# Watt hours



## coulombKid (Jan 10, 2009)

major said:


> O.K. bj,
> 
> Here's your thread. Please tell us why EVfun's statement is "not quite" right.
> 
> ...


Now I see the error in previous posts w.r.t. an efficiency guage. While going on about an watt-hour per mile gauge I forgot the dimensional analysis. In fact, the read out would be simply watts per mile. The hours units in the denominator and numerator would cancel. In function it would be similar to the miles per gallon readouts first see on '80 era Caddys. (A driver training device). The predictive reciprocal readout was already on the EV1, miles left on the charge. (subtractive intregal)


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## bjfreeman (Dec 7, 2011)

Sorry I did here.
http://www.diyelectriccar.com/forums/showthread.php/amps-watts-coulombs-67463.html


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## major (Apr 4, 2008)

major said:


> bjfreeman said:
> 
> 
> > EVfun said:
> ...


So here's your answer from your thread: 


bjfreeman said:


> So if you have a Battery that is rated at 100 Ah and has a charge Differential of 3 Volts. lets say you have a flow of 100 amps for one hour.
> This is not the same electrons for the whole hour so you will have 360,000 amps in one hour. At 3 Volts you will have expended 1,080,000 Watts or 300 watt hour.


Do you realize you say that 1.08 megawatts is available from that cell? That is 1448 horsepower. You must realize that something is wrong with your understanding or use of convention.

Regards,

major


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## major (Apr 4, 2008)

major said:


> Do you realize you say that 1.08 megawatts is available from that cell? That is 1448 horsepower. You must realize that something is wrong with your understanding or use of convention.





bjfreeman said:


> So if you have a Battery that is rated at 100 Ah and has a charge Differential of 3 Volts. lets say you have a flow of 100 amps for one hour.
> This is not the same electrons for the whole hour so you will have 360,000 amps in one hour. At 3 Volts you will have expended 1,080,000 Watts or 300 watt hour.


Hi bj,

I think you don't understand the concept of a rate. So if I asked you how many miles per hour you traveled last year, you would calculate it as such:

Average 50 mph,

24 hours in the day, so 1200,

365 days in a year, so 438000,

So you'd say you did 438000 mph last year. Right?

major


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## bjfreeman (Dec 7, 2011)

major said:


> Hi bj,
> 
> I think you don't understand the concept of a rate. So if I asked you how many miles per hour you traveled last year, you would calculate it as such:
> 
> ...


show me how fast a charge travels is the same as your example.
note the charge rate of travel is constant speed of light
Now if you want to use the example of cars (charges) passing over a road (wire) you are inline with Charges flowing


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## major (Apr 4, 2008)

bjfreeman said:


> show me how fast a charge travels is the same as your example.
> note the charge rate of travel is constant speed of light
> Now if you want to use the example of cars (charges) passing over a road (wire) you are inline with Charges flowing


So you agree that my analogy example doesn't make any sense? Yet you do the same thing when it comes to Amperes and Watts


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## bjfreeman (Dec 7, 2011)

major said:


> So you agree that my analogy example doesn't make any sense? Yet you do the same thing when it comes to Amperes and Watts


unlike what I did I showed you what be correct and why
and part of our problems is you don't understand Electricity. You don't carry your thought process through to conclusion. you shift your reference.


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## JRP3 (Mar 7, 2008)

bjfreeman said:


> and part of our problems is you don't understand Electricity. You don't carry your thought process through to conclusion. you shift your reference.


LOL  This is too much.


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## major (Apr 4, 2008)

bjfreeman said:


> unlike what I did I showed you what be correct and why
> and part of our problems is you don't understand Electricity. You don't carry your thought process through to conclusion. you shift your reference.


I understand electricity pretty well 

So let's go back to what got me started in the first place....your use of W/s. Explain please.

Ref: http://www.diyelectriccar.com/forums/showpost.php?p=275431&postcount=71


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## bjfreeman (Dec 7, 2011)

major said:


> I understand electricity pretty well
> 
> So let's go back to what got me started in the first place....your use of W/s. Explain please.
> 
> Ref: http://www.diyelectriccar.com/forums/showpost.php?p=275431&postcount=71


No lets continue so you can understand what I do 
http://www.diyelectriccar.com/forums/showthread.php/amps-watts-coulombs-67463.html


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## major (Apr 4, 2008)

bjfreeman said:


> No lets continue so you can understand what I do
> http://www.diyelectriccar.com/forums/showthread.php/amps-watts-coulombs-67463.html


O.K. Address my post, #4 in that thread, please.


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## coulombKid (Jan 10, 2009)

major said:


> I understand electricity pretty well
> 
> So let's go back to what got me started in the first place....your use of W/s. Explain please.
> 
> Ref: http://www.diyelectriccar.com/forums/showpost.php?p=275431&postcount=71


The metric of merit for EVs efficiency seems to be watt-hours per mile. By reading voltage and current through the A/D multiplexer we can calculate watts. The VSS returns a velocity. I suspect dividing instantaneous watts by miles per hour will return watt hours per mile. If correct this should tell me quickly if I should be in second gear for given conditions verses fourth gear. Most probably the marketed instrumentation does all this and more. Taking voltage and current at the (near) same time should cancel out errors due to pack voltage sag.


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## bjfreeman (Dec 7, 2011)

major said:


> I understand electricity pretty well
> 
> So let's go back to what got me started in the first place....your use of W/s. Explain please.
> 
> Ref: http://www.diyelectriccar.com/forums/showpost.php?p=275431&postcount=71


i did in 
http://www.diyelectriccar.com/forums/showthread.php/amps-watts-coulombs-67463.html


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## major (Apr 4, 2008)

bjfreeman said:


> i did in
> http://www.diyelectriccar.com/forums/showthread.php/amps-watts-coulombs-67463.html


Then address my post #4 in this thread.


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