Hemonster's ACIM conversion

Post up a thread for your EV. Progress pics, description and assorted alliteration
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Post by coulomb »

Sorry. As long as the chargers can withstand full pack voltage, that should be OK. Not sure what I was thinking there.

And of course you need one charger per 48 V module/group, and need to run all of them at once.
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Post by Hemonster »

acmotor wrote:
Hemonster, I would not underestimate the 0-40kmph acceleration of your proposed setup. I would predict it to be quite satisfactory. It will be the higher speeds where performance will fall short. By then you will have the EV bug and a good stepping stone.
It would seem like top end speed is the bug bear for most of the AC conversions I've seen so far - surely with a 2 pole things would improve as you only start getting a dropoff in torque at higher revs? Of course without the gearbox things would seem sluggish on the low end torque, but then again with a big enough controller, my 2-pole will give me 150Nm of torque, that's still pretty decent at low revs isn't it? (say with a 3.5:1 diff?) Isn't this around what a ICE typically gives out peak anyway?
acmotor wrote:
Keep the weight under control though. Image
It's had one too many donuts ;)
But a point you made earlier about dropping the motor weight being relatively insiginificant (to the weight of the car) is quite true. When you have 350kgs of battery to reckon with, even a 100kg drop in motor/gearbox setup may only just get you within GVM (with 320kgs worth of passengers), and even then only on a select few cars. The battery IS the bug bear no matter what the conversion is, DC or AC ... and more to the point, PbA is where the optimisation really needs to happen. That's why I'm coming round to the idea that I will need to spend money on the battery if I'm to get not only decent power to weight for the car, but also better pack ageing, better Wh/km and hence better range. That's a lot of plusses ...


Last edited by Hemonster on Fri, 24 Apr 2009, 08:24, edited 1 time in total.
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Post by Electrocycle »

Hemonster wrote:Of course without the gearbox things would seem sluggish on the low end torque, but then again with a big enough controller, my 2-pole will give me 150Nm of torque, that's still pretty decent at low revs isn't it? (say with a 3.5:1 diff?) Isn't this around what a ICE typically gives out peak anyway?
yep, that's close to the peak torque of a <2L 4 cylinder engine, but don't forget that'd be like taking off in 4th gear.
1st would usually give you another 3:1 reduction.
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Post by Hemonster »

Ahh true true ...
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Post by Hemonster »

On the subject of CVCC chargers, I'm looking at these puppies:
http://www.wellforces.co.nz/index.php/C ... e.tpl.html

edit: might help if I put the link in Image
Last edited by Hemonster on Fri, 24 Apr 2009, 08:39, edited 1 time in total.
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Post by Nutz »

Just made a trip to the garage for you, Here is some info on the wife's Nimbus(Chariot) cargo area.ImageImage
The finished floor sits approx 15 cm above the actual flat(ish) steel floor under the seats, and a bit deeper under the storage unit (pictured). There is nothing stoping you from raising the finished floor height a bit so that you do't need to cut the floor and venture into engineering chaos. With the center seat pulled back as far as possible (to accomodate for grown-ups and teenagers there is approx 105cm from lip of door opening to the back of the seat base(depending on desired measuring points), width between wheel-arches is also 105cm.
Happy to give more info if requested.
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Post by Nutz »

I'll be watching your build with interest, it may be more reasonable to convert the nimbus than my toy (a '68 mazda 1500 that is yet to be restored)Image I may even be less fussy with specifications Image It would also get more use. It's auto though and the wife cannot drive manual with hand controls.
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Post by Hemonster »

Hey thanks Nuts, you've given me something to consider now ... :) We will chat more as time progresses I'm sure.
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Post by Hemonster »

Just an update. My 2pole motor came as a foot mount and today I connected a flange mount to it for mating to a gearbox better. I took the oppurtunity to take some photos of the insides of the motor.

Image
The shot of the motor with the front face off, you can see the rotor and the stator windings. Sorry for the blurry shot.

Image
The rotor, showing the centre bit which houses the squirrel cage, cooling fan fins as well as bearings at both ends.

Image
Other side of rotor.

Image
Looking into the stator windings. You can see how all the windings end up as six wires coming out at the RHS of the picture to the breakout box.

Probably should mention as well that there is a thermistor built into the stator windings which can be hooked up to the VFD for monitoring as well. It's really neat how things in an induction motor just look so "simple" and elegant looking ... thank you Nikola Tesla! :)


Image
This is the motor complete with the flange fitted, and the new rubber seal placed to ensure its IP rating is met.

edit: Added picture of motor with flange fitted.
Last edited by Hemonster on Sun, 26 Apr 2009, 08:23, edited 1 time in total.
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Post by Hemonster »

weber wrote:
Hemonster,
You did an awesome job of summarising that huge thread on AC motors. Now here's another one for you (not quite so long) on "To chassis-earth or not to chassis-earth?".


I'm still working my way through this thread, it's filled with goodies but does need a bit of a summary for somebody just walking into it. I'll reply there once I have attempted some type of summary myself - even if just to align my own thoughts with others here.
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Post by coulomb »

Hemonster,

thanks for the pictures.

Can you give a hint about your solution for attaching the flange? We're having trouble getting our preferred motor (thank you, MEPS!), and I suspect it might be easier getting model that is just foot mounted.
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Post by coulomb »

Duh,

I see you ordered a flange with it, sorry, I'd forgotten.

Image
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Post by Hemonster »

Hi Coulomb,

I had to get a foot mounted motor as it was what was available 2nd hand going for cheaps. The flange I ordered direct from TECO the manufacturer and cost half as much as the motor again, but still all up the price of the motor with the flange was ok - and really the motor hasn't even been used. In effect I've got a brand new motor for NZD$600 which I don't think is too bad. I just hope I'm going to be able to use it after all that. (ie. it's not too heavy).



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Post by Hemonster »

Ponderings ....

EVPST cells are great for an elegant solution, however they aren't truly great on price for the amount of range you get. Here are my calculations:

Say it takes 8kw to run my car on average at 50 km/hr, and for now we simplify things by averaging out the accelerations and decelerations to be inclusive of that figure.

EVPST LiFePO4 cells:
10AHr - 224 cells gives a 7.2kwh pack, at 80% DOD this is 5.73kwh. This pack costs USD$7980 inclusive of cells, BMS, ABS housing and 3A charger. This pack will get me 35km at the average energy demand. This pack weighs in at approx 110kgs.

12AHr - 224 cells gives a 8.6kwh pack, at 80% DOD this is 6.8kwh. This pack costs USD$7879 inclusive of cells, BMS, ABS housing and 3A charger. This pack will get me 42.50km at the average energy demand. This pack weighs in at approx 110kgs.

Greensaver PbA cells:
20AHr (2 hours) - 52 cells gives 12.48kwh pack. However these cells are much heavier at 360kgs, so the average energy to move that weight increases (when averaging accels and decels)- say to 9kw (conservative?). This means it will be drawing 14.4A at the average power requirements, hence energy density closer to 9kwh due to peukert's coefficient. At 80% DOD this is a 7.2kwh pack. This pack costs USD$1759 inclusive of 52 cells and 5A charger, but doesn't come with a BMS. This pack will get me 40km and about 400 cycles at 80% DOD. This pack weighs in at 360kgs.

Frieght has been excluded on prices. All of these packs meet the power density requirements of my conversion for continous and peak amp discharge, so that isn't compared.

So my dilemma is still, should I go with PbA or pay the HUGE premium for LiFePO4 ... thinking, thinking ... thinking.

Thoughts anyone?


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Post by Johny »

Thinking along the same lines. There are a couple of other choices for PbA as well. To get the weight down a little I have been pondering Firststart 18AH (6kg each). I have also had a price from Ponilion for a 20Ah AGM at around US$21 (6.5kg).

My thoughts are that in 1.5 to 2 years I will be looking for my second set of batteries (I am planning on around 500 cycles as I will rarely go below 50% DOD - I only need 30k range on a normal day) and the Lithium (or other) choices will be wider.

If Lithium is 5 times the price for 4 times the range (2000cy) - I'd rather wait.

The Lithium issue would be an easier path if there was something like the TS or Sky that could handle 80-90 Amps for 20-30 seconds and come in at the TS US$1.10/ah price - but there isn't.
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Post by Richo »

Hemonster wrote: Thoughts anyone?


The EVPST cells are cylindrical cells spot welded together.
Personally I'd rather spot weld them together myself and save the weight and cost of thier packaging.
There are plenty of chinese suppliers that have cylindircal cells that would suit anyone's need.
If your not up to spot welding or don't have accesss to one then give that option a miss.

So the short answer is NO but the long answer is YES.
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Post by woody »

Hemonster wrote: Thoughts anyone?


From a dollars and cents point of view the Greensavers are a clear winner.
(If you take both EVPST + Greensaver at their word for cycle life)

The only downside I see is the weight and size.

The weight + size is the killer for me due to my choice of donor vehicle and driving habits.

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Post by woody »

Richo wrote: The EVPST cells are cylindrical cells spot welded together.
Where do you get this from? (All I have to go on is the pictures)
Image
The 7Ah above could be welded cells
Image
This one looks like TS-style with vent...
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Post by Richo »

you could also tell by the size...
So the short answer is NO but the long answer is YES.
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Post by weber »

Hemonster wrote:So my dilemma is still, should I go with PbA or pay the HUGE premium for LiFePO4 ... thinking, thinking ... thinking.

Thoughts anyone?

IMHO, you should not pay the huge premium for LiFePO4. This has more to do with your personal experience than any technical aspect of the conversion. You are clearly a brilliant guy and know the theory, but I'm guessing you are new to most practical aspects of this field. This first conversion should be a low-risk low-cost learning experience. I'd even suggest starting with second-hand lead-acid and use a van with some seats removed, as you suggested, and build the battery boxes on top of the floor for the first pass. This is how my mentor Ross Pink did his first ACIM conversion.

If you can find a business that services UPSs they should be willing to let you go through their discards with a test lamp and multimeter to find those that might still have usable capacity. In Ross Pink's case, he owns a business that services UPSs, in Brisbane. Sometimes only one battery has failed but the full set (typ. 4) in the UPS must all be replaced. This type is very popular:
http://www.panasonic.com/industrial/bat ... D1217P.pdf
12 V, 17 Ah, weighs 6.5 kg. You might need to take home 100 for further testing to find 54 good ones. There are many brands in the same standard format.

You probably won't get 90 amps out of them but you should get more than enough for the 15 kW VF drive.
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Post by Hemonster »

weber wrote:
This first conversion should be a low-risk low-cost learning experience. I'd even suggest starting with second-hand lead-acid and use a van with some seats removed, as you suggested, and build the battery boxes on top of the floor for the first pass.
Actually I was considering going for the more expensive route to "simplify" the design (believe or not)and manage risk better. Areas for which I have less experience is weight distribution, design for road handling and mechanical restraining. Having the pack in the passenger cabin complicates this no end as you have to robustify the pack (according to NZ EV standards) an order of magnitude more. Also with the LiFePO4 pack enables me to come in close to the vehicle kerb weight after conversion, which is much better for handling even at city driving speeds - so consideration for the more expensive pack does simplify the design and reduce the risk.

I really don't doubt the electric motor side of things will work anyway, just give it a large enough DC bus and the thing will turn. Ensure you have a big enough motr and controller and you'll ensure that the car will move at a decent speed and get there in decent time. In fact just about everything on the electrical side of things is a straight line challenge (ie. I can see my way through it in my head) - where it gets blurry is the mechanical side for me.

With lead acids, I will have to start with a heavier vehicle as it needs to hold more weight - this means I'm limited to vehicle classes that can carry more than 4 people, or a ute, I can't consider removing seats in a 4 seater because it's not the project brief (I want to take my family for a drive). With the lighter pack, I can in fact choose a family sedan, I was thinking a Galant Viento V6. The V6 engine would weigh heavier and hence give me more weight clerance to work with when putting electric components in.

BUT! of course the EVPST cells (and even TS cells for that matter) are still unproven for cell longevity both in time and cyclic life. So this is the "true" risk ... this coupled with custom unproven BMS designs just adds to this.

But it all does come down to money in the end and greensavers do "save" the day. If anything they prolong the decision to go with lithiums until they become more affordable. Money is the principle decision maker and as most of you will know it is a democracy in any family ;)   

I could go DC in a small car running a small voltage, and yes there is some merit to doing that. But I prefer the challenge of AC and to prove that it is doable safely and economically.

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Post by a4x4kiwi »

hi Herman,

This pretty much replicates my thought process as well. :)


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Post by Hemonster »

Hey, has anybody considered these 48V 20AH battery packs from Headway?

http://headway-cn.en.alibaba.com/produc ... _pack.html


http://headway-cn.en.alibaba.com/produc ... ttery.html
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Post by Hemonster »

Contactors:

Incidently I'm planning on getting these 48V contactors from NanFeng direct.
http://www.contactordc.com/9_zjwh100a_dc_contactor.html

It is a SPDT which I'm going to use per 48V pack. When the coil is energised it is connected to the HVDC string, when it is deenergised it is connected to the charger. They are 100A continuous rated, but I'm sure they are capable of higher amps peak. Not bad for USD$8 each!

These are not intended for breaking the main traction pack on load. I'm choosing Tyco Kilovac EV200, one on each of the main HVDC terminals and probably one at the split pack as well.

Anybody know how relay economisers work? 12V 1A per 48 module to energise these puppies is quite a bit of power, the EV200 manages to reduce this significantly.


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Post by antiscab »

Hemonster wrote: Anybody know how relay economisers work? 12V 1A per 48 module to energise these puppies is quite a bit of power, the EV200 manages to reduce this significantly.


The number of amps needed to hold a contactor closed is significantly lower than what is needed to actually close the contactor.

so a resistor is used to lower the continuous current to only a bit more than what is needed to hold the contactor closed.
A cap is used to supply the initial burst of current needed to actually close the contactor.

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