lookingelectric
100 W
- Joined
- Sep 2, 2007
- Messages
- 102
The beginning
-------
Heres how my ebike adventure started:
A few months ago, I found myself looking for an easy, low-cost, medium-range method of transportation. It was to be used both for general transportation and for going up a particularly horrendous hill 2-3 times a day. I started looking at electric bikes and scooters and found myself looking at 3 categories of machine:
1) $300-400 commercially manufactured bike with Pb batteries
- Unable to climb the hill
- Batteries expected to die in 3-6 months
2) $900-$1000 hub motor bike (500 series motor, controller, batteries and a steel walmart bike)
- Additional $500 required to move from Pb to Li batteries
- ebikes.ca seems to be the main source for the best hub motors, but they often dont have everything that one needs in stock
- Expect to spend 1300W climibng steep hills (http://endless-sphere.com/forums/viewtopic.php?t=1177&start=0)
3) $1000-$1500 electric scooter
- eGo2 would have been first choice
The cheap, commercially manufactured bikes were out. Although they would help me get around town, they would not get me up the steep hill.
I had to eliminate the eGo2 electric scooter as well; although the scooter has a 1500W motor, there were reports that it would burn out when climing steep hills. Since a large part of my reason for wanting this vehicle was uphill travel, this wouldn't work.
So I set my sights on building a hub motor bike similar to those presented by the user "d" here: http://endless-sphere.com/forums/viewtopic.php?t=1177&start=0
Specifying myself away from a hub motor
---------------------------------------------------
This is what my rough pricing looked like:
$100: walmart bike
$135: 72V, 40A controller from ebikes.ca (48x20 wont do the 1300W that I'll need)
$450: hub motor from ebikes
-------
$685 before batteries
My expected maximum mass (myself+bike+stuff) was around 220 lbs. I wanted to be able to travel under 1300W of power for about 20 minutes (thats a 3 C discharge, or 390 Wh.
Since 96 Wh of Pb batteries weighs about 5 pounds, I estimated that each Wh of energy from a Pb battery would cost about 0.053 pounds. Multiply that by 390 for 21 pounds of batteries. Sounds acceptable? Because of sulfation, Pb batteries don't live long if they are fully drained. In fact, one common suggestion is that they not be drained below 50% capacity. This means that I would need 780 Wh if I intend to deliver 390 Wh and have the batteries survive more than a few months. That means adding ~20% to my mass and therefore to my energy requirements. Between this and the knowledge that good treatment would bring the battery life only to a year, I decided to eliminate Pb batteries from consideration.
As I was considering the problem of batteries, I started to think about streamlining my propulsion needs. I put together a little calculator which told me that, for a reasonably speciified geared system, I would need 1220W of peak power and 875W of continous power to go up my hill. The 1200W was based on the need to accelerate uphill and the 875 on continuous travel uphill.
The move to a geared bike
-----------------------------------
At the same time, it became known to me that a user on this board had a 500W cyclone geared bike for sale. The cyclone motors (http://www.cyclone-usa.com) operate through the bicycle chain, allowing you to use your rear gears in conjunction with the motor. Although the bike would not be able to provide the nearly 900W continuous that I would need, I decided that I could deliver the remainder via pedaling. I purchased the bike.
A battery interlude
--------------------------
With this system, I would ask the batteries to deliver 750W for 20 minutes (225 Wh). Again I considered and rejected lead acid batteries. I didn't want to have to baby batteries with memory effect problems so I eliminated NiMH and started looking at lithium ion batteries.
I picked out 3 possible sources of lithium ion batteries: Dewalt battery packs (36V), Milwaukee battery packs (28Vx3Ah) and LiFePO4 batteries from China. All three were in the same range in terms of price/Wh, so I decided to compare them on convenience and longevity. With two different sources of LiFePO4 battery packs, I decided to eliminate the batteries from China right off. I would have effectively no warranty with them, and the sellers know it. If they were to die because of manufacturing defects the week after arriving, I would have very little recourse.
I was left with the power tool batteries. Both types of batteries were designed for high current use and both could be expected to last over 1000 cycles (1.3 charges/day->~2.1 years). The longevity of LiFePO4 packs is very well advertised, and Milwaukee thinks enough of their packs to warranty them for 1000+a fractional 2000 charges. Of the remaining two, I chose the Milwaukee packs because the previous user of the bike had used them and because they were available on sale.
At $85/pack, 4 packs would offer 336 Wh for $340, which I found to be reasonable.
I did a little research on what causes lithium ion batteries to die. Lithium manganese batteries such as those in the Milwaukee packs have two (chemical, room temperature) failure modes. At extremely low voltages, the manganese dioxide in the battery dissolves in the electrolyte, and at high voltages side reactions take place which damage the battery. I found out that leaving a lithium ion battery on the charger to "top off" is EXTREMELY BAD and that I could expect my batteries to last an extra 50-75% if I took them off the charger and ran them for just a minute to keep them from being stored full. (side note: much of the reason that LiFePO4 batteries have such long cycle life is that they are charged to lower voltages.)
I would be free to drain these batteries to about 15% after charging them to around 95%. This 270Wh (336*0.8) would be enough energy for my task.
Troubleshooting the geared bike
--------------------------------------
The person selling the 500W cyclone bike had experienced some problems with it.
-Problem: A clicking noise when the bike was ridden
-Problem: Instability to the point of unusability when the bike was ridden with the freewheel on
-Problem: Heat generation near the battery packs
Soltuon: Adjust tensioner The clicking problem was caused by the chain. The tensioner was too loose. I tightened it and the clicking went away.
Solution: Adjust tensioner/live with it I was, however, left with a bike whose pedals spun anytime the motor was on. I looked into the cause of that problem and got a few hints that it might be due to a mismatch of old and new parts. When a sprocket and chain are used together, they stretch and wear to fit each other. Since the freewheel system was a new sprocket, it did not mesh with the old chain. Between this and the (previously) loose tensioner, this resulted in uncontrollable skipping. Improving the tensioner moved the problem from uncontrollable to slightly annoying, at which point I was satisfied.
Solutuon: Replace existing connections with Anderson Powerpoles I solved the problem of heat generation near the battery packs by replacing most of the connections with Powerpoles. Remember when I said that I had identified the two room temperature chemical failure modes for these batteries? Well there is a third failure mode which is made worse by heat. Replacing the existing connections with powerpoles got rid of the main source of heat in the battery bag. (note: the batteries themselves dont get even noticably warm.)
I knew beforehand that the bike was a bit underpowered for my use. It would take me up the hill with a llittle help from my feet, but I would have to stop partway each time because running it at max power (as opposed to max sustained power) for 10 minutes caused it to shut down.
Welcome to Idiotsville, population me
----------------------------------------------
After almost 2 months of relatively happy biking, I had a stupid day and decided to do a little experiment. If I were to switch the bike from 28V to 56V, would I be able to deliver more power and get up the hill before shutdown kicked in. I sorta-kinda remembered something about the previous owner of the bike using it at 56V and figured that if there was a problem, it would simply shut down to cool, resulting in a 5-10 minute inconvenience. I decided to give it a try.
I was right about it going up the hill more quickly, but when it shut down, it was forever. I had blown the controller.
Moving to 1000W
----------------------
I was left with a couple of choices; I could replace the 500W motor (the controller was in the motor housing) for $210 or I could order a 1000W kit from cyclone taiwan for $460. I decided to go for the 1000W unit so that I would not be left needing to fix the same problems as before.
I ordered and the parts arrived about a week later. The old picture on the cyclone-tw.com website showed a standard bike with the 1000W motor arranged in the same way as the 500W system shown here: http://www.cyclone-usa.com/images/hex04-16.jpg
I assembed based on those instructions and found that the chain would come off the motor almost immediately after startup. The problem was the sprocket provided by cyclone.
Problem: Jumping of the chain While the 500W system had a 14 tooth sprocket, the 1000W system from Cyclone Taiwan had only a 7 tooth sprocket. This made jumping of the chain extremely easy, especially at the speeds accessed by the 1000W motor. Partial solution: Change bike configuration Cyclone advised me to arrange the system as it is currently displayed on the website: http://www.cyclone-tw.com/images/1000Wbike.jpg
and I did so.
[Problem: Mismarched sprockets from cyclone[/b] Soon, I ran into another problem. While the large freewheel sprocket provided by cyclone was designed for 1/2" x 5/32" chain (in modern times, the most common type of bicycle chain), the motor sprocket was designed for something different. After spending a lot of time thinking that the problem was the pitch, I discovered that the problem was the width. The motor sprocket was designed for 1/2" x 1/8" chain.
Solution: Use a chain that fits the smaller sprocket well and the larger sprocket decently After a week of frustration, I purchased a 1/8" width chain and attached it; I had a chain that fit the motor sprocket. While it would operate with the larger sprocket as well, it would not be a great fit and would be bound to cause me some sort of trouble in the future.
To be continued......
-------
Heres how my ebike adventure started:
A few months ago, I found myself looking for an easy, low-cost, medium-range method of transportation. It was to be used both for general transportation and for going up a particularly horrendous hill 2-3 times a day. I started looking at electric bikes and scooters and found myself looking at 3 categories of machine:
1) $300-400 commercially manufactured bike with Pb batteries
- Unable to climb the hill
- Batteries expected to die in 3-6 months
2) $900-$1000 hub motor bike (500 series motor, controller, batteries and a steel walmart bike)
- Additional $500 required to move from Pb to Li batteries
- ebikes.ca seems to be the main source for the best hub motors, but they often dont have everything that one needs in stock
- Expect to spend 1300W climibng steep hills (http://endless-sphere.com/forums/viewtopic.php?t=1177&start=0)
3) $1000-$1500 electric scooter
- eGo2 would have been first choice
The cheap, commercially manufactured bikes were out. Although they would help me get around town, they would not get me up the steep hill.
I had to eliminate the eGo2 electric scooter as well; although the scooter has a 1500W motor, there were reports that it would burn out when climing steep hills. Since a large part of my reason for wanting this vehicle was uphill travel, this wouldn't work.
So I set my sights on building a hub motor bike similar to those presented by the user "d" here: http://endless-sphere.com/forums/viewtopic.php?t=1177&start=0
Specifying myself away from a hub motor
---------------------------------------------------
This is what my rough pricing looked like:
$100: walmart bike
$135: 72V, 40A controller from ebikes.ca (48x20 wont do the 1300W that I'll need)
$450: hub motor from ebikes
-------
$685 before batteries
My expected maximum mass (myself+bike+stuff) was around 220 lbs. I wanted to be able to travel under 1300W of power for about 20 minutes (thats a 3 C discharge, or 390 Wh.
Since 96 Wh of Pb batteries weighs about 5 pounds, I estimated that each Wh of energy from a Pb battery would cost about 0.053 pounds. Multiply that by 390 for 21 pounds of batteries. Sounds acceptable? Because of sulfation, Pb batteries don't live long if they are fully drained. In fact, one common suggestion is that they not be drained below 50% capacity. This means that I would need 780 Wh if I intend to deliver 390 Wh and have the batteries survive more than a few months. That means adding ~20% to my mass and therefore to my energy requirements. Between this and the knowledge that good treatment would bring the battery life only to a year, I decided to eliminate Pb batteries from consideration.
As I was considering the problem of batteries, I started to think about streamlining my propulsion needs. I put together a little calculator which told me that, for a reasonably speciified geared system, I would need 1220W of peak power and 875W of continous power to go up my hill. The 1200W was based on the need to accelerate uphill and the 875 on continuous travel uphill.
The move to a geared bike
-----------------------------------
At the same time, it became known to me that a user on this board had a 500W cyclone geared bike for sale. The cyclone motors (http://www.cyclone-usa.com) operate through the bicycle chain, allowing you to use your rear gears in conjunction with the motor. Although the bike would not be able to provide the nearly 900W continuous that I would need, I decided that I could deliver the remainder via pedaling. I purchased the bike.
A battery interlude
--------------------------
With this system, I would ask the batteries to deliver 750W for 20 minutes (225 Wh). Again I considered and rejected lead acid batteries. I didn't want to have to baby batteries with memory effect problems so I eliminated NiMH and started looking at lithium ion batteries.
I picked out 3 possible sources of lithium ion batteries: Dewalt battery packs (36V), Milwaukee battery packs (28Vx3Ah) and LiFePO4 batteries from China. All three were in the same range in terms of price/Wh, so I decided to compare them on convenience and longevity. With two different sources of LiFePO4 battery packs, I decided to eliminate the batteries from China right off. I would have effectively no warranty with them, and the sellers know it. If they were to die because of manufacturing defects the week after arriving, I would have very little recourse.
I was left with the power tool batteries. Both types of batteries were designed for high current use and both could be expected to last over 1000 cycles (1.3 charges/day->~2.1 years). The longevity of LiFePO4 packs is very well advertised, and Milwaukee thinks enough of their packs to warranty them for 1000+a fractional 2000 charges. Of the remaining two, I chose the Milwaukee packs because the previous user of the bike had used them and because they were available on sale.
At $85/pack, 4 packs would offer 336 Wh for $340, which I found to be reasonable.
I did a little research on what causes lithium ion batteries to die. Lithium manganese batteries such as those in the Milwaukee packs have two (chemical, room temperature) failure modes. At extremely low voltages, the manganese dioxide in the battery dissolves in the electrolyte, and at high voltages side reactions take place which damage the battery. I found out that leaving a lithium ion battery on the charger to "top off" is EXTREMELY BAD and that I could expect my batteries to last an extra 50-75% if I took them off the charger and ran them for just a minute to keep them from being stored full. (side note: much of the reason that LiFePO4 batteries have such long cycle life is that they are charged to lower voltages.)
I would be free to drain these batteries to about 15% after charging them to around 95%. This 270Wh (336*0.8) would be enough energy for my task.
Troubleshooting the geared bike
--------------------------------------
The person selling the 500W cyclone bike had experienced some problems with it.
-Problem: A clicking noise when the bike was ridden
-Problem: Instability to the point of unusability when the bike was ridden with the freewheel on
-Problem: Heat generation near the battery packs
Soltuon: Adjust tensioner The clicking problem was caused by the chain. The tensioner was too loose. I tightened it and the clicking went away.
Solution: Adjust tensioner/live with it I was, however, left with a bike whose pedals spun anytime the motor was on. I looked into the cause of that problem and got a few hints that it might be due to a mismatch of old and new parts. When a sprocket and chain are used together, they stretch and wear to fit each other. Since the freewheel system was a new sprocket, it did not mesh with the old chain. Between this and the (previously) loose tensioner, this resulted in uncontrollable skipping. Improving the tensioner moved the problem from uncontrollable to slightly annoying, at which point I was satisfied.
Solutuon: Replace existing connections with Anderson Powerpoles I solved the problem of heat generation near the battery packs by replacing most of the connections with Powerpoles. Remember when I said that I had identified the two room temperature chemical failure modes for these batteries? Well there is a third failure mode which is made worse by heat. Replacing the existing connections with powerpoles got rid of the main source of heat in the battery bag. (note: the batteries themselves dont get even noticably warm.)
I knew beforehand that the bike was a bit underpowered for my use. It would take me up the hill with a llittle help from my feet, but I would have to stop partway each time because running it at max power (as opposed to max sustained power) for 10 minutes caused it to shut down.
Welcome to Idiotsville, population me
----------------------------------------------
After almost 2 months of relatively happy biking, I had a stupid day and decided to do a little experiment. If I were to switch the bike from 28V to 56V, would I be able to deliver more power and get up the hill before shutdown kicked in. I sorta-kinda remembered something about the previous owner of the bike using it at 56V and figured that if there was a problem, it would simply shut down to cool, resulting in a 5-10 minute inconvenience. I decided to give it a try.
I was right about it going up the hill more quickly, but when it shut down, it was forever. I had blown the controller.
Moving to 1000W
----------------------
I was left with a couple of choices; I could replace the 500W motor (the controller was in the motor housing) for $210 or I could order a 1000W kit from cyclone taiwan for $460. I decided to go for the 1000W unit so that I would not be left needing to fix the same problems as before.
I ordered and the parts arrived about a week later. The old picture on the cyclone-tw.com website showed a standard bike with the 1000W motor arranged in the same way as the 500W system shown here: http://www.cyclone-usa.com/images/hex04-16.jpg
I assembed based on those instructions and found that the chain would come off the motor almost immediately after startup. The problem was the sprocket provided by cyclone.
Problem: Jumping of the chain While the 500W system had a 14 tooth sprocket, the 1000W system from Cyclone Taiwan had only a 7 tooth sprocket. This made jumping of the chain extremely easy, especially at the speeds accessed by the 1000W motor. Partial solution: Change bike configuration Cyclone advised me to arrange the system as it is currently displayed on the website: http://www.cyclone-tw.com/images/1000Wbike.jpg
and I did so.
[Problem: Mismarched sprockets from cyclone[/b] Soon, I ran into another problem. While the large freewheel sprocket provided by cyclone was designed for 1/2" x 5/32" chain (in modern times, the most common type of bicycle chain), the motor sprocket was designed for something different. After spending a lot of time thinking that the problem was the pitch, I discovered that the problem was the width. The motor sprocket was designed for 1/2" x 1/8" chain.
Solution: Use a chain that fits the smaller sprocket well and the larger sprocket decently After a week of frustration, I purchased a 1/8" width chain and attached it; I had a chain that fit the motor sprocket. While it would operate with the larger sprocket as well, it would not be a great fit and would be bound to cause me some sort of trouble in the future.
To be continued......
