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Discussion Starter · #1 · (Edited)
Hello all,

I'm looking to convert my 65' Corvair, but I'm having a hard time choosing between an AC or DC system.

Does anyone have any "lessons learned" or "wish you would haves" using either of these systems?
 

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What are your goals? In general, you can get more performance "bang for your buck" with DC but it does have limitations : no regen, easier to damage for new drivers. Not a single OEM uses DC. DC is not as sophisticated as AC.

Sent from my SM-T380 using Tapatalk
 

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You have several choices depending on budget and requirements

Cheapest and best is the drive unit from a production EV - that is the way I would go today

Then there is second hand DC - Forklift motor - LOTS of grunt simple and cheap - but not as sophisticated as AC

Then you have a "New" AC system - wimpy and expensive - but you do get regen - which is not worth that much unless you are a Taxi driver

Then you have a "New" DC system - just as expensive as a new AC system but no regen and more power

Finally you have "new" top level AC systems - $20,000 and nearly as much power as the first two
 

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Discussion Starter · #4 ·
For now I plan on building a commuter (60mi) to get my feet wet, then moving into a performance build. I was really disappointed to see what $5k could get you in regards to an AC "kit" and am hesitant to fork over that much money to buy into manufacturer constraints. I've built a three-phase controller that was capable of spinning a motor, but my design still needs refinement. I think this will save me some money, provide more system versatilely, and help further the development of my controller by applying it to this build.

AC seems like the way to go to avoid runaway if the controller should fail (as in the case of a DC controller failure), and it would help me recover some losses involved with running an external pump on my PG, etc..

Have y'all seen anyone use a general purpose induction motor for a build? I was thinking a 50hp. I know the weight will increase significantly with all of the extra iron (I will be upgrading the suspension and brakes to accommodate), but I feel like for the money a reconditioned motor or even a motor core would be better than spending a ton of cash to buy to an overpriced motor. I've thought about trying to find a model S motor (w/ no controller), but I haven't had any luck. I prefer to buy the motor once, so I'm looking for something that has potential (heh).

Some before shots of "Joule":
phase zero_1
phase zero_2
phase zero_3

Anyone looking for a flat-6 with less than 1k mi (runs great)? I won't be using it... :sneaky:
 

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Discussion Starter · #5 ·
Cheapest and best is the drive unit from a production EV - that is the way I would go today

Then there is second hand DC - Forklift motor - LOTS of grunt simple and cheap - but not as sophisticated as AC

Then you have a "New" AC system - wimpy and expensive - but you do get regen - which is not worth that much unless you are a Taxi driver

Then you have a "New" DC system - just as expensive as a new AC system but no regen and more power
Duncan,

After rethinking my approach, I decided to dig a little deeper and check the specs on what I'm considering to buy:

HPEVS AC-51 - @144V, 500A (suggested peak approx. values) ~ (1.73)(0.83[assumed PF])(144V)(500A)=103.5kW. With a motor weight of a whopping 115lbs, that would give you about 900W per pound. One of these motors go for a little over $3K

One of the better 50HP 3-Phase motor I've seen on ebay: @ 208V, 128A ~ (1.73)(0.878)(190V)(142A)=41kW. With a motor weight of 460lbs you are only getting sadly about 89W per pound... while coming in significantly cheaper on ebay at $975 w/ freight.

NetGain Warp 9 - @~144V, 500A =72kW. With a weight of 156lbs you are getting about 462W per pound. I see these motors going for a little under $3K

From these numbers, I've concluded that buying the AC-51 is the way to go based on the wattage per pound... I've read about people who have taken the warp 9 past 1000A with card upgrades and water cooling, which leads me to believe that the AC-51 can also exceed the manufacturer's specs if cooled. I'm thinking the AC-51 is also Class H insulation (as is the warp 9) due to the max temperature rating of 180C, but that's just an assumption. The RPM of the AC-51 out spins the Warp 9 by 4000RPM, which could give me some room to have an "educational" re-gearing. Being an induction motor, you also get a little more recovery with the regen feature as you have mentioned (might be nice for stopping at lights and for traffic?).

To me, the extra money spent is money well spent in the case of the AC-51 vs the Warp 9.

Can you explain you thoughts behind why the new AC systems are wimpy? I would like to know what I'm getting into and would appreciate your incite.

Cheers!
 

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Forklift motors
The Hitachi motor in my device is 102 kg - and I'm feeding it 1200 amps and 340 volts - its peaking at 500 hp and it cost me $150
The motors are limited not by the motor but by the controller
And you can buy much more powerful controller's for the DC motors - but not for the AC motors
 

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What about a Leaf? For maybe $6-8k, you get the whole car—motor, inverter, batteries, and a few other bits. Less if you can find a "good" wreck. The Leaf motor outperforms all the Hyper9s and ACs I've seen...the only tricky bit is getting the voltage high enough for the inverter (Thunderstruck says that 140V is the bare minimum).

The manufacturer constraints start leaving when you use aftermarket computers...and if you're willing to remove the inverter board, you can pretty much do anything you want with the motor.
 

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Discussion Starter · #8 ·
Forklift motors
The Hitachi motor in my device is 102 kg - and I'm feeding it 1200 amps and 340 volts - its peaking at 500 hp and it cost me $150
The motors are limited not by the motor but by the controller
And you can buy much more powerful controller's for the DC motors - but not for the AC motors
1200A and 340V?!?

I am going to do the polite thing and not ask the fifty million question speeding through my head and just ask two... Would you be willing to share the OEM specs of your motor (so I can better understand your starting point) and what battery chemistry you are using?

What about a Leaf? For maybe $6-8k, you get the whole car—motor, inverter, batteries, and a few other bits. Less if you can find a "good" wreck. The Leaf motor outperforms all the Hyper9s and ACs I've seen...the only tricky bit is getting the voltage high enough for the inverter (Thunderstruck says that 140V is the bare minimum).

The manufacturer constraints start leaving when you use aftermarket computers...and if you're willing to remove the inverter board, you can pretty much do anything you want with the motor.
I've considered it, but I'm hesitant about using permanent magnets (even if they are good quality) with motors, but I am a fan of that particular battery chemistry.. Have you had success with a leaf build? If so, what kind of performance are you seeing?
 

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The motor is a Hitachi
In the forklift its rated at 48 volts and 10 kw (200 amps) - and it will go forever at those loads! - and 1400 rpm

I am overloading it a touch !

But its not as bad as it seems - when I feed it 1200 amps I accelerate rapidly - haven't done a 1/4 mile - I planned on doing one at the end of the season last year but Covid intervened
On the 1/8th mile - I did a 7.8 seconds and 96 mph run - motor rpm would be 5300 rpm
The motor was getting the full current up until about 60 mph when the current would start to drop as the revs were rising

So it was full current for only about 4 seconds

The other reason I can do this is that I have a spare motor - which cost me $200

Battery
I'm using a Chevy Volt Battery - it seems to be OK with the mistreatment - but again its only for seconds

On the road I limit myself to 500 amps - and the motor limits itself to about 170 volt

On the track (not drag strip) I find that I'm on the power for only a couple of seconds before the next chicane
I don't have a license for high speed events - just autocross - and the organizers are meant to keep the speeds down by keeping the straights quite short
 

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Discussion Starter · #11 ·
My Mini: Nissan Leaf into Rover Mini...🤞

It'll spin the sticky tires up to 30-40mph, but it's a light FWD car with a top speed of about 70mph (due to gearing).
That is one rad ride sir, and I tip my hat to you!! Any kind of issues with the CANbus (this is completely new territory for me)?

The motor is a Hitachi
In the forklift its rated at 48 volts and 10 kw (200 amps) - and it will go forever at those loads! - and 1400 rpm

I am overloading it a touch !

But its not as bad as it seems - when I feed it 1200 amps I accelerate rapidly - haven't done a 1/4 mile - I planned on doing one at the end of the season last year but Covid intervened
On the 1/8th mile - I did a 7.8 seconds and 96 mph run - motor rpm would be 5300 rpm
The motor was getting the full current up until about 60 mph when the current would start to drop as the revs were rising

So it was full current for only about 4 seconds

The other reason I can do this is that I have a spare motor - which cost me $200

Battery
I'm using a Chevy Volt Battery - it seems to be OK with the mistreatment - but again its only for seconds

On the road I limit myself to 500 amps - and the motor limits itself to about 170 volt

On the track (not drag strip) I find that I'm on the power for only a couple of seconds before the next chicane
I don't have a license for high speed events - just autocross - and the organizers are meant to keep the speeds down by keeping the straights quite short
I am besides myself with what you have accomplished using a 48V DC motor! This gives me an itch I cannot scratch with conventional means..

If the motor is truly limited by the controller... I guess I should attempt to build one and see.. Do you think some of these could work?

120516
 

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Discussion Starter · #13 ·
Why? Do you realize that the majority of current production EVs use permanent magnet synchronous 3-phase motors?
This is true, most of the manufacturers are using PM, but I'm not ready to introduce a cooling system yet. I plan to run the motor hot on multiple occasions until I figure out some things regarding my controller. I don't think this particular motor will like what I have planned as I make my way through this process, and possibly motors. :whistle:

While I think this is a great setup, I don't think this motor will suit my needs right now, but I may be thinking about this wrong being wet behind the ears. What are your thoughts?
 

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Discussion Starter · #14 ·
Thank you for the tips everyone.

@brian_ After a little education, I see the why everyone is a fan of the internal permanent magnet synchronous reluctance motors: extra torque and higher efficiencies. Since the magnets won't be heated by the rotor, they won't be easily permeated. So more power at better efficiencies for the same size package, thanks for the eye opener:


I've gotten my hands on a performance Model S LDU and have been fiddling with that.

Now I'm that I've got some traction, I'll be starting a new thread to record my progress.

Thanks again.
 
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