Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[nigezero]

Fantastic data and effort dgh853. I can see a trip over to your place coming up soon for some enhancements on my DS!

[Francois]

on the gen 4 size 4 you can tun the same what are the limit someone know?

[evtricity]

on the gen 4 size 4 you can tun the same what are the limit someone know?

The Gen4 data sheet at http://www.sevcon.com/media/2461/Gen4%20Aug%202013%20web.pdf has the amp limits for both the size 4 and size 6 contollers so you can compare.

[Francois]

hi, on my dvt i do not have the power limit, do you have specale dvt file?

[evtricity]

If you click on power maps there should be 3 items appearing. Select the first one and that should bring up the torque limit at each rpm as per the torque curve screenshot at the start of this thread.

[RNM]

Brammo Empulse R:
http://electricmotorcycleforum.com/boards/index.php?topic=3871.0
Torque at rear axle:
1st: 882.09 N-m or 650.60 ft-lbs
2nd:721.33 N-m or 532.03 ft-lbs
3rd: 597.68 N-m or 440.83 ft-lbs
4th: 507.00 N-m or 373.94 ft-lbs
5th: 428.68 N-m or 316.18 ft-lbs
6th: 391.58 N-m or 288.81 ft-lbs

Zero SR:
http://electricmotorcycleforum.com/boards/index.php?topic=3872.0
Torque at rear axle: 633.6 N-m or 467.32 ft-lbs

So an SR is equivalent to an Empulse R in 3rd and a Zero S is equivalent to a 5th gear?

[protomech]

Zero SR is 637 Nm
Zero S is 434 Nm

So yes, that's about right.

With a rider the Zero ZF12.5 bikes weigh about 10% less than the Empulse, so the effect will be closer to matching acceleration in 2nd gear with the SR and 4th gear with the S.

[frodus]

Yeah, they'll pretty much be the same at those different gears with the Brammo.... and here's the math to back up Protomech (because I'm bored at work), ignoring road resistance/aero. Yay math!!!!

Zero SR 12.5 is:
188kg (~12% less weight than the Empulse)
1983 N at the tire
(http://electricmotorcycleforum.com/boards/index.php?topic=3872.0)

Zero S 12.5 is:
185kg (~13% less weight than the Empulse)
1353 N at the tire

Brammo is:
213kg
1st:  2760 N at the tire
2nd: 2258 N at the tire
3rd: 1871 N at the tire
4th: 1587 N at the tire
5th: 1342 N at the tire
6th: 1226 N at the tire
(http://electricmotorcycleforum.com/boards/index.php?topic=3871.0)


Lets say a rider like myself, ~90kg rides all three bikes. We know F = m*a. We want to know a, so a=F/m. Total Brammo weight is 213+90=303kg. Total Zero SR 12.5 weight is 188+90=278kg. Total Zero S 12.5 weight is 185+90=275kg.

Zero SR acceleration:
1983N/278kg = 7.13m/s^2

Zero S acceleration:
1353N/275kg=4.92m/s^2

Brammo acceleration:
2760N/303kg=9.11m/s^2
2258N/303kg=7.45m/s^2
1871N/303kg=6.18m/s^2
1587N/303kg=5.24m/s^2
1342N/303kg=4.43m/s^2
1226N/303kg=4.05m/s^2

Just going off those numbers, Brammo is only 6.5% quicker than a Zero S if the Brammo was left in 4th gear. Likewise, the Brammo is only 4.5% quicker than a Zero SR if the Brammo was left in 2nd. That's a pretty close acceleration between the bikes with the Brammo in 2nd and 4th.

What we don't have here is the torque curve of each motor (I kinda wish we had exact curves, they'd be fun to look at). The torques above are max torque. Torque rolls off at higher RPM, so this really only tells you what the max torque from stop/low RPM would be. Over 4kRPM, I'm not sure what each motor would deliver for torque. Its something only a Dyno (or some torque curves) would tell us.

[RNM]

.

Looking at the two curves together it seemed to me that there was an opportunity to increase the SR's torque at higher rpm without reaching the motor's limits which would result in motor cutouts. After some trial and error on the road and recent testing on the track, I have been able to successfully increase torque by 30Nm @ 4680 rpm and by 45Nm @ 5320 rpm as shown in the updated torque curve at the bottom of this post.

Increasing 45Nm @ 5320 rpm is an increase of 25 kW!
Are you sure?

[evtricity]

I can confirm those are the actual before and after Nm values in the controller.

I've increased the torque by 25% (45/180) for that rpm range.

I don't believe that correlates to 25kW as the changes are to motor torque not actual power.

Bear in mind that for the SR, the max power is 50kW and 144Nm.

Others who understand the link between torque and power can comment here but if there was a direct correlation between the two then the increase would correlate to 25% of the maximum power of 50kW or 12.5kW.

[RNM]

The way to calc power is this:
Power (kW) = Torque (Nm) * rpm* 2*PI/60

So, 45 Nm @ 5320 rpm is 25 kW

[morimaxx]

The key highlights are 100% torque from 0 rpm and a tapering of that torque beyond 2350rpm (default motor max is 6,000rpm). I asked some forum members about what would happen if I increased these settings and was told to watch out for two things - motor cutouts and to stay within the 6,000rpm limit. I was also told that field weakening limits motor performance as rpm increases and so I can't be like a kid playing with his Dad's graphic equaliser and put everything up to the max!

Can anyone explain the technical background why the torque needs to get lower at higher rpm? Why does the motor cut out if the tourque is set too high?

[RNM]

Mechanical power is product of torque and rpm (see above)

Electric power is V * A

If 160Nm was constant until 6000rpm the motor would produce 100kW.

If the motor is 90% efficient, that would mean 10kW of heat and the Zero motor wouldn't be able to dissipate that amount of heat...

[Cortezdtv]

I have fastest zero on paper? No way..... I know there are quicker in here. Who owns that 757 tandem bike?    No he got me beat power to weight


Sr. tune vs gutted fx frame   

[RNM]

Do you mean Death bike 7.0?
The owner is liveforphysics, in the endless-sphere forum

But that is, supposedly, a bicycle, not a motorcycle