Going faster

[gudy]

So, it's been about 1 month of effective riding since I got my e-bike, and I've got about 500 miles on it.
My setup is fairly simple : Nine Continent 2807 on 700c wheel + 40A controller from ebikes.ca and a 48V 20Ah battery from ping. I get about 28 mph - 30mph out of it depending on wind, on flats.

I'd like to go a bit faster (say be able to get to 35mph with some wind against me, and 40mph with no wind), and I'm exploring multiple options :
1. Add an other battery pack, say a 24V 20Ah, which would bring the overall actual voltage to 78V (52 + 26), has anyone here been using a 9C at 78V for a long period? How did it handle it?

OR

2. Change the hub motor to something like a 9C 2805 or a Crystalyte 5303... and that's where I get confused ... if I try the simulator on ebikes.ca, I don't see a huge torque difference with my current motor (ok there is a small one), but I see a huge difference in max speed.

Option 2 seems to be the easiest, fastest and cheapest (especially with the 9C hub) ... but I must be missing something ... could anyone explain ?

 

[auraslip]

Today I reprogrammed my Lyen controllers speed setting to %120. It got me 3-4 mph boost.

I think it's a pretty easy mod to install the usb adapter...It might be worth your time.



I'm also intersted in this, since I have the same set up (but with a differeant controller).

I've considered using my SLA 12v 14 ah cells in serial to do some speed tests. For "science."

Perhaps 24volts of 10 ah nicads or nimh in serial with a switch for a sort of "booster pack?"

 

[dogman dan]

Lots of folks are going to 72v on the 9c motors. I'm not sure how far they can go in summer weather at that voltage before things get hot though. Higher volts is said to run cooler than higher amps. Not sure though, if they mean the motor or the controller or both.

But if looking for just a few mph, a 2806 would be an easy change. By the time you go to the 2805 though, you will be losing some performance on hills and startups. Essentially, you'll have a motor that makes heat instead of motion when it luggs. There is no real difference in torque between windings. But the slower winding motors DO handle putting out the torque they have with less heat at slow speeds. So in an odd way, the torque there is is more avaliable. The fast wind motor just ends up going fast, and in that part of the power band, there is no torque. So in the end the slow wind motor feels torquey.

Does your bike really handle 40 mph? 4 out of 5 of my bikes don't. Got a $2000 full suspension bike with disk brakes? Or at least something very strong framed? If so go for 72v. But if not, maybe just going to 12v more would make more sense.

See ya in the next, " I crashed my 72v bike" thread.

 

[Drunkskunk]

Voltage is the way to go, if you want more speed.

I briefly tried my 9X7 at 74 volts(84 peak). it ran a solid 35mph, and might have given a bit more if I had tucked into the wind a bit. but that bike couldn't handle it.
I normaly run the bike at 55.5 volts(63 peak) and get a solid 29mph from it. but at anything above 25-27mph, the cantaliever rear brake becomes worthless, and I can overheat the 160mm front disk.

 

[auraslip]

Drunk skunk I am curious about your setup.....I got about 30mph with a 48v ping (52v really) before I tweaked the settings on my controller. I have the same 9c 2806 motor.

Also to note I just got up to 39 mph going down a long hill and pedaling my ass off!

Also as far as brakes go I'm finding regen is great.

Especially with ebikes ability to eat through brake pads!

 

[GrayKard]

1. Add an other battery pack, say a 24V 20Ah, which would bring the overall actual voltage to 78V (52 + 26), has anyone here been using a 9C at 78V for a long period? How did it handle it?

Long term I don't think your controller will survive 78volts. From what I've read it will have 63volt caps in it stock. If you upgrade those I believe then you would be OK.

2. Change the hub motor to something like a 9C 2805 or a Crystalyte 5303... and that's where I get confused ... if I try the simulator on ebikes.ca, I don't see a huge torque difference with my current motor (ok there is a small one), but I see a huge difference in max speed.

But if looking for just a few mph, a 2806 would be an easy change. By the time you go to the 2805 though, you will be losing some performance on hills and startups. Essentially, you'll have a motor that makes heat instead of motion when it luggs. There is no real difference in torque between windings. But the slower winding motors DO handle putting out the torque they have with less heat at slow speeds. So in an odd way, the torque there is is more avaliable. The fast wind motor just ends up going fast, and in that part of the power band, there is no torque. So in the end the slow wind motor feels torquey.

+1 for what Dogman said about that option.

Let me add a this option:

3. If you are good at tinkering you might consider a Delta/Wye mod. Would be a bit of work but should be a pretty cheap option. Should see speeds greater than 40mph too. Hope you have disk brakes on the front.

Here's something you posted in your build thread that I thought might be apropos:

3. The one thing that scares me would be the front wheel / front arms breaking. Seeing that I have no extra weight there (batteries are in the triangle, and motor on the rear wheel), my main question is "can my front wheel handle 25 / 30 mph continuously ?"

A stronger bike/frame might not be a bad idea.

Gary

 

[tycreek]

FWIW... I run about 30mph at just over 1000w with a 700c wheel and 48v, but can easily hit 35mph if I open the speed limiter jumper and turn the throttle more. I don't know what the BMC hub reliability would be if I held 35mph constant but do know that my 30mph cruise speed @ mfg specifications is working fine for the last few months of commuting. At 40mph on 48v I'm quite sure the V3 with stock wires would melt if held there for very long.

My considerations were lower voltage and weight when trying to balance continuous and top speed targets. The trade-offs for speed I found were in starting torque or launch feel and to get both the hub weight doubled. Please don't take my results with BMC as saying it is right for you, etc... only that I would lean toward option 2's line of thought. If you really want solid 40+mph then you'll probably have no choice but to up the V's, modify controller and one of the hub choices (basically all new eparts) or go RC.

 

[Drunkskunk]

Drunk skunk I am curious about your setup.....I got about 30mph with a 48v ping (52v really) before I tweaked the settings on my controller. I have the same 9c 2806 motor.

2806 or 2807? I've got the 9X7, 2807. I'm running 700C X 37, but the diamiter measured exactly the same as my 26" X 2.50" so it should be real close to your 2.45" tires. By a Solid 29, I mean I can pull 29mph all the time, while sitting up, and with normal wind.
Whats your actual full charged voltage on the Ping?

 

[Whiplash]

I second the delta/wye setup if you are into tinkering, I have seen a lot of cool results on the forum and Youtube, you can get insane speed, the only thing is, you have to make sure you don't use it too early in the power band as it will pull a lot of amps in the lower RPM range, but if used carefully, I think its a viable option and I will be testing it for my bike on a momentary button instead of a switch so it will act like a BOOST button when I need some extra speed (like running late for work!).

 

[gudy]

Ok, I think that I'm going to try this delta/wie mod ... doesn't seem too bad to put in place, but I'm going to need some new tools, I'll also use the opportunity to change the wires that get into the hub.

I'm heading to the delta / wie thread to ask build questions ... even after reading the 30+ pages from that thread, there are still some unclear details on how to do it.

Thanks all, and I'll keep you updated.