Got 37v Lithium + 250w Hub motor BUT WANT TO GO FASTER!!

[Mark_A_W]

Hi guys, it's my first post here

I'm in Melbourne Australia, in the south east. I noticed another Melburnian, from Greensborough, so I'm not alone.

I have a 37v 10Ah Lithium pack, and a "nominal 250w" front hub motor. 250w is kinda legal here, if you assume 80% efficiency it's bang on the 200w limit. The motor is branded "Nine Continents", it's brushless and gearless, about 3kg's.

With 37v (or 41v fully charged) I can cruise unassisted at 28km/h or so.

And I can pedal medium hard and maintain 32km/h, maybe 33...but I can't go faster. The no-load speed of the motor is 34km/h, so I'm topping out.

The performance up hills is good - I can cruise up a previously 11km/h hill at 26 or 27km/h.


But I'd like more top end speed. I can think of a few things, and still pay lip service to the law here:

1 - Series a 12v (11.1v?)Lithium with my 37v pack. Need a 48v controller.

Is it really that simple? Just whack them in series? I'd separate them for charging. Wouldn't be legal anymore, but the motor still says 250w :wink:




2 - Change to a through-gears system. I have excess amp hours (battery range is 50km, commute is only 30km), so using more power out of current battery would be ok.

Sort of like an Elation kit: http://www.elationebikes.com.au/prod01.htm

Or this Swiss system:
http://www.bike-elektro-antrieb.ch/

There's a video of the swiss system here: http://www.bike-elektro-antrieb.ch/startseite.htm

The elation kit is kinda cheap, with a brushed motor. But the price is high - A$800.

I shudder to think what the Swiss system would cost - especially that freewheel, but gees it's nice.



3 - Convert my hub motor to a through-gears system, Stokemonkey style, but I'd really like a freewheel on the cranks, unlike a Stokemonkey system.




Brett White in Newcastle has been a great help, but he said with his hub motors I wouldn't gain anything with the current voltage.




Anyway, I'm after some advice. How can I go 38-40km/h with medium hard pedalling, paying lip service to the law? More voltage? Geared system? Give up and be content?

Thanks

Mark

 

[monster]

i herd that some motors are internaly speed limited? is this true? and if so is there a way to de-limit them? -need others help here.

-this might be your problem.

37v lithium should be fast. when i had my old 200w motor i could do 25m/h down hill on 24v 7ah (9amp NiMH)

 

[Miles]

I have a 37v 10Ah Lithium pack, and a "nominal 250w" front hub motor. 250w is kinda legal here, if you assume 80% efficiency it's bang on the 200w limit.

Nice try, but surely the limit is for a "200W rated motor"? Or is there an absolute limit of 200W? The efficiency is irrelevant, in any case....

 

[knoxie]

Hi

These hub motors are not limited in any way, the only way you will find the limit of the motor is when it gets too hot and smokes or the windings de-laminate and short blowing the controller.

A 200W rated hub motor can normally operate at twice its rated power quite easily, the Xlyte hub motors can be safely operated way above their continuous rated power.

You need to post more pictures and details of your set-up, it could no doubt be made to run much fast quite easily.

Geared through the chain systems dont seem to be what they are cracked up to be, initially I was quite exited by the cyclone and other kits but reports back from them have been very luke warm to say the least, I have yet to see a decent and reliable chain driven system other than the Currie system and Randys system which isnt available as kit so is not an option.

Knoxie

 

[Mark_A_W]

I have a 37v 10Ah Lithium pack, and a "nominal 250w" front hub motor. 250w is kinda legal here, if you assume 80% efficiency it's bang on the 200w limit.

Nice try, but surely the limit is for a "200W rated motor"? Or is there an absolute limit of 200W? The efficiency is irrelevant, in any case....

The law is really vague - it doesn't specify whether the 200 watts is at the wheel or current draw.

All motors sold here as "legal" - like mine, are actually more than 200 watts, except one. The CSIRO motor fitted to an Avanti bike kit. According to Brett it's actually 200w and is pathetic.

Lobbying is going on to raise the limit, but I hope we don't get a 32km/h speed limit, that would really suck - I'd rather the 200w power limit, at least you can get creative with that.

 

[Mark_A_W]

Hi

These hub motors are not limited in any way, the only way you will find the limit of the motor is when it gets too hot and smokes or the windings de-laminate and short blowing the controller.

A 200W rated hub motor can normally operate at twice its rated power quite easily, the Xlyte hub motors can be safely operated way above their continuous rated power.

You need to post more pictures and details of your set-up, it could no doubt be made to run much fast quite easily.

Geared through the chain systems dont seem to be what they are cracked up to be, initially I was quite exited by the cyclone and other kits but reports back from them have been very luke warm to say the least, I have yet to see a decent and reliable chain driven system other than the Currie system and Randys system which isnt available as kit so is not an option.

Knoxie

Hang on, pics coming, gotta mind a 20 month old screamer..

 

[Miles]

The law is really vague - it doesn't specify whether the 200 watts is at the wheel or current draw.

In EU it's the nominal continuous rating of the motor, which is the best case

I agree with Knoxie. The things counting against all the available chain-drive systems, for me, are: noise from gear reduction needed to get down to crank rpm; under-specified freewheeling cranks........

 

[Mark_A_W]

Ok, here's a few pics of my my setup - Mark 1.

The bike has just about had it, I'm currently looking for a 2nd hand Cross-Country Dually to fit the electric gear and slicks - that will be Mark 2.

Battery lives in my backpack. I tried it on a Rack, and despite it only weighing 3kg, it made the bike feel like I was doing a paper round with 100 papers in a box on the back...ick.

Plus when it's in the bag I don't leave the expensive battery on the bike, chained outside the shops when I go shopping with the kiddy trailer.

Battery doesn't get warm in my bag, and yes I already fell on it once and it didn't explode, but now I have padded it in foam.

The controller is labelled 250w 36v - I've already talked idly with the local seller about a 48v controller. (Ebay ID = Rugged Machinery - A nice bloke named Richard).

I have 3 x 20w halogens in series as headlights, drawing 1.8 amps - about 70 watts. Don't know if I'll make my 30k commute with the lights on for half an hour on the way home, but I think I will.

I have a thumb throttle mounted on teh bar end, as well as the twist throttle. I'm hoping it will work wired in parallel to give me two throttles - one for each riding position.

My brakes suck, I want discs for the next bike - at least one, and I might try and mount a disc on this motor. Drill and tap holes for the disc in the side plate, if it's thick enough. I bent the front rim already - I'm rough on bikes, so the v-brake doesn't work very well. Got to fit a new rim...looking forward to that..

I'm happy with the hill performance, I'd just like more speed. If I can get it to 37-39km/h on the flat with pedalling, I'll beat my car on my 15k commute each way (at peak hour).
It's a car replacement for me. Time is everything as I have a wife at home with young kids = ticking time bomb


Could I add a 11.1v Lithium in series? Can you mismatch batteries like that? Charge separately, to keep things simple.

Cheers

Mark in Melbourne

 

[xyster]

Could I add a 11.1v Lithium in series? Can you mismatch batteries like that? Charge separately, to keep things simple.

Welcome to the humble Spheroid.

Add 1/3rd more voltage, get 1/3rd more speed and 1/3rd more power for better acceleration and hill climbing. Yes, it's really that simple so long as the controller and motor can handle the added voltage.

I don't know in your case if the controller will handle 48v. The motor almost certainly will, though as a brushed motor (I'm assuming from the looks of the controller), there's less voltage headroom than with a brushless motor. I've yet to see a 36v brushed motor burnout at 48v so long as amperage is the same or less. 60v might be pushing it.

When charged separately, you can mix in series any voltage source under the sun so long as it can provide sufficient current (amps). You could use a methanol fuel cell if you had one and wanted to. It's best to employ a pack of similar capacity so as to lessen the risk of depleting one pack before the other, which, depending on if it has its own low voltage cutoff or not, can cause the lesser pack to go into cell-reversal and die. On my Currie bike I use an 8V lithium-ion pack in series with the main 24V SLA pack, charging the two separately but simultaneously.

 

[knoxie]

Hi

Thanks for the pictures, it sure looks like a brushless hub motor to me as the controller has 3 phase wires, can you tell me how many cores you have going down to the motor, it looks like the controller that Doug at EV tech ships with the Puma motors which is brushless, most brushed motors will have just 2 wires coming from the hub, they may have more but generally 2 power wires, brushless ones tend to have 3 minimum and 8 Generally 3 for the phases and 5 for the hall effect signals.

It looks possible to run this at higher voltages, you could certainly add in another 12V, one thing is make sure that you don't have an led fuel gauge throttle though as they will blow if you go over voltage. You can slide the guts out of the controller and check the big capacitors on the board, you can also check the fets, they will most likely be 100V rated, check on the part numbers.

If you are worried though you can just connect a 36-72V xlyte controller to it, you may have to play with the phase and hall configs to get it running right but there aren't that many combinations, colour for colour is normally a good start then work from there.

Good Luck

Knoxie

 

[fechter]

Going to a higher voltage is the easiest way to get more speed. I'm not familiar with the insides of that particular controller, so I don't really know how much it can safely take.

Possibly somebody else has tested one like that.

The no-load speed will be nearly porportional to the voltage, so you can estimate the results of increasing the voltage.

If your controller is not suitable or blows up during testing, that motor should be compatible with a Crystalyte controller (72v max).

Knoxie is right, the actual power rating of the motor is probably much higher than the stamped number. Heating is the limiting factor.

 

[BiGH]

Hi Mark from Melbourne,
I'm Haydon From Melbourne

I've ridden a 250w bike before (quick test ride) and can understand why you're looking for an upgrade. What knoxie said about the crystalite controllers sounds about your best bet.

Personally though i'd (assuming money isn't too much of a problem) set a new bike up with one of Brett's crystalite kits at a higher voltage. This way you can have a backup bike while you're developing up ur new bike. and would also allow you to have one bike on charge while the other can be used. (and since this bike is falling apart sounds about right.)
The ohter thing is, i'm not sure if many of the people here have had experience with that particular motor type, however there is a LOT of experience with the crystalyte and PUMA kits.

I'm currently bikeless, slowly progressing towards my purchase of a kit

 

[TechBikes]

Hi Mark,
I don't think you should uprate the kit you've got at all. This is only because your front hub is currently located in a mag alloy front fork. These have proven to be highly brittle many times, and these ebike forums have been littered with woeful tales of failure over the years.
They just shatter suddenly, it happened to me; these forks are not designed to survive a twisting action in the dropouts.
Steel - the thicker the better - is the answer.

 

[knoxie]

Hi Steve

Yes good point, I missed that Devin posted a picture of his forks where this had happened, he could fit a torque arm of course but steel forks would be preferable, I run the BMX motor in a steel fork and run a torque arm as well such is the turning force of the Puma.

Knoxie

 

[Mark_A_W]

I have two torque arms from Brett White, I've got to grind/file and hammer a bit, but they are going on.

I picked these forks (2nd hand) because they have they most aluminium I've ever seen around the dropouts. Yep, I'm familiar with fatigue - I'm a mechanical engineer. I'm keeping a very close eye on them.

They are very stiff as well. I don't like them much as they don't have a topout spring, but they are strong. I need suspension forks (or even a dually) as my commute involves rutted dirt roads, 10 gutters and a long stretch over grass - I take short cuts.

I tried to find steel dropout suspension forks, but they are like hen's teeth.

I take the warnings seriously, I've heard it before, but real world feedback is invaluable.

The motor is brushless. It has 3 power wires + 5 hall effect wires.


I've talked to Brett, he said with 36v none of his motors would give more speed and I would need a geared system (or more volts).

Also, all the rear hub motors would struggle to fit a 8 or 9 gear rear cluster + disc. Seems to be two bad choices if you want a suspension bike with full complement of gears. Can you mod your gear shifter to only work on 5 or 6, instead of 7, or 8...or 9?

Thanks

Mark

 

[knoxie]

Yes this is what can happen, you may have seen this before.

You should be ok to eek a little more power than you have, 7 or 8 speed shifters dont work well on 5 speed cassettes, you dont need to go rear drive try upping the volts first, if not run an xlyte controller, 36-72V 20A, you can make a torque arm up easy enough, I just used an old spanner until I got something made.

Cheers

Knoxie

 

[TechBikes]

Mark, it sounds like you're nearly there....

Currently, your no-load speed is 34kph, and you achieve 28kph unassisted; your motor is operating efficiently. This is behaving like a high winding hub - torquey but slow at 36v, likes more volts.
Pushing the voltage up to 48v gives an approx no-load speed of 45kph, so travelling at 38-40Kph is what it'll do. It won't go as far though, as wind and waste heat start to kick in. Medium hard pedalling will redress this, and you still look legal too.

The 10Ah 12v Li-Ion pack is the perfect plan, but look out for:

THe 12v pack needs a low cut off BMS too. You won't know which pack is depleting fastest as you ride.
Will the BMS on the 36v or new 12v Pack be affected by each others presence?
Will the controller take the 48v? I don't think anyone here can truly answer that.

Well worth doing, but a few things may break on the way. Welcome to the upgrade club. :wink:

 

[TechBikes]

you can make a torque arm up easy enough, I just used an old spanner until I got something made.

Cheers

Knoxie

Yeah Paul, but yours SNAPPED!! Puma motors are beasts!

 

[Mark_A_W]

Ok guys, an update.

I've started fabricating fork reinforcement. It will be a torque bar welded to a length of tube sliced in half vertically, this goes on the front of the fork.

The other half of the tube will go on the rear side of the fork, and hose clamps will hold them together - forming a steel sheath around the fork.

I will preload it, by sizing it so the hose clamps pull the torque bars inwards, against the dropouts.

One each side. Probably end up fitted to a Marzocchi Bomber JuniorT Downhill fork - triple clamp.


I've pulled my motor apart, to see if there is enough room under the motor cover to clear bolt heads - to bolt a 203mm disc to the side of the motor for disc brakes. Looks like there will be heaps of room.

It's finally raining here, after 10 years of drought, and my V-brakes aren't cutting the mustard...especially on a dinted rim.

Anyway, I'm halfway through replacing the rim, we'll see if I have to take it to bike shop to get trued up, or if I do it myself eventually. But I still want disc brakes.

Here are some pics of my motor - it looks VERY SIMILAR to the pics of the GL2 motor on Brett's Island Earth website. Even has the little bamboo toothpicks holding the wires. About the only design difference is it has the yellow "pcb" around the windings. Everything else is the same, from the black axel with shiny bearing area, to the way the wires are glued in with white goop.

Except it's about 80mm smaller than the GL2, and 3kgs lighter. I'm happy with the torque of this motor, so the GL2 must have heaps.

So any thoughts on whether it will take 48v? The winding wire looks to be about 0.6-0.8mm diameter.

Might bid on a Jamis XC Dual Suspension bike tomorrow.

Cheers


Mark

 

[Lock]

...this Swiss system:
http://www.bike-elektro-antrieb.ch/

Sweet! But I'm having difficulty making out the details of the system
Lock

 

[Lock]

...I have yet to see a decent and reliable chain driven system other than the Currie system and Randys system which isnt available as kit so is not an option.

You are kidding, right? Man, I am so tired of stretching #25 chain on a Currie 350w kick scoot.
tks

Lock

 

[Mark_A_W]

Ok, I've just rebuilt my wheel into another rim. Despite all the warnings I read about how this is no DIY job, it was actually pretty easy.

It's not perfect, but it's good enough. Less than a mm of buckle (L-R) and 2mm of "bobble" (up-down). "Bobble" is harder to work out. L-R buckle is easy.

I could get it better, but I'll put the tyre on tomorrow and go for a ride, then check it again.

My fingers are sore

But it's done