Hi, I'm a senior engineering student and I've chosen to build an electric-solar bike for my senior project.
So far I have a brand new Schwinn Meridian adult tricylce and about 66 A123 LiFe batteries (loose cells).
I've been trying to decide on what motor system to go with and what other components I will need.
With a 36v setup, I'm at 36.3v on a full charge. I have enough batteries to put 11 in series, 6 in parallel, giving me a 19.2 Ahr pack.
With a 24v setup, I'm actually over voltage to 26.4v on a full charge with 8 in series, 8 in parallel, giving me a 25.6 Ahr pack.
What's better 24V or 36V?
At first I was looking at a 600W 24v brushless motor, but then I realized that I would have to design mounting brackets and a pully system to hook into the chain... then I started looking at hub motors and right now I'm looking at a 600W 36V brushless hub motor.
Basically the hub system would save me a lot of time and money by not having to design and build the mounting system for the motor. Are there any major drawbacks of using a front hub motor instead of a normal motor running the back wheel(s) by chain?
Also, can anyone recommend a good controller/charging system to use with my LiFe batteries? You can quick charge these cells at up to 10A per cell in parallel, so most chargers won't give me as good of charge times as I could get. Most controller and motor systems I've been looking at give very little specifications as to maximum RPM, voltage range, amps, how to set cutt-off voltage (if you can set or adjust it), if it's compatible with brushless motors etc... These LiFe bats have high power capabilities, what system will let me get the most out of them?
I was looking at the 1000W systems, but they're a bit more pricey and they don't make them in brushless hubs (as far as I know).
I am also wanting to make sure 600W is enough power for me on a trike and some extra weight. I'm about 210, not sure how much the trike weights, shipping weight is 70 pounds, so I'm guessing around 60 pounds out of the box. Then there's about 10 pounds for batteries and approximately another 10 pounds for other equipment. That makes a total guess at 290 to 300 pounds. I don't need or want that much speed because this is a trike and I'm not sure how well it will handle over 20mph, so 20 is my max. I guess I could always gear down and get a lower top end and more torque. But I'm also thinking that 1000W is a bit more than I need and would probably drain my batteries a lot faster than a 600W.
Any suggestions would be much appreciated! I'm new, so be nice!