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Hi Linz

The Kelly controllers should be considered "on probation" until they prove themselves more (at someone else's cost ...). I was initially very hopeful of the new entrant Kelly controller when they came out. ZEVA offerred the 144A 500A Kelly for series wound DC motors earlier this year. Then I noticed that ZEVA withdrew ("discontinued") the Kelly 144V 500A line. I didn't get an answer to specific questions to Ian Hooper of ZEVA on the reasons for the change (which was perhaps badly asked by me since it was on a public Australian EVA listserver discussion). Then I read Ian's account of finishing his EV MX5 sportscar and his comment that he substituted the Kelly with a Curtis 1231C because the the Kelly was "hopelessly under-powered". I also read that the 500A rating is not continuous and good for a number of seconds, while the continuous current rating is only 250A. Makes the Curtis look quite grunty by comparison. I wonder if the same limitation applies to the 800A model? It would be very limiting and wouldn't achieve the aim of breaking out of the 500A straight-jacket if that were the case.

Ian Hooper is slowly developing his own DC controller. In the past he indicated that his controller would have a rating of about 800A. More recent comments have tended to slide back a little towards a rating more in line with those of the Curtis 1231C.

I think that we definitely need a high current controller option. I am driving in Dunedin hills and see my battery current swing into the +400A territory when accelerating uphill even with a pack voltage of 144V nominal. I would love to have some more top-end current capacity for acceleration. We have more and steeper hills than continental countries like US and UK, so the controllers that they might be happy with over there are a bit anaemic in NZ cities. Even with a higher rated controller, the load on the battery of +500A currents is opposed by significant internal resistence effects of flooded lead-acid batteries such as mine. If you go to Absorbed Glass Mat batteries (AGMs such as Optimas and Orbitals), then you get much better current parameters but pay with both higher purchase cost and shorter cycle life.

I also wonder if this is another factor that will push us towards AC conversions. In the past we have had a fairly negative / blinkered view of AC gear cost arising from the 'Metric Mind effect' (Metric Mind sells AC kits of high quality and stupendously high cost). Things are definitely on the change with the first NZ conversion using an industrial Variable Frequency Drive and induction motor in Ashburton under way by Graeme Church and some commercial AC gear coming in at more reasonable prices. My point is that AC conversions are more flexible in accepting higher DC voltages and currents than the presently available DC controllers. If the availability of DC controllers with NZ-friendly current ratings becomes a bottleneck, then there will be an impetus pushing us to explore the AC option more thoroughly. One additional benefit of the AC drives are that the current loading on the battery string is lighter than DC controllers.
 

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Even with a higher rated controller, the load on the battery of +500A currents is opposed by significant internal resistence effects of flooded lead-acid batteries such as mine.
I'd be careful with pulling 500A from 6 volt golf cart batteries on a regular basis. My understanding is they don't like it very much and die an early death. A controller with a higher motor current limit will reduce the need to change gear, but even a 500A Curtis is enough to damage golf cart batteries if you ask for too much battery current for too long.

Motor current is roughly proportional to torque
Battery current is roughly proportional to power

I also wonder if this is another factor that will push us towards AC conversions. In the past we have had a fairly negative / blinkered view of AC gear cost arising from the 'Metric Mind effect' (Metric Mind sells AC kits of high quality and stupendously high cost). Things are definitely on the change with the first NZ conversion using an industrial Variable Frequency Drive and induction motor in Ashburton under way by Graeme Church and some commercial AC gear coming in at more reasonable prices.
I'd be interested in comparing the performance and lifetime of an industrial drive with my Siemens system. Does Graeme have blog or a website? I also have a friend who is looking for a controller to drive a 5kW PMAC motor, he's used a industrial BLDC drive but it causes a lot of vibration.
 

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Discussion Starter · #9 ·
I did wonder how much current a lead-acid battery could handle. How about reducing either the total power required by down-sizing the vehicle to a compact (removing the rear seats) or reducing (battery) current with parallel strings somehow protecting against current loops and fault shorts?

The AC option shoulds really interesting, how easy is it to adapt to an ev application, and hows the efficiency of an induction motor (eddy current losses?)
 

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I did wonder how much current a lead-acid battery could handle. How about reducing either the total power required by down-sizing the vehicle to a compact (removing the rear seats) or reducing (battery) current with parallel strings somehow protecting against current loops and fault shorts?
Sure, the lighter the vehicle the less power you need for the same performance.

To increase the power available from a particular battery type you need more battery. You can either get the same number of bigger batteries, more of the same in series, buddy pairs or parallel strings. Since you've got more batteries, your performance is reduced because you have more weight. I'm not sure when or if diminishing returns sets in.

More of the same in series is a problem for the Curtis controllers as I believe the highest voltage model is 144V nominal. From what I've read, it's not particularly reliable if you use it at that voltage either.

If you want lots of power you really don't want to use golf cart batteries. I understand they are good for about 3-4kW each. If you've got 10 of them you shouldn't really pull more than 40kW, and if you've got a few minutes of hill climb at full power, I'd ask for a safe maximum power from someone more knowledgeable than I.

The AC option shoulds really interesting, how easy is it to adapt to an ev application, and hows the efficiency of an induction motor (eddy current losses?)
Efficiency will depend on the motor & VFD you use. If you operate it near the nameplate specs, you ought to get close to the nameplate efficiency.
 

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Discussion Starter · #11 ·
There are perhaps three issues for hill-climbing performance-
1) power to weight ratio of total vehicle, so for a given battery type the most that can be safely installed. The total size of the vehicle should not matter, the proportion of battery weight:total weight does.
2) The max Volts*Amps of the controller.
3) The max Volts*Amps a battery type can deliver

As 2) decreases the total vehicle size decreases. The suitability of a type of vechicle for modification maximises 1) and budget determines 3) for a given size of vehicle.
(if only designing to meet min requirement of making it up a local towns hills)
So I was thinking to meet these take a suitable small vehicle, load it up safely with FLA or AGM along with a standard controller.
The trade-off is that the design will be tilted towards performance and range will be less than ideal.
 

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I also wonder if this is another factor that will push us towards AC conversions. In the past we have had a fairly negative / blinkered view of AC gear cost arising from the 'Metric Mind effect' (Metric Mind sells AC kits of high quality and stupendously high cost). Things are definitely on the change with the first NZ conversion using an industrial Variable Frequency Drive and induction motor in Ashburton under way by Graeme Church and some commercial AC gear coming in at more reasonable prices. My point is that AC conversions are more flexible in accepting higher DC voltages and currents than the presently available DC controllers. If the availability of DC controllers with NZ-friendly current ratings becomes a bottleneck, then there will be an impetus pushing us to explore the AC option more thoroughly. One additional benefit of the AC drives are that the current loading on the battery string is lighter than DC controllers.
Jens,

Where would one go to get a reasonably priced industrial VFD controller? I take it these are mostly used for AC induction machines? Aren't synchronous and brushless DC motors easier to control? ie. no flux induction in the rotor to worry about? shouldn't this make them cheaper? Where then also do you go to get cheap industrial AC induction or synchronous motors? do you have a source in mind (2nd hand)? How much are these typically that will compare with what azure and metric mind have on offer?

Regards,
Hemon
 

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Hi Hemon

Used induction motors come onto the market on a regular basis. Finding a cast-off induction motor shouldn't be the problem. They are used in hundreds of settings, usually with DOL or star-delta starter circuits. Occassionally, the VFD unit comes with an induction motor, or separately. It would probably help if you are in the trade, but there are also second-hand dealers that gut former factories and premises then on-sell the contents.

In Dunedin, Rietvelds is the main on-seller of industrial equipment. They won't give them away, but it should be a fraction of new purchase price. In NZ we also have a manufacturing capability in VFDs. The company used to be called PDL, but now goes by the name Schneider. Plants in Christchurch and Napier, I think still.

Graeme Church is / has bought his motor and VFD brand new and will priced the range already. Be worthwhile getting in contact with him directly.
 

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Something's going on at ZEVA (Ian Hooper's Zero Emission Vehicle Australia website and company; zeva.com.au).

The on-line store is selling down and out of the Kelly controllers that they had been carrying. It looks like Ian is discontinuing with Kelly. Ian has repeatedly said that the Kelly is grossly under-powered since fitting one to his MX5 (it barely pushed the thing along enough to break the city speed limit).

Second, Ian Hooper blew up the Curtis 1231C controller in his Mazda MX5 conversion. Somehow he should not have been too surprised since the MX5 is fitted with a powerful 9" DC series motor and it is direct coupled to the diff. Without the benefit of reduction gearing or gears the acceleration current on the controller must be pretty horrendous, quite a load on a 500A controller.

Third, the ZEVA brochures now show pictures of a green 600A ZEVA controller that Ian has been threatening to build for a few years.

Could this signal the release of Australiasia's very own "Zilla" version onto the market? Is Ian going to be the next Otmar?! I will be interested in the price point and how many Ian can produce once he finally does announce it.
 

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Something's going on at ZEVA (Ian Hooper's Zero Emission Vehicle Australia website and company; zeva.com.au).

The on-line store is selling down and out of the Kelly controllers that they had been carrying. It looks like Ian is discontinuing with Kelly. Ian has repeatedly said that the Kelly is grossly under-powered since fitting one to his MX5 (it barely pushed the thing along enough to break the city speed limit).
The above sounds accurate for the "higher power" Kelly. The lower power versions may be somewhat more realistic in their ratings. See this post to the evtech mailing list for more Kelly Controller details. Unfortunately you have to be a member to see it.

Second, Ian Hooper blew up the Curtis 1231C controller in his Mazda MX5 conversion. Somehow he should not have been too surprised since the MX5 is fitted with a powerful 9" DC series motor and it is direct coupled to the diff. Without the benefit of reduction gearing or gears the acceleration current on the controller must be pretty horrendous, quite a load on a 500A controller.
It was an 11" motor and it blew up because the Curtis design cannot handle a big motor turning slowly, not because the direct drive motor overheated the controller. See his report into the failure.

Third, the ZEVA brochures now show pictures of a green 600A ZEVA controller that Ian has been threatening to build for a few years.
Got a link? I couldn't find anything beyond a rendering.

Could this signal the release of Australiasia's very own "Zilla" version onto the market? Is Ian going to be the next Otmar?! I will be interested in the price point and how many Ian can produce once he finally does announce it.
I don't think ZEVA control is imminent, he's currently waiting for his own Zilla (see the evtech post above).
 

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So this just leaves Zapi H3 and Logisystems for DC (series) controllers rated over 500A?

List of logisystems stuff here- http://www.grassrootsev.com/control.htm
(fairly new to the market, but ev specific)
Zapi http://www.electrofit-zapi.com/hfsermotor.htm
(built for low-speed industrial vehicles, regen has been problematic for ev)
The Soliton1 is rated 1000A and then there is also the HPEVs 650A AC system, unfortunately only 120v nominal though. For a bit more money you can go with EvolveIT 75kW motor and controller (Siemens & RMS inverter) which does some decent torque up to 4000 rpm at 300v. AZD motor controller package is available ex Oz for about 12k (aud) but there is no canbus solution available to actually operate it.

I didn't even know zapi was still available. I have only ever seen them mentioned on jerry halsteads site in regards to his first EVE project. As i recall he had much issue with the advertised but inoperable regen. I keep reading mixed reviews of the Kelly controllers but have nothing against them - in a golf cart.
 

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Why would anyone want a Zilla when you can buy a Soliton1????

Zilla's are over priced and are developed out of a computer Nerd's wet dream!!

Controlling up to 2000amps/360 volts via a telephone plug??? what planet was he on????
 
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