In part 2 of my interview with Brian Seymour from HPEVS, we talk about what size electric vehicle motor will best match your car, NEV, or golf cart.
Then we talk about system voltage (these AC-50 motors are producing snappy acceleration in a light car at 120 volts!), "twinning" your motors, and automatic vs. standard transmissions in your electric car conversions.
Just as we've always suspected, size DOES matter: )
I'll show several sizes of the HPEVS motors below, but they all look pretty much the same, especially in pictures. The weight and the torque is the only way you'd be able to tell the difference.
Lynne: What size car can I drive with your AC 50? Is there a weight limit?
Brian: As a general rule, we like to see the vehicle weight under 3000 pounds, but we have had customers install them in light pick up trucks.
My NEV would use a different electric vehicle motor than the AC 50, correct? And if so, then would it also use a different controller?
The AC 50 needs at least 96 volts. NEV's can be 72 or 96, so you can use a 72 volt or a 96 volt controller.
If I want to put an AC motor in my Zap, or other light NEV sort of car, can I use one of your electric vehicle motors? I suppose I'd use one of the smaller ones, correct? The AC-35, say?
You could try it. The problem with the ZAP vehicles is the gear ratio. We like to see 8 to 1 or even 12 to 1, the ZAP's are 4 to 1. Since AC motors can, and need to run at high RPM the gear ratio is a problem.
NEV's that use a golf car style axle are no problem.
So do you sell AC drive systems for golf carts, too, for people that want them to go faster?
Yes, the AC9 is the golf car motor, it runs on 48 volts. 25 MPH is our normal golf car speed setting.
Does a golf car not have the gear thing going on? Just forward and reverse? I never thought about how that would work, really. Unlike a Zap, they don't have to go faster than 25, so no need to gear them for different speeds. The Zap, set up for SWDC motor - I'm guessing - uses a slow/fast setting so it can get up to 45 or whatever it does.
Golf cars are standard with a 12 to 1 gear. With their tire diameter we run the motor at 6000 RPM to get 25 MPH. On an On Road electric and their tire diameter we run 8 to 1 and set the motor for 8000 RPM, this gives us 65 MPH. If you could change the gears in a ZAP to 8 to 1, then you could do highway speeds, though I don't think I would want to in one of those things, yikes.
What if I have a bigger conversion? Can I use two electric vehicle motors at the same time? I have heard of electric race car drivers doing something like that.
Yes, two electric vehicle motors can be used at the same time.
Do I need two controllers for that, or just a bigger controller?
You would need two controllers, one for each motor.
I've heard that AC conversions work best at higher voltages, like 300v and up. People who have tried to make AC conversions at lower voltages (120v-144v) end up with sluggish acceleration. Yet, your AC 50 seems to turn that wisdom on its head, and 120v systems in light cars are quite snappy! So how did you do that?
Here again, secret sauce. The higher the voltage, the easier it is to produce higher horsepower and torque, thus eliminating the need to shift gears. Most of our on road applications couple to the standard transmission, so shifting the gears helps with the acceleration.
I don't want to give away the family secrets! I'm just trying to make sure I haven't misunderstood something.
So...it seems like I remember that SW DC conversions have this different torque curve than an ICE standard transmission can really relate to, so people tend to lock them down to two gears, well, three if you count reverse. Okay. And we know the high-voltage AC cars coming out now, like the Nissan Leaf, have what is basically a single-speed transmission. As you say, with higher voltage and AC control, there's no need to shift gears, torque can be accomplished with, what's it called - slip?
Sort of. Slip is required to generate torque, but too much is bad. High voltage allows the motor to run at higher RPM without loss of torque, some have just as much torque at 12,000 RPM as they do at 1,000 RPM. With the AC50 our torque is flat until 3,500 RPM, the it starts dropping, so if you shift gears at 3,500 RPM you keep the motor right at it's sweet spot.
But your electric vehicle motor is actually using the transmission to help with acceleration?
Most of the time, yes. For a conversion it is easier to use the transmission. But, in the Wheego since we had a blank sheet of paper to start with we chose to use a fixed ratio transmission, which works okay. But with a transmission that you can shift you can have wheel spinning torque at start and 100+MPH top end in 4th or 5th gear.
I'm wondering what's to prevent someone from using an automatic transmission to help with acceleration rather than the standard? They're programmable now, aren't they, electronic sensor feedback and all that jazz. So, isn't it just a matter of programming? Sounds like it's right up your alley.
Automatics are power hogs, though.
A standard transmission uses only a couple HP to operate where an automatic uses 20 to 30 HP. We have worked on theories to electronically control one of today's automatics but don't see much use for it. We have however converted a 2008 VW Jetta which uses a DSG transmission which is a manual transmission that is shifted with a computer. This is a better option, but it still has a lot of friction and looses inside that drastically reduce range. Their have been simple 2 speed designs, but not a large enough market to be worth mass producing, at least not yet.
A way to use an automatic transmission in a conversion has got to be right up there at the top of the EV crowd's letters to Santa, but it's still not a great idea at this point. Got it. Thanks, Brian!
In Part 1 of Best Electric Vehicle Motor Yet, we talked about the revolutionary HiPer AC-50, the Curtis 1238 controller that works so nicely with this motor...and most importantly, how can I get one of these great electric vehicle motors for my next conversion project, and what conversion shops are using these motors now.