i need a battery pack of 120 volts for a motorcycle. i'm on a bugdet. so does anyone have any suggestion on small, powerfull batteries that i could use.
Some of you have been following my project to upgrade my little 180W ebike.
I have all ready posted on upgrading the hub motor from the 180W 36V system to the 1000W 48V system.
I promised to post on the performance when I got my new battery, and it finally came in.
I ordered a 48V 15Ahr LiFePO4 battery pack with BMS and charger from China off ebay for ~$250 shipped.
I hooked it up to the charger after unwrapping. I found the charger shut off after only 10minutes, so that means it did not self discharge during the 6 week boat trip it took to get here. Thats good news.
Another note is how they made it. Its simply duct taped together, but over all looks fine. IF I want to change the shape, I should be able to remove the tape and change it how I like.
In just a few minutes, I had it in the scooter.
There is nothing under the seat. That silver cube is the whole battery.
OK, its not pretty, but I will clean it up as time allows.
I finally got to go on a real test ride.
Here are the results:
Top speed is ~20MPH using a GPS.
It goes about the same speed up or down hill, so the speed must be governed by the controller.
It has plenty of torque. If I put my feet on the ground and pull the throttle, the front wheel will come up (but no, it wont wheelie while moving).
I can go up pretty steep hills with out loosing speed.
So far, I have gone about 8miles on the battery, and there is no noticeable drop in performance.
I pulled over and checked, and nothing (motor, controller, BMS or battery) was hot.
The only downer is that some times when accelerating from a stop (and pointing up hill) the current shuts off and then back on and off making a jerking motion. Since it did not do the same with the SLA batteries, I am sure that this is the BMS which came with the LiFePO4 system. It is protecting the battery from over current, or under voltage.
This tells me that I should have bought the 20Ahr battery, not for the additional range, but for the increased supply current under heavy load. Still, this issue is not common, and over all the bike is very ride-able, and I do not feel the need to order a larger battery.
So, the verdict:
Fun little scooter. Since I started with such a small frame, it is really light and maneuverable. The small LiFePO4 battery in the floor does not weigh much. The whole scooter weighs 32kg. It seems like is has plenty of range, and is fast enough to be usable. Also it is an e-bike, not a scooter. Only need a bike helmet, not license or registration. I am happy enough with it to want to finish off all the details like new lights and key switch. Get the regenerative breaking working and so on.
At my work, we have a recycle tub for used batteries. I decided to try to make use of the used laptop batteries for a little stand up electric scooter by sorting through them and finding the cells that were still in good shape.
There are many types of Li-ion rechargeable cell chemistries. (scroll down this link)
Typically, laptops (and the tesla roadster) use Li-ion cells with the CoO2 cathode. LiMn2O4 cathodes are used in the "X-treme" Li-Ion bike. LiFePO4 batteries are quickly gaining momentum as the battery of choice for scooters because they are inherently safer. LiPo (lithium polymer) is some of the most powerful, but also the most dangerous.
OK, so, the most common size of the CoO2 cathode Li-Ion cells is called an 18650 which is simply the dimension of the cylindrical cell (18mm diameter x650mm in length). Here you can see how they are laid out in a laptop battery.
These cells do not last for ever. Their capacity diminishes over time even with out going through charge cycles.
That said, some cells will degrade faster than others, so in each laptop battery, there is likely some cells still in good shape. You can see that to make this work, you would need to start with a lot of cells.
These cells had to be taken apart one at a time and remove the BMS. If the voltage of the cell was below 2V, dont bother trying to salvage the cell. It has probably become defective. Any of the cells that have over 3V have a good chance of recovery.
A new 18650 cell has ~2Ahr capacity, and can discharge 4Amps.
I decided to put 6 in parallel so that I can discharge as much as 24A, and if the cells were new (which they are not) I would have a 12Ahr battery pack.
I did not have a spot welder, so I decided to solder the cells into a 6 cell parallel battery.
I then used 8 batteries to make a pack.
Now for the safety part.
I found a really cool BMS by ecity power to use for the pack.
You can order them off ebay for $40 shipped. (search for BMS li-ion)
Software and diagrams can be found here.
It can handle 8-12 cells, up to 40A, and the voltages can be programmed by the computer for your specific battery chemistry. For the CoO2 Cathode, the cut off voltage should be 4.2V.
Unfortunately, I had trouble getting the BMS to recognize all 8 cells. While messing around with it, some wires touched and zap-pop, melted the wires. So now I am ordering another one.
Until then, I charged up each of the 8 batteries separately and hooked it up and rode it around.
None of the batteries got hot, nor did the voltage seem to drop on hills. When I get my new BMS in, I will be a little more brave on how hard I push it, and update the blog at that time.
In the beginning, there were a few battery manufacturers that you could go to for electric car applications.
That was a bad thing.
There was practically no competition, and the few manufacturers knew this, and so would set extremely restrictive conditions for purchasing their batteries.
Among them were,
1. We're going to take a long time. Don't hold your breath.
2. We'll need an unbreakable commitment for a large quantity ahead of time, whether you're going to need all of them or not.
3. Large minimum purchase quantities/cost.
4. Wrong format? Take it or leave it (one company delivered batteries that were TAPED together, rather than deliver them separated for the car manufacturer to secure using more robust means.)
5. Wrong specs? Again, take it or leave it.
6. Did we mention we want lots of money?
Alan Cocconi came up with a novel solution to all this;
Take advantage of the intense competition between laptop battery manufacturers, and you will get the most energy in the smallest space (and least weight) for the least cost.
The only caveat to this method was that you would have to weld thousands of 18650 (a number that relates to the cell dimensions in mm's) together to power a car.
Well, so be it.
Each eBox we make uses 5,088 cells, most of which are in parallel for current, and then in series for voltage.
I've got help now, and that's a rare thing. The third weld station is now operational, and the preliminary numbers on the output from these machines support making the necessary quantities of modules to meet our eBox production schedule.
It's pretty exciting to see it all come together like this, especially during a recession, but I guess electric cars will be a much more effective means of bringing jobs and our economy back from the brink than it ever was before.
We'll see. - George
10/11/2008: 3rd test ride: Farther. Went on a 5 mile loop. Very windy, long rolling hills for the most part. I adjusted the pedaling gears so that I could contribute from about 15mph-22mph. Everything went very smooth. This thing is really fast! Scary fast!
10/9/2008: Second test ride: This time with another rider with a spedo. Flats: about 23mph. Slight downhill hits about 28mph. Almost too fast for the 'hood. Ordered a ecrazyman brushed controller and throttle. This should make a big difference. I noticed that if I flip the switch too early (big current draw), the battery cuts out. I don't think this is a problem with the battery or BMS, just the BMS doing its job (I guess...).
10/6/2008: First test ride: Tightened everything REALLY good and installed the torque arm. Found a good, flat straight away and got up to about 20mph (estimated). Flipped switch and it took off...probably mid 25mphs...very strong pull. No noticable heat or general breakage. Will try it again and get a controller.
10/4-6/2008: Prepped Raleigh aluminum bike with Kollmorgen rear brushed hub motor. Motor is rated at 24V, so a bit worried about running it at 60V. Don't have a controller either, so this will be a "flip-switch" test with a 20a automotive switch. Have a 30A inline fuse too. Using somewhat small gauge wire 18ga.(?) so that there is a voltage drop to wheel. Have an old EV Warrior kickstand that I'm using, which is needed cuz this thing wants to fall over all the time with the batt. on the rack. First test: spun wheel with pedal and flipped switch: Wow. Went strong and very fast. Then I smelled burning and shut it down. The wheel had torqued itself loose from the mounts and nearly came out. Need to tighten things down....
Note that this is a pic of the Kollmorgen hub mounted in a "pusher" vehicle (see this photo if interested --> 122.jpg (32.78 KB) Didn't work great. Lots of wheel hop, and weirdness when turning. But it was easy to go from ebike to regular bike...)
10/1/2008: Hooked up charger and ran it over night. Charger ran RED for just a few minutes, then to green. No noticed "balancing" (turning red again). Charged voltage for this 48V pack is ~60V (!).
9/25/2008: Received Ping battery. 48V, 16ah, ~17lbs. Packaged well and arrived apparently safely with 2A charger. Was headed out for a 5 day trip, so had to leave it be :(
does any one know how to dismantle the battery box on a 48v crystalyte
I bought a bionX 500HS motor with li ion 36 volts battery one moth ago.It is mounted on a good city bike. I have heard (apparently this news comes from the one of our european importer) that is is not good at all to use the recharge function of the bionX; the battery longevity would suffer from it. Is it llike cellular batteries? ie it is not good to recharge constantly the battery ?
Does somebody have experienced shorter life or problems to their bionx battery because of this practise ?
I have decided to note every charge I make and the milage per charge I get. So far, I can do 50 km staying mostly on Nb 1 or 2 assitance. The motor is so powerfull that I do not need (except long hills) much more assistance.