[M_a_t_t]

I commute 4 miles each way. A wind screen in the winter helps.

4 miles is quite the trek for me. I hardly could do 3 miles on a pedal bike, and I'm 19 years old. I'm not comitted yet, but I don't think I am going to ride in the winter.

I think you might be better off going with a 36v battery and using a DC-DC converter to get 36v from your panels. Reason being, voltage is what determines top speed. With the same motor I have, running 24v would give you a top speed of about 13mph with a full charge, and less as the battery voltage drops. More amps adds acceleration, but not top speed.

The controller auto detects the battery voltage and sets it accordingly. I don't know how that would react to the converter.

If you have any form of lithium on a BMS, it should control the charge for you and turn off the current as soon as any one cell hits max voltage. Meaning you don't need a charge controller.

Wouldn't the voltage have to be somewhat regulated? Reason I ask is because solar panels are constant current and the voltage changes as the sun changes, which is what the point of the controller is. Or atleast that is what it says in the manual for the controller.

Now that I think about it there is a load connection that supplies up to 10A. I could just get the BMS set for 12v charging and plug it in there, kind of bypassing the charge function, so no worry about 36v charging. Does that sound plausible?

I think if I go for 36v I'll just change cells and not use the 12v pack I have. It would be cheaper using a pack like what Ecky used, than to have to buy individual parts and put together myself. It would also have excessive power (36V 20Ah pack would be the result). How do you charge your ebike Ecky? I don't see a charger on the build list you posted, only a plug.

Thanks, Matt