Taking the edge off: smaller assist and longer battery life?

[Dunhill_BKK]

I was wondering if anyone is looking at small, long-life systems, that are enough to give you a bit of a boost and don't drain batteries quickly?

I notice many folks going for maximum speed and maximum power, but not many looking to do things on a small consumption/long-term scale.

I might be lucky in that Canberra is relatively flat with heaps of bike paths. When I get my system it won't have to do much, just help me along a bit and quicken the commute. I could go whole hog and probably not have to pedal at all, but I could use a bit of exercise while I'm at it.

I'm also thinking of battery lifespan. Would I have to recharge my packs less with a smaller motor and a big Lithium pack?

Just curious. I don't have the cash for a system yet.

Cheers,

 

[marty]

Dunhill_BKK,
Look at Sram Sparc Geared Hub Motor
http://endless-sphere.com/forums/viewtopic.php?f=2&t=3045

Here is the site, click USA, then Products, and the SPARC will be on the drop down list,
http://www.sram-imotion.com/
Cheers!

SPARC is on the right.

I got Bionx PL350 http://www.bionx.ca and love it. But it's slow. Go here is see how to disable speed limit.
http://endless-sphere.com/forums/viewtopic.php?f=2&t=896
Top speed is still about 20 MPH

 

[Drunkskunk]

I was wondering if anyone is looking at small, long-life systems, that are enough to give you a bit of a boost and don't drain batteries quickly?

I notice many folks going for maximum speed and maximum power, but not many looking to do things on a small consumption/long-term scale.

I might be lucky in that Canberra is relatively flat with heaps of bike paths. When I get my system it won't have to do much, just help me along a bit and quicken the commute. I could go whole hog and probably not have to pedal at all, but I could use a bit of exercise while I'm at it.

I'm also thinking of battery lifespan. Would I have to recharge my packs less with a smaller motor and a big Lithium pack?

Just curious. I don't have the cash for a system yet.

Cheers,

In a Word, Yes.

Most of us are addicted to speed, but the same technology works well for building an efficent, low power usage bike.
Kits like the Spark and the Bionx require you to pedal, and are considered Pedal Assist. they do well for moving you around efficiently, but you don't get the option of just letting it drive you.

But building a system of your own gives you some flexibility. You can start off with a low power motor like a tongxin, which can pull you along at 15 MPH reasonably well on the flats, but needs your help with pedaling to climb hills. it uses very little power, so it can go a long way on a battery. But then there are the medium sized motors, like the Puma, the Ezee, and the Crystalyte 4 series. Those can be overpowered to reach speeds normally thought of as insain on a bicycle, Or they can be tailored to run on low power, and be just enough to help you get around.

 

[Johnbear]

Hi, I am aiming towards smaller assist. I live in hilly Vancouver and I find 350watts to be plenty. (36v 17A controller). But the motor is still around 13 lbs. Anything more and I don't seem to get enough exercise. I would like to get a 250-300 watt light geared rear quiet brushless motor, but I am pretty much at my budget(and storage space) for e-bikes. Hopefully in the spring I may sell some stuff. The lower draw motor are definitely easier on the batteries! 8)

 

[Ypedal]

I like my high-powered bike for getting me to work in a hurry...

But, recently i bolted up an eZee kit to one of my bikes

http://endless-sphere.com/forums/viewtopic.php?f=4&t=3081&start=0

And for a light-weight kit, it's really nice with leg power, if you honestly want to pedal, it's best to keep things as light as possible.

 

[vanilla ice]

If you want to have manly muscles instead of look toned, pedal the heavy bastard up to speed only from stops, and use the motor to do all the cruising to maintain your speed.

 

[Johnbear]

Ypedal, what kind of front suspension do you have on your ezee hub bike? After one experience using ok alloy suspension (the dropouts really do break as I discovered.) I am wary of putting a hub up front on a decent set of forks.

 

[fechter]

Yes, the minimal assist approach has some benefits. One member (sorry, I forget who) used a tiny RC outrunner motor geared to the BB and ran about 150w max. The whole setup weighed only a few pounds including batteries.

At low power levels, I think of it as being more like having a really lightweight bike. In fact, it might be more like a helium bike with negative weight compared to a regular bike. Guys spend thousands of dollars on super lightweight frames and components, when you could get even better results with a Walmart Huffy and a low end hub motor.

 

[Mark_A_W]

I was wondering if anyone is looking at small, long-life systems, that are enough to give you a bit of a boost and don't drain batteries quickly?

I notice many folks going for maximum speed and maximum power, but not many looking to do things on a small consumption/long-term scale.

I might be lucky in that Canberra is relatively flat with heaps of bike paths. When I get my system it won't have to do much, just help me along a bit and quicken the commute. I could go whole hog and probably not have to pedal at all, but I could use a bit of exercise while I'm at it.

I'm also thinking of battery lifespan. Would I have to recharge my packs less with a smaller motor and a big Lithium pack?

Just curious. I don't have the cash for a system yet.

Cheers,

A Tongxin motor and a Soopower 37v 10Ah lithium would do the trick = about 7kgs all up. Same setup as the EV vehicles kit, but you could do it for half the price, sans fancy bag.

It would be legal-ish (shock horror).

What you'll find is you'll build a legal one, then want MORE. 500w is nice

 

[Timbo]

A Tongxin motor and a Soopower 37v 10Ah lithium would do the trick = about 7kgs all up. Same setup as the EV vehicles kit, but you could do it for half the price, sans fancy bag.

It would be legal-ish (shock horror).

What you'll find is you'll build a legal one, then want MORE. 500w is nice

I have the Electric Vehicle EVO 3 Lithium kit & I think it's great. Range is about 43km. Flat speed is ~35/40 no pedal/pedal. Perfect for my 10km commute, local errands & visiting the folks. When I want to go fast I take my ICE scooter. (Vectrix on wishlist!!)

If price is a problem try the Tongxin, but if convienience is on top of the list EV are great to deal with. Excellent aftersales service from Scott at Noble Park.

http://www.currietech.com.au/EVS EVO Conversion Kit.shtml?openmenu=[\url]

 

[Dunhill_BKK]

Thanks for all the links and the advice.

At the moment I'm leaning towards LiFePO batteries. This is part of the reasoning behind wanting them to last a damn long time, as an early adopter (in relative terms) I'm paying a fair amount for the power. If all works out I'd get one pack to last several years (until the ultra capacitors become commercial).

I'll have to look at more motors now.

As an aside it would be great if we had a repository for all the various motors, for comparison purposes.

 

[mvadventure]

For about ten years I used a ZAP friction drive motor off my rear wheel. With a fresh 12 volt 20 AH battery it would provide more than twenty miles of ASSIST. Without assist it would go 8 mph. After the ten years the tire was still good, the motor and wiring system were still good but I was on my fourth battery. Sold it to a satisfied customer on ebay.

Using it when peddling provided distinct advantages on hills, when the wind was in my face or when I was tired. It was an ideal situation for a long time and had my situation not changed I would still be using it. Now however the Crystalyte 5304 w/LiPO4 batteries give me LOTS more range and speed and no peddling which is better for now.

Except for batteries the ZAP required no maintenance and did not affect brake wear. Same can't be said of the current system re the brakes.

Mike

 

[monster]

i had a 200w brushed hub motor for 6months. you cant go wrong with brushed. the controller broke in the first 2 months and i simply rigged up an on/off switch on the bars. it got 10-12 miles on 24v 7ah, much better range than my X5 (7-10miles on 72v 7ah)

 

[Eric G]

If you pedal to about 10km/h and then apply the throttle,use both motor and leg power throughout your commute and try not to use full throttle all the time any battery system should last a long time.

If you size the batteries to your needs and pay attention and care for them properly you can get a few years and a few thousand kilometers out of them...even SLA.

Eric

 

[kbarrett]

I was wondering if anyone is looking at small, long-life systems, that are enough to give you a bit of a boost and don't drain batteries quickly?

Lower voltage and more amps ... if you were using 6 12V-7A SLAs, you would be better off doing 2 rows of three for 36V-14A, rather than putting them all in series ( 72V-7A ). Technically, the 72V is supposed to just do the same distance faster ... but it doesn't work out that way in reality.

You might also want to consider a smaller 20" wheel ... more torque at less speed.

I plan on dumping down to 36V LiFePO4s ... I'm using a 20" 405 hub. I expect much more range at a slower speed ... and expect to be pedaling a lot more as well. I can't keep up trying to pedal while running with 48V ... just too damned fast, even with a 20" wheel.

 

[Dunhill_BKK]

You make a really good point about being able pedal. Have you considered something like the Bionx regulation of the power assist?

 

[Mark_A_W]

Change your ring gear for a 52t one.

 

[Timbo]

[ I can't keep up trying to pedal while running with 48V ... just too damned fast, even with a 20" wheel.

How fast is too damned fast?

 

[kbarrett]

[ I can't keep up trying to pedal while running with 48V ... just too damned fast, even with a 20" wheel.

How fast is too damned fast?

Problem aint speed ( I get about 23 MPH with a 405 on a 20" wheel at 48 volts ). It's just that I can't pedal that fast with the pedal crank I have even at best gearing on my 32 speed.

I'm dumping down to a 36V LiFePO4 ... and if I still can't contribute some pedal power, I'll change my pedal crank gear.

 

[Eric G]

I'm in the same boat almost...I get to around 21mph with 36volts in a 20" wheel and with the crank chain ring I have now you can comfortably pedal along up to 16mph.I've got another crank chain ring with more teeth,I've just not had the time to put it on,Hopefully this summer coming.

Eric

 

[Timbo]

I'm dumping down to a 36V LiFePO4 ... and if I still can't contribute some pedal power, I'll change my pedal crank gear.

OK, I'm with you now. When my chain & cassette are worn out I plan to re-jig the gearing too. I'm looking at 38 and 52 teeth up front and a rear cassette with 11, 12, 13, 14, 16, 18, 21 & 23. It's kind of overkill since I only use three gears currently - 13, 15 & 17, all on a 48 crank, but if I ever choose to go without the motor I reckon there's enough flexibility in the mix. Definately need the larger crank & smaller rears for use with motor.

 

[Dunhill_BKK]

Good points about the cranks and tooth counts.

What about the electronic control for pedal assist as with the Bionx kits? Any comments in that area?

 

[ericslai]

On my BionX PL350 equipped Rans Zenetik Tour with 26" rear, my cruising speed on the flat (A1 assistance) can be maxed out at around 20 mph (no more assistance beyond 19.2 mph) with 52x13 on 152mm cranks. A1 equals to 35% assistance only. If I had enough juice from the battery to cover the distance, I could use higher gearing and reach my workplace sooner provided the assistance is not limited by the control. The BionX as well as any other store bought powered bikes are limited to 20 mph by US law. It is even lower in the EU.

 

[Johnbear]

As I ride more my second motor (Me), is getting stronger and I am finding the desire for a lighter bike and less power. A Tongxin is on the drawing board and a light alloy MTB frame with lifepo4.

 

[eP]

Good points about the cranks and tooth counts.

What about the electronic control for pedal assist as with the Bionx kits? Any comments in that area?

You should tell us what kind of asssist you want and you need.
Do you need assist for longer range or for shorter trip time - higher speed ?
Do you need assist at flat or at hilly area only ?

What kind of battery you interested in - cheap as much as possible or light ?
What is the range you need ?

Would you like describe your preferences and give us right answers for questions above ?

If you need assist mostly at flat - you need very efficient motor at light loads and/or lower air drag at high speed.
If you need assist at hilly area - maybe you need more torque at lower speed and/or more efficient battery system.