I Feel Like A Noob Asking This Question!

[DAND214]

I have 3 MAC 8T motors, all on 12s4p lipo. All have EB3xx controllers set at the same battery amp and phase.

I am trying to figure out why one is much faster than another. Fatser one has CST cyclops 26x2.4 other one Big Apples 26x2.35 tires. The one with the Cyclops has a EB306 controller the Big Apples has EB312 controller.

As I said both set the same settings. SOOO why is the one with the bigger tires 7 miles faster? And also has better torque off the line.

Both have 4110 fets and the traces are beefed up. The slower one also has the better batteries being all Turnigy 20c 6s packs and the other has a mix of Zippy 15c and 20c and a few Turnigs.

The faster Mac also a 8t or 320rpm was bought used from Bruno (blackarrow) about 5 months ago in need of repair. I replace the halls and upgraded the phase wires to 12g, new clutch and gears. I did the gears and clutch since I had blown 2 clutches in my other Macs, not that they were needed.

So guys, what do you think?

Dan

 

[bowlofsalad]

For future reference, posting threads with subjects about how you feel is useless. It might be better to post something along the lines of 'Why does a larger wheel make my ebike go faster?" Try not to be offended by this, this is useful information to all of us and I say this without emotion or negativity. In other words, 'no offense'.

The reasoning for the increased speed is like saying gear ratio.

http://ebike.ca/simulator/ Have you played with this? Leave the simulator at default and just play with the wheel size. Setting from 16" to 700c will give you a big variation in top speeds.

Larger tires make your bike go faster, it's like being in a faster/higher gear. I might not have guessed that acceleration is faster though with a larger wheel. One certain upside to having larger wheels is a possibly more comfortable ride. I am not sure if you understand this and need a very complex or deep explanation, or if you think there is something else causing this speed increase.

 

[mark5]

Bowl, did you see how long DAND214 has been an E-S member?

 

[bowlofsalad]

Bowl, did you see how long DAND214 has been an E-S member?

No, and I will refrain from making this observation. May I ask, why do you care if I have seen how long he has been an e-s member and how come you decided to ask me this question here? If you are going to ask me if I have seen post count, the answer is again, no, I have not.

 

[johnjcbs]

Tire size is not the reason.
There is only 6mm difference in circumference,between the two tire sizes. (0.28%)


That motor may be a faster wind,or the upgraded phase wires could be much more efficient.

 

[wesnewell]

The one with the faster acceleration is pulling more amps, thus producing more power to the motor. The slower one has maxed it's loaded speed with the amps it's getting. if you check unloaded speed of the two, using the same battery they should be the same. If they aren't, the faster ones controller has it's speed percentage programmed higher than the slower one. Just a wag.

 

[John in CR]

Check unloaded speed of them to verify that the motors are really identical wind motors. If they are, then it has to be the controllers and the slower one isn't getting the current you think it is. I take it there isn't a big difference in weight and aerodynamics. I bike ridden in a much more upright position can be much slower, especially if a lower current is added to the mix.

 

[d8veh]

Timing can make a big difference in speed, which can come from difference in software, position of hall sensors, or whatever. The KU series controllers from BMSBattery can boost the speed by about 10% by altering the timing somehow with sensored motors. They activate it with one position of the three-speed switch.

 

[Thud]

This may shock long time readers here.....but (beleive it or not) quality controll in the chinees factorys, sometimes, lets some things go through.....maybe mis-labled(different wind)

Or some one was having a great day on the winding/assembly bench & you received the best motor ever built off that line!
Mechanical things all vary a little bit.....but if your really curious, swap controllers & have another run off.

I am allways amazed for all the trickery that is ellectronics, they are still prisner to their mechanical assembly...a shunt wire value off by a % or two, just having a great set of fet's can make a seat of the pants differance.

Even the mighty cycle anilyst is prisoner to the guy setting it up. Its amazing how many guys think its plug & play.

 

[dogman dan]

Start swapping controllers, that will tell you which controller is actually the hot one. I'm assuming you don't have wattmeters to tell you at a glance which controller has more amps. Bet one of them does.

One of the motor could be a different winding as well. That might also become obvious if you swap stuff around and keep notes.

It's definitely not the tires size.

 

[cal3thousand]

do you have CAs on these bikes? Looking at how many watts are drawn is important.

Short of that, I would swap first controllers to see if it is them. Then I would swap back and do the batteries. Nothing like some A-B testing

 

[majornelson]

Maybe a Noob answer (from me) but on my MAC setup, I have a 3 position switch that limits the controller. I remember if I didn't install it, it would default to one of the slower settings. Are all of your controllers setup with the same gear (throttle, switches, etc.)?

I like a good mystery.

 

[el_walto]

My vote is the 3 position switch.

Second guess would be one of the MACs is actually 6 turn.

 

[DAND214]

Maybe a Noob answer (from me) but on my MAC setup, I have a 3 position switch that limits the controller. I remember if I didn't install it, it would default to one of the slower settings. Are all of your controllers setup with the same gear (throttle, switches, etc.)?
I like a good mystery.

Yep all 6 of them. 3 speed works. O did reprogram the 6 fetdown to 25 battery and62 phase. It did tame it down a bit but still stronger.

As for being a 6t, I don't thing so. Don't think the 6et would last.

Put a CA on the faster one and the amp draw was close, so back to the station to do some detective work.
All I can come up with is there must be a shunt off rating.
I'll have to open it up and look.

Anybody have the post from Methods on calibrate the shunt?

Dan

 

[mark5]

Anybody have the post from Methods on calibrate the shunt?

methods:
Re: Large Screen CA - $120 shipped - Free calibration servi
http://endless-sphere.com/forums/viewtopic.php?f=31&t=31548#p457115

stingray17:
Re: calibrating a cycleanalyst with a watt meter?
http://endless-sphere.com/forums/viewtopic.php?f=2&t=32370#p469872

 

[DAND214]

Anybody have the post from Methods on calibrate the shunt?

methods:
Re: Large Screen CA - $120 shipped - Free calibration servi
http://endless-sphere.com/forums/viewtopic.php?f=31&t=31548#p457115

stingray17:
Re: calibrating a cycleanalyst with a watt meter?
http://endless-sphere.com/forums/viewtopic.php?f=2&t=32370#p469872

Thanks Mark.
Sorry but that's not what I thought it was.
I need to find out how to get the shunt resistance in the controller. Reason is that all controllers are not created equal.

Dan