Esk8 Calculator

General Discussion
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33

@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!)

2 Likes
34

This is awesome!

35

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.

36

This should a sticky thread. Super useful.

37

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

38

thanks for the in-depth comment

I’ll probably try do an new ‘staging’ version of the calculator some time soon, even if right now I’m more focused and exploring the vesc uart interface (hopefully I will not break any other vescs ^^)

all your points are valid, let’s separate them even if in the ideal world we would have an almighty solve-all tool:

  • Load defaults / presets - esk8 database

requires a “database” to pick data from

my opinion: very good, would be awesome, but it’s a great effort - it requires a “database” (can even be a spreadsheet / a markdown / csv file hosted on github) that needs to be maintained / updated and checked (declared specs vs actual specs can vary)

also that would probably be better in/with @Okami 's project instead of retro-fitting this on a simple value calculator like this one

links: http://www.electric-skateboard.builders/t/new-builder-list-of-known-and-commonly-used-parts/2983/1 - http://www.electric-skateboard.builders/t/new-builder-list-of-known-and-commonly-used-parts/2983/1

but I agree, a tool like that it would be awsome

  • Calculate range based on battery wh

That would be good but I think it will be very approximate!

There are few issues in doing a good range calculation, there are few factors that can really vary the outcome: hills, quality of asphalt (both not really well defineable), weight (that’s a big factor), mechanical efficiency (drive train, bearings etc, hubs), wind, average speed …

the good thing is that there are some easily factorable values like travel speed + motor kv + gearing but I don’t think they’re enough

Maybe a statistical analysis ( one was started here http://www.electric-skateboard.builders/t/ride-time-how-long-can-you-ride/1316/5 ) would be better? I think we could try to have both but still, that requires managing data, not only fixed formulas (easier), some effort, but yes it could be very useful.

p.s. I like to tackle quick wins ^^ so if you find an utility that can be coded quickly (<1 day), that is useful and that doesn’t needs maintainance (e.g. you just need to make sure it stays online, no need to update/recheck etc.), then I can probably do it do it :slight_smile: .

39

About the database -

As of now it is this far:

http://gct-hp.de/esk8/index.php

It has its interface but the data output with tables and parameters to choose from are still missing.

@Deathcookies is the guy to contact, if you’'ve got any other ideas or you want to help.

@karma tried to take part in this project, although I am not sure how far did @deathcookies arrange the process between them.

So far it looks promosing to me, it just need to be finished, so any help would be great, especially from people who know how to output data fields / records and similar stuff!

1 Like
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@Okami, @DeathCookies sent me massage 5 days ago and said I could start helping but unfortunatly I started university 6 days ago and I have no time at the moment. I will contact him if I get any spare time. :slight_smile:

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Hi there! I am new but I thought id contribute this, I just made it for range or distance instead of speed, feel free to check it out! https://jscalc.io/calc/rdJYgcAquv9oqdcu Thanks, Clayton

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42

wow it looks awesome! I didn’t know about https://jscalc.io , pretty cool! :thumbsup:

my values < the range is pretty much that

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by your calculator, the larger the motor pully the bigger the range. so if you go light speed you have lots of km’s https://jscalc.io/calc/rdJYgcAquv9oqdcu#{“1”:149,“2”:43,“3”:20,“5”:125,“6”:10000,“7”:10000000,“8”:1}

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@Hillso So with both my calculator and the speed calculator that makevoid made if you put the massive motor gear with the tiny wheel gear it will give bad results (http://calc.esk8.it/#{“batt-type-lipo”:1,“batt-cells”:10,“motor-kv”:200,“system-efficiency”:80,“motor-pulley-teeth”:100000000,“wheel-pulley-teeth”:1,“wheel-size”:83}|) < example, this is because as long as you can get enough tork to move the board this speed is possible, but that amount of torque would be insane and unrealistic. Both calculators should work close to perfectly if you give it proper numbers to work with. The calculators do not include the torque number because most hobbyists don’t know the amount of torque they have… only the wattage. Thanks for the feed back though… Clayton

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45

I can’t seem to enter the cell count as a decimal. Am I missing something?

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lol you have to be quick (I should fix that), but really if you’re quick (like in half a second 2 digits) and you insert a dot as decimal separator it works :smiley: sorry about that ^^

1 Like
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Thanks for the tip. I figured it out. You have to enter the numbers first then go back and add in the decimal point.

48

even for normal numbers, I thought the lower the top speed the larger the range. 22 km for 36 km/h 30 km for 48 km/h oh I get it. it’s like that because you get to the same speed with lower voltage on higher top speed, so lower watt. but than you need higher amps so no. idk

49

That part is calculated using the amps, the slower you go the less amps you will pull and therefor the farther you go!

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but according to your calculator the faster you go the farther you go. or I’m dumb? idk.

51

So glad i found this, thanks

52

How do you guys decide what to put in the efficiency tab?