Watts

[Bill Snow]

I have had an interest in gas motorized bicycles for several years and put together a few bikes, some good, some not so good.

I intend to swing from gas into electric bikes but need to learn more than a few things. I am also on the motoredBikes.com forum which I think very highly of. Already have received some good help from a couple members on that forum about the electric approach. This forum was recommemded and after reading some of the posting for the last couple of weeks I can see why. There are some pretty sharp people here. Much of what I read seems to go right over my head, but just joined the forum thinking that if I get a little involved some may sink in.

Here is where I plan to start: Using a terra recumbent trike using bike chain and gears as the electric drive train and having the ability to shift into low or high range gears. I used this same system on a Tour Easy recumbent powered by a 1.6 hp Subaru motor and it works very well. In low gear it will climb a telephone pole. I am interested in a top speed of 20-25 mph, maybe even 30 mph but that maybe asking a little much. I need to go for some good range (25-30 miles???) and at the same keep the weight down.

All the above is intended to give a little back ground and briefly explain what I'm trying to do. So, here comes my first question: Watts, If I use a 36v high watt motor, say a 1000w motor as opposed to a 36v 500w motor. I think I read somewhere that it does bad things to a 1000w at slow speeds, 7-10 mph. With the ability to shift gears and speed of around 20 mph with a top of 25-30 mph, 1000 watts maybe an over kill anyway?????.

I will be interested in what your thoughts are.

Best Regards

Bill Snow

 

[deardancer3]

Welcome on-Board, as they say.

Looks like you have done some home work.. Congrats.

Since I am a big advocate of chain drive, I think you have done the homework well.

addressing the question:
" Watts, If I use a 36v high watt motor, say a 1000w motor as opposed to a 36v 500w motor. I think I read somewhere that it does bad things to a 1000w at slow speeds, 7-10 mph. With the ability to shift gears and speed of around 20 mph with a top of 25-30 mph, 1000 watts maybe an over kill anyway?????."

The major issue I THINK you are referencing is what happens to single speed motors as ebike speed decrases under load, IE worst case is a high speed crystalyte hub motor, non geared, going up a long steep hill; motor speed decreases, gets off the efficiency sweet spot, turns more electrons to heat versus motion, gets hotter, needs lots more power to move slower than designed, etc.

On a chain drive, IF one downshifts, the motor speed stays fairly decent and does not get too far off the sweet spot when you get to big hills; efficiency stay more constant. At the wheel you get less mph and more torque per motor rpm, but efficiency does not change a lot. Electric motor curves and sweet spots are differnt from ICE, so there is some thought that goes into differing ratios, but that is not the biggy here.

I think that is the principle you were asking about, but before going into other details, lets see if that is what you were asking.

we will hold of on the "1000w overkill" question for just a moment.
d

 

[Ypedal]

Welcome to ES ! 8)

Q: How many telephone poles do you need to climb ? and how often ? :lol:

ok, on a serious note, electric motors are worlds apart from ice's.. efficiency makes a differrence with electric as batteries tend to be heavy and big.. so the less you need the better it is.

A bit more info regarding your needs would be helpfull, how far do you usually travel on a ride ? how much do you weigh ? and what type of terrain ? ( flatlander ? or San Fransisco hills ? )

A direct drive hub motor has a surprising amount of power if fed correctly, chain drives are cool but only needed on the most extreem end of things ( like having to make due with 500w and going very slow up that hill ).

 

[TylerDurden]

The electric powerband is much wider than ICEs. Max torque at stall.

You'll only need to use half the gears to stay sweet. (same width, i.e. .3 - 2.0, but fewer steps needed... less shifting.)

The game is to build a system that delivers the desired power with the most efficiency; to reduce the amount of batteries carried for the range desired and keeping the motor cool.

1000W would be fine for a geared drivetrain. EV motors are rated for continuous duty, outputting rated power without overheating. Installing more motor than needed is rare, since the motor will stay in the efficiency zone more. Conversely, buying too little motor usually means buying a bigger one anyway, after the first one burns up.

 

[Drunkskunk]

Welcome to the Forum. I'm also a member on motoredBikes.com, been slowly working on a ICE (intermal Combustion Engines) bike for a couple years now.

Your 1.6hp Subaru is rated at peak output. 1.6 horsepower is 1200 watts (1 horsepower is 750 watts).
An electric motor is generaly rated at normal load, constant power, not at peak. Peak power is determined by the controller, and how well you can manage the excess heat. a peak power of 2000 watts from a 1000 watt motor is modest and reasonable. 3-4000 is not unreasonable either.

You'll notice some diffrences between ICE and electric. ICE makes peak torque at near peak RPM, and nearly nothing at very low RPM. Electric motors are the oppisite. Peak torque is at near zero RPM, and the torque drops steadly up to peak RPM. That means the way you use them, gear them will be diffrent.

 

[deardancer3]

I believe you have a very streamlined low rider aero recumbent tadpole with a 20" rear wheel, unless you have the SL model.
Between 29 and 40 pounds naked.

http://www.terratrike.com/models.php

Finding a good model rear hub at 20" will probably mean converting to a 7or 8 speed spin on freewheeel, so if you have a 9 speed setup, that means a shifter conversion. No rear disc brake?

You probably dont need much power to propel you on the flat at 20-25 mph compared to an upright mtb. But Many bent riders dont have the accomplished recumbent legs of the pro 'bent riders, so the human assist given is less uphill than the assist delivered by an upright rider. And due to the increased rolling resistance of a trike, and base weight, going uphill will be the biggest load on your system, and will be about the same load as an upright.

What speed would you like to have for these uphills?

Also there is plenty of places to put a midrive on a 'bent trike, and can either complicate or simplify the chainline routing depending how your go.

With a chain drive you will most likely not NEED a 1000w motor. But, having somewhat more motor than one neeeds gives increased longevity.

on the hills, is this used for a route that is predictable, or is this a general purpose go anywhere I feel like it machine? How big and long a hill do you want to design for? (The bigger the number you over-estimate, the more expensive. the smaller the number the more disappointment you risk)


IN summary, I think your big assist need will be uphills, you will need a clutched system as you dont want/need full time assist on the flat much, you proably have a 20" rear wheel and you might have a 9 speed rear cassette.

your feedback?

 

[Little-Acorn]

Bill, welcome! I'm a newbie too, and am just getting my first ebike together. Mine is a 48V 1000W rear hubmotor, which several people tell me might be a Nine-Continent brand motor, and a 48V 20Ah battery.

The bike has 700C wheels, and gets a top speed of 29mph. Upright posture, and I'm a fat guy (265#), so I figure that's pretty good performance. The bike is a Trek 7500 aluminum-frame hybrid with front suspension. I hope to get a 30-mile range out of this motor and battery combo.

Unlike some here, I do NOT take it for granted that small electric motors are more efficient than larger ones. I'd like to find the answer to the question: "If you have two identical bikes and riders, but one bike has a 1000W motor and the other has a 500W motor, and you ride both of them at a speed of 15mph, which one uses more electric power?" With a gasoline engine the answer would almost certainly be, "The smaller motor", but with brushless electric motors I'm not so sure. It might turn out that both motors are equally efficient (I don't know, I'm just guessing here), and so they both use the same amount of current.

If that's the case, there might be no reason to get a smaller motor instead of a bigger one. My 1000W motor goes just a hair under 30mph at full throttle (level ground, no pedaling) on my bike with me as a rider. The same motor on the bike you described, might go a little faster since I imagine a recumbent would have less aerodynamic drag.

The two most common kinds of batteries used on these ebikes, seem to be sealed lead-acid (SLA) batteries, and Lithium Iron Phosphate (LiFePO4) batteries. SLAs weigh about twice as much as LiFePO4s for the same power capacity. LiFePO4s cost about three times as much as SLAs for the same power capacity, but they also last for MORE than three times as many charge/discharge cycles, from what I've heard. SLAs' voltage tends to sag when you discharge them deeply, and when you draw high currents (the kind that ebikes often draw). LiFePO4s have much less of this tendency.

Bottom line, from what I've been able to put together: LiFePO4 batteries are more economical in the long run for Ebikes, despite their higher initial cost. And they tend to run ebikes better: If you go up a long, steady hill, you might find your bike slowing down with SLA batteries, even if the battery has substantial charge left; but LiFePO4 batteries will do this a lot less.

SLA batteries are made all over the world, including many places in the U.S. But the LiFePO4s we can get here, see to come almost exclusively from China. Since both kinds of batteries are heavy, shipping can add considerably to the cost, especially for LiFePO4s.

Finally, I've heard many horror stories about controllers burning out, batteries malfunctioning, motors overheating or dying, etc. I was expecing to have to repair a bunch of stuff, change a bunch of stuff, etc. when I put together my first ebike. But as it turned out, it all bolted together easily, ran well, and it seems that the horror stories are unfounded, at least in my case.

I got my hubmotor kits (includes the wheels, throttle, brake handles, charger, battery bag etc.) for $299 shipped from a Chinese supplier on an Ebay auction. He calls himself daoji888 or daoji666, depending on what auction you click on, with a company called YXM Corp. I recommend them - they offer many options, and can send you special stuff if you want. I don't know if they can supply their hubmotors on the small size wheel that recumbent bikes have, but I suggest you email them and ask, you might be pleasantly surprised. Their communication has been good, both before and after the sale.

I got the battery, BMS, and another charger from an outfit called ep-battery, in Hong Kong I think. He has since vanished from Ebay, I don't know why. All the parts he sent me had stickers from the "VPower" company, which is a brand sold by many vendors on Ebay. They all seem to work well. Cost was $402 shipped... but they shipped it by a VERY slow boat from China. I ordered them on Oct. 29, it arrived on Dec. 24. If I had it to do over, I'd pay extra to have it shipped by EMS as the hubmotor kit was - the hubmotor got here in about 2 weeks.

Hope this helps!

 

[Bill Snow]

Thank you for the nice welcome and the interesting response.

Level ground will be my area of travel and just casual rides to the store, parks, or just a nice day ride, no commute. May like longer rides ( 25-40 miles if I can)and at speeds of 20-25 mph. Bought a trailer to carry extra batteries which will be wired to the main system with a switch installed, this is down the road aways and just a thought at this time.

Slow speed in the park, slow stop and go riding in traffic or just slow and checking the sights out. Not so much in the hills.

Still thinking of chain drive but learning of the wide power band in the electric motors and the flatland I will be riding on may change my thinking to a quality hub motor. Maybe a 1000w motor if the slower speeds on level ground are not a problem If I use a hub motor. Don't think chain gearing should be a problem at low speed though. I still think 36v should be the limit, 48v seems like an an awful lot of power to tote around. Maybe when I get more accustomed to the electric powered bicycle idea,I may change my tune.

I only plan to climb telephone poles when things get rough at home. I told my family I will stop doing all this stuff when I grow up, but I'm only 74 years old, so you see, I have a long way to go.

I have not been too keen on ordering from China, but maybe some of the suppliers as mentioned are coming up with some reliable quality. I think for now I'll stick with something sold in the US, of course it will probably be made in China. Batteries, I'm not sure of yet. There seems to be considerable problems with these light weight batteries, but then again others are starting to do very well. The price is on the high side so for now I think I will put it on hold until I get a clear picture of the motor, controller and drive components. However, Thank you for the recommended Chinese source, it may still be of interest.

Well, thank you, I like the way everyone is explaining in a clear manner that I can understand, ways to set up a good electric drive system ,and the questions you ask as well. I will respectfully continue to watch for your Ideas and suggestions, also appreciate the help.

Best Regards
Bill Snow

 

[amberwolf]

How DIY are you willing to go with the motor/drivetrain?

There are some "interesting" ways of adding the motor, and of motor sources and types, which are not typical of ebikes in most places but of which there are at least several people here on ES building/using them (including me).

 

[zenon]

Hi Bill,

I build a tadpole trike last winter from ground up, I decided to go with a hub motor because of its simplicity its plug and play. My setup is moded for more power because of my home terrain, it vary 0 grade up to long hull of 15-25 degree hills . I travel 50km average all the time.

With your goal of 25-40 miles range and a speed of 20-25mph which is scary speed on a trike for the first time.
A hub motor with around 30 amp controller and 48v 12 amp hour pack is more than enough to do the performance on a flat terrain.

See Justin at Ebike.ca his got variety of hub motor kits, probably the Nine continent kit # NC20R will work.
You will need a battery pack and a charger with the kit which he also got.

Hope that helps

Cheer's

 

[liveforphysics]

I would personally go at least 48v, and at least 20Ah. That mean's you've got about 1kwhr to burn, which would mean you could average 1/2hp of help for 2hrs before the battery runs out.

I personally don't pedal, so I tend to favor a larger battery. If you're always pedaling hard, you could get by with half that much battery. If you build a 48v 20ah pack from something like the new 20Ah A123 pouch cells, the battery would be a neat little brick with a footprint about half the size of a sheet of paper, a few inches thick, and ~15lbs. An absurdly high 5,000 cycle lifespan claimed by A123. lol

 

[dogman dan]

Re little acorns post, The main differences in efficiency I have noticed while testing out various hub type motors has been between brushed ones and brushless. I don't have cycleanalyst data, but have run a lot of different motors on the same battery.

In the brushless category, same rider, same or similar enough bike, riding the same way and speed, ranges are very very , very similar. The distance a 5304 can go when riding using 350 watts is about the same as the 350 watt motor goes. Of course there are efficiency differences, but they don't add up to more than a half mile difference in range.

Let that larger wattage motor out of the cage though, and then you see the range drop dramaticly for the larger motor. No suprise, the faster starts possible with the big motor cost ya. Pulling 20 amps will of course use up the battery much faster than pulling 10.

Just try to consistently ride a 1500 watt motor using 350 watts though. So if you want efficiency a smaller motor may be the way to go. Amps can be limited by using a cycleanalyst or a smaller controller though. One reason to go with a large motor, such as a 5304, woud be it's ability to soak up heat for a longer time.

 

[Bill Snow]

I don't want to get into a big DIY project as mentioned by Amberwolf. I have seen some real neat custom projects but I don't think I am ready to take one on. Maybe later when I understand Volts,amps,watts and apply it to a bicycle.

I have never been on a recumbent trike with two wheels in front let alone ride one. they looked so close to the ground, stable and well balanced that I thought they would be perfect for an electric application until I talked to Kyle the other day. He has been putting about 10,000 mile a year on his trike and yes, he has flipped it. Zenon has warned me that 20- 25 mph can be scary at first on a trike like this. Mine should arrive this week, then I'll take a few rides to see how I do.

So then, Low power for range as Dogman wrote and high power for speed. As pointed out a little earlier, 4 cylinder or V/8.

Well, it is begining to look like this: 600w so as to not over power or underpower the trike and on flat land a good hub motor maybe as good as any. Even the hub motor Little acorn ordered from China seems to be holding up well. I do want to keep it simple with reasonable performance.

OK, with this very helpful information I have received it will help me greatly with my decision making. Some members have closed their comments by writing "I hope this helps'". You bet it does!, by now I think you know I appreciate the time you have taken to write recommendations based on your knowledge and expierence.

Best Regards

Bill Snow

 

[docnjoj]

Tadpole rikes rule! I too have flipped my old one but it was due to my building negligence! They are stable and really handle well, but over 25 mph is really pushing it! I prefer small geared motors as they allow the suspension to work better than a boat anchor motor like 53xx on the rear!
otherDoc

 

[AussieJester]

Tadpole rikes rule!

but delta trikes look bad ass
c'mon Doc we have been over this all before

Good too see you joined up here Bill, best of luck with the lecky im sure
you will soon be experiencing the 'ev-grin'.

Welcome aboard...

KiM

p.s if you need a hand with image hosting give us a shout mate, set up is a bit simpler
on this site than motoredbikes, you can upload pics via the text editor here on Endless Sphere
rather than using a '3rd party' hosting service...

 

[Rassy]

Bill, I know I sound like a broken record, but I'm big on putting my power in a pusher trailer. One of the best parts is, your trike is virtually unchanged and can be used in pedal only mode whenever desired. With the trailer, you don't have to worry about fitting the rear wheel and altering your original drive chain. Plus, you don't end up overloading the rear wheel. Plus you end up with extra room for groceries, etc.

Anyway, you mentioned using a trailer.

So, welcome to the forum. I'll be 70 this Spring and have quit riding 2 wheelers as of last fall. I love the Tadpole, but the steering does take more getting used to than the Delta I've had for several years.

Good luck with whatever you decide!

 

[Bill Snow]

No, you don't sound like a broken record Rassy. I am considering all the information presented here and glad to get it.

I may make changes or maybe redo the whole thing after I get going with this project and some riding expierence. I have already backed off a little on the speed requirement and will go for range. Nothing record breaking, but enough for 2 or 3 hours (I hope), and with the neck breaking speed of around 18 to 20 mph. That is really not so bad considering it is a good bicycle speed.

When done, I'll post some pictures and maybe contribute a few comments also.

 

[docnjoj]

Hi AJ! Glad you are around to disagree!
otherDoc