Many have connected the batteries through switches directly to brushed motors - hub motors and relied on the resistance of the windings to limit the power and run at certain speeds instead of using a variable speed control. You would start off with the batteries in parallel and pedal a lot to get going then kick in different voltages. Many of the hub motors are brushed so the controller can be simple. Brushless controller tend to be more difficult to find because of the under engineering that most have - they don't allow for the high starting currents and the motor inductance variations at different speeds. Be careful when mounting front wheel motors as the forks have been known to fail suddenly from the motor loads on the forks.
Kits for hub motors are available at Battery Space.
I bought the 600 watt brushed hub motor from wilderness energy. It came with 12 amp hour batteries. They gave about 9 miles range on the first charge at about 18 mph. I have the 600 watt 24 inch wheel on the front of a trailmate ez roll regal trike that I streched 10 inches. It was easy to stretch the frame as it is built of square tube. This made it much more comfortable to ride and pedal. It has a three speed hub. The motor quickly outruns the stock gearing. I guess I should post a pic in the garage. I am running 36 volts. The site claims the motor could handle 72 volts if you provide an adequate controller. I can't say about that. The motor is fine when on the ground but if you accelerate the motor with the wheel off the ground you can easily feel that the torque constant is not constant. You can buy the wheel by itself for about $159. It is made in China. I might do it again but the quality is about what you might expect. Not supurb but adequate. All the reaction is taken by the hub shaft. If the axle is not tight it will turn and cut the wires off. Ask me how I know.
I have installed 18 Ah batteries but not ridden it since. It is too cold. I actually put this together for my oldest brother who can no longer drive so I have not actually ridden it much at all.
They offer a brushless 600 watt motor that is supposed to be more efficient. I picked the wilderness energy motor after quite a bit of looking. Price was a major factor for me.
ok, I think I'm set on gettin the Phoenix Cruiser hub motor, and spend the exra $50 to get it as a rear hub with a gear cluster, and controler, but I really want to ditch the lead acid gel battery pack because it's heavy (35-40 pounds) so I need a 36 volt battery pack, the stock one that comes with is around 12amphour, what are sugestions on a good battery under $200? I like the DeWalt Lithium
I have a number of freinds who don't own cars, and at -20F + windchill still ride their bicycles every day, and even on perfect days in the summer they don't like to come to my house because of the hills you have to come up to get here.
I really like the idea of pure human power, but between hills, and haveing a job that is slightly phisicly demanding (fabricating and installing granite countertops... stone is heavy) being able to get home would be nice.
this is what my compleated electric bicycle looks like, the battery pack dubbles as a rack, the motor is a 3 phase gearless brushless motor that is also the rear wheel hub, and the controler box is bolted to the front water bottle braze on, with the current battery pack the range is about 10 miles with alot of hills, top speed is around 20mph, and it's silent, street leagle, and alot of fun.
I'm looking in to other batterys to extend the range to 20-30 miles, and give it the proper top speed of 25mph, I currently have 30 "D" cell NiMh flashlight batterys in the copper tubes, and they just don't have enough guts.
with a 2.5 amp charger to interact with the batterys.
the bicycle was free from the dump,
$60 the bike shop to get a used front wheel, two tires, two tubes.
$730 or so with shipping for the rear wheel motor laced to the rim, 36V motor controler, thumb throttle switch, battery charger, and bag of correct wires and plugs to hook things up, I could have spent less on the throttle switch but I got one with LED battery leavle lights, and I could have spent $50 less on the wheel, but I wanted one with the rear gear cluster, and I got the "Cruser" wheel, so it's the middle speed range of the lower voltage.
So far I've spent $160 on 30 "D" cell batterys, and $36 on copper pipe, and maybe another $15 on misc fittings, wire, and screws, altho I'm not impressed with this battery pack, so I'm going to keep looking at battery options, the D cell batterys can't discharge as fast as the motor asks them, so the voltage tends to drop, and my top speed goes down, the big upside of them is that they are light (15 pounds for a copper and steel rack with 30 batterys inside), and they make the bike look cleaner, but I have a big hill to clime to get home so I want a little more power. www.electricrider.com is the compeny that I bought the parts from (they sell compleat bikes too) they sell parts so you can build a kit to meet your exact needs or compleat kits that you just bolt on to a bike you have, with batterys starting at $400 and going up to $1,049 for a full kit with batterys that can top out at around 37mph the parts I chose gave me more torque, lower top speed, and a better range