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Discussion Starter · #1 ·
Hi Guys

I am having a hard time trying to decide which of the following systems would give me the best bang for my buck:

The Hiperformance AC conversion :http://www.thunderstruck-ev.com/index.php?dispatch=products.view&product_id=97

or China motors 30 Kw BLDC conversion, rudimentary motor specs here: http://www.china-electricmotor.com/motor/Cars_brushless_motors_833_120.html
With matching controller, the BLDC kit is about 300$ more expensive.

I'm thinking of using TS Lipo for both conversions, the only difference being the pack voltage and capacity: 108V 200 a/h for the Ac conversion or 320V 60 a/h for the BLDC conversion

The BLDC pack costs 300$ less than the AC pack effectively rendering the cost of either conversion identical, excluding shipping

I need to do a 40Km commute (one-way) to work on fairly hilly terrain characterised by long, gentle slopes, but has a rather steep,short slope thrown in for good measure. I would like my travel speed to average around 100Km/hr and I can recharge at work.

Attached is my intended donor vehicle, hopefully it's still for sale! Based on a VW beetle chassis it has a fiberglass body. Unfortunately no specs on drag or weight just yet, but a guestimate would put it at around 800kg.

What do you guys think?
 

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One consideration Bent, is that the chinese motor is a permanent magnet, not a true AC. It's possible these motors loose their magnetisation over time. And therefor loose power. I have no evidence or read literature about this. But it is something to investigate further if I where you.

Another thing, although the BLDC pack is less in kWh, but the higher voltage, and therefor lower resistance losses might compensate that. Maybe. And the AC50 is not very efficient if I remember correctly. What also can result in a significant difference in range.
 

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Discussion Starter · #3 ·
Hi Jan

From what I can gather the BLDC motors are only prone to losing magnetization
if they overheat, a condition I will hopefully be able to avoid, but are otherwise very reliable and apparently have a higher power to weight ratio, but I can't back this up 'cos I can't remember where I read it, or even if its true!

According to my maths the 200a/hr 108V pack gives 21.6 Kw/hrs and weighs 214Kg while the 60A/hr 320V pack gives 19.2Kw/hrs and also weighs 214 Kg.

Basically, for all intents and purposes the two are identical except for the AC vs BLDC debate with regards to efficiency, power availability and the various torque curves which are all over my head at this point. I must mention that this will be my first EV conversion and I would like to do it right first time.
 

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...except for the AC vs BLDC debate with regards to efficiency...
Bent, it's not the general debate, but that this particular AC50 drivetrain is not very efficient. If I remember correct 80% is the max under ideal circumstances, and much less otherwise. While a BLDC including its inverter can reach close to 90% pretty easy. If that's the case for this particular one, I don't know.
 

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Discussion Starter · #5 ·
So can I count on your vote for BLDC then?:) Or can you recommend a different AC system in a similar price range? ~$4000-5000 for a kit sans batteries.
 

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So can I count on your vote for BLDC then?:) Or can you recommend a different AC system in a similar price range? ~$4000-5000 for a kit sans batteries.
I don't know. It's hard. Look at David85's build thread. He is one of the few who has experience with chinese stuff. There are some issues....
 

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Looks like a fun car when it's not raining. :)

Just happened across this kit on eBay after reading the thread.

D&D #ES-15A, twelve horse power continuous and forty HP Peak at 72 VDC, adaptor plate, , Alltrax #7245 controller and a couple other things.Buy it now price $2,300.00 with $150 for shipping.

Seems a little underwhelming power-wise to me, but, what do I know? (answer: not so much, so caveat emptor etcera etcera)
 

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Hi. This gentleman, Chris from Low Carbon Idea, seems to have a good BLDC package for a little less: http://www.diyelectriccar.com/forums/showthread.php/80kw-motor-controller-package-sale-49438.html. The 80kW motor plus the controller size turned out to be too large to fit in my (VW Cabrio) car. Chris might have smaller motor/controllers kits.

On the flip side, consider that the AC50 package is complete, including basic readout panel and wiring. I think you need to add a contactor and accelerator and that's it. The AC50 package works with <120V pack. The BLDC typically requires ~288V. While the cell pack price difference might not be much for equal kW rating, weight does increase for a higher volt pack. More batteries also means more connectors (a chances for bad connection), cables, maintenance and battery boxes.

JR
 

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Haven't heard much about that chinese motor/controller, but the AC-XX motors and curtis controllers are proven in many conversions and have a great support base. I own an AC15

So consider that you're taking a risk and might not get the support you want.
 

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Hi Bent

Why AC/BLDC?
Why not series DC? - can be a whole lot cheaper! - leaves more money for batteries!
 

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I just took out a Chinese BLDC (M C motors), and replaced it with a netgain.

The hall sensors went out on it last summer, and M C wouldn't sell me new ones. They would only sell me another motor.

My motor was only rated at 15kw, and the hall sensors went out driving into a head wind at 45mph.

If you know how to replace the hall sensors, I could give you a good deal on the motor and controller. I have saw hall sensors for bikes, and they only cost ~75cents, and there are usually only 6, if someone replaced them all. but 15kws isn't much of a motor.

It would make a good motor for lower speeds. I got great mileage and regen, but I couldn't keep up with the highway traffic around my home.
 

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I would avoid a Chinese controller at all costs! The specs are likely exaggerated, and reliability is well proven (to be terrible).

The hall sensor might need to be aligned with the rotor on your motor, this is why they want to sell you a whole motor. It would be like replacing a distributor without owning a timing light.



I just took out a Chinese BLDC (M C motors), and replaced it with a netgain.

The hall sensors went out on it last summer, and M C wouldn't sell me new ones. They would only sell me another motor.

My motor was only rated at 15kw, and the hall sensors went out driving into a head wind at 45mph.

If you know how to replace the hall sensors, I could give you a good deal on the motor and controller. I have saw hall sensors for bikes, and they only cost ~75cents, and there are usually only 6, if someone replaced them all. but 15kws isn't much of a motor.

It would make a good motor for lower speeds. I got great mileage and regen, but I couldn't keep up with the highway traffic around my home.
 

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Discussion Starter · #13 ·
Hi Bent

Why AC/BLDC?
Why not series DC? - can be a whole lot cheaper! - leaves more money for batteries!
I'm not averse to a DC system, I think I just like the idea of regen ( I know it doesn't contribute much to range, but it's cool!)

If I can source a DC system at an awesome price, I will probably go for it.
 

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Hi Bent

I got a lovely just rebuilt forklift motor for $100 and I have bought an OpenRevolt controller kit for $600
(Did I say I was a Scotsman?)

Read the fork lift motor thread on the motors forum and look up the OpenRevolt stuff on the controllers forum

I think this is the cheapest way to go - not necessarily the best! but definitely the cheapest
 

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Discussion Starter · #15 ·
Hey Guys!

I just discovered that Albano ( a senior member of this forum) lives just down the drag from me and we have been in telephonic contact. He is helping me to get a system together for my conversion and has basically convinced me to go DC!
I was set on an AC\BLDC system but simply for cost considerations I'll
take his (and your) advice to heart and go with DC for my first conversion.

I hope to start within the next month or three (waiting for my bonus:rolleyes:)
and will keep you posted.
 
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Have you considered battery space for the what you will need. Cool little car but looks to be built on a shortened wheel base. Less room for batteries. VW based conversions are good. You will like going with the DC. I too wanted regen but after careful consideration I went with the low cost DC systems and found you need good brakes but don't truly need regen. It's over rated but still a nice thing to have.

Pete :)
 

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I was set on an AC\BLDC system but simply for cost considerations I'll
take his (and your) advice to heart and go with DC for my first conversion.
cost and risk managing the OVER-charge of LI pack puts me directly in the DC camp unless I were building a stop-and-go delivery vehicle.
 
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