EV Segment on the ABC's Checkout program

Post by **Johny** » Thu, 18 Apr 2013, 19:27

I set up my laptop and logged my dash data this morning on the way to work. The dash outputs a comma delimited serial string of Battery volts, Battery Amps and Motor RPM every 1/2 second. Unfortunately traffic biased me along a flatish path to work today so no really big hills and also the terminal software stopped logging after 20 minutes. There is enough data to use though. Below is the Average AH for the trip then the Drive only then the Regen only. The WH figure comes from using the average voltage over the trip - not quite right but near enough.

           Average Current    Drive Current    Regen Current
Current    2.604437185        2.91582959       -0.311392405
Watt/Hour 1612.600719        1805.406911      -192.8061921

You can see that regen gave me about 11%. It essentially lowered the batter capacity required for the trip from 2.91 to 2.6 AH

Graph of battery current over 20 minutes. I pretty much only used the brake pedal to hold on hills and maybe did one or two mechanically assisted stops.

Post by **Richo** » Thu, 18 Apr 2013, 20:30

11% is still worth it.

But doesn't really explain effects of up/down hill vs flat over same distance and speed.

Post by **Johny** » Thu, 18 Apr 2013, 20:40

Yes, acmotor has mentioned this and my experience with the Leaf and the Vogue pretty much support it. That is - it REALLY depends how you drive.

If I drive like a Nanny then I'm constantly looking at how early I can lift my foot and coast to a stop. Under these conditions regen only is a benefit on hills.

If I drive slightly harder but within regen-only stopping distance I get maximum benefit. Harder again I start to run into hydraulic braking and I loose the benefit.

Likewise if a hill is too steep and I have to go UP then DOWN, I lose overall because the regen won't hold me going down (I haven't hit this condition yet). I have max. regen at 12kW at the moment and since I don't have traction control or ABS I have to be careful not to wind it up too high in the config - especially this time of year - wet roads.

There a lots of shades in between.

Post by **Johny** » Thu, 18 Apr 2013, 20:44

I have made this morning's raw log available at:
https://dl.dropboxusercontent.com/u/463 ... EV-0NE.TXT
I won't stay there forever so if you are reading this post after 2013 it's probably a broken link.

Fields are: EV, Batt volts, Batt Amps, RPM
Entries are at 1/2 second intervals.
Vehicle speed in km/hr is RPM/40

Post by **weber** » Thu, 18 Apr 2013, 21:05

Good to have some real-world data. Thanks Johny.

Post by **acmotor** » Fri, 19 Apr 2013, 00:10

Yes to regen when driven hard.
This blast from the past agrees with Johny's data.
viewtopic.php?title=red-suzi&p=7619&t=615#p7619
Regen current was integrated in spreadsheet to give 16.97% though the SLAs would not have done the justice to the power that lithiums do.

Oops, just realised, is that where the 17% number came from ? I didn't know anyone read the post.

Post by **Johny** » Fri, 19 Apr 2013, 16:19

Yes with aggressive acceleration and de-acceleration, rolling resistance would be swamped and regen would play a bigger part. With my quiet(ish) driving I can almost get to work without brakes even with NO regen. That would amount to 0%. In fact I did this when driving the Honda Jazz CVT to see what economy was possible.

So with aggressive regen, the harder you drive, the bigger part it plays.
IMO

Post by **BigMouse** » Fri, 19 Apr 2013, 18:42

Theres some really good discussion in here about regen. Any way we get get the relevant posts moved to their own thread? In a year's time when I want to come looking for this again, I may not think to look under "ABC's Checkout program"

Post by **whimpurinter** » Sun, 21 Apr 2013, 14:51

I keep thinking that regen is a bonus but nothing more.

With the Prius, the bar graph shows when you are at maximum regen (before the brakes kick in - if the video is to be believed

)
The way I would handle this is to let the car freewheel as much as possible when approaching lights and then use max regen to stop at the lights.

If you're not on the perfect downgrade where freewheeling means a constant speed to a set of lights, then I would use freewheeling as a means of slowly stopping (where there was no car behind (and no traffic in sight, ideally

)) as opposed to using battery to maintain a speed up to the lights and then using max regen within a short distance to stop at the lights.

Wind and rolling resistance are the constant enemy and regen just aids them in stopping the car. Electric drive fights wind and roll all the way.

When you consider how long and how much power is required to charge a car, say 3hrs or 5 hrs or 7 hrs, and then think about how much time elapses when regenning (and then rarely at maximum), it might be say 3 mins of time for regenning on a trip around town? That's why I think it is a fun and very useful aspect of ev's for converting the wasted energy into good stuff and reducing maintainence compared to standard rubbish cars.

The technical information as supplied by Johny and all you others makes a very interesting topic and something I would very much like to truly understand so I really welcome it.

Post by **acmotor** » Sun, 21 Apr 2013, 16:56

Gentle, smooth nana driving uses least energy overall in ICE, hybrid and EV.
However, I dislike people driving to save energy when it impacts on other road users. e.g. if you are trying to set a distance record, it MUST be done at the speed limit with realistic accel and decel otherwise it doesnt count IMHO. We will all end up in 8kmph goffas, but not yet.

Regen then steps in for AC hybrids and EVs. Now the equation has changed and driving harder (call it more road friendly) has less detrimental impact on overall energy usage. Rather than throwing the stopping/braking energy away as heat, you get much of it back.

Hard acceleration is marginally less efficient than gentle accel. (batery, controller, copper losses etc). Probably a few %.

Don't forget BC, regen for 3 min at 16kW compared to charge at 2.4kW is a factor.

Website · Post by **Simon** » Sun, 21 Apr 2013, 18:13

Driving my Prius efficiently I will rarely get any stars on the display indicating 50Wh regen. The most I have ever seen is 150Wh on a single trip. I know Justin who makes the Cycleanalyst has tested regen on Ebikes and it was something like 1-3% increase in range.

*edit* hmm tried to find a link for the ebike regen % but can't find it.

Post by **acmotor** » Sun, 21 Apr 2013, 23:37

Yes, and that is the comment. Regen when driving 'efficiently' is minimal.

Simon ,try Greenmount hill.
Actually, the problem with hybrids like the prius is that they very quickly mask the ability to see the cumulative effect of regen.
e.g. Greenmount hill returns over 1kWh of regen. more than the prius battery pack free space so you don't get to see the net regen.

Website · Post by **Simon** » Mon, 22 Apr 2013, 03:02

Big hills like greenmount yes you will quickly fill the battery and have to waste the rest. The only thing you can do in a hybrid like the Prius for this is to try and arrive at the top of the hill with a low SOC. I did go up to the zigzag in my Prius once late at night and manage to do 11km without the ICE firing but that was before I had an EV! Hehe.

But EV's have the same problem too when the SOC is above 80%. I think the Leaf doesn't have much/any regen till you burn a couple bars? Tesla model S loses regen when the battery is cold too.

Post by **acmotor** » Mon, 22 Apr 2013, 05:02

My observation with the iMiEV and regen when fully charged is that regen surges (on the power meter with a small feedback of same to vehicle motion) The control system is shuffling around at top of charge.
Most people who drive the vehicle don't notice what is being sorted out in the background.

If I start off down hill with a really full battery I see this surge. Knowing what it is I turn the aircond or heater or lights on.
This levels things out fine though would perhaps not do so on a steep hill.
It would appear that after a km or so of travel this 'regen full surge' doesn't occur and full regen is available.
No need to get down to 80% SOC for full regen but then I don't do Greenmount downhill first thing.

Post by **IVI** » Wed, 24 Apr 2013, 17:32

Short-Term thinking disappoints me...

I'm confident that even folks who may be suffering
"can't imagine that ever working here" -will- get
& use (when it finally arrives) SAFE, GREEN THORIUM:

+ eg: Liquid Fluoride THORIUM Reactors (LFTR's)

Cf Sorensen's 10-min talk on TED.com

For the details, search YouTube for "Thorium Remix"

PS It's be a while, unless we push for -regulatory-
changes affecting nukes in AU.

But we're used to that, because some have had to do
that kind of pushing to help bring EVs in, or we may
need to do that kind of pushing when they arrive.

(Or their makers will)

Post by **acmotor** » Wed, 24 Apr 2013, 17:43

If helping to bring EVs in means we have to go to the wrong sources of power then I'll just walk thanks.

Post by **antiscab** » Wed, 24 Apr 2013, 21:02

more than regulatory changes are needed to see a nuke reactor within australia

basically reactors require a scale of economy (1 GW+) to be economic (ie cheaper than renewables assuming risks assumed/subsidised by the state)

we aren't able to attract a sufficient number of people to build one, nor do we have a port large enough to import one....

Matt

Post by **jonescg** » Wed, 24 Apr 2013, 21:05

Yeah nuclear will be a viable source of electricity for many northern hemisphere populations, but it'e economic silliness to build one here. Renewable might also seem economically silly, but when you have so much of the resource around, its not so silly. And what could be sillier than venting sh*t from the ground and burning it to run a 1950's technology?

Post by **Johny** » Wed, 24 Apr 2013, 21:38

...then having the permanent burden of guarding the waste product for a few thousand years - like Britain's future generation legacy.

Post by **karlg** » Thu, 25 Apr 2013, 05:09

Hey guys, I have a really strong opinion on nuclear power too, but is there somewhere else we can have a good stouch aobut it? After all, this is meant to be about EVs..

Post by **whimpurinter** » Thu, 25 Apr 2013, 05:16

AC said:
>Regen then steps in for AC hybrids and EVs. Now the equation has >changed and driving harder (call it more road friendly) has less >detrimental impact on overall energy usage. Rather than throwing the >stopping/braking energy away as heat, you get much of it back.

Ac., Is this really true? When you drive a Prius, for example, you have limited acceleration using battery power, then motor power is added and then more motor power for greater acceleration with accompanying standard ice fuel consumption. A video I watched says that best petrol consumption is achieved when the instrument graph is between 24% and 75% for motor usage (but below the "power" section of the graph, so generally, if I want to appear less "limp" on the road, I use this amount of acceleration on the roads unless something more is required. If I roar around the roads and then take full advantage of regen, I think that will not give me better fuel consumption. An American Prius test drive concluded that if you drive one with no regard for fuel consumption, you end up with around 5.5L/100km no matter what you do, so the Japanese have taken care of that.
On a recent trip over 20km or more, I averaged 3.9 L/100 there and 4.5L/100 back. That's not driving without regard.

>Hard acceleration is marginally less efficient than gentle accel. >(batery, controller, copper losses etc). Probably a few %.

I'm not talking about a battery ev here but a hybrid. Until we have a plugin with lots of range, I think that how efficient the electric drive is is of minimal effect.

>Don't forget BC, regen for 3 min at 16kW compared to charge at 2.4kW is a factor.

I dug 3 mins out of the air but even then, we are looking at ok regen but never anything approaching a standard plugin charge.

You'd have to go from Gympie to Brisbane (after all, it's downhill all the way) to recharge the battery.

Edit: forgot to show last quote was a quote.

Post by **acmotor** » Thu, 25 Apr 2013, 06:45

Prius and probably most hybrids are not good examples of significant regen performance since they run out of battery space for any reasonably large regen event like a long hill. Simon's prius noticed that too.
Non the less, part of the prius's low fuel consumption in a city is down to regen.
I can assure you that a prius driven hard can use over 8 l/100k. I've done many thousands of km in them.
Hey I'm not really a fan of hybrids, even the volt.

Yes, driving nanna style at low speeds likely gives the best economy in most vehicles. But what I'm observing is that driven harder (more realistic on the road) results in less increase in energy consumption in an EV than in an ICE. One of the biggest factors being that regen braking returns much of the energy normally thrown away in mechanical brakes when driving harder.

At another extreme... people have recharged EVs totally by towing them and using regen. Purely an exercise mind you.
http://www.youtube.com/watch?v=5Sujv90PLLY