Originally Posted by
rscamp
As an electrical engineer, surely you want to know your instantaneous energy per unit distance, MIN/MAX speed, current, voltage, set cut off voltage/max current and have a PI controller at your disposal for additional control options. You want a Cycle Analyst whether you know it now or not.
And why limit to 36V?
Are you familiar with battery management? Are you planning to balance on charge? How will you know when to stop using the motor without damaging the battery pack? Rather than dumb systems with no monitoring on the bike or during charge, build a system that you can measure battery performance (as with a CA and a charger that measures things like mAh in, internal impedance and maybe even has a computer interface so you can see the voltage profile and state of balance on charge). The CA was designed by an engineer (Justin). Nothing compares to it in capability. Check out the latest info on it at ebikes.ca. He is even working on a PWM I/F to work directly with R/C controllers...
I think the point of him saying he's an EE, is that he wants to go as cheaply as possible, since he wouldn't need a full blown altogether kit, because he can do the wiring himself.. And adding a CA will add $150 to the price tag..
The kits I sell and use are 36v 500w systems complete with everything you need except batteries...
And I'll tell you, the batteries from Ping (Lifepo4) are considered the best (albeit the priciest of the "duct tape vendors".
I buy my batteries from yxm on eBay and their 15ah lifepo4 is $300 and their 20ah (really 21Ah) lifepo4 is $389 (both prices are shipping included) and has worked beautifully for over a year with no problems whatsoever.
The 15ah batt should get you about 22+ miles at 20mph and the 20ah one will get you close to 40 miles at the same speed for only $89 more.
Just my .02
P.S. If anyone has any questions about my kits, just PM me.