battery matched to motor question

This is my first post so I'd like to thank everyone for the countless hours people have put into building this cosmos of knowledge. I've been researching my first build for almost a year now.

Still on the fence of whether to go with a bbs02 or a rear hub motor. But I've decided to wait till more of the bugs are worked out and go with a bafang geared rear hub. I can pedal hard and for a long time (ex courier) but I want a faster commute. I work a very physical job so want some help up the hills on the way home.

Anyhow...

I'm going modest on my first build.
http://www.greenbikekit.com/36v-500w-8fun-bpm-e-bike-kit.html

With either this
http://www.greenbikekit.com/36v-samsung-bottle-ebike-battery.html

This
http://www.greenbikekit.com/36v-12ah-38140-headway-battery.html

Or this
http://em3ev.com/store/index.php?route=product/product&path=35&product_id=160

I'm not sure if the first one is powerful enough for the 500watt bafang. I want geared so that I can pedal past its speed limit on the flats and downhill.

I don't know if the headway comes with a BMS if not I'll pass on it. Just thinking about 12ah.

The em3ev battery looks good but I'm seeing if I can keep cost down. Then again would be good with a 36v bbs0n down the road.

Any thoughts?

Thank you!
Joe

That is a slow wind motor and I think you will need a 48V battery to get above 20 mph.
In general, a mid wind (260 rpm @ 36V) is best for most riders.
The only BPM on that page that has a mid wind is the CST. It is $100 more, but if your bike has a decent 8, 9 or 10 speed cassette, you can retain it. Then you don't have to buy a $30 free wheel.
If you are not interested in the CST, look at the offerings at BMS Battery for a better selection of motor kits and batteries. The have a BPM II that is a mid wind.
A 260 rpm motor should top out around 22 mph. on 36 V and 25 mph on 48V.
25 mph iw a good top speed for a moderate Ebike conversion.

Thank you for the heads up motomech.

I didn't realize I can use a 48v battery on a 36v motor. If I do go with a 48v battery then I'd be able to use it (if it's still alive) in a year or two when I go for a mid drive. I'd like to wait for more of the bugs to get worked out of the bbs02 before I go that way. I need reliability beyond all else.

I'm putting this system onto a a 24 speed late 90s hardtail mtb. I have a good 11-30 8 speed xt that I'd love to be able to use. There's 46 tooth raceface big ring on the front, plus the other two.

Is this the mid speed wind you were talking about: http://www.greenbikekit.com/electric-bike-kit-1/rear/100cst-cassette-freewheel-e-bike-kit-36v-250w.html

There's the other one but I don't want a very large hub. This cassette hub above is listed as 250w, but is that relative to the controller? IOW, if I were to go with an external controller I could run it at a higher wattage (but not crazy) and not worry about the motor?

I don't need a ton of power. I'm looking for pedal assist to get me up to speed faster. I plan on always pedaling and standing on my starts and for steep hills, as usual. I want a geared motor so that when I pedal past 30kmh I'm not fighting the motor. My bike will pedal beyond 50kmh as it is but I'm not in that kind of shape anymore!

Back to the drawing board.

I don't want to have to deal with freewheels (was exhausted by the exhaustive discussion of elusive good 11t freewheels) so I need cassette.

Q100C built up by bmsbattery in a 26" rim. If I like I'll relace it down the road. Half twist throttle, 26" wheel, 328 rpm.
http://www.bmsbattery.com/ebike-kits/615-250w350w-q-85100sx-motor-e-bike-kit.html

48v rack battery from bmsbattery: http://www.bmsbattery.com/48v/468-24v-lithium-ion-little-frog-abs-shell-ebike-battery-pack.html

Now it doesn't say which controller comes with the kit, just 250w 6 mosfets. I've read that it's best to go sensored with a high rpm. Can anyone suggest which bmsmotors controller I should order with this setup?

Q100C 26" 328 rpm
48v 10Ah 13s Li-Ion
11 tooth cassette, 48 ring.
150lbs, fit cyclist. Relatively light hardtail bike with rigid front fork. 1.75" slicks.
Relatively flat commute, 18 km return.
Anything past 40kmh is gravy. I'm looking for faster starts, easier cruising up the rises, easy ride home after a hard day's work.

thank you!!

Also, I'd like to add a torque sensing BB and V3 CA from Grin down the road. I imagine these would work together?

Ok one more tonight (getting rather excite)

The Q100C kit is on sale for 140 right now but shipping drops over $100 without it being built into a wheel. More than worth it to build it myself. But now I need to put together a "kit" myself. I'm going to email them to see if they could do the same kit but with a bare wheel and what they would charge for that.

But then I might as well pass on the crappy ebrakes and get an inline brake sensor, if it's reliable (?) and see about a better controller. My left lever is an integrated xt and the right is an xt with the integration ground off for another 8sp shifter pod when the old one couldn't take more rebuilds.

The torque simulators have me very interested. There are also the sine wave controllers, but at this point it's all way over my head.

A left handed half twist makes sense to me to keep my right hand shifting the rear derailleur.

Ok it's too late at night and I'm getting too excited.

Too many choices. The Q100CST is not particularly powerful. The best you can do with it is the 201 rpm one with 12S (44v), which will give just over 20 mph. If you want proper torque to get you up hills, you need the 500w Bafang CST and the S12S controller. At 36v, it'll do about 22 -24 mph. With that setup, the PAS works really well, so you don't need a torque sensor. I get them from BMSB because they have a better choice of batteries. Their 20aH 36v shrinktube one is my favourite because it can comfortably give 30 amps and is very light for it's size. Plus, it's cheap.

It's a good idea to get all your stuff from one supplier to avoid double duty charges.

Here's a couple of bikes with the 500w Bafang CST and that 20aH battery that I built, which gives a nice compromise between power, weight and stealthiness:

d8veh, are those throttle only speeds? I want to still pedal hard up hills I just want to go faster. This bike will be pretty much commute only. I have a 40 minute heavy traffic commut. I stare at the bike lane beside me the whole time. I bike it sometimes but I never know when my work will wipe me (marine industrial rigger).

The bafang is a good 5 lbs heavier so I'm inclined to steer away from that. I've read that 328 rpm on the Q100C will work for riders under 75kg. I float around there. I'm basically looking for a turbo boost not so much a sit back and throttle kind of ride. That'll be the next build

The 328 in a 26" wheel is not a good choice unless you wear Lycra and live in Holland. It runs mostly out of it's best efficiency range and tends to heat up the controller. I have a 328CST in a 24" wheel, but it doesn't care much for hills.
Since you seem intent on a mini, consider the Q100H up front. Low power frt. drives work very well and all your shifting stuff stays intact.
Also, consider the SO6S sine wave controller and display from BMS Battery if you are ok with 36V or Lipo(44V max for that controller) or KU63 or KU65 or green life bike controller if you want to use 48v
More reading, search thru D8veh posts, or perhaps mine.
My build links are mostly Q100 and frt. whl. drive.

So my wheel circumference is 2.03 meters * 328 rpm * 60 minutes / 1000 = 39.95 km/h.

Is this number the wheels ideal speed or is it top speed? Also, is this unweighted speed? If so, I've read a shorthand is to subtract 20%, so 32 km/h.

The 201 rpm comes out to 24.5 km/h and 19.5 km/h is 80% of that. That sounds slow to me. What am I missing here?

I see why you advocate 260rpm. 32 km/h and 25 km/h as a happy medium of top speed to climbing speed, keeping the hub closer to ideal rpm climbing but also giving some half decent top speed. But is there a 260rpm cassette hub? I don't want to go down the freewheel route.

These motors are small, so not massive power. The 260rpm ones are the best balance of speed and torque. the problem with the 328 rpm ones is that they have low efficiency right up to 25km/h, so the controller gives the maximum current most of the time, which makes it get very hot, plus a lot of battery is wasted making heat in the controller and motor. The 328 rpm Q100 would be good for someone less than 80kg with a lightweight bike that only uses the power to boost cruising speed. If that's what you want, it could work.

If it was low efficiency up to 18 or even 20 km/h that would work but up to 25 isn't enough torque for what I'm looking for. Maximum speed isn't as important as average speed. If it was a long ride along a flat highway it would be one thing. Stop and go through two abbuted cities is another. OK 201 or 260 it is. Thank you for the convincing.

Have a look at the new batteries and kits on the BMSB site. Installation would be really easy now. You just need to choose the right motor:

http://www.bmsbattery.com/new-products

That's awesome. I was thinking about Paul's use of these cases and lectrics but I've been wanting to keep my first build cost low. I've only ever ridden a bionx bike around a parking lot and I'm looking for something to help me get back on the bike after a car crash.

I've read that Panasonic NCR18650PF batteries are prefered to the samsung. And for less money. I understand that Paul does way better quality control but I don't have the funds for the hassle less insurance.

I've made a cardboard cutout from the given dimensions and the pictures and I think it will just fit, maybe with some mods. Or get a mount lasercut at work.

Rear BPM 2 48v 500 watt motor
http://www.bmsbattery.com/rear-driving/351-bafang-350watts500watts-bpm-motor-e-bike-kit.html

48V11.6AH BOTTLLE-09 PANASONIC BATTERY & CHARGER
http://www.bmsbattery.com/battery-pack/684-bottle-ebike-battery.html

Extra gears
http://www.bmsbattery.com/accessory/634-gear-set-for-bpm-bpm-cst-motor.html

Left throttle
http://www.bmsbattery.com/accessory/611-thumb-level-throttle.html

Thumb throttle for another option
http://www.bmsbattery.com/accessory/231-thumb-level-throttle.html

10 pole PAS
http://www.bmsbattery.com/ebike-parts/579-pas-pulse-padel-assistant-sensor.html

Speed sensor
http://www.bmsbattery.com/controller/550-s-led770-e-bike-led-meter.html

Hidden wire brake sensor
http://www.bmsbattery.com/accessory/459-hwbs-hidden-wire-brake-sensor.html

Ebrakes if no luck with hwbs
http://www.bmsbattery.com/ebike-parts/52-brake-grip.html

Torque arms
http://www.bmsbattery.com/36v/450-a-pair-of-ebike-torque-arm.html

Three switch (for presets?)
http://www.bmsbattery.com/ebike-parts/53-three-speed-switch-kit.html


I'm stumped at the controller. Any suggestions? Sine wave sounds great. The forum search is not so great (try "Mac" - nothing). I haven't been able to find info on torque Sims.

Deffinately get the S12S sine wave with SLCD-3 display.
The 5 level assist is great, you can use the lower settings to get perfect assist power 400 to 500 watts.
D8veh soldered the shunt on his for 27 Amps.
search his posts with S12S keyword.

The S12S is a really nice controller and it's well matched to a 500w BPM, but your battery is close to the current limit. They also sell that battery with an included 20A controller, which is a better match, or consider other batteries with a higher discharge rate and the S12S.

Ah yes I see it now. A 20 amp sine wave, with all the bits I was going to order as extras, the waterproof wires I wasn't sure about and all the right connectors. Perfect.

One last thing to figure out. I'm only seeing the BPM CST as a 36v. Is there any difference, other than the freehub, between this and the 48v BPM?

Ok I did a live chat with bms about the new bottle batteries with built in 20a controller.

http://www.bmsbattery.com/battery-pack/680-bottle-ebike-battery.html

I told them I wanted to buy a spare. Said it's not available. Asked if it will be available. "of course". Can I order it now? "wait a minute I'll ask"... no.

I then asked about ordering a different controller as a spare. perhaps the s12s. I said that it can draw 35a and asked if it could be restricted. No. I asked if the supplied 20a controller can support all functions of the lcd3. Can it measure motor heat? They logged off. Well, thanks.

So here's the problem: Am I putting myself into a dead end with this supplied 20a controller in the new bottle battery? It supports the lcd3, which I really want, but I also want the new battery pack. I don't want a bulky frame bag or a high centered rack battery. 11.whatever Ah is perfect for me. But only 20a continuous. That's fine, I don't mind running the motor under it's full potential. I figure it will last longer and I'll pedal more. But I don't see another S series controller that can run the lcd3 that will also only pull 20a. Am I misunderstanding how this works?

holy crap I'm so close.

Maybe if I get the s12s and don't run it at level 5 assist?