EV energy losses (college thesis)

[freebeard]

Thanks. I see where it is, very near to the handbrake, but beyond that I don't have a clue.

So the lever shaft is cut and welded in a way that allows the top right corner of the Fluke to fit between them? Maybe the pot is a bias control and the button on top the shift lever is normally used?

Maybe I confuse easily?

[EVmetro]

Originally Posted by freebeard

Thanks. I see where it is, very near to the handbrake, but beyond that I don't have a clue.

So the lever shaft is cut and welded in a way that allows the top right corner of the Fluke to fit between them? Maybe the pot is a bias control and the button on top the shift lever is normally used?

Maybe I confuse easily?

That pic with the fluke in it was just a pic to show how the top half of an automatic buick shifter was grafted onto the 5 speed manual shifter that I use. The button on top of the shifter is no longer used to release the shifter interlock to take it out of park as it did on the buick that I got it from, now it controls the potentiometer below it that is mounted to the shifter shaft. The big button allows very precise control of the regen, from no regen at all to emergency braking power. The linkage is set up so that it gives progressively more regen the further I push it. So the sequence is that I push the button down, which turns the knob on the potentiometer, and the potentiometer changes determine how much regen is applied.

I found that setting the "off throttle" regen to just a tiny little bit made it so that the motor does not free spin so long. When the off throttle regen was set to zero, I could put the transmission in neutral and rev it up, and the motor would free spin for about a minute before finally coming to a stop. By playing around with tiny amounts off off throttle regen, I was able to come up with a setting that feels like no off throttle at all, but lets the motor idle down in just a few seconds. I was also able to fine tune it so that I have really nice clutchless shifting. I do have a heavy duty and very functional clutch, but it is nice to not have to use it if I don't want to. With just the right amount of off throttle regen, clutchless shifting is a little sweeter than clutchless shifting in a DC set up.

The driving experience is a lot nicer when you don't have to use the foot brake or the clutch. The thumb pot gives more precise braking action than the foot brake, and with far less effort. When I built this set up, I was not sure how easy it would be to adapt my driving habits to it, but it turns out that it is a lot easier for humans to adapt to things that are easier to do in the first place. I am finishing a Cadillac EV conversion right now, and am installing the same system, since the theme of this build is luxury. This build won't have a traditional shifter to use as a control location, so I am building a custom mount for it that is easy to use.

[freebeard]

Got it. The Buick half has an internal rod the button actuates. So you stop the car with your thumb.

In principle, the button could be anywhere (or everywhere) you might have your thumbs. The steering wheel, the driver door window sill...

[EVmetro]

Originally Posted by freebeard

Got it. The Buick half has an internal rod the button actuates. So you stop the car with your thumb.

In principle, the button could be anywhere (or everywhere) you might have your thumbs. The steering wheel, the driver door window sill...

Exactly. The key is locating the thumb pot in a location that is really easy and natural to use. What would be really cool, would be a ring around the back side of the steering wheel, so you could squeeze it in any position

[jjackstone]

Thanks for the detailed information. I know that ranges will vary with all the normal factors such as speed, stop and go traffic, hills etc. Care to venture a guess as how much energy the regen saves you as general percentage?
JJ

[sendler]

Interesting that this company is showing the brake specific energy consumption efficiency of their 125 PowerPhase motor as a vertical line at low rpm. Might as well floor it on take off.
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[EVmetro]

Originally Posted by jjackstone

Thanks for the detailed information. I know that ranges will vary with all the normal factors such as speed, stop and go traffic, hills etc. Care to venture a guess as how much energy the regen saves you as general percentage?
JJ

In my first conversion, I run an off throttle set up in a Metro, and in my second conversion, I run a DC set up with no regen capability at all, again a Metro. The variable-on-demand system is in my third metro conversion, again a Metro. During my 10 mile commute each way in heavy city traffic, I use at least 15% less energy with the variable on demand system than what I use for either the DC or the off throttle Metros. If I really push the limits of eco driving, there is no way that I can get home on as little energy with the off throttle or DC Metros, compared to what I can do in the variable on demand one. The DC and the off throttle Metros are remarkable, and use about the same amount of energy for that commute, but they just can't compete with the variable on demand.

I also do 55 mph range tests on my Metro conversions here in the flat Sacramento valley, and all three conversions use about the same amount of energy. The variable on demand system still does a little bit better, but I also did more things on this build to reduce the weight, and I also have an economy switch to limit maximum amps when it is switched to that position.

I also drive a lot in the foot hills where I have several 6% to 8% up and down grades, and lots of twisting roads with switchbacks and such. This is where the variable demand system shines the best, and it is also the type of terrain that I have to use my friction brakes the most on my ICE Metros. I know these roads well, and I make no effort to conserve energy at all. These roads are recreational driving to me, and I push the EVs to their limits. The variable on demand system makes this kind of driving really fun compared to having to use friction brakes, and it collects large amounts of braking energy

Regardless of the type of driving that I do, the variable on demand regen proves to be the ultimate eco mod, and yields superior efficiency compared to what is available in manufactured EVs. Here in CA, the difference in registration fees between a 20 year old Metro and a new manufactured EV is enough by itself to pay for 15,000 miles per year in electricity, so between that and the variable on demand system, I don't see myself owning a manufactured EV. Eco mods rock.

[jjackstone]

Thanks once again. Flat highway negligible gains were expected. I would have guessed between 8 and 10% difference for stop and go traffic so the 15% is impressive. Really didn't have a guess at all for hillier terrain so if it's better than heavy traffic that is truly great.
JJ