# Best range efficiency.



## Simon the Frenchie (Nov 13, 2012)

Hi,
I'm always surprise to see range differences between cars on evalbum.com with about the same battery pack.
What does such a difference? The efficiency of the motor, the minimum SOC available for your battery, and? What about the controllers, does it make a big difference? and the BMS too?
To make long story short, how to get the best range out of the same battery pack?
Thanks,
Strauss Simon


----------



## Yabert (Feb 7, 2010)

Simon the Frenchie said:


> To make long story short, how to get the best range out of the same battery pack?


Find a car with the lowest drag coefficient...


----------



## EVEngineeer (Apr 11, 2012)

Aerodynamics at highway speeds and light or reduced weight at street speeds.


----------



## Simon the Frenchie (Nov 13, 2012)

Ok I notice, so choosing a good car. Aerodynamics and/or light weight.
But does the controller and bms change the range capacity?


----------



## Tesseract (Sep 27, 2008)

Simon the Frenchie said:


> ..
> To make long story short, how to get the best range out of the same battery pack?
> ...


Differences in controller efficiency are going to be minimal, even for radically different types of controller, like, say, one for series DC vs. a 3ph. inverter. Yes, the inverter will be "half" a efficient as a DC motor controller, but that will still only amount to about 1-2 percentage points (ie - the 3ph. inverter might be 96% efficient vs. 98% for the DC motor controller).

Differences in motor efficiency can be more substantial and _possibly_ worth pursuing. A 3ph. synchronous AC motor with PM field (aka PMSM) is about the most efficient motor there is, and if sized properly could deliver an average efficiency of about 90%, compared to, say, 85% for a similar sized induction motor or 80% for a similarly sized series DC motor. So, up to 10 percentage points of efficiency difference, then.

However, by far the biggest factors in determining range for a given battery pack energy rating are vehicle weight and aerodynamics. There can be as much as a 3:1 difference in the rate of energy consumption (given in watt-hours for every km) between vehicles. This totally swamps any differences in the efficiency of the electric drivetrain components themselves.

For example, a small lightweight vehicle might require 120 watt-hours per kilometer while a large luxury sedan could easily require 360 Wh-km. If the energy consumption rate of 120 Wh-km for the small car is with a PMSM then switching to a less efficient induction motor will increase that to 126 Wh-km, perhaps. That's totally unnoticeable compared to picking a different car


----------



## Simon the Frenchie (Nov 13, 2012)

Thanks Tesseract, it's precise as I like!
So aerodynamics is the most important point for a EV.


----------



## Ziggythewiz (May 16, 2010)

Simon the Frenchie said:


> Thanks Tesseract, it's precise as I like!
> So aerodynamics is the most important point for a EV.


For cruising range, yes. For stop&go / in town weight trumps aero.


----------



## major (Apr 4, 2008)

Simon the Frenchie said:


> Hi,
> I'm always surprise to see range differences between cars on evalbum.com with about the same battery pack.
> What does such a difference? The efficiency of the motor, the minimum SOC available for your battery, and? What about the controllers, does it make a big difference? and the BMS too?
> To make long story short, how to get the best range out of the same battery pack?


Hi French,

We (Darlene and myself) have been using an EV almost every day for the past 4 months. I installed a kWh meter on a dedicated branch circuit for the L2 EVSE in the garage where we do like 99% of the charging (pretty much every night). We record every kWh and odometer reading on paper. Here are some of my thoughts on the subject.

It makes a difference in reported Wh/mi figure depending on how and where the measurements are taken. Is it an on-board instrument or stationary meter like I have? Obviously I have my charger efficiency included. And what is the accuracy of the instruments and calculations used to present the Wh/mi figure?

The condition of the vehicle makes a difference. Like tire pressure, alignment, lubrication, etc. Also the accessories in the vehicle make a big difference since it all comes from the battery. My electric heater is 4 kW. I take a huge hit when driving in cold weather.

But the biggest difference in Wh/mi which I see is the way the vehicle is driven. From hypermiling to racing, along with all other factors, on the same vehicle, roughly, can make a 4 to 1 difference in reported Wh/mi.

From personal experience, range anxiety is very good method to improve your energy consumption when driving an EV 

Regards,

major


----------



## dragonsgate (May 19, 2012)

Simon the Frenchie said:


> Hi,
> I'm always surprise to see range differences between cars on evalbum.com with about the same battery pack.
> What does such a difference? The efficiency of the motor, the minimum SOC available for your battery, and? What about the controllers, does it make a big difference? and the BMS too?
> To make long story short, how to get the best range out of the same battery pack?
> ...


I too have wondered about this. I like to look at the other builds and many of them are good examples of how it should be done. The stats on some of the EV’s in the garage are a little over the top though. This could be from simple math mistakes, or over enthused estimation. There is one full body car that is running 12 volt lead batteries that claims 80 miles or better and the total weight of the car is almost the same as my car is with out batteries wich is 1626 pounds. I am still trying to work that one out. Take in all the info you can and then do your own best calculations.


----------



## mizlplix (May 1, 2011)

My $.02

Most important to less important:

#1= Vehicle weight.

#2= Driving habits-rapid starts or normal starts.

#3= Local Terrain. Hills or flat. City or country driving.

#4=Tire pressure/alignment,(rolling resistance)

#5= Aerodynamics-(40 mph and over)

Miz


----------



## dladd (Jun 1, 2011)

I can get anywhere from 250Wh/mi to 400Wh/mi in the same car. Same weight, same aero. Only difference is driving style. Just like a gas car, a heavy foot = poor efficiency.

Also, take info at EValbum with a grain of salt... Much of it is 'theoretical' or wishful thinking, imo.


----------



## Simon the Frenchie (Nov 13, 2012)

mizlplix said:


> My $.02
> 
> Most important to less important:
> 
> ...


I understood from other thread that weight is important for stop/start driving like in town, and aerodynamics for country/road use.
I'm living in the flat country side so for me aerodynamics will be more important, I still keeping weight in mind.
I'm use to very slow acceleration, anticipating a lot and all of these.
And for 4th and last point my father is car maniacs, it's going to be always clean.

Otherwise I found for 500$ near where I live a Opel Calibra, car that got the best cx and scx as I know, cx:0,26 scx:0,49, but it weight 1250Kg (with a 2L engine). Taking out a heavy engine and using light LiFePo4 battery it should stay in about the same weight. Anyone used this car as a EV?

Still searching...

Did anyone use this website to calculate their range? http://www.evconvert.com/tools/evcalc/ Is it approximatively right?

Thanks


----------



## Simon the Frenchie (Nov 13, 2012)

I just search and found this about the Calibra, http://www.diyelectriccar.com/forums/showthread.php/considering-opel-calibra-conversion-21280.html lets read!


----------



## tomofreno (Mar 3, 2009)

All the things mix and major said plus some just pull a number out of an orifice before their car is even completed. Or they might guess at a wh/mile and divide the total capacity of their pack by that, whereas others guess a bit different number, or divide 80% of their pack capacity by that guess. I think there are many range numbers on the evalbum that are not actual measured values. There are some pretty fantastic numbers on there for lead acid packs.


----------



## kennybobby (Aug 10, 2012)

*Mizl is right on target!*



mizlplix said:


> Most important to less important:
> #1= Vehicle weight.
> #2= Driving habits-rapid starts or normal starts.
> #3= Local Terrain. Hills or flat. City or country driving.
> ...


Here is a link to an on-line calculator in which you can vary #1,4,5 to see how the load power changes, and how for a given weight, the Rolling Resistance is the dominant factor below about 40 mph.

http://ecomodder.com/forum/tool-aero-rolling-resistance.php


----------



## Nathan219 (May 18, 2010)

our experience it has been 
1. drive system efficiency 
2. vehicle aerodynamics
3. vehicle weight.

It would be interesting to see a comparison between high voltage 300V or more AC and DC motors. 
I will be interesting to see if we get better than our previous 155 watts/mile with our new body.


----------



## Tesseract (Sep 27, 2008)

Nathan219 said:


> our experience it has been
> 1. drive system efficiency
> ...
> It would be interesting to see a comparison between high voltage 300V or more AC and DC motors. ...


How did you conclude that drive system efficiency is the number one factor in determining the rate of energy consumption in a vehicle without comparing different systems (as the follow-on comment suggests)?

At any rate, I did a simulation of a 3ph. inverter and a buck converter with all other parameters except circuit configuration the same (ie - input voltage, switching frequency, output power, heatsink R_theta, etc.). At 20kW output the inverter produces 450W of waste heat (n = 97.8%) while the buck converter produces 230W (n = 98.9%). Either amount of loss is a tiny fraction of the total power required to propel the vehicle at the 75 mph used in this example.* 

Of course there is also the efficiency of the motors to consider, but there is not necessarily as much difference between AC and DC as people might otherwise assume. It costs money (in materials and machining precision) to make any motor more efficient, and while a brushed motor will tend to have a slight disadvantage in efficiency overall, it may not be enough of a penalty to offset the advantage conferred upon the DC system by the buck converter topology.

At any rate, both the AC-50 or the WarP-9 claim a peak efficiency of 88%, which brings the total losses** up to 3180W for the AC system and 2960W for the DC system. Over the course of 1 hour the vehicle will have traveled 75 miles at an energy consumption rate of 23180W/75 = 309 Wh-mile for the AC system and 306 Wh-mile for the DC system. Heck, even if you knock 5 points off the efficiency of the DC system it still only brings the energy consumption rate up to 324 Wh-mile, which is going to be very difficult to differentiate between a slightly stronger headwind on the drive... 

In other words, the effect of drive system efficiency is hardly noticeable, much as I said in my less rigorously argued initial post to this thread.


* - for this example I used this handy calculator with Cd = 0.3, A = 21.5 ft², W = 3500#, V = 75 MPH.

** - 20000W/0.88n = input power of 22730W to the motor required for 20kW output, or net loss of 2730W.

EDIT: yes, I realize that I should change the output power of the motor controller to reflect the inefficiency of the motor but I am being lazy because the point of this post is to illustrate how irrelevant the drive system efficiency is in the overall scheme of things.


----------



## Nathan219 (May 18, 2010)

Somehow we are bettering 90% efficiency for the whole system, or our batteries are holding much more energy than they were ratted for.
99 cells 
100 ah
216 miles 
cd 0.23
area ~2 meters sq 
~55 mph
When 1% means 2 miles and you have to get 200+ range you buy the most efficient system you can afford. Efficient power delivery effects all portions of the vehicle operating range.


----------



## brainzel (Jun 15, 2009)

Tesseract said:


> Differences in controller efficiency are going to be minimal, even for radically different types of controller, like, say, one for series DC vs. a 3ph. inverter. Yes, the inverter will be "half" a efficient as a DC motor controller, but that will still only amount to about 1-2 percentage points (ie - the 3ph. inverter might be 96% efficient vs. 98% for the DC motor controller).
> 
> Differences in motor efficiency can be more substantial and _possibly_ worth pursuing. A 3ph. synchronous AC motor with PM field (aka PMSM) is about the most efficient motor there is, and if sized properly could deliver an average efficiency of about 90%, compared to, say, 85% for a similar sized induction motor or 80% for a similarly sized series DC motor. So, up to 10 percentage points of efficiency difference, then.
> 
> ...


I'm saving for about two years to replace my Curtis 1231C next year against a Soliton junior, to see if I consume less with the new controller.
And now you write that the most likely have no effect ... I hope my wife does not read your statement ;-)

Michael


----------



## brainzel (Jun 15, 2009)

We rebuild our car last year.
- update from 36 to 45 cells (120V to 144V)
- update from Curtis 1221C to 1231C
- update from D&D Motor to Netgain WarP9

gain:
1,51 kWh/100km or 24,3 Wh/mi
same car, same driver, same weather, same environment, same charger
long time measurement, measured all at wall charger (charging losses included)

Michael


----------



## Tesseract (Sep 27, 2008)

brainzel said:


> I'm saving for about two years to replace my Curtis 1231C next year against a Soliton junior, to see if I consume less with the new controller.
> And now you write that the most likely have no effect ... I hope my wife does not read your statement ;-)
> 
> Michael


Oh, there are plenty of good reasons to replace the 1231C with a modern digital controller (like the Soliton), not the least of which is that they are much more safe. Any difference in efficiency is going to be minimal, at best, though.


----------



## Simon the Frenchie (Nov 13, 2012)

brainzel said:


> We rebuild our car last year.
> - update from 36 to 45 cells (120V to 144V)
> - update from Curtis 1221C to 1231C
> - update from D&D Motor to Netgain WarP9
> ...


I'm not surprise, even more that higher voltage make your motor more efficient.
Within a maximum allowed by your motor.


----------



## brainzel (Jun 15, 2009)

Tesseract said:


> Oh, there are plenty of good reasons to replace the 1231C with a modern digital controller (like the Soliton), not the least of which is that they are much more safe. Any difference in efficiency is going to be minimal, at best, though.


Yes, I will update next year. No doubt.
But you know how wives think about something like that?
"A new controller? Is the current one broken?"
"What would we save? Ah, not really much? And what would it cost us? Ah, 2.000!"

Everything has to be well-founded ... besides buying shoes! ;-)


----------



## major (Apr 4, 2008)

brainzel said:


> We rebuild our car last year.
> - update from 36 to 45 cells (120V to 144V)
> - update from Curtis 1221C to 1231C
> - update from D&D Motor to Netgain WarP9
> ...


Nice data point. What was the base or percentage improvement?


----------



## brainzel (Jun 15, 2009)

major said:


> Nice data point. What was the base or percentage improvement?


base: 25,76 kWh/100km or 414,57Wh/mi
after rebuild: 24,25 kWh/100km or 390,27Wh/mi
5,86% improvement


----------



## gunnarhs (Apr 24, 2012)

Hi,

previous posts have mentioned major factors , like speed, weight and acceleration.
To add to that:

Heating (up to 30% loss!!)
Gearing/ATM 10-15% gain
Regen 5% (more if driving concious)

The difference we have experienced in the control-box is efficient field-tracking which has to do more with the software than hardware 
(assuming pro hardware). This craves motor knowledge in the algorithm.
Software-gain: 20-30% (for Sepex-Ex DC and and Induction AC).

The range limit we have experienced is about 10km/kWh per 1000kg vehicle weight and average drag, driving average speed about 70 km/h in mixed condition. It is similar when "rolling" at 90 km/h in best condition.

The most common usage is 5-8km/kWh.
Worst performance in Iceland was by MIEV having an average of 4km/kWh. 
Possible explanations for that:
1) Cold area
2) Higher average speed in Reykjavik and less regen due to low traffic.
3) Indication that PMSM are better on the testboard than in real life


----------



## tomofreno (Mar 3, 2009)

gunnarhs said:


> The range limit we have experienced is about 10km/kWh per 1000kg vehicle weight and average drag, driving average speed about 70 km/h in mixed condition. It is similar when "rolling" at 90 km/h in best condition.


 That's very good! What vehicle mass and drag coeff?


----------



## kennybobby (Aug 10, 2012)

*What's your pack voltage and vehicle weight?*



Nathan219 said:


> Somehow we are bettering 90% efficiency for the whole system, or our batteries are holding much more energy than they were ratted for.
> 99 cells
> 100 ah
> 216 miles
> ...


And what chemistry battery cells are you using?


----------



## gunnarhs (Apr 24, 2012)

tomofreno said:


> That's very good! What vehicle mass and drag coeff?


Peugeot 106 SepEx 1200 kg (after conversion) , drag-coeff. 0,34, 
8 km/kWh, well proven and well tested
Suzuki WagonR AC + ATM 1300 kg (after conversion), drag coeff 0,4
estim. 10 km/kWh, has yet to be verified better with higher speed.


----------



## Simon the Frenchie (Nov 13, 2012)

gunnarhs said:


> Gearing/ATM 10-15% gain


You mean that using the unitial gearing we use less energy as in direct drive?


----------



## Simon the Frenchie (Nov 13, 2012)

gunnarhs said:


> Peugeot 106 SepEx 1200 kg (after conversion) , drag-coeff. 0,34,
> 8 km/kWh, well proven and well tested
> Suzuki WagonR AC + ATM 1300 kg (after conversion), drag coeff 0,4
> estim. 10 km/kWh, has yet to be verified better with higher speed.


If with a heavier vehicule and higher drag coeff you're able to get a better efficiency this defintly show that there isn't only aerodynamic and weight in ev conversion.


----------



## gunnarhs (Apr 24, 2012)

Simon the Frenchie said:


> You mean that using the unitial gearing we use less energy as in direct drive?


It is not neccessary the original gearing but a gearing that helps the motor work in an optimal point (best efficiency in a longer frequency range). Can also be reached up a certain point by software control.
Depends on the motor type, 
AC-induction has problems in lower speeds.
PMSM seems to have BIG problems during higher speeds.
DC has no special problems at all (but a less overall efficiency)
Using a gearbox /ATM gives you the possibility of using a smaller motor up to certain speed , 100 km/h in our case. If you want to drive faster and be able to overtake at that speed, a bigger motor is neccesary.



Simon the Frenchie said:


> If with a heavier vehicule and higher drag coeff you're able to get a better efficiency this defintly show that there isn't only aerodynamic and weight in ev conversion.


Well, I have not much possibilites to change this two factors if I want to keep the original function of the car , I would if I had a few 100.000$ 
So we are trying to squeeze a few percentage here and there.
The two biggest factors are skipping electric heating (Peugeot uses Webasto-gasoline, Suzuki has no heating yet, will use Webasto) and using software field control (makes driving more lame though, will be optional).

It seems that we will be limited to 200 km range in most cases, but I promise that we will not be less than 150 km in any condition above -20 C!!!!


----------



## Nathan219 (May 18, 2010)

*Re: What's your pack voltage and vehicle weight?*

Lithium Iron Phosphate


----------



## Simon the Frenchie (Nov 13, 2012)

As you have seen on a other thread I'll be extending prius battery instead of converting a car because of French laws.
This project isn't even started yet I already have a other one in mind!
I already tough about putting a electric motor in a velomobile;








For the ones that don't know about it; this is, and I'm proud saying it; a French invention dating from 1913 if my memory still clear.
It's a faired recumbent trike weighting for the early models in around 25-30 Kg and with a Cx of more or less nothing 0.08 for the one in picture, there is even lower Cx.
It's said that anyone like you and me can develop about 150w by pedaling, those velomobile drives at 25 to 35 Mph with this power. A pro cyclist can develop way more and drive it around 60Mph continuously.

There are few that have electric assistance, (they usually don't human power is enough) and allow a normal user to drive as fast as a pro cyclist.

This is for the story of velomobile, but for the project I may buy one of those and put a 2-3Kw motor in it with some battery and see what it does!

If it gives idea to anyone to try I'll be happy.


----------



## Simon the Frenchie (Nov 13, 2012)

Just to give a idea of the potential of it, my avatar is the Polyjoule a French made record breaker.
This isn't comfy as a velomobile would be and you don't have any space for luggage but as I said this is only made for record.
They can drive 700 miles with 1Kwh.

```

```
http://www.polyjoule.org/article-55

```

```


----------

