Power calculator

Post by **Miles** » Mar 17, 2007 10:17 am

This spreadsheet calculator was posted on the Power Assist list sometime ago. Credit for the program to Dave Everett. I've corrected one of the slope conversion formulas, that's all.

Post by **Miles** » Jun 07, 2007 3:44 pm

Just tidied this up a bit.

Post by **Miles** » Jun 30, 2007 5:03 am

Version 3 attached.

The expressions used for the formula in cell G7 were revised to enable the spreadsheet to function correctly on Google Spreadsheets.

You can now use this calculator without the need for Microsoft Excel.

Create an account with Google and upload the file to http://docs.google.com/

Please post any bugs/suggestions here.

Miles

P.S. I'm intending to append a table of "typical values" to the spreadsheet, so that people will be able to enter the value that most closely corresponds to their specific case.

Post by **Miles** » Sep 05, 2007 9:49 am

If you don't have spreadsheet software, you can also upload this program to: http://www.editgrid.com/site and use it online. Editgrid seems to be better than Google Docs.

PJD · Post by **PJD** » Nov 01, 2007 10:07 pm

As far as power calculations for climbing various grades, a while back I set up a spreadsheet so I could use the various slope hills in my area, along with a drag force calculation as a sort of poor-boy dynamometer test.

The spreadsheet is attached. It provided actual motor performance graphs for a hub-motored bike, or it could be modified easily for a chain or reduction gear.

It gives the calculation results and both metric and US units, but the raw data has to be in US units, sorry.

The numbers entered on it representing the actual performance on my e-max.

Post by **fechter** » Nov 02, 2007 9:02 am

Whoa.. almost 5kw. That's a pretty spunky scooter.

deardancer3 · Post by **deardancer3** » Dec 09, 2007 11:57 am

I like this power calculator; thought I would share.

(It lets you easily swap out different bike frames with default setting)

http://www.kreuzotter.de/english/espeed.htm

Dick in colorado

paultrafalgar · Post by **paultrafalgar** » Jun 11, 2008 6:40 am

PJD wrote:As far as power calculations for climbing various grades, a while back I set up a spreadsheet so I could use the various slope hills in my area, along with a drag force calculation as a sort of poor-boy dynamometer test.

The spreadsheet is attached. It provided actual motor performance graphs for a hub-motored bike, or it could be modified easily for a chain or reduction gear.

It gives the calculation results and both metric and US units, but the raw data has to be in US units, sorry.

The numbers entered on it representing the actual performance on my e-max.

That's a fascinating spreadsheet, PJD. What I find interesting is comparing Row 12 with Row 16.
You have halved (approx) the speed and EVEN though it's doubled the slope, you use 60% of the power!!!
SLOWING DOWN ON THE CLIMB is the way to go.

Post by **Miles** » Jun 11, 2008 6:52 am

paultrafalgar wrote: SLOWING DOWN ON THE CLIMB is the way to go.

Slowing down makes very little difference to the total energy consumed to climb hills.....

paultrafalgar · Post by **paultrafalgar** » Jun 11, 2008 7:05 am

Not according to PJD's spreadsheet.

paultrafalgar · Post by **paultrafalgar** » Jun 11, 2008 7:09 am

Miles wrote:If you don't have spreadsheet software, you can also upload this program to: http://www.editgrid.com/site and use it online. Editgrid seems to be better than Google Docs.

Just a little plug for OpenOffice. You don't need to be without a spreadsheet! OpenOffice is FREE for both Windows and Linux (probably Mac as well, I don't know).
IMHO better than Microsoft Excel by far.

Post by **Miles** » Jun 11, 2008 7:14 am

If you halve your speed you take twice as long to climb the hill.....

Sure, we know the power required to overcome air resistance goes up with the cube of the speed but if the power required to climb goes up linearly then slowing down on hills will have less effect on the total energy consumed than it would on the flat.

Post by **Miles** » Jun 11, 2008 7:16 am

paultrafalgar wrote:
Miles wrote:If you don't have spreadsheet software, you can also upload this program to: http://www.editgrid.com/site and use it online. Editgrid seems to be better than Google Docs.
Just a little plug for OpenOffice. You don't need to be without a spreadsheet! OpenOffice is FREE for both Windows and Linux (probably Mac as well, I don't know).
IMHO better than Microsoft Excel by far.

I certainly wouldn't disagree with this

I moved from Excel '98 to Open Office Calc after trying Microsofts' latest.......

Post by **Miles** » May 13, 2009 12:31 pm

Latest version, in ODS format:

Eric · Post by **Eric** » May 21, 2009 8:27 pm

Am I the only one who cannot open this due to its password protection? It probably works fine in other spreadsheets, but Xcel is having issues.
Eric

paultrafalgar · Post by **paultrafalgar** » May 22, 2009 3:15 am

Eric wrote:Am I the only one who cannot open this due to its password protection? It probably works fine in other spreadsheets, but Xcel is having issues.
Eric

It's an open-source format that OpenOffice uses, I'm not sure if Microsoft recognises/tolerates importation of .ods, but if you ask Miles nicely, he will convert it using Openoffice to Microsoft .xls format! BTW IMHO Openoffice calc is vastly superior to Excel and it's a free download, so why not get a copy that runs on Winders (if you must use a c**p operating system.

)

Post by **Miles** » May 22, 2009 4:26 am

Hi Eric,

Here's an older version in Excel format and a conversion of the latest from .ods to .xls:

Post by **Miles** » Sep 14, 2010 1:37 am

Revision 5.

- Added breakdown of torque at the wheel.

- Altered background colours of cells.

Post by **Miles** » Sep 14, 2010 8:27 am

Revision 6. Simplified version.

- Removed battery characteristics; motor efficiency and torque inputs.

- Removed distance and amps outputs

- Added motor torque output.

OpenOffice format (for Excel format see 2 posts down).

Post by **Miles** » Sep 21, 2010 7:53 am

Reference for aerodynamic data: http://books.google.co.uk/books?id=0JJo ... on&f=false

Post by **Miles** » Sep 21, 2010 7:57 am

Revision 6 as an Excel file:

Post by **Miles** » Jul 17, 2011 5:16 pm

Good reference for rim/tyre sizes:

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3802

crossbreak · Post by **crossbreak** » Aug 08, 2013 8:54 am

thx so much, we should develop this further and add a motor simulator like PeakEff. Then we would have something like the ebikes.ca/simulator as stand alone Excel software

Post by **Miles** » Aug 19, 2013 2:01 am

Feel free to take it in any direction you like CB..

I thought that this would be more useful to others than, in practice, it has been... For most people, the Kreuzotter calculator seems to be sufficient.

crossbreak · Post by **crossbreak** » Aug 19, 2013 8:37 pm

wasn't aware of this one.. use my own Matlab simulink Simulation which can do something with motor resistance, e-rpm, inductance and so on.... i like the ebikes.ca simulator for the variety of different motors. It's just not sufficient to input "Watts" if a motor is involved IMO. The ebikes.ca simulator shows this very good, but does not take eddy current etc into account. When my Simulink stuff is perfect i'll try to do something similar with Excel

Endless Sphere

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