Ordering 1500W Kit.

[thatdifferentguy]

Hey guys, I got my first electric bike about a month ago and instantly became addicted. However its a hub motor with a 300 watt, 24 v setting and only goes about 32 km/h. I wanted to get up to 60 km or so. I found some kits online but I'm wondering if their maxing out the stats (70km/h top speed, 1500 watt 48v hub motor with a 20 A 48V lithium battery) and using the motor or battery at that setting burn out the controller? Or possibly shorten the life of the motor or battery?

 

[arkmundi]

Hey guys, I got my first electric bike about a month ago and instantly became addicted. However its a hub motor with a 300 watt, 24 v setting and only goes about 32 km/h. I wanted to get up to 60 km or so. I found some kits online but I'm wondering if their maxing out the stats (70km/h top speed, 1500 watt 48v hub motor with a 20 A 48V lithium battery) and using the motor or battery at that setting burn out the controller? Or possibly shorten the life of the motor or battery?

Yes, all online vendors will exaggerate and make claims. Did you really think otherwise? In part, the value of the ES community is to level all claims and report on actual experience, good or bad. My concern with your 1500 watt 48v hub motor with a 20 A 48V lithium battery equation is the battery. Li-ion batteries are spec'd on voltage, capacity and C-rate. My general recommendation is that all ES buyers look at the datasheet of the batteries they're thinking about buying, several in fact and compare. For a 1500 watt motor (if its that), I'd get something more robust, like a 72 volt battery. And I'd be sure the cells have the C-rate needed to deliver the amperage draw, probably at least double 20 amps, in the order of 40+ amps. And have sufficient amp-hours to deliver a decent ride for the distance & terrain you'll be riding. No, its unlikely you'll burn out a controller. And likely not the motor. But the batteries? Yes, and unfortunately the most expensive component in the setup you're inclined to purchase.

I recommend you at least look at the http://www.falcoemotors.com/ 1500 watt motor. And be assured purchase of a whole kit from a quality vendor will be component matched.

 

[thatdifferentguy]

There is a 3,000 watt wheel, I'm assuming I need to purchase a higher spec system to get a consistent speed I want?

I know Voltage = Top speed and Amps = torque/power. Would a 40 amp 72 v battery give stable consistent speed at 60-70 km/h?

 

[arkmundi]

There is a 3,000 watt wheel, I'm assuming I need to purchase a higher spec system to get a consistent speed I want?

I know Voltage = Top speed and Amps = torque/power. Would a 40 amp 72 v battery give stable consistent speed at 60-70 km/h?

You should go back to the drawing board and reconsider everything. You're planning on putting this on a bike? What about being street legal at those speeds? Suspension? Tires & tubes & rims? To be safe on the road at higher than bike speed, you need to think about the whole apparatus. And get it registered, which is a whole other league. Fastest bikes should go on the road is 35 km/h (22 mi/h). Voltage + Amps = more battery = expense = less distance per amp-hour used. Think about all that.

 

[Drunkskunk]

First of all, a 70kph bike is called a motorcycle. A bicycle can survive hitting that kind of speed for a moment, but sustaining that kind of speed will tear a normal bicycle apart. standard brakes, tires, bearings, and frames will all fail at those speeds. In order to build an ebike that can travel at motorcycle speeds, you need to run some specialized parts.

As for the motor, 70kph takes 2500 to 3000 watts of power for a typical bicycle shaped vehicle. to sustain that kind of speed, you need a motor that can handle the heat, and a battery than can pump out that many watts normally. Few motors will do it at just 72 volts. As for the battery, there aren't many options for a battery that can sustain that kind of output. A typical ebike battery was designed around giving 360 watts output continuously, and maybe twice that for short durations (36v 10Ah 1C battery, 2C peak). That's good for 32kph on most systems. Anything above that is going to need higher performance batteries.

Also consider that 72V 40AH of LiFePO4 battery would weigh 30KG, 66lbs! And would be something like 300mm X 300mm X 250mm. Try strapping 66lbs of bulky battery to your bike frame in a way that doesn't compromise handling. Ain't going to happen. you'd need a frame the size and strength of a motorcycle to house that kind of bulk securely.

 

[thatdifferentguy]

Where I live (rural) its mostly straight flat roads and very little traffic. Anything under 70 km/h is legal. And I forgot to mention This is a completely new build. Trying to get the electric part decided before I purchase the bike parts.


Again I won't be doing any mountain biking or going offroad.

 

[tahustvedt]

I hit 70 km/h regularly on my road bike. My fastest speed ever is 80 km/h. I weigh 64.5 kg. Heavier riders than me go much faster. The bikes are designed to handle heavy riders going fast. I ride with people weighing 80-130 kg on road bikes. I wouldn't worry too much about the brakes if you're a light rider like me, but the power train and drive wheel will really suffer if it regularly has to handle 3000 W, the dropouts probably can't handle it either if it's a hub motor.

70 km/h on a road bike takes about 1600 W to do in a tucked position. A MTB needs 2600 W to do it without tucking.

 

[thatdifferentguy]

I hit 70 km/h regularly on my road bike. My fastest speed ever is 80 km/h. I weigh 64.5 kg. Heavier riders than me go much faster. The bikes are designed to handle heavy riders going fast. I ride with people weighing 80-130 kg on road bikes. I wouldn't worry too much about the brakes if you're a light rider like me, but the power train and drive wheel will really suffer if it regularly has to handle 3000 W, the dropouts probably can't handle it either if it's a hub motor.

70 km/h on a road bike takes about 1600 W to do in a tucked position. A MTB needs 2600 W to do it without tucking.

Thanks very much for your perspective, my first bike was pre-built and this will be my first time choosing components , I have standard 26" mountain bike. I'm trying to convert the volts, amps and other measurements into the speed goals I want. Approx 60 km/h maybe 70 on those long straight away. Yet I don't wanna constantly run the motor or battery at its peak to obtain these average speeds. I'm currently looking at a 1,500 w front wheel setup with a 48v, 20 AH LiFePO4 battery. Or a 3000 watt midmounted kit at 72 v and 12 AH kit?