Conversion Kit Build

[raydaffurn]

Hi All,

Been reading the forum for the last month or so trying to gather up as much info on this as I can and have decided to register as I am now looking to purchase the parts required to build my e-bike.

I haven't purchased a bike yet so was looking to get a secondhand geared alu framed mountain bike (£100-150?) with suspension and then fit a kit to this. To be honest I have no idea if I need to get a specific type of bike or would what I have suggested be suitable or what must it have to do a conversion?

I weigh 80kg approx and was looking at purchasing a 48v 1000w rear wheeled kit and fitting a LifePO4 battery to this with a BMS. Im looking to use it mon-fri commute to work, 9/10 miles with some up/down hills along the way. Trying to get something built for the £600-700 mark

The kit I am looking at is

http://www.ebay.co.uk/itm/190918732542?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The battery I am looking at is

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=181440457652

I would then build some kind of case and mount to the frame. (any suggestions welcome)

From what I have read a 15ah should allow me to get to work, charge it then get back home (correct me if im wrong)

A few questions I have:

Does the bike/battery/kit I have suggested look ok and would it suit what I need it for (would the battery cover the miles I need it to do)
What else do I need other than what I have listed
Is there any other similar spec kits anyone knows of that is cheaper
Is this easy enough to build, I have basic mechanical knowledge
BMS - I cant see one in the battery pic, is this just a monitoring system to show how the cells are and I just watch this and make sure they are equally balanced.

Any help is appreciated and thanks in advance.

Ray

 

[raydaffurn]

Also forgot to advise had been looking at this kit also:

http://www.bmsbattery.com/hub-motor/429-magicpie3-third-generation-ebike-hub-motor.html

Is this a better kit than what I had looked at and if so does it come complete with everything I need (except bms battery) and if so will it be suitable with the battery in the link above.

Thanks
Ray

 

[Deleted member 4366]

Hopefully the BMS is inside the covering, but you need to check with the Vendor to make sure. Personally, I wouldn't recommend a LiFePO4 battery because they're a bit on the heavy side. Yo'll struggle to put it anywhere other than the rear rack. With a very heavy rear motor too, your bike will be unmanageable. Also that battery is a bit on the week side at only 15ah. Its rated at about 15A, but the controller is at least 25A. Plus, a lot of people have problems with thosr cheap LiFePO4 batteries.

Have a look at BMSBattery.com. They have some high discharge rate batteries for 25A or more.

If you want to go for a high power motor like that, you'd be much better going for a donor bike with a steel frame and disc brakes. Those full suspension Trax bikes are pretty good if you can find a disc brake version.

 

[raydaffurn]

OK so for bike steel frame and disc brakes.
I take it with gears/suspension is OK and the alu bikes is it because they are too soft? And as long as the battery fits in the frame I should be OK?

What about the kit which one looks better (personally I think the BMS one) and do they come complete I.e. other than a battery I don't need anything else?

Regarding the battery on the BMS site it refers to 3 batteries that will suit that particular kit (30-60a discharge current - Ill make sure I get one above 25A) but all of these seem to the LiFePO4 batteries which are the heavier ones.

Can I pick one of the normal lithium (lighter and cheaper) ones?
What ah do you recommend then for my needs?

 

[raydaffurn]

Looking at these 2 options if the standard lithium ones are ok, would they be suitable

48v 15ah 4.3kg 30-60a $309
http://www.bmsbattery.com/battery-pack/664-36v-12ah-38140-lifepo4-battery-12-cells-ebike-battery-pack.html

48v 20ah 6kg 50-100a $419
http://www.bmsbattery.com/673-high-c-rate-48v-20ah-li-ion-battery-heat-shrink-battery-pack.html

 

[Deleted member 4366]

Yes, those batteries are suitable, but you've got to think about installation. Those big DD motors are surprisingly heavy. you need to get the battery as low as possible and in front of the seat-post, which is not easy. The preferred reliable option for those that want to go fast is the modified MAC motor from Em3ev,com along with their triangle battery and frame bag, but you're looking at over £1000 for the kit. Building an electric bike is easy with low power, but as you go up in speed, it becomes a lot more expensive and complicated.

If I were you, I'd start with something a bit less powerful. High powered bicycles are not that pleasant to ride - as you'll probably find out.

 

[raydaffurn]

I need higher power as I'm quite busy so want the commute time to be as short as possible.
If I get a bike that I can fit one of those batteries in the frame then am I good to go, just the kit and the battery nothing else needed?

Only other question I have is do I need 15ah or 20ah what sort of distance would I get full throttle constantlywith each?

 

[Deleted member 4366]

You'll use about 1ah per mile or maybe a bit more.

 

[raydaffurn]

thanks.

right one last question before I purchase, will the kit take a bike with a rear disc brake? and also what is the max gears it will take, I have read up to 7 (so 3x7, 21 speed) cogs at the back so stay away from 8 and 9 cog bikes, is this right?