Hemonster's ACIM conversion

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Post by Hemonster » Mon, 29 Jun 2009, 15:53

coulomb wrote:
Hemonster wrote: The standard Headway forwarder was $500USD !!! ... by sea! just be weary of that.

Could this US$500 be the AU$700 that Matt spoke of?


$700USD was quoted to me for air freight. That's probably what Matt is referring to. I had to ask for sea freight, and then I had to ask them specifically to investigate other options. The forwarder that GS were using weren't known to HW, and they haven't got a business contract with them when I asked them - so the number given was merely a quote and not anything based on a real figure they could use from a past transaction. However if GS have used them in the past and are happy with them, I can't see why that HW would not use the same one.

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Post by antiscab » Mon, 29 Jun 2009, 20:17

Hi Guys,

to get 25x 40AH TS cells from a ship in fremantle(WA), through customs, and to be able to pick up, it cost me $AUS980.

~AUS$750 was fixed port/customs clearance charges.
the rest was GST+5%customs fee that apply to all imports.

this is on top of shipping.

If it went via dhl, aust post, etc then i would only be up for the GST (and even then not always).
If you can, have it sent via china post, as they use Aust post for final delivery (they have on site customs, who dont look all that closely at item values).

so yes, doing an import is definately more worthwhile in quantity.

Matt
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Post by Johny » Mon, 29 Jun 2009, 20:42

Thanks Matt.
I just found Mal's (a4x4kiwi) post on his costs bringing in 360kg of Greensavers.
a4x4kiwi wrote: Here is a breakdown of my costs for the sea freighted batteries from China. the shipping component of the batteries was something like USD65

55 batteries   AU$2290.48
Bank Fee AU$ 20.00
GST and Duty AU$ 423.77
Customs Agent AU$ 137.5
Port Fees   AU$ 248.05
TOTAL   AU$ 3119.08
or $56.72 each

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Post by Mesuge » Tue, 14 Jul 2009, 08:44

Speaking of cylindric cells, one of the most underestimated problems is the correct vibration free mounting, especially the early adopters in EV bikes destroyed many packs by too much force applied on the contacts.
Here are some clever hints how to approach building a better frame-pack:
http://www.endless-sphere.com/forums/vi ... 0&start=15
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Post by woody » Fri, 17 Jul 2009, 20:17

I haven't had a look at the Headways much until now, but ev-components lists them:


two versions: 38120P (Power? 8 Ah 5/20C) and 38120L / S (S = Screw L = Tab 10 Ah 5/15C)
1.8mR internal resistance
307 grams
US$17.00 ea ($16.50 for 200+)

The 38120P cells have 20C for 3 minutes listed (ev-components) and 15C for 4 minutes. Either of these would drain the cell 100%.
The 38120L & S cells have 15C with no time listed.

So the power cell can do 160A, the normal cell can do 150A. Not a huge difference for the 20% reduction in capacity....

If the internal resistance is right then about 440W out of each L/S cell, 466W from P cell.

Interesting problem of how to mount the BMS boards because each cell is double-ended...

For me they are a better fit that my old favourite EVPST-10:

The Good:
45% cheaper, 40% lighter, 35% smaller, much more widely used, similar low internal resistance, Western Reseller.

The Bad:
Cyclindrical form - mounting + BMS issues
44% lower peak power (15C vs 30C)

That lower peak power doesn't really affect me much as my chosen controller and motor would only use a fraction of that extra EVPST power, so the light weight more than makes up for this.

Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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Post by Johny » Fri, 17 Jul 2009, 20:34

woody, what we found was that it is barely any more cost (admittedly straight from them) to get a mini-pack with BMS. The idea that we would mod the BMS to bring out an opto signal rather than use whatever power FET they used.
Anyway, this is how headway mount the cells in their packs.
http://headway-cn.en.alibaba.com/produc ... l#inSearch

Edit: Spelling
Last edited by Johny on Thu, 06 Aug 2009, 06:23, edited 1 time in total.

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Post by Mesuge » Sat, 18 Jul 2009, 02:28

Johny, look at the page #1 as I've linked previously, the Headway provided assembly blocks tend to crack rather easily. Also, I think they have to change the supplier of their BMS, so there are issues on this front as well. In any case to design/build your own case/assembly frame + BMS = more work & money, but we knew it already..
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Post by Hemonster » Sun, 19 Jul 2009, 21:11

Hey Mesuge,

Thanks for posting that article from Endless Sphere, the foam mounting looks quite interesting - I might have to try it out first for my ebike with these test headways I've got here. Interesting to know that the cases they sell normally might have issues with vibration, certainly hadn't considered that. However even using those bits of foam, I would have thought that connecting with flexible wire between cells would be more beneficial than the metal plate as it would have more give in it. I wonder if the cells themselves will deteriorate with constant vibrational forces.

Certainly has me thinking about soft mounting the entire battery rack as well ... hmm.

More to think about.


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Post by Hemonster » Thu, 06 Aug 2009, 02:38

Hi all,

Sorry for the long leave of absense - things have been pretty busy around here.

Anyway I have managed to do another discharge test on the Headway cell. Image

It is interesting to note that even at the lower continuous discharge rate of ~3C, the cell is getting up to 50 deg C. It is putting out 8.8 AHrs (based on median voltage over the discharge) - this rate is similar to the higher rate pulse discharge that I did in my earlier experiment.

3C discharge is about 20kw for the 14x48V stack that we are considering, so this is like cruising at 100km/hr? Good news is that the battery does handle this and the temperature rise is notable, but not concerning. This especially seeing that there is no forced fan cooling for this test. Even a car moving up a hill slowly will have more forced air cooling than what I'm giving it here.

I'm still quite happy with these cells.

However I was contacted by HiPower and they now say they have a 48V20AHr and 30AHr LiFePO4 cell which they are offering at:
48v20ah - USD$576
48v30ah - USD$864

These include the BMS and 8A balancing charger. The balancing charger itself was USD$120. These cells are touted to do 5C continous and 10C peaks, and these come in a prismatic format and not cylindrical which might be of interest to some.

Anyway, thought to share the info ...

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Post by Johny » Thu, 06 Aug 2009, 14:08

Thanks for that info Hemonster. Thanks also for the HiPower prices.
With HiPower's 8A charger charging a set of 12 x 48V packs comes to 5376 Watts output (allowing 3.5V per cell).
That's a tad high for my wall socket.
Have I got this right?


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Post by Hemonster » Thu, 06 Aug 2009, 14:15

Hi Johnny,

Yes, that's a bit high for me too (and I imagine for most) ... that's why I've asked them for a 3-4A charger instead (preferably 3). Also the 8A chargers are 3.5kg and 263*120*157mm ... a little large to have 14x of these around.

I also like the idea of equalisation circuits on the BMS rather than a balancing charger, then you can put any old regulated supply on the battery and know that the batteries will just do their equalisation charge when they are full.


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Post by Johny » Thu, 06 Aug 2009, 16:14

I should add this one into the mix.
I contacted this company via alibaba and after several emails clarifying what I wanted I got this one.
(The "truth words" part was because they offered me a lower price if I was "selling on" and I replied that it was a private project).
---------------------------------------------

Dear John,

Thank you so much for your truth words. I appreciate it so much.

Anyway, I still would like to give you a good price and I will talk with our boss.

So the final price for the battery pack would be:

576V 20Ah pack:
The battery price: USD5,294.12
Packing Material cost: USD235.00
BMS system: USD1,764.71

For the charger, of course we already have the charger, I suggest you use 576V 5Amp charger, the charging time would be about 4 hours.
The price for this charger is USD765.00

For your information.

I just hope after you use our products you will find our battery's advantages and you will get more sales on this products or introduce other customers to us.

Thank you so much.
Very best regards,

Maggie
Oversea market Manager
OPTIMUM BATTERY CO., LTD
Tel:+86755-84630787
Fax:+86755-84630785
Mobile: +86-13480904606
Email:maggie@optimum-china.com
MSN: maggie-optimum@hotmail.com
Skype: maggie-optimum
Website: www.optimumchina.com


Edit: Removed some line spaces
Last edited by Johny on Thu, 06 Aug 2009, 06:15, edited 1 time in total.

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Post by Richo » Fri, 07 Aug 2009, 09:59

So per cell
USD$19.20 from HiPower with BMS and charger.
USD$17.00 from eVcomponents.
USD$16.50 from eVcomponents in Bulk for AC car.
USD$14.71 from Optimum in bulk for AC car.

Has anyone confirmed the internal resistance of these cells?

I liked the idea of the foam surround until I thought about unlikely events.
So if one failed and got too hot the foam could melt and the structure would fail.
Maybe a hard thin plastic backing with a hole slighty larger so the foam is the common support.
But then in a failure the plastic is the backup.

edit: typo
Last edited by Richo on Fri, 07 Aug 2009, 00:00, edited 1 time in total.
So the short answer is NO but the long answer is YES.
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Post by Johny » Fri, 07 Aug 2009, 15:41

Add to that the 60V 20Ah pack from Headway for US$600.
Per cell.
USD$15.00 from Headway for 60V 20Ah with BMS

Similar price per cell for the 48V 20Ah Headway pack.

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Post by Richo » Sun, 09 Aug 2009, 03:09

As for the internal resistance it is claimed to be <10mR.
NOT 1.8mR.
The 1.8mR is the BMS resistance (shut off fet/relay?)
So the short answer is NO but the long answer is YES.
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Post by Sparky Brother » Tue, 18 Aug 2009, 01:33

Hi Hemonster,

I don`t want to hijack the convo here but I see Johny and you discussing the chargers issue. I was just wandering if you ever considered the 3 Phase rotary converter (The AC motor of the car idling) charing the battery pack via the Inverter as an option?

I know that Johny doesn`t like this idea for his own good reasons but this is what I am pretty much inclined for my conversion for now.

I would like to hear all the anti and pros on this. Didn`t want to agitate this thread. Apologies for that I simply found no other thread on the forum that`s closer to this topic than your one.

Cheers

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Post by Hemonster » Tue, 18 Aug 2009, 02:16

No problem Sparky Bro.

I can't really speak for 3 phase rotary converters because I haven't really dug deep into how this could be implemented. Can you give me your ideas on how you will implement it, and what sort of issues are you likely to face ... some of the aspects I don't find too alluring is the fact that during charging you have a high voltage bus. Where as I'm more inclined to breakup my pack into 48V modules when the car is parked. This makes things intrinsically safer - my pack is likely to be a gynourmous 600V one which calls for extra care. Also what is the charging efficiency like for a rotary converter compared to a fixed voltage SMPS? This may have a bearing on your well-to-wheel efficiency - or may not make any difference??

I like the idea of using what is readily available, ie. an isolated SMPS that converts mains to 48V, each charging the portion of the battery bank that is in series. This together with a good enough BMS (which you need anyway), is to me a bit more straight forward - though this comes at the expense of volume of these chargers (you'd need a few of them on board).

I'd like to hear more about your ideas though ...




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Post by coulomb » Tue, 18 Aug 2009, 05:08

Sparky Brother wrote: ... wondering if you ever considered the 3 Phase rotary converter (The AC motor of the car idling) charging the battery pack via the Inverter as an option?

Weber and I plan to use the inverter as a charger. We hope to use three phase most of the time, and hope to avoid spinning the motor while charging, but that won't be possible for single phase charging.

We can't break our battery pack into equal sized pieces, as the pack is spread over several cages, each of different odd numbers of cells. However, we'll have defeatable interlocks so the user won't be able to accidentally touch the pack while charging, but we can debug the charging process when necessary.

We haven't sorted out the exact way of setting up the charger for single phase charging. AC propulsion seem to insert the mains in series with one of the motor phases; we have yet to figure out why they do that, how it works, and if we want to do that. This is complicated slightly by the fact that AC Propulsion claim a patent on some aspect of this, so information is less available. It's hard to see what part of charging via the inverter is patentable, but Telsa seem to think it's valuable enough to license some technology from AC Propulsion.

Our method, assuming we succeed of course, will be free and open, as such ideas and techniques should always be, in my opinion.

Some claim that the motor has to be isolated for this to be legal in Australia. We don't believe that to be the case. The entire high voltage system will be non-isolated from the mains while charging. This is a slight additional hazard, as the whole battery is electrically hot while charging; while driving, touching any one part of the pack should be non-lethal unless there is an insulation failure. We also plan to use an insulation monitor, obviously disabled while charging.

Edit: leakage -> insulation failure; leakage detector -> insulation monitor. See next post.
Last edited by coulomb on Tue, 18 Aug 2009, 05:17, edited 1 time in total.
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Post by Richo » Tue, 18 Aug 2009, 05:28

coulomb wrote:AC propulsion seem to insert the mains in series with one of the motor phases; we have yet to figure out why they do that, how it works, and if we want to do that.


Well you now have a sine wave connected to an inductor.
So by switching the bridge on that one phase it becomes a boost circuit.
Nifty.
That's one cheap charger.
Cost of a contactor perhaps?
And some firmware in the VFD.

But yes no isolation.
One more reason to isolate the pack and have ground fault detectors.
So the short answer is NO but the long answer is YES.
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Post by coulomb » Tue, 18 Aug 2009, 05:54

If you weren't using your brake chopper for braking, you could rectify the mains, add a large inductor in series, and use the brake chopper as a power factor corrected boost converter.

We might consider this if we can't convince the main inverter to connect to single phase. It might also be a cheaper contactor even if you are using the brake chopper, as we plan to.
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Post by coulomb » Tue, 18 Aug 2009, 06:05

Richo wrote: Well you now have a sine wave connected to an inductor.
So by switching the bridge on that one phase it becomes a boost circuit.
Nifty.
That's one cheap charger.
Cost of a contactor perhaps?
And some firmware in the VFD.

You need the other end of the inductor (the motor) connected to battery positive or negative. Alternately to get full phase operation (or use a bridge rectifier). That means switching a second phase synchronously with the mains. The third phase should be open.

Doable, especially for people that design their own controller Image . But for an industrial controller, it might not be possible to persuade the back end to connect like that.

The advantage of this scheme is that the motor doesn't need to spin. Though it may emit a buzzing or humming sound.

The brake chopper idea also avoids the motor spinning, and it may well be easier to control the brake chopper PWM ratio than ask the triple half-H-bridge to connect in a very non-standard way.

Great thoughts, thanks Richo.
Last edited by coulomb on Mon, 17 Aug 2009, 20:07, edited 1 time in total.
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Post by Richo » Tue, 18 Aug 2009, 08:32

Yes during half of the mains cycle one bridge is connect to - of pack.
The other half of the mains cycle the same bridge is connected to + of pack.
The other side of the motor has variable PWM depending on req V or I and mains cycle to boost.
This should give a near 1 pf which is nice.

But a contactor is needed to break the other phases up so they don't move the motor?

Yes for industrial controller not so easy.
So the short answer is NO but the long answer is YES.
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Post by Tritium_James » Tue, 18 Aug 2009, 13:37

Here's what ACP do:
Image
Note that the pack will move around relative to the mains (at 100Hz), which is why you need a floating pack. The floating motor I'm not so sure is necessary, but all their documentation is pretty adamant about that point.

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Post by Hemonster » Tue, 18 Aug 2009, 13:49

Say however that you wanted to implement a rotary converter, does that mean turning the 3P AC motor with another 1P motor and asking the inverter to effectively regen the energy back into the pack?

I would think that means you need to be able to disengage the motor from the drive shaft which means retaining the gearbox. I think I'm likely to do this as I'm experimenting with a 2 pole motor, however all the rest of you seem to be ditching the gearbox and direct driving with a 4 pole - so this would make things more difficult.

Anyway, if you were able to disengage the motor, what speed would it need to spin at? I suppose whatever sync speed the driving motor is, the slippage (ie. charge current) of which is controlled by the inverter? But wouldn't there be a loud hum in the garage for most of the night? Also does the 1P driving motor need to match the speed of the 3P ACIM? ... and where would you mount it?

You could leave the driving wheel engage and turn the wheel Image but that might have implications on tyre wear.

Using the motor inductance as a boost converter is a brilliant idea. AC propulsion did it because they did have control over the source code, oh what a luxury (or curse!). You'd certainly need back door access and secret handshakes to get the Danfoss to do that. Isn't isolation a big problem though? If you are charging from home you could have an isolation transformer, but carrying one in the car for a quick oppurtunity charge would be more weight. For us in NZ you'd actually have issues getting the electrical certification for that ... esp with a pack voltage such as ours!

Coulomb, that's a pity you can't break up the pack and charge. But can't you still do it, albeit with perhaps some of the chargers being a different voltage? ie. match it to what ever size of battery you need? say you break up the pack into 48V modules in the back, but else where you work with 24V modules? ... it is still CC CV so they should all charge in the same time?

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Post by coulomb » Tue, 18 Aug 2009, 14:34

Hemonster wrote: Say however that you wanted to implement a rotary converter, does that mean turning the 3P AC motor with another 1P motor
No need for that, just use capacitor start. These are cheap and available, though you may need several in parallel.
and asking the inverter to effectively regen the energy back into the pack?
Yes, you do a flying start, which tells the controller it's not starting the motor from rest, so figure out what it's doing from back emf and/or the resolver, and yes, exactly that, demand negative torque and it will do the rest.

Oops, I've just realised it's not quite that simple. Usually it will implement negative torque by changing the slip, which means increasing the frequency a few Hertz, but it must not ever change the frequency. Somehow it has to be told that the frequency is not changeable. It should vary only the duty cycle. Again, this is sounding like a bit much to ask of an industrial controller.

So my brake chopper idea is starting to sound better. I'll whip up a circuit soon so you can appreciate the genius of it     Image .

Edit: It's in this thread.
I would think that means you need to be able to disengage the motor from the drive shaft which means retaining the gearbox.
Yes, if the motor spins you need that.
Anyway, if you were able to disengage the motor, what speed would it need to spin at? I suppose whatever sync speed the driving motor is, the slippage (ie. charge current) of which is controlled by the inverter?
It will be spinning at a little under 3000 RPM (for 2 pole), I believe. And as noted above, the inverter mustn't attempt to change the frequency of all the generators in Australia    Image
But wouldn't there be a loud hum in the garage for most of the night?
Yes, there will be the motor spinning. But you can use a separate inductor instead of the motor, or use one of the solutions that doesn't spin the motor.

Richo: The motor will have no torque with single phase applied and no capacitance to shift the phase of any other phases. It may hum fairly quietly, or possibly buzz due to the PWM through it.
Isn't isolation a big problem though? If you are charging from home you could have an isolation transformer, but carrying one in the car for a quick oppurtunity charge would be more weight.
An isolation transformer would be a show stopper, at least for me. But the motor is designed for connecting to three phase all day every day, so single phase should be no problem. The only issue may be the earthing; I would think that you simply connect mains earth to chassis earth and that's how the motor works normally in a factory.
For us in NZ you'd actually have issues getting the electrical certification for that ... esp with a pack voltage such as ours!
We have similar rules in Australia, in fact I think we share the design of these rules. So we'd have the same issues. I don't see that it's any more difficult than usual. Certainly any insulation failure would be a problem, and you can't earth the centre of the pack.
Coulomb, that's a pity you can't break up the pack and charge. But can't you still do it, albeit with perhaps some of the chargers being a different voltage? ie. match it to what ever size of battery you need? say you break up the pack into 48V modules in the back, but else where you work with 24V modules? ... it is still CC CV so they should all charge in the same time?
Yes, that's the fallback position I suppose. It might be tricky finding odd voltage chargers, and matching the (scaled) charging currents so they all finish at about the same time. But certainly possible.

Edit: leakage -> insulation failure
Last edited by coulomb on Sat, 07 Nov 2009, 16:35, edited 1 time in total.
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5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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