[cyberhedz]

Hey all, I've been lurking around here for a few weeks and decided to make an account and try to get some help from the experienced, and the experts in EV. I keep reselecting components because I don't know what is actually going to meet my needs. I've looked at AC and DC, I am currently liking the cost of DC, but the controller of AC... the motors I'm also interested in are DC. Below are my requirements, and the options I'm considering

350km range
120km/h top speed
tons of torque
will be used offroad, trails, and paved surface. (looking at building something similar to a SxS)
total vehicle weight under 700kg

AWD - currently looking at Qs 273 8kWh hub motors, have also considered the WARP series.
Controller..the Curtis HPEVS seems great for AC, not sure about a DC controller
If I go with the warp motors, or any other "standard" motor as I call it, then i need 90 degree single speed gear reducers, not a big deal, just something to consider because I need a narrow profile.
Batteries...well, the hub motors are 96V, but if i dont use them, i'm open to whatever. currently, i'm selecting the Tesla 3kWh packs that come from the smart fourtwo, since i can get those at around 600 a pop, if there is better and cheaper, please help.

back to AWD, how the hell do I compensate speeds of the wheels during turns?
if no power is delivered, will both dc and ac act like the clutch of an ICE is pulled in? the reason i ask, say i only want the front wheels powered, i'm not removing the rear motors, but i dont want the power draw or a crapload of drag.

 

[cyberhedz]

One more design idea....because its not complicated enough...

I'm wondering if using a CVT instead of direct or single speed reducers, is even possible on a AWD system. I assume yes, but.....yea..

 

[galderdi]

I think you need to rethink your expectations.

Mine is only 530kg, it does reach 120kmph and has 7kwh of capacity. But the range is only about 10-15 km. Granted this is all stop start and extreme acceleration. But even if I double that by driving casually its still only 30km (10% of your target).

While building mine I did some analysis on actual range from converted cars. Typical is about 199Whrs per KM. Optimistic is about 160 Whrs per km. So to reach 350km of range you are looking at a pack of around 56kwhrs. Each kwh will likely weigh about 5kg, so to achieve 350kg you are lugging 280kg of batteries alone. If I made that change to mine it would take it from 530kg to 750kg plus another 40kg in reinforcement to handle the extra weight = around 800kg. You might be able to drop 30kg or so if you are only designing for a single seat but I just don't see how 700kg is achievable. But if you are serious you will be forced to go with AC so you can benefit, slightly, from the regen abilities (you might only need 50kwhs = 250kg of batteries). You might also be able to save another 25kg by not running a gearbox and opting for direct drive instead. But then you'll sacrifice acceleration and possibly top speed too.

 

[cyberhedz]

I hate to hear that, but its exactly the type of information I need to hear. battery technologies really seem to be the drawback here....if only i could get my hands on a portable thorium reactor....lol

as far as gear box, yea, i dont have one in teh plans currently, its either hub motors or single speed gear reducers.