Azure AC24LS underperformer

[Dave Hale]

I have about 500 mi on my car now. I drive daily to work, about 34 mi
round trip, plus I take it whenever I need to run to the store, etc.
It's integrated into our lives pretty well. But I find that I cannot
just go anywhere; I have to be very careful planning my routes. Hills
are fine if surface streets and taken at slow speed, but I have to be
extremely careful about which freeways I drive on. If the freeway has
even the slightest incline, I can not drive it safely. A freeway which
I had previously not even realized was inclined has become off-limits
to me now. The best I can do is 45 mph; in a 65 mph zone where people
routinely drive 10 over, this is not safe. And for the down-hill
freeways that I am able to drive on, I am limited in my on-ramp
selection: the on ramp has to be long enough and not have any
inclines, or I will not have enough time to get up to 60 mph. The
acceleration is extremely poor. This can't be right. Why is this motor
acting like this? Is it a property of the motor, controller, software,
or what? Is there any way to enhance this motor/controller pair to
enable safe acceleration? As we've learned, the Aptera will have the
same motor/controller, so presumably it's not a dead-end technology.

I picked the AC motor because of the promise of great range and speed
(ElectoAutomotive's website has since been revised, now at 125 mi
range and 100 mph, but when I purchased the kit they claimed 150 mi
range and 100 mph). But their site still says "ultimate combination of
performance, range and affordability" -- I would say I have no
performance at all; it is embarrassingly slow to get moving., Over the
weekend I drove Lou's car (Porsche 914) converted with a DC motor,
running at 132V. That car had great acceleration, speed, could drive
on the freeways (uphill, even) and has the same range that I have in
my AC car (60-80 mi).

To attempt to answer my own question, in the end, it has to be energy
delivered to the wheels as a function of time. For a given amount of
power you get an increase of energy per unit time in a linear fashion,
linearly tied to the acceleration. The remaining variable is then the
mass (force=m*a). So to get more acceleration I have to have more
energy, or less mass. Going up hill there is another force, the force
of gravity pulling the car back down the hill. So to counteract that
additional force and maintain constant force I again need more energy
or less mass.

It is beginning to look like it's a real matter of batteries. I did a
quick estimate using the dimensions of the 160Ah ThunderSky LFP
batteries and we should be able to fit about 54 of them in the same
space as the EA kit's FLA battery boxes. That makes a nominal pack
voltage of 172V and half the weight. If using the 90Ah units then we
could fit in more batteries or have less weight. But there goes
another $14k.

--Dave

[Tim Kutscha]

Hi Dave,

I think most people who have purchased the 914 AC kit has had
a similar experience with lack of power. At the last local EV meeting,
someone had taken the 914 AC kit and replaced the batteries with
330V of Li-Ions. The car really goes. He also replaced all the
fenders and bumpers with fiberglass ones to save about 350 pounds
of additional weight. The lighter weight and higher voltage really makes
a difference. Of course, he also paid over $60K for the professional
conversion...
One minor trick you can do when starting on steep hills is to rev
the AC motor and ease in the clutch like on a gas car. That got me
going in several situations where starting with a stopped motor didn't
work. Beyond that, I agree that the ElectroAuto specs are way off.

I sold my 914AC a few months ago and now drive a Civic with a DC
motor. The range is much less, but I can easily accelerate up to 80
on the freeway and hills are no problem, plus it only cost me $10K
to convert.
If you find out any limiters that improve the 914AC performance,
let us know...

Cheers,
Tim

[David Hale]

hi Tim,

Yes, going in to this I knew that people were disappointed with the acceleration, but I didn't realize it was THIS bad. I guess that's what you get from the qualitative statement, "acceleration is not great". That coupled with ElectroAuto's statements that it could go on the freeway, and even Ross' video blog saying "highway capable", led me to decide I would prefer a little extra range and not worry about winning races. I read "poor acceleration" in comparison with other electric cars that burn rubber. Fine, I didn't care about that. But what I didn't realize was that it REALLY meant "freeway capable if the freeway is all down hill".

I am encouraged by hearing the story of the AC kit and LiOn, that adding a little power and decreasing a little mass makes a big difference. Can you tell us just which batteries he is using and just which motor it is?

I just don't have the means now to spend another $10-$15k on more batteries but let's say I did that. OK, now I'm into the Porsche conversion for $30-35k. That is really pushing it (so $60k seems crazy to me). In another handful of years we'll be able to buy the Model S for that much, and have a comfortable car which carries four people twice as far, and have modern luxuries like airbags, air conditioning, etc. 

Anyway, I'd be really anxious to hear more info on the other 914's AC motor and batteries.

Thanks,

--Dave

[Tim Kutscha]

I didn't get all the details, but he's also using the AC24LS motor and DMOC445, just with a much higher voltage.  I believe the batteries are thundersky 90A, but I'm not entirely sure.

Cheers,
Tim

---

From: David Hale <astrono...@gmail.com>
To: 91...@googlegroups.com
Sent: Monday, May 18, 2009 11:39:45 AM
Subject: [914ev] Re: Azure AC24LS underperformer

[Randy Pollock]

Hi Dave,

Sounds like my performance too (but I do not have the AC24LS - just the
stock AC24). I will take the freeway too work (mostly downhill) but take
surface streets home. My drive is short enough that this isn't too big a
hit in time.

> It is beginning to look like it's a real matter of batteries. I did a
> quick estimate using the dimensions of the 160Ah ThunderSky LFP
> batteries and we should be able to fit about 54 of them in the same
> space as the EA kit's FLA battery boxes. That makes a nominal pack
> voltage of 172V and half the weight. If using the 90Ah units then we
> could fit in more batteries or have less weight. But there goes
> another $14k.

Last week, I actually looked at using Sky Energy 120Ah batteries:

http://www.evcomponents.com/ProductDetails.asp?ProductCode=SE120AHA

Their wide dimension matches the US Battery narrow dimension to 1 mm.
You can get ~ 4.5 of them into the space of a single 8V. This makes
packaging using the existing boxes pretty straight forward and doesn't leave
too much wasted space.

51 units will fill the engine compartment and gas tank battery boxes.
This provides 163 Volts with slightly more available capacity (assuming 50%
DoD on the lead and 70% on the lithium). This set up will cost about $8k
including Manzanita BMS - selected since I am using their charger.

It drops the car's weight by about 600 pounds (~20% of the weight of the
car). The controller/motor should do much better under heavy acceleration
as the lithium's voltage supposedly doesn't sag as much - keeping the
voltage higher under load. Between these two changes, I suspect the
performance will be much, much better.

Another $4k will fill the front battery box and up the voltage to the
mid 200's. Another 250 pounds increases the voltage (and performance) and
adds more range.

I am thinking about swapping out the lead for the smaller system late
this year (too many new projects around the house now that the 914 is on the
road). If range becomes and issue, I can look at adding the extra $4k up
front. With a good BMS, mixing the pack shouldn't be too bad.

Attached is what I think a reasonable layout would be.

I am encouraged that this is the first time I've looked at Lithium
batteries and not seen costs in the $20k to $30k range...

On 5/18/09 11:28 AM, "Tim Kutscha" <tim_k...@yahoo.com> wrote:
> He also replaced all the fenders and bumpers with fiberglass ones
> to save about 350 pounds of additional weight.

I've looked into this too. I think I will strip my car to get it
repainted when I swap out my first battery pack. I will probably at least
replace the trunk lids. I am reluctant to replace the bumpers for safety
reasons. The fenders might be worth it.

Good luck all,

- Randy

[David Hale]

Now that's a good question ... let's say for a moment that I would consider the ThunderSky batteries. They can be discharged more deeply that FLAs, right? So if that's true, could I replace my 170Ah FLAs with 90Ah LFPs and possibly experience the same range? Not surprisingly, the 90Ah are about half the weight of the 160Ah available from ThunderSky.

--Dave

[David Hale]

hi Randy,

On Mon, May 18, 2009 at 12:07 PM, Randy Pollock <ra...@alumni.caltech.edu> wrote:

Hi Dave,

   Sounds like my performance too (but I do not have the AC24LS - just the
stock AC24).  

Yeah, the "LS" doesn't seem to have done too much for me except cost more. Maybe somewhere in there I do experience a little more torque but at this level it's probably nothing against the 1100 lb of battery.

 

I will take the freeway too work (mostly downhill) but take
surface streets home.  My drive is short enough that this isn't too big a
hit in time.

I've at least doubled my commute home now because of this, close to 50 min now because even the surface streets have hills and some of them I can't do more than 30 mph on (in a 35 zone). Building this car has probably only hurt the cause for EVs because it's a rather bad image example, I'm afraid. :-( Don't get me wrong, I DO enjoy the car, I love it a lot! But I am a little hesitant to tell people about the real-world performance. People have this image of EVs as slow-moving, low-range golf carts with no modern options, no air conditioning, etc. Well, that's pretty much what I have at the moment.

 

   I am thinking about swapping out the lead for the smaller system late
this year (too many new projects around the house now that the 914 is on the
road).  If range becomes and issue, I can look at adding the extra $4k up
front.  With a good BMS, mixing the pack shouldn't be too bad.

OK, well as much as it pains me to consider it, having only a few weeks on these otherwise new FLAs, and as much as my wife might kill me, I think I will have to consider them as well. I'd want to think a bit more about which capacity to buy, however. Do you think that if we had a few other people in on this, in the same general SoCal area, we might get a price break? 3 or 4 or even 5 guys might mean 150-250 batteries for them. Just a thought. 

Let's hear it... anyone else out there on the fence about LFPs?

--Dave

[Lou]

Hi All

A couple of you have expressed an interest in having their cars appraised and asked for my experience.

I used Automotive Appraisal Services in Yorba Linda and dealt with Mark Koch who I think is the owner.

http://www.automotiveappraisals.com/  1 800 495 2525

He was professional and prompt. It cost $200 and it was done over the mail with photos, receipts, and a lengthy questionaire.

I was his first electric car so there was a bit of a learning curve for him.

I got the car appraised to 42K and it was accepted by my insurance after a brief inspection at my house.

The premium difference for 40K is pretty minimal too.

Good luck to to all those interested.

Lou

[DanP914]

Hello Dave,
I'm not in the SoCal area, but am on the west coast (Oregon). I'd
definitely be
interested if we could work something out on a group purchase for Li-
ion/BMS systems.

Regards,
Dan

[Peter Thompson]

Hi Folks,

I find this whole discussion extremely timely. I'm getting ready to
buy batteries, and all these reports of poor performance worry me.

Another point to think about is that the calculation given above is
for 50% DOD on the lead - shouldn't that be 80%?

I may end up going for the minimum lithium system after I do more
research.

Cheers,
Peter

[David Hale]

hi Peter,

Yes, but I think you mean 20% DOD (DOD is the inverse of SOC, so you're using the top 20% of the battery's capacity in this case). I think it is fairly common to see people talk about 50% DOD figures, my guess is so they can advertise more capacity or range. But I think the safer figure is 20% DOD. That is how ElectroAutomotive has designed their "SOC" gauge -- when it gets to 80% SOC then the gauge reads 0 (it is just a voltmeter with a range from 126-152V, printed to read 0-100%). So actually when I get to "0" on EA's meter, my batteries will be at 82% SOC (or 18% DOD). Very safe. And very underpowered; you'd better hope it's all downhill home from there, because when the voltage gets that low you're not climbing any hills with this AC system and all that lead.

--Dave

[Lou]

isnt 20% soc the same as 80% dod?

---

From: David Hale <astrono...@gmail.com>
To: 91...@googlegroups.com

Sent: Wednesday, May 20, 2009 8:58:20 PM

Subject: [914ev] Re: Azure AC24LS underperformer

[David Hale]

Indeed it is. 

State of Charge is 0%=empty, 100%=full.
Depth of Discharge is 100%=empty, 0%=full.

[David Hale]

hi Peter,

I got an immediate response from Azure asking for a data capture and information about the vehicle, which I sent. Bill Lenter from ElectroAuto was also in on this e-mail. After I sent my initial capture they analyzed it and called me. He gave me some new parameters to load into the Azure controller and said I would be extremely happy. Well, I think I could notice a small difference, but it certainly wasn't the night & day change that was implied. So they asked for another capture with my new settings. I sent that capture, then Bill called and said do not drive the car until I hear back from him.

That was a week ago. Nothing heard since from EA or Azure.

I think this is just the nature of the system. I don't think EA or Azure is going to be able to pull any miracles out of their hats as long as we're towing half a ton of lead and operating at only 144V.

As for me and Lithium, I believe this is the way to go but I don't have the means to purchase them right now. I've been talking with a company that sells LFPs and he tells me to wait a bit. "A little bird" tells him that in "a few weeks" there will be 190Ah LFPs which have the same physical dimensions of the 160Ah LFPs. He also says there would be a good discount if two people went in on a purchase.

That's where I've left it. I still need to work out the details of how many 190Ah LFPs will fit, what the voltage and weight will be, and the actual cost.

--Dave

On Fri, May 29, 2009 at 3:57 PM, Peter Thompson <PThomp...@gmail.com> wrote:

Hi Dave,

Any word on the 914 project?  I'm holding off on my battery purchase
decision until I hear how this turns out.  If it turns out that you
don't have a lot of time to work on it, I understand...I have a lot
more work to do on mine.  :)

Please keep the group posted on any progress.

Good luck!
   Peter