[ausev] EV Calculator Script

[Carey King]

Nick,

I think you're on track by using power available in the batteries to 
figure out torque/speed limitations in the EV. A good example would be 8 
of 12V batteries vs. 12 of 8V batteries, and does each set allow for the 
same total series voltage and current capabilities (i.e. which one is 
more limiting)? I don't know influential the difference would be.

Good work on what you have. I like your site. My recommendation would be 
(albeit somewhat involved) some basic graphing to show people results of 
their inputs. I suppose this might involve some Java programming or 
something (which I can't claim to know at the moment). If the Y-axis 
were a few basic variables (battery energy storage (V, I), cumulative 
distance traveled) and the X-axis were one of time or distance.

carey

Nick Viera wrote:

>Hi Mark and all,
>
>Mark Hastings wrote:
>  
>
>>There is a section on Uves calculator where it lists the max speed in
>>each gear and whether it is RPM or voltage limited.
>>    
>>
>
>Right, I did see that. Unfortunately that section fails to list the most 
>important limiter of max. speed: available battery power. For example, 
>Uve's calculator tells me that I can go 77mph max. in 3rd gear with 
>battery *voltage* being the limiting factor. I know from real life that 
>this is not true; and that my max. speed is actually around 64mph with 
>battery *power* being the limiting factor (unfortunately) :-/
>
>My EV-RATS script calculates and shows an EV's top speed not by doing 
>simple gearing-RPM calcs but by taking the maximum available power from 
>the battery pack and back solving for how fast you can travel 
>(regardless of gear), still having enough available power to overcome 
>all sources of drag (aero drag, rolling resistance, etc.). I think this 
>makes it more practical and useable. Comments?
>
>  
>
>>The further sections where it shows 1st gear at 90mph and shows
>>speed/draw/etc are confusing but if they were somewhat accurate it
>>would be useful. If I was to make one easy change to those
>>1st/2nd/3rd/4th/5th gear section where it shows speed/draw/etc at
>>each speed it would be to put N/A in all the speeds that weren't
>>available in that gear.
>>    
>>
>
>Agreed! That's the minimum that should be done to make Uve's 
>calculations more applicable to a given vehicle.
>
>  
>
>>I tried the new calculator and it showed my S-15 pickup getting
>>18miles. Which is a little low unless it is winter but I probably
>>don't have all the figures properly set for the vehicle.
>>    
>>
>
>Hmmm... okay. All the feedback I've gotten so far indicates that this is 
>the case (EV-RATS being overly pessimistic about range). I'm trying to 
>figure out if this is due to calculation error(s), or if user's aren't 
>putting in accurate variables for their EV's, or ??  Could you give me 
>an idea of how far off its range calculations are for your vehicle and 
>what Cd, Coefficients of drag and rolling resistance your using?
>
>  
>
>>That was another nice feature of Uves calc where it had templates for
>>some base vehicles. Perhaps including some links to sources where one
>>could easily find that information would be better then templates.
>>    
>>
>
>I'd love to do this, but it seems like a really really laborious task 
>given all the different types of components and vehicles out there. Not 
>to mention that it would be hard to guarantee the variables (esp. for 
>batteries) wouldn't change and then the template(s) be incorrect at a 
>later date. Maybe a good compromise would be to make it possible for 
>users to upload their numbers to files that EV-RATS can load, e.g. 
>creating a database of "user submitted templates" for the calculator?
>
>Thanks for the input!
>
>  
>