[few2many]

Hey kelmark, just found youre thread, looks great, eager to see how the drive train comes out.

[Kelmark]

Hello everyone,

Just wanted to give an update;

I got the body back on the chassis but found that there was a substantial space above the rear tires due to using smaller diameter tires and a 3" body lift kit seen in post#53. Adjusting the spring plates won't be enough so I will have to do some custom fabrication to lower the rear suspension.

The wife says I have to pay off a couple bills before I continue on my project so that has been my focus but hope to be able to start diverting some money back to my project soon.

Also been rethinking the AC motor... I am now considering 11" Kostov with Netgains Warp Drive controller. The efficiencies should be close but potential power is much greater and price is about the same. Any thoughts?

[maxvtol]

Originally Posted by Kelmark

I am now considering 11" Kostov with Netgains Warp Drive controller. The efficiencies should be close but potential power is much greater and price is about the same. Any thoughts?

Not from experience, but from calculations... make sure your power is in the rpm range you want it for the voltages you're going to use. I put the 11" WarP motor in my spreadsheet and it really didn't give any better performance, actually worse than what I wanted. Torque was too much on the low end (tires would spin more than a Warp 9) and there wasn't enough power on the higher rpm range to give the top speed I wanted.

If you put enough voltage to the motor, I'm sure you could get the performance you want, but that's more $$$.

P.S. on my spreadsheet if you use it, your car is so light, I wouldn't expect to much more acceleration in G's (~ 32 ft/sec^2) than the what the weight ratio is on the rear wheels, ie if you have .5 on the rear, a little over .5 G's or 16 ft/sec would be about max acceleration with standard tires of the appropriate width. Over that and the tires would probably spin.

Oh, and don't forget to tell your wife how much money you're saving when you buy parts, just like she does when she buys her shoes.

[Kelmark]

Originally Posted by maxvtol

Not from experience, but from calculations... make sure your power is in the rpm range you want it for the voltages you're going to use. I put the 11" WarP motor in my spreadsheet and it really didn't give any better performance, actually worse than what I wanted. Torque was too much on the low end (tires would spin more than a Warp 9) and there wasn't enough power on the higher rpm range to give the top speed I wanted.

The reason I started looking at the 11" was because Netgain came out with the HV version. But netgains motor has too much torque and is too heavy so I was reading the history of white zombie and they used the 11" Kostov which has interpoles, less torque, and is lighter.

Originally Posted by maxvtol

If you put enough voltage to the motor, I'm sure you could get the performance you want, but that's more $$$.

I would use the highest pack voltage (450?) and would limit motor voltage max rpm 5000. Top speed on this car is going to be limited to 70mph, I am not sure I would feel safe driving the kit car much faster and there isn't really a need, 90% of my driving will be in town.

Originally Posted by maxvtol

P.S. on my spreadsheet if you use it, your car is so light, I wouldn't expect to much more acceleration in G's (~ 32 ft/sec^2) than the what the weight ratio is on the rear wheels, ie if you have .5 on the rear, a little over .5 G's or 16 ft/sec would be about max acceleration with standard tires of the appropriate width. Over that and the tires would probably spin.

Thanks I will have to play around with that calculator. The main purpose of going with the 11” kostov was to have “interpoles” which will give me a greater torque band. Also wanted to use a large enough motor that the draw on amps would be less and be more efficient overall.

Originally Posted by maxvtol

Oh, and don't forget to tell your wife how much money you're saving when you buy parts, just like she does when she buys her shoes.

LOL

[maxvtol]

I'm just starting my project, but my thoughts on higher voltage, higher voltage = more batteries = more connections = more potential problems.

I could get a longer torque (but lower) band using an Impluse 9" and higher voltage on my project and shift through the gears to get the performance I want, or use a WarP 9" and lower voltage and just start off in 3rd, it calculates about the same as far as acceleration performance on 0-60mph. If you only need to go 70mph, I don't know if you would really need to go real high voltage. I don't know the efficiency difference between 144v vs 300v+ but I think it would be small.

Again, just my thoughts, but if you had a real high power motor and single speed and neeeded to go 10K + rpm, high voltage would make sense, but for 5k rpm and if you plan to keep and use your transmission, someone would really have to explain the benefits to me.

On a different subject, what seats are you using and where did you get them? How much do they weigh?

[Kelmark]

Originally Posted by maxvtol

I'm just starting my project, but my thoughts on higher voltage, higher voltage = more batteries = more connections = more potential problems.

On a different subject, what seats are you using and where did you get them? How much do they weigh?

The seats are from JcWhitney, GaragePro I think. I got them for $200 on sale with a discount. They are a bit heavier than I would like at 33 pounds each but I can always upgrade later.

I am planning on using prismatic cells which will have lots of connections no matter what voltage I choose anyway. But I will have the modules assembled professionally and then I will install them.

[Kelmark]

I have been considering another drive for my project that I really think will work well but I thought I would bounce the idea off all of you. Here it is;

Battery Pack

100 Calb 40Ah
320V nominal 360V Charged
Weight- 331 lbs

Drive system

55kW BLDC Motor / Controller. Weight-66.14 lbs

312V nominal 55kW peak power 22kW nominal. 250Nm Maximum Torque (84Nm Nominal) Air-Cooled, with Full Brake Regeneration

The battery pack would be on the small side but I plan on upgrading on my next pack as battery technology improves and prices come down. But as this will be used for local car shows and I live 2 miles from work my actual daily driving will be less than 30 miles.

With this setup I should be able to keep the finished weight of the car under 1700 lbs with pack over and forward of the rear wheels I think this car would have impressive acceleration and handling.

So what do you guys think?

[maxvtol]

Nice looking motor. Whatabout cost?

I assume since there is a torque curve with it, it's good for a traction motor. A sensorless controller / BLDC motor setup in RC is best for propellers where there is no resistance to starting the propeller. I would just make sure it's a sensored controller / BLDC motor setup or that it actually says it's a traction motor.

55kw / 320 v = 171 amps or over 4 C for the batteries, if you plan on using maxing out the motor. Might shorten the life of those batteries a little. If you're close to the Tesla at highway speeds at ~ 20 to 25kw, thats 1.5 to almost 2 C. Seems I've seen 1 C is good practice for the batteries for extended periods.

Complete speculation on my part, but I'm not of the opinion batteries will get any cheaper, maybe better, but not cheaper. They're already cost competive with oil (if you believe the cycle life claims), and they seem to be gaining popularity, you know that ole supply and demand thing.

[Kelmark]

Originally Posted by maxvtol

Nice looking motor. Whatabout cost?

I assume since there is a torque curve with it, it's good for a traction motor. A sensorless controller / BLDC motor setup in RC is best for propellers where there is no resistance to starting the propeller. I would just make sure it's a sensored controller / BLDC motor setup or that it actually says it's a traction motor.

55kw / 320 v = 171 amps or over 4 C for the batteries, if you plan on using maxing out the motor. Might shorten the life of those batteries a little. If you're close to the Tesla at highway speeds at ~ 20 to 25kw, thats 1.5 to almost 2 C. Seems I've seen 1 C is good practice for the batteries for extended periods.

Complete speculation on my part, but I'm not of the opinion batteries will get any cheaper, maybe better, but not cheaper. They're already cost competive with oil (if you believe the cycle life claims), and they seem to be gaining popularity, you know that ole supply and demand thing.

maxvtol,

This same motor is offered through Current EV Tech as a traction motor for use in EV's just a little less expensive. You bring up a good question on the sensor though I will have to check and see if there is or not.

As for the batteries I have limited my weight to <350Lbs to maximize performance and efficiency. So for this first pack I will limit peak amps to around 145A and I do not think I will be running near 80A continues during normal driving probably closer too 45A or less for <50mph.

The price of Calb are very good just not the weight, my hope is that I can double (80Ah) for the same weight or lighter for less money in 5-8 years than it costs to do now which is $18,000 - $30,000.

Thanks for the feedback!

[Kernel Panic]

What seats are you using in your Kelmark GT. I am also in the process of converting a Kelmark GT into an EV. Looking forward to the completing this project. Hard to find seats for this little car.