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Lazarus 01-02-2008 08:08 PM

Electric bike hub
 
I've been looking for a way to increase my speed commuting. My commute varies between 13-25 miles one way depending on what I'm doing. My average speed is about 17 mph on the bike and 35 in the car. I'm trying to close the gap. I'm looking at adding a electric hub motor that should close the gap to about 20 min or less on the longest trip. I would plan on just using the motor as an assist so would be able extend the range a little but it looks like the batteries would take a pounding due to little chance for recharge. The hub pretty expensive and then I probably be looking at $120 buck a year in batteries which make it a little cost prohibited. There also may be an issue with the front fork spacing which I'll have to deal with. Any ideas on the batteries and how I could make them last a little longer?

http://www.alienscooters.com/compone...e38a226022.jpg

dremd 01-02-2008 08:34 PM

I have a 3phase hub motor on my bike.
I got the motor from an e-bay auction for around $60
The controller I can't remember where I got from. (e-bike store online)
My batteries are (30) D size NiMh Tenergy batteries I think cost was around $150 for the pack (assembled it myself) I have over a hundred cycles on them now and they show no sign of slowing. My guess is still 300 cycles (one pack per year on a commute). I know that doesn't help, but well I guess I just wanted to share.

On the Idea front look for some cheapo Lead acid Sealed bats. I used 4 spotlight batteries ($5 each on sale)on an E scooter.

On the speed front, I can't move my feet fast enough to do more than 30mph (need taller gears) but I THINK you could sustain 35 witht he correct gears.

Mine draws 700 watts(ish) wide open and the efficiency spot appears to be 300 watts.

300 watts will get you 14mph unaided and 700 watts will do 19~20mph unaided.

I hope some of that is helpful to you.

Lazarus 01-02-2008 09:24 PM

Quote:

Originally Posted by dremd (Post 3816)
I have a 3phase hub motor on my bike.
I got the motor from an e-bay auction for around $60
The controller I can't remember where I got from. (e-bike store online)
My batteries are (30) D size NiMh Tenergy batteries I think cost was around $150 for the pack (assembled it myself) I have over a hundred cycles on them now and they show no sign of slowing. My guess is still 300 cycles (one pack per year on a commute). I know that doesn't help, but well I guess I just wanted to share.

On the Idea front look for some cheapo Lead acid Sealed bats. I used 4 spotlight batteries ($5 each on sale)on an E scooter.

On the speed front, I can't move my feet fast enough to do more than 30mph (need taller gears) but I THINK you could sustain 35 witht he correct gears.

Mine draws 700 watts(ish) wide open and the efficiency spot appears to be 300 watts.

300 watts will get you 14mph unaided and 700 watts will do 19~20mph unaided.

I hope some of that is helpful to you.

Do you have any pics of the set up? What kind of speed using the 300 watts while pedaling can you get?

dremd 01-02-2008 10:28 PM

I can take pics tomorrow.

300watt + pedaling essentially doubbles your pedaling "effort" cruisewise. I can do 25~30 mph If I work it; but cruise as long as I want at 22~24.

I'm far from in shape, and it is a full suspension mountain bike with knobby tires.

I built the bike with the money it would have cost me to park for a semester at school. In the end I figure I ended up with a $100 bike (spent too much$).

I do still need to do some work on it. it needs a Light, switch, horn Desperately; However I've run completley out of handle bar room. (2 Brakes, 2 shifters, Cycle computer, Whatt's up, and a load cables that need to be trimmed down to size.

On a side note WEAR A HELMET!!!!!. NO BODY EXPECTS A BIKE TO GO THIS FAST. I would "speed" (5 over) through a neighborhood + school zone everyday. I would get passed by EVERY SINGLE SUV, when they realized they were doing 15~20mph over the limit; they would nail the breaks. I rear ended 1 of them and let me tell you, it hurt (no injuries/ damage).

MetroMPG 01-02-2008 10:55 PM

What's the terrain like on your commute? If it's hilly, you may be able to close the time gap by using most of your assist on the uphill bits - in other words, without running the pack into the ground flat-out all the way there.

I like dremd's idea of spending a bit more up front for a good quality nimh pack though. If you size your pack properly, and treat it nicely (proper charging), it'll last a LONG time.

Toyota used NiMH in its RAV4 EVs, and some have gone well past 100k miles with no significant loss in capacity.

dremd 01-02-2008 11:23 PM

The batteries I use are more expensive than I remember (may have gone up).
http://www.all-battery.com/index.asp...ROD&ProdID=202

Real world Drawing 300~400 watts it is a 8 ah pack
if you draw a constant 100 watts it is a 12 ah pack
If you do flat out (600 watt once hot) it is a 5 ah pack

Watt's up = The Shiznit
http://www.trextuning.com/wattsup.php

MAX output is 10 amps regardless of how heavy of a load you put on them, but that is probably a good thing (keeps the pack temp down)

I use there batteries in lots of stuff round the house, for the price they can't be beat. The AA's are better than the Energizer NiMh's in my experience.

Lazarus 01-03-2008 01:02 AM

There is always rolling terrain. I average about 170-190 watts for the whole commute. I was hoping to get an additional 100-150 watts to the rear wheel. I don't know how much that would translate into power from the front hub to achieve that. My plan was to use the batteries once up to speed and off on the down hill portions. I'll have to look into the better batteries. You think it would be better to get the SLA to get the learning curve figure out and then once they need to be replace go with the better ones?

AndrewJ 01-03-2008 01:11 AM

just out of curiosity, what kind of bike do you commute on?

MetroMPG 01-03-2008 09:58 AM

Quote:

Originally Posted by Lazarus (Post 3863)
You think it would be better to get the SLA to get the learning curve figure out and then once they need to be replace go with the better ones?

That would be the way of the ForkenSwift, yes. (Minus the last step about getting better ones.)

A tip that might solve the expense problem: I know a guy who services security & fire alarms. He can pretty much keep me in as many used 12v 7AH SLA batteries as I can take. I've actually been using them (a couple in parallel) in the ForkenSwift for accessory power.

These are automatically replaced when they don't meet the company's 80% performance criteria.

Might be worth dropping by a local security alarm business or making a few calls.

Lazarus 01-03-2008 11:00 AM

Quote:

Originally Posted by MetroMPG (Post 3881)
A tip that might solve the expense problem: I know a guy who services security & fire alarms. He can pretty much keep me in as many used 12v 7AH SLA batteries as I can take. I've actually been using them (a couple in parallel) in the ForkenSwift for accessory power.
.

Actually I know someone that does. Great idea thanks.

Quote:

just out of curiosity, what kind of bike do you commute on
It just a standard 18 speed road bike made by Iron Horse.

AndrewJ 01-03-2008 09:46 PM

Quote:

Originally Posted by Lazarus (Post 3884)
It just a standard 18 speed road bike made by Iron Horse.

Ok, thats at least a good starting point, I was sure it had to be a road bike by the 17mph average speed, but hey, who knows, you could have been Lance Armstrong on a DH bike or something.

Anyway, if you're trying to get faster, keep in mind that the aerodynamics of bikes is a bit different than cars. Namely, the "tipping point" where aerodynamics become an important factor is around 20mph (or so I have heard from multiple sources)
It seems that once you pass 20mph on a bike, over 50% of your energy is going to combat aerodynamic drag, and it just goes up from there. I think the source for that tidbit is the League of American Bicyclists' "Road I" course, but I could be wrong.

So, the key to making a battery last longer might be aeromodding your bike. Look into time trial stuff for your bike. Most of it is expensive, and somewhat heavy, but an aerobar wouldn't cost much, and getting into a more aerodynamic tuck would be hugely helpful.

SVOboy 01-03-2008 09:56 PM

Quote:

Originally Posted by MetroMPG (Post 3881)
That would be the way of the ForkenSwift, yes. (Minus the last step about getting better ones.)

A tip that might solve the expense problem: I know a guy who services security & fire alarms. He can pretty much keep me in as many used 12v 7AH SLA batteries as I can take. I've actually been using them (a couple in parallel) in the ForkenSwift for accessory power.

These are automatically replaced when they don't meet the company's 80% performance criteria.

Might be worth dropping by a local security alarm business or making a few calls.

You (or someone else in the know) should post up sometime on various sources of free batts and things that might be useful to people (like the vw solar panels), you know?

Lazarus 01-03-2008 10:07 PM

Quote:

Originally Posted by AndrewJ (Post 3965)
Ok, thats at least a good starting point, I was sure it had to be a road bike by the 17mph average speed, but hey, who knows, you could have been Lance Armstrong on a DH bike or something.

Anyway, if you're trying to get faster, keep in mind that the aerodynamics of bikes is a bit different than cars. Namely, the "tipping point" where aerodynamics become an important factor is around 20mph (or so I have heard from multiple sources)
It seems that once you pass 20mph on a bike, over 50% of your energy is going to combat aerodynamic drag, and it just goes up from there. I think the source for that tidbit is the League of American Bicyclists' "Road I" course, but I could be wrong.

So, the key to making a battery last longer might be aeromodding your bike. Look into time trial stuff for your bike. Most of it is expensive, and somewhat heavy, but an aerobar wouldn't cost much, and getting into a more aerodynamic tuck would be hugely helpful.

Good points. I've tried the aero bars and it a little to dangerous for city commuting. Quick access to brakes is a common reality, also control and visibility are a little marginal when dealing with cars and road debris. I've thought about a fairing of some sort like a motorcycle but I think the increase in drag would offset the aero benefits for a standard bicycle.

MetroMPG 01-03-2008 10:41 PM

Re: in-town riding... Do I take it a 'bent is out of the question then? Do bents not offer more efficiency?

AndrewJ 01-03-2008 11:15 PM

Depends on the hillyness factor. 'Bents are better in the flat stuff because of the better aero. On the hills they suffer because the riders seating arrangement isn't ideal for powering up a hill.
On a "normal" bike the rider can use gravity (their own body weight) to assist them in climbing by standing up on the pedals.

As with everything, what you're dealing with here is tradeoffs. If you're looking to go faster up the hills you'll need something completely different than if you're looking to bomb down the flats faster.

MetroMPG 01-03-2008 11:18 PM

So it would seem to me then that an e-assisted bent would be the best combination of compromises...

AndrewJ 01-03-2008 11:24 PM

Quote:

Originally Posted by Lazarus (Post 3973)
Good points. I've tried the aero bars and it a little to dangerous for city commuting. Quick access to brakes is a common reality

Have you thought then about full on TT bars?
http://www.planet-x-bikes.com/triath...r/DSC00402.JPG

for commuting I would switch the placement of the shifters and the brake levers, and add cyclocross-style "interruptor" levers on the straight part of the bullhorn bars.
http://www.sheldonbrown.com/images/i...ter-levers.jpg

That way you have one set of brake levers for each hand position.

Lazarus 01-04-2008 09:55 AM

Interesting idea with the brakes.

No bent here. I don't want to start a which is better debate but I prefer a road bike. I have a lot of rolling terrain and I like the hight, visibility and maneuverability of a road bike.

MetroMPG 01-04-2008 11:13 AM

Them's fightin' words!

Just kidding. :)

Christopher Jordan 01-04-2008 09:34 PM

Quote:

Originally Posted by AndrewJ (Post 4004)
Depends on the hillyness factor. 'Bents are better in the flat stuff because of the better aero. On the hills they suffer because the riders seating arrangement isn't ideal for powering up a hill.

Kind of a myth since that depends on the engine. Some are slow, some aren't: same as 1920 diamond frame bikes. But anyway; in this thread the engine is a combination of human power *and* a hub motor, is it not?

Excellent addition! I had an Electric Sierra Cycles 36 V hub motor installed in my fully enclosed recumbent trike, and hills are no problem at all!

countersTrike :D <---------------:turtle:


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