Help needed with buying components

[Moss Davis]

Hi everyone,

A couple of years ago I had an amazingly powerful 500W 48v hub motor system from these guys - https://www.electricbikesales.co.uk/boss-super-system

Stupidly I sold it when I needed the cash, and I'm looking to build my own kit now on the slightly cheaper side.

Basically I would like some advice on a decent motor/controller setup. All the ones on eBay look terrible quality - the kit I has last time was really good quality and took an absolute beating.

Thank you!

 

[Deleted member 4366]

That Boss Kit adverts used to show a 500w geared hub-motor, either a Bafang CST or a MXUS or Xofo clone. It's not clear what motor they use now. One forum member went in for one of those kits, but he got a 1000w direct drive motor and an overweight LiFePo4 battery hanging over his back wheel that made the bike unrideable.

You can buy a really nice kit with that motor at relatively low cost from BMSBattery, where I get most of my stuff. How fast do you want to go because it's important that you choose the right voltage and RPM to get that speed? Are you able to build your own wheels or do you need a ready built one?

You can see the first monstrosity (minus the battery) in this thread along with the second version that used the Bafang motor at the end of the thread. There's now off-the-shelf batteries that go nicely with the motor, so no need to make anything special.

http://www.pedelecs.co.uk/forum/threads/help-wanted-with-boss-adjustment.17988/page-3

 

[Alan Quay]

I have a 500w CST here, 270 RPM (22-23 mph) in a 26 wheel. Its done about 500 miles.

I may be prepared to sell it (and a suitable 30a controller) if the price is right. I would prefer a smaller rear motor, with cassette.

 

[Moss Davis]

I have a 500w CST here, 270 RPM (22-23 mph) in a 26 wheel. Its done about 500 miles.

I may be prepared to sell it (and a suitable 30a controller) if the price is right. I would prefer a smaller rear motor, with cassette.

How much are you asking? - I have no idea what it would be worth haha

I was planning on building a custom shaped battery? is this doable with the right BMS and Cells?

 

[Moss Davis]

And essentially I want to match the Boss Kit I had before - that got me about 35-40MPH

 

[Alan Quay]

And essentially I want to match the Boss Kit I had before - that got me about 35-40MPH

Ah, well this motors no good for you then.

 

[Deleted member 4366]

You need 1000w to reach 30 mph and about 2250w to reach 40mph on a MTB type bike. That's output power, so you'd be looking at 1400w and 3kw from the battery.

30 mph can be done with some off-the-shelf kits, like what Em3ev sell. The cheaper Ebay kits probably fall a couple of mph short, but the batteries won't give you much range at that speed.

If you want 40 mph, you're looking for some serious kit that won't be cheap.

I just fitted a slightly hot-rodded BBSHD kit with 14S (52v ) battery. It does around 30 mph and cost about £1200 plus duty.

 

[Swytch Bike]

HI Moss

We recently added stock of the Bafang 500W rear drive motor kit. With a suitable battery we have managed to get 60kph out of it on a racing bike.

It's an authentic Bafang 8FUN motor and a decent control system, so it will take a good beating, and the power and quality is second to none.

Obviously there are other similar kits out there for you to look at but this one is worth a look

http://www.pandaebikes.com/product/bafang-500w-rear-wheel-ebike-electric-bicycle-kit-48v-authentic-8fun-motor/

Cheers

 

[Moss Davis]

HI Moss

We recently added stock of the Bafang 500W rear drive motor kit. With a suitable battery we have managed to get 60kph out of it on a racing bike.

It's an authentic Bafang 8FUN motor and a decent control system, so it will take a good beating, and the power and quality is second to none.

Obviously there are other similar kits out there for you to look at but this one is worth a look

http://www.pandaebikes.com/product/bafang-500w-rear-wheel-ebike-electric-bicycle-kit-48v-authentic-8fun-motor/

Cheers

That looks like the one! Epic, thanks

 

[Deleted member 4366]

Bear in mind that a BPm that can do 60km/h will have a very low efficiency when climbing, so you'll get less power and it'll overheat.

For a BPM in a MTB with 26" wheels, the best winding is round about 260 rpm (code 12 or 13).

 

[Moss Davis]

Bear in mind that a BPB that can do 60km/h will have a very low efficiency when climbing, so you'll get less power and it'll overheat.

For a BPM in a MTB with 26" wheels, the best winding is round about 260 rpm (code 12 or 13).

I'm a complete novice, I have no idea what you just said haha!

 

[Moss Davis]

Just found your quote from a 2014 post about the BOSS Kit. Here you said

"That's interesting. It's a 48v Bafang CST with a code number on it like you get on the BPM. I've not seen that before. In fact, I don't think I've seen a 48v CST before. It's marked code 9, which means 352 rpm. That's about 25 mph; however, I'm not sure if you get a 33% increase on that speed with 48v. I didn't think you did, but they're claiming 30+ mph, so it's probably 33mph."

I need this motor! Im telling you the setup was insane.

Many thanks

 

[Deleted member 4366]

When you buy a hub-motor, you have to balance a number of parameters. Basically, you can't have one that can go both fast and slow. Also, you need to match the speed and power. A BPM is a 500w motor, which means that you can run all day with an output of 500W, which is about 24 mph. You can run it with higher power for a short time, but it will eventually overheat.

To sustain 60km/h you need about 2000w output power, which means 2700w input power from the battery or 56 amps from the battery. The highest you can safely run a BPM is 25 amps at 48v. In other words, you can lift the wheel of the ground and if it will spin up to 60 km/h, the only way you'll get that when riding is down-hill with the wind behind you unless you have a streamliner type bike, so don't expect to put that motor on a bicycle and ride around at 60 km/h. Note that Panda mentioned it was on a road-bike, probably in a full tuck wearing lycra and shaved legs, not an MTB.

If you don't understand these things, don't buy a motor without discussing it with us first. If you tell us what you want to achieve: What sort of bike. what sort of rides, how heavy you are, how much you want to spend and how fast you want to go, we can advise you on suitable kit.

 

[soundwave]

http://www.ebay.co.uk/itm/122018434932?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

how fast could that go max every thing power wise?