Electrified Downhill bike

[BrianG]

Originally Posted by zeropointbug

Wait, isn't Sine = 0.7x something, so how do you get more than the average voltage when rectified and filtered? Shouldn't the voltage be pretty close to the AC voltage? Or am I missing some current formula that has to be factored in?

Transformers are rated in RMS voltage. But when you rectify and filter them, you get the peak value. 40v AC rms = 56.5v DC (with some ripple depending on capacitance used and current load). Minus around 1.4v for the bridge rectifier diodes gets you around 54v. Oh, and do use a bridge rectifier because instead of the 60Hz ripple, you actually get 120Hz which is easier to filter.

[zeropointbug]

0.71 = Sine Right, okay, I thought you still got the RMS voltage. Yeah, definitely would want bridge rectifier to get maximum power from it. Really gonna consider this as a charger setup for the bike, but later in the summer when he moves away and needs one. It would be nice to get a full charge from empty in less than an hour, and probably less than 1/2 hour regular use.

Was calculating some energy stuff, the bike will have a MPG equivalent of 1800mpg @~25mph. Also, with 16 cells, or ~750Wh, the battery will have nearly the same energy as 1 Cup of white rice, or ~650 Calories.

[zeropointbug]

Brian, do you think you could make up a simple circuit diagram sometime, no hurry, whenever you have time. Nothing fancy, just so I understand what I would be building before I actually did it, and so I have time to think of a good design/circuit setup and materials needed. Thanks.

[zeropointbug]

Alright, I sent a quote for 16 15Ah cells. That's over 50volts for most of the runtime for the bike. Should be able to do 50km or 31mph no prob with the FAST 9C kit. Buying the kit today, about $500 before taxes/shipping with the upgraded 40A controller and a 8 speed freewheel. That comes with a DP-Cycle Analyst which is nice.

[zeropointbug]

16 cells will be here in about 10 days time. $600 + $130 shipping and fees.

Working on designing a good termination plate and the enclosure now.