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Power calculator

Posted: Mar 17 2007 10:17am
by Miles
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.

Posted: Jun 07 2007 3:44pm
by Miles
Just tidied this up a bit.

Posted: Jun 30 2007 5:03am
by Miles
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.

Posted: Sep 05 2007 9:49am
by Miles
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.

Posted: Nov 01 2007 10:07pm
by PJD
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.

Posted: Nov 02 2007 9:02am
by fechter
Whoa.. almost 5kw. That's a pretty spunky scooter.

Posted: Dec 09 2007 11:57am
by deardancer3
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

Re:

Posted: Jun 11 2008 6:40am
by paultrafalgar
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.

Re: Re:

Posted: Jun 11 2008 6:52am
by Miles
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.....

Re: Power calculator

Posted: Jun 11 2008 7:05am
by paultrafalgar
Not according to PJD's spreadsheet.

Re:

Posted: Jun 11 2008 7:09am
by paultrafalgar
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.
:D

Re: Power calculator

Posted: Jun 11 2008 7:14am
by Miles
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.

Re: Re:

Posted: Jun 11 2008 7:16am
by Miles
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.
:D
I certainly wouldn't disagree with this :D

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

Re: Power calculator

Posted: May 13 2009 12:31pm
by Miles
Latest version, in ODS format:

Re: Power calculator

Posted: May 21 2009 8:27pm
by Eric
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

Re: Power calculator

Posted: May 22 2009 3:15am
by paultrafalgar
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. :D )

Re: Power calculator

Posted: May 22 2009 4:26am
by Miles
Hi Eric,

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

Re: Power calculator

Posted: Sep 14 2010 1:37am
by Miles
Revision 5.

- Added breakdown of torque at the wheel.

- Altered background colours of cells.

Re: Power calculator

Posted: Sep 14 2010 8:27am
by Miles
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).

Re: Power calculator

Posted: Sep 21 2010 7:53am
by Miles

Re: Power calculator

Posted: Sep 21 2010 7:57am
by Miles
Revision 6 as an Excel file:

Re: Power calculator

Posted: Jul 17 2011 5:16pm
by Miles
Good reference for rim/tyre sizes:

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

Re: Power calculator

Posted: Aug 08 2013 8:54am
by crossbreak
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 :)

Re: Power calculator

Posted: Aug 19 2013 2:01am
by Miles
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.

Re: Power calculator

Posted: Aug 19 2013 8:37pm
by crossbreak
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