Hey guys, I just got back from my new project! I'm new to the electric bike thing, but I have some experience with electric motors and batteries from my former hobby of RC cars, planes, boats, and helicopters.
So, I just finished building my first e-bike. It started out as a 5303 running 12S (44.4 volts) 10ah lipoly rated at 10C continuous and 20-30C peak. The controller was a Castle Creations HV Phoenix 110 which is a 50 volt 110 amp continuous brushless sensorless RC model controller that has awesome software control. It ended up being a pedal first type. First twist of the throttle and I didn't expect alllllll that power!!!! I actually ended up almost killing myself. It pulled a wheelie and I almost fell right off! Top speed was at mid 30's mph. So, I decided I need to be safer so intead of having a knob to turn, I ended up buying a 1/2 twist grip and the Crystalyte 72 volt controller. It took me forever to aquire the 8 additional cells but now I'm running 74 volt li poly 10 ah. The controller isn't the greatest because I instantly noticed the lack of acceleration when compared to the RC controller (probably due to amperage limitations) but I got scared after hitting 44.4 mph and didn't want to go any faster!!! I think if I were to wear skin tight stuff and tuck, I'd hit over 50 mph!
This is such an awesome bike! I can't believe all the fun it is. It's totally stealthy - full suspension Schwinn mountain bike I got at Target for 199$ a few years ago. I got some slick tires and a seat post bike rack that holds all the lipos. You can hardly tell I have an ebike from the front or back. Just the hub motor gives it away but VERY small pack in the back.
I'll post up a picture as soon as I get a chance to take one. I'm speechless/breathless! It wasn't cheap though! I got the rear motor for almost 500 bucks, controller for 300 bucks, twist throttle and new cushy seat, bike rack, tires and that was about $1000 total w/o the battery and charger! I'm not even going to go into details about the cost of the battery. I'll leave it at it's 74 volt, 10 AH, 10C continuous (100 amps), and supposedly can peak out at 200-300 amps. I've soldered them myself, they all have cell balancing taps and are balanced at every charge using some stuff from my RC hobby (Astroflight Blinky balancers, Astroflight 109 charger).
Whew! This is awesome!!! Can't wait till Sunday morning rides in the fall....
Using the Castle Creations HV Phoenix 110 and a "servo tester" (the knob) and at 12S (44.4 volts). I topped out at 38 mph but generally seemed like it was mostly cruising at 35 mph. That's with me sitting directly upright. The controller was barely warm and the batteries which were enclosed in a bag were barely warm too. I actually rode it full bore for about 10 miles and the batteries were far from being discharged - I'd venture to say about 1/2 used up? During some preliminary tests, I ran it at 6s (22.2 volts nominal) and I'd get roughly 1 mile per 1 ah. When I had the 6s3p packs, I could almost go 40 miles per charge at the max speed of about 22 mph - this was extrapolated. I have a watt-meter hooked up to it so I could monitor voltage, amp usage, etc - you have to be careful not to overdischarge Lipolys.
So, to explain the pictures... First picture is a 6s pack which is 22.2 volts and 10ah. Second picture shows all 20 cells (20s) which is 74 volts (nominal) and 84 volts at peak charge and 10 ah - the total weight is ONLY 10 pounds!! (roughly 1 12 volt 12 ah battery but 6 x the energy density!!!) Next picture is the bike rack. The side pockets have tools in them - patch kit, pump, wrenches. Next is the batteries in the bag. The controller is on top of the bag in a mesh thing for cooling. The little green thing is the Phoenix HV 110 that I was using with 12s (44.4 volts) earlier. The next picture shows all the silicone insulation over the connections. The bag is padded to protect the cells. 44.4 mph max speed (could go faster if I had fully charged, tucked better, and wore clothes that didn't flap so much in the wind). A sample picture of the taps so I could balance the cells.
Update: I checked the individual voltage of the cells and it appears one of the cells went dead! All are at 3.7 volts but one cell is at .3 volts (not good). So, I ordered 2 more individual cells and now I'm going to keep the packs smaller (3 cells) so it'll be easier to diagnose/swap/repair any issues with bad cells.
In addition, I noticed I often go for short bike rides (less than 10 miles) and I am working on a smaller pack - 72 volts 4 ah. This pack would be less than 5 pounds and good for at least 10 miles going at a reasonable speed (25ish mph). This new pack is rated at 25C continuous so it can still handle 100 amps easily. I'll also be adding individual battery alarms so EVERY cell will have a voltage monitor so I can protect against a dead cell scenario.
I'm not sure if they're cheaper or not - but each cell is about 35 dollars (10 ah) and all you need is 10 for 37 volt 10 ah. 20 of those and we have 74 volts 10 ah for about 700$. The benefit is energy density and high discharge capability.
You can blow them up by overcharging but by using the new generation of chargers with built in balancers, it's impossible to destroy via charging (esp because no charger I know of charges at over 8 amps). I blew up a 2 amp hour battery by overcharging it at 8 amps once. It went beyond the max charge very rapidly and before the charger knew it was full, it ignited.
I also purposefully punctured one and short circuited to see what would happen. Definitely puncturing a charged cell will lead to a dangerous fire too. Puncturing a totally discharged cell doesn't do anything.
I keep my cells in a padded container and all the wire leads are insulated to prevent short circuits. Only way to explode is a MAJOR accident or negligence.
I went for another bike ride today - it is so easy to ride 10 miles. I added a side mirror to it. It's much easier to take a quick glance at the mirror than turn my head around. Much safer - especially at 30+ mph. So far, no battery issues. I'm building another pack - a 5 pound pack that's 74 volts at 4+ ah. I might run them in parallel so I have 74 volt 15 ah or just use the 5 ah pack because most of my rides are not so far in distance. The new cells are "Hecells" from china and are rated at 25C continous so 100 amps! When I'm done with the small pack, I'll post pictures...
I bought a electric form y birthday last week & its working good i have gone for a number of time for a long drive on it & hada great experience & he also added various accessories like side mirror,lights etc
the side mirror has made my ride enjoyable & easy by adding beauty also to my bike
Oooh, just got some more cells off EBAY. I know everybody is going the LiFePO4 cells, but I like the other Lipoly chemistry better (I'm not sure which chemistry it is, but it's not the Manganese one). So, my total battery power is 74 volts 20 amp hours. Hey, that's about 1.5 kWh!!! That's a LOT of riding. I could simply change the connectors for 37 volts and 40 amp hours! That's probably like a hundred miles of riding before I need to recharge doing about 20 mph - LOL.
So today was the Chicago Marathon so I took a 26 mile ride today. I only used my single 10AH pack because the 19AH pack weighs 20 pounds. After 26 miles, my voltage was at 73 volts which means that I'm a little below 1/2 capacity. Average speed was 23 mph and my top speed (which was done at mile marker 25) was 51.1 mph.
I also made another pack for my father-in-law. I gave him my 5305 48 volt 12AH SLA bike for his birthday, but he seems to run out of power after 17 miles or so. He's always a mile or two short so I made him an "emergency" lipoly battery. It's 44.4 volts and 5 AH so that should be good for another 7-8 miles. I purposely made it only 44.4 volts. Under full charge, it's 50.4 volts and 44.4 volts nominal. When the pack hits 40 volts, the controller shuts off so the safety goes off when each cell is 3.3 volts which is a safe voltage to cut off (2.7 is the lowest you should use a lipo). However, on occasion, if one cell has less capacity, it'll have faster voltage drop. The cool thing is that extra 7-8 miles only adds 4 more pounds. So, a 4 pound battery gives him 5 more AH. Also, this lipo set is 25C so it can handle 125 amps continuous with good cooling and his controller max is 50 amps so the batteries hardly even get warm.
Hey brownj24! I'm still actively changing the configuration of my ebike, but for the most part, the parts that I'm definitely keeping is the Phoenix Racer motor (5303 motor) that can be had from electricrider.com. I got the 26" rear motor. I also got the 1/2 twist controller with it an the 72 volt phoenix controller. However, the controller can only run 72 volts and will not allow you to run 36 or 48 volts because the voltage cutoff is 60 volts or so. I am still waiting for my order of the 36-72 volt digital Crystalyte controller so I can use different battery configurations so I can limit my speeds to high 20s mph. I'll probably change the battery configuration so it is going to be only 37 volts but 20 amp hours. That 36-72 volt digital controller has been ordered from ebikes.ca
IMO, the most important part of the whole electric bike is the power supply. In my case, the secret is in the Lithium Polymer packs which are about 2x the energy density of LiFePO4 and 6-8x of lead acid! I got my lithium polymer batteries at maxamps.com and I got the 10,000 mah cells. Previously, you could get individual cells for under 40 bucks each so my 74 volt 10 ah pack cost about 800 bucks. Unfortunately, due to demand, they have DRASTICALLY raised their prices to 100 bucks a cell so a 20 cell pack is gonna cost $2,000! That's 1/2 the story. I had to get a 50 amp power supply to power the peak detection/balancing chargers. The 50 amp power supply I got from ebay for 150$ or so and the chargers (I have 4 of them) are Astroflight 109 peak chargers x 3 using their astroflight blinky cell balancers. I also have another charger but I find the Astroflight 109 chargers to be easier to use. I got those at towerhobbies.com I charge my cells 4 cells, 4 cells, 6 cells, 6 cells at a time so I'm able to balance each cell.
So, the batteries presently = $2000
motor, throttle and controller = $850
bike = $200
seat post mount and bag = 80$