View Full Version : Learning
06-23-2009, 10:01 PM
Yes this is a thread about learning as you go. I'm not an electrical engineer or anything even close so I learn from my mistakes and from my successes if there ever are any.
Today I took the new Pat out for a ride. It didn't seem quite right so after the first ride that got me less than two miles and much less speed than I remembered from the first time I rode it, I checked and found the chain too tight. Who would have thought that the chain tension would make that much difference.
I charged the batteries and took it out again. I got two miles with the motor still running but running very slowly. However I ran the bike wide open the whole time. I wanted to see how fast it would go. I wasn't worried about range at all.
Tomorrow I am going to ride it for range. Just enough power to climb the hills and the rest of the time coast and pedal.
One more thing I learned about the two speed part of the bike. Not to use the lower speed except to start it. Since it uses just one of the batteries it pulls it down well below the other one. When one battery goes down it effects the overall performance of the bike.
I am going to have to be very careful how I use that feature. I need to use it on hills when pulling up from a dead stop, but not on flats when pulling off I can pedal it enough to prevent the chain jerk.
I got about two miles running it wide open throttle, so tomorrow I will see how I do with power management. I would expect about 3 miles range.
Also the more powerful motor on this Pat is pulling more from the battery I'm sure.I guess I am going to look at better batteries after all.
Also I think I want to know what is the optimum size motor for an assist bike. I may have over reached with the 450 watt. The 350 had pretty good power and on the 26" mountain bike I had pretty good pedal assist going.
What I need to do is to run the 450 with the two speed control power management tomorrow. then recharge the batteries and hook them to the 350 with controller and throttle and see how that compares. That should tell me a little about two things the motor and or the controller throttle vs two speed switch. Not to mention the different wheel sizes.
I do love a good experiment.
06-24-2009, 02:58 PM
Well test one of the new motor bike is disturbing. The motor went out at the same place two miles. Whether I ran it wide open throttle and just pedaled to keep the speed up or if I goosed it the mileage was pretty close to the same. Now I am running a 7ah battery pack so I expected it to be small but not that small.
Those batteries are charging now. I will put them on a bike with a controller and throttle next. It has a smaller wheel so that might make a difference it also has a smaller motor which might also make a difference. I will let you know what if any difference there is.
I also never expected the pedal assist to be the same as the w.o.t. test. That was the biggest surprise. Maybe the controller and smaller wheel and motor will make a difference.
The bike test is complete the 350 with the small wheel and controller wins the range test but it isn't quite that simple. It never is.
On the hills I had to pedal sooner and harder. The top end speed is significantly lower. But it did get about 35% better range. I honestly do not think the controller had anything to do with it. I ran the bike at wot all the time. It is a bit easier to start but I didn't throttle back any so the mid ranges were really unnecessary.
I would have had to pedal less if the bike had more speed heading into the hills. I am beginning to wonder if the best compromise wouldn't be a 350 watt motor on the 16" wheel.
The speed difference in the two bikes is really significant. I'm pretty sure the range difference is in the motor size and maybe a little in the wheel size.
The question is do I need all the speed of the 450 watt motor.
06-24-2009, 11:00 PM
I tested the 350 watt for distance and found that I got a significantly better range with it. I'm thinking now that the big wheel with the 350 motor and the small wheel with the 450 motor might have the same or close performance characteristics. So I'm giving that a try now.
I got the bike wheel on the 350 watt motor. Unfortunately it took all day so I didn't get a good test done. It is faster which I expected... the range went down which I wasn't sure would happen. So I'm thinking the combination of the bike wheel on the higher watt engine was the death throw for range. I'm expecting that the small wheel on he 450 watt will be about the same as th 350 watt with the big wheel. If so I will have two similar bikes. Not a bad thing but not a great one either.
more tests tomorrow and more learning I hope.
06-27-2009, 09:03 PM
The last set up I finally got to work is a 16 bike wheel with a scabbed on motor scooter 55 tooth sprocket. The engine is a 500 watt 24 volt currie motor. The combination is pretty fast with good hill climbing power. I have it mated to a 20 frame bike with a 26in front suspension fork running a 20 wheel there. I'll make some pictures soon.
The one I am working on now is a 350 watt 24v scooter with a scabbed on bike sprocket. It will power a 20" 6 sprocket rear wheel. No the gears on the pusher won't change but I suppose they could be made to change. I have a controller and throttle that might or might not work. If not it's back to the straight on off switch. I like those just as well as a throttle.
I seem to be moving to the robot tandem concept. A tandem bike where the second rider is the electric motor. I suppose eventually I will try two matched rear wheels. Right now the twenty inch one I'm working on will be mated to a 24" mountain bike
06-28-2009, 10:55 PM
I worked on a new bike still trying to figure out the perfect engine for power. I also rode the 500 watt PAT and realized that it was too much motor. Let me describe how the 500 watt 16" PAT performs. I have a two mile test track laid out in the residential neighborhood behind my house. I has three short steep hills. One long steep hill and two long moderate hill. Each hill has a downside of course. It's pretty typical of the geography of this part of North Carolina.
So off I go on the 500 watt pat. It runs up all the hills no pedaling. As a matter of fact it goes so fast that I can't catch up with the pedals. But the power consumption is awful. The two laps or four miles test ride ate up about all the available power of a 12ah battery pack. If I had gone farther the batteries would have been damaged. I think the batteries are good as long as I don't go below 11volts.
So instead of building a bigger, faster PAT, I asked myself what do I really NEED. I need a bike that will run along on the flat at about the speed of a competent bike rider. About 10 to 12 mph without any assist would be nice. I think moderate pedaling up hill is fine. About the same amount I would have to do on the flat with a non power bike. I would also like to get 6 miles on a 12 am battery pack before it gets dangerously low on power. Now that is a tall order but it's my next challenge.
I have a 350 watt motor ready to go. I had used it on a 12inch scooter wheel. I have since wedded a bike sprocket to the motor. I plan to use it with a 16 bike rear wheel. I have to get another one since the last one has a fast scooter rear wheel sprocket wedded to it. Setting that up is the next challenge. I want to see how close I can come to my goal before I throw in the towel. In the meantime, I have the 500 watt I feel comfortable with for short trips around here.
I also have the 250 hub motor that will do about five miles on the charge so it is close. I think I can do better with a PAT than the hub so I will see what I see.
By the way the hub motor is acceptable but I would like just a tiny bit more help on the big hills.
07-05-2009, 09:49 PM
For all intents and purposes I have finished building new bikes. Now begins my leaning adventure riding them. At the moment I have two PAT bikes. Bikes with a pedal assist trailers hooked onto the rear.
This is a new kind of ebike motor arrangement for me. Since I built it, it might be new to almost everyone. The very first thing you notice is that the thing skips along during tight turns. There is no real loss of control so it's just a minor annoyance.
My econo model isn't any cheaper to build but I think it will get more miles from a battery charge. It is a 350 watt electric scooter motor pulling a 16" bike wheel. So far it requires more pedaling than the 500 watt motor but it is not hard pedaling. It gets about good speed going up hill with the rider pedaling. The speed and effort is about the same as most bikers would do on the flat.
The Brutus model is 500 watts and doesn't need much help at all. It is more a motor bike with a slight assist from the pedals but only slight. I think the range will be less so I added a set of 7ah batteries to my standard 12ah pack. I would only need to go four mile round trip at the most. It should do at least 6 miles. If I can conserve power it might do the ten they promised me with the tiny lil hub motor. It is waiting for either a brain transplant or to be shot.
So as I ride more I'll let you guys know what I learn. Whether you want to know or not.
07-06-2009, 08:47 PM
Both of them are complete so it's time to enjoy them. I put the new controller on the 500 aka brutus today. It might be just a tad less powerful since the controller limits the draw to 30amps. I had a forty amp fuse on it before. I rode it today for a mile. It pulls just fine even with extra weight of the additional batteries.
I think I am going to take the econo bike to the park for my walk tomorrow. If that works out okay, then I will probably give the brutus bike a shot at a longer trip to the lake. I really want a bike that will make that trip.
Well more later....
07-07-2009, 01:13 PM
I rode the econo bike down to the walking trail this morning. I had some big time noise on the push wheel. Since there was nothing I could do about it on the road, I just ignored it. When I got home I found that the chain was too tight. I loosened it and I will let you know what happens tomorrow.
07-07-2009, 06:11 PM
Okay I'm not the shiniest tool in the bag. That noise in the rear wheel drove me crazy. I thought it was the chain, then maybe the bearings in the pusher wheel, and now I'm pretty sure I found the problem.
When I welded the scooter sprocket to the bike sprocket I hit a spoke and burned it into. Since the wheel does not support any weight I didn't fix it. I removed the part that went into the nipple. I did not remove the other end and that is what I think was jingling. Anyway it's out now and we shall see tomorrow.
07-07-2009, 10:40 PM
I rode my fast pusher tonight and learned that I need to stiffen the side rails. I also need to made a change to the motor mount, but it shouldn't be a big deal at all. Actually I'm getting bored without a bike to work on so it will be good for me.
I also learned that a too hot iron is just as bad as a cold iron for making solder joints. Oh well live and learn.
07-09-2009, 10:12 AM
Yesterday I learned the value of checking your nuts and bolts for tightness before you do anything else. I had a pusher throw a chain because it wasn't rigid enough. I welded some join braces on and it got rigid but it still wanted to twist. The nuts on the bolts that hold it to the frame were loose. Sometime today I'm going to put locktight on them. I bought the stuff to do that with and now it's time to do it. I think I pretty much have it set up so that it will work for a while.
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