRPM = (voltage)x(kv rating)x(pole pairs, 7 for most 50-63mm motors)

e.g.: 37 volts (10s) with 200kv motor and 7 pole pairs:

372007 = 51800 eRPM. From what i’ve read you do not want this to go beyond 60000 on the VESC

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• number of cells is now a float (you can add decimal values) @jinra

I’ll probably add more voltage presets later like full/nominal/min for both lipo and li-ion

• new feature! pastable configuration link

This is my configuration:

#### My Conf

http://calc.esk8.it/#{“batt-type-lipo”:1,“batt-cells”:8,“motor-kv”:190,“system-efficiency”:80,“motor-pulley-teeth”:15,“wheel-pulley-teeth”:36,“wheel-size”:97}|

The link is a bit long because it has in it all the paramters required but it was easy to implement. Having the values in the link means that I don’t need to store it anywhere (db) / make the user log in and stuff…

(refresh with shift pressed to clear the cache and see the latest version)

edit: modified the link so it works with the forum in both forms

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@makevoid Awesome! This looks great!

@makevoid

I’m not sure if you are still interested in tinkering with this tool anymore, but have you considered adding an option, or revising the calculation to set a target speed? I think this function would be really useful to new DIYers who may have restricted budgets, or already have certain hardware (i.e. speed controllers restricted to 6s voltage).

I reckon the less experienced or technically minded DIYer would find this really useful, and give them an opportunity to reverse engineer a board that will operate efficiently to the specifications and capabilities they want, rather than potentially buying incompatible motors/escs, or operating them at too low a voltage.

If you could put in your targeted top speed (weighted), and perhaps some other variables perhaps available voltage, wheel sizes (which may already have been purchased), it could provide guidance in terms of motor and wheel pulley ratio will need to purchased to get to the speed they want.

You might also put in an range estimation (for flat ground) based on the amp hours of the battery they may already have.

If the tool could do this, then it would take a lot of the guesswork out ensuring that first builds are successful (at least electrically speaking).

Not sure if this is feasible, but I can imagine esk8 parts vendors using this sort of calculator on their websites to recommend certain components, instead having their products and their technical specifications (perhaps in drop down boxes) in the fields of the calculator. (nudge nudge!)

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This is awesome!

I like your idea very much… I remember myself entering values numerous times, just to get to see what output speed will I get… This could optimize the process, for sure…

I know it is hard to estimate but someone more calculations savy could also come up with a way to calculate torque, although it seems ppl are usually fine, if they don’t go way too extreme on some of the parameters for their builds.

This should a sticky thread. Super useful.

Calculator is exact. Tested it today on my board. 80% efficiency and I am 45kg