first build

[haddy]

hello

i am a 65 year old electrician and BSA restorer. I am looking for a more sedate ride 20 k distance max.My plan is a two wheel drive using magic pie edge and two 15ah batteries driven by a throttle,Each battery bank will be turnigy 18v 5000mah.
running at 36v. Six batteries in each bank. Giving me 36v and 15 amp per bank.
Any advice on my plan would be helpful

haddy

 

[dogman dan]

Should work fine, but unless you tell us why you need two motors, you don't. Not enough information about your battery to know what you mean on that.

36v 15 ah is more than plenty to go 20 k per charge. 36v 10 ah plenty, actually.

 

[pwd]

How fast do you need to go? What kind of bike are you using?

As dogman has already pointed out; you probably don't need 2WD. The Edge looks like a pretty nice motor. I've been using magic pies for 5+ years and the internal controller do make for a cleaner setup.

 

[haddy]

Hello
The bike will come from the Dump Shop.
Two wheel drive for grunt and low batt loading.
I will make my own battery packs using Turnigy LI-Po 5000mah 18v from Hobby King $60 each.
Six batteries in a series parrallel circuit gives me 15ah at 36 volts.Two packs one for each wheel.If 10ah per wheel gets me 20k range even better.
haddy

 

[motomech]

I think you need to rethink your plan and maybe do some reading on using LiPoly, as you are going to have a mess of wires, connectors and batteries to deal with.
What is your charging plan?
What is your plan for a BMS?
The first rule when using LiPoly on an Ebike is the have a hard Low Voltage Cut-off(LVC). I match my controlles to my packs and the best match is 12S. Most 48 V controllers have a 42 V LVC, which when using 12S, the LVC is 3.65 V/cell, very good. A 36 V controller with a LVC of 31 Volts leaves a 10 S pack with the cells @ 3.10, tool low. 9S works ok. For that, and many other reasons, I would use 12S.
The second rule is, don''t "break" the pack to charge. It leads to accidents and makes keeping the cells balanced more difficult. That means bulk charging w/ a system to check and balance the cells when necessary. Lot's of good solutions here if you care to do a search.
To facilitate bulk charging, the third rule is, use the largest bricks that fit the space to get the Voltage you want, to eliminate as much of the "rat's nest" as possible. It the required constant dis-charge is 40 Amps or less, Multistar is the LiPoly to use. It trades high dis-charge rates for lighter weight and greater capacity for a given size. They are also available in large bricks, like 6S/10Ah and 6S/15Ah. If they fit your space, you could use 4 bricks of 6S/15Ah to get 12S(46V)/30Ah and it would be much simpler.
This is enough to get you started to research your build.
Other things you will need to considerare;
How to interface a throttle(s) to 2 controllers.
and
how to keep the frt. whl. from spinning when a powerful rear whl. system tend to lift the frt. end of the bike.

 

[haddy]

Motomech
Thanks for the input a lot to digest. What is BMS.

i have been building switchboards for automated systems for 20 years so the wires wont be a problem. The way i look at it is a li-po cell is 3.7 volts.So to get 36v at 10ah can only be done one way.IE ten cells in series parallel with ten cells in series regardless of brick size.Granted it would be less wire.
The only reason i consider this system is because i can make a 36v 10ah batt for $240. If i could get a ready made batt for a reasonable price i would jump at it.
My only experience with li-po electric is model aircraft. I have drawer full and chargers.
The only reason i am going for two wheel drive is because i can and have made this post to see why i should not. Falling of hurts.
haddy

 

[haddy]

As far as the throttle a single throttle paralleled to the two controllers i thought would work maybee
haddy

 

[macribs]

I salute your choice of going 2wd. Nice.

I think 2wd will be sweet. Have been only a few of them build here, ie look up the duty cycle awd for inspiration. Those mac motors he runs I am pretty sure I've read here on ES have been run successfully at 3kw. And the weight is only about 4 kilo.

I think you will find lighter and cheaper motors then the magic pie edge, as I've seen those MP edge retails for >500 $. The weight iirc is about 8 kilos?

Have you had a look at that front wheel motor with 20 mm thru axle from http://www.ebikes.ca? I think they are planning a rear wheel version too. This front motor is only 4 kilos. They also have a tiny form factor foc sine wave controller called phaserunner. Of course there are other small and light motors that would be well suited for a 2wd, and also a wide range manufacturer and vendors both for motors and controllers.

What is your target max speed and max laod? And what type of riding and terrain? That will possibly impact your choice of motors, controllers and wheel size. If you run direct drive hub motor wheel size will be your gear ratio, higher outside diameter means less RPM for motor and harder for motor to work. If wheel size matters to you say for design purpose or you just fancy tall wheels look at geared motors as well. Typical geared motors are lightweight only like 2-3 kilos or so.

Check out the e-bike simulator where you can get some ideas how how different motors and controllers will behave on various loads and various steep grades the hills you will be riding.

There are loads of motors to choose from. When you decide you should read up on the chosen motor here on the forum to see what to expect and if there are certain do and don'ts for the motors of choice. Be sure to play with the simulator to see how well motors will work for you and your type of riding, terrain and load haul.

Enjoy your e-bike journey, and welcome to the community.

 

[OptimusPrime]

If you just go with one motor the money you save will allow you to buy a great pre built battery. I match a 52 volt 13 ah battery with a magic pie edge and love it. If you did that you'd have money left over and running at 52 volts instead of 36 would make up for the lost motor to a large degree.

 

[d8veh]

Where are you located? If you live in UK, it's likely that the cops will take a bike like that from you and crush it. You need something more stealthy. Also, there's little point in using lipos these days. Weight is your enemy, and modern ebike batteries will weigh half as much and last twice as long without costing much more. They're plug-and-play, so no complicated charging procedures.

 

[ferret]

modern ebike batteries will weigh half as much and last twice as long without costing much more.

To my knowledge, it's the other way around, can you post a link to those modern ebike batteries that outperform LiPo?

Avner.

 

[haddy]

Thanks Macribs for the advice and encouragement. The more i learn the more complicated it gets.

setting the system up won,t be a problem but sourcing the right components is.The best price i have so far for spokeing two hubs is $500 AU that includes double wall rims.

haddy

 

[motomech]

It IS complicated, especially using LiPoly.
If you don't know what a BMS(Battery Management System)is, you really shouldn't be messing around w/ LiPoly.
I think maybe Dave mis-spoke, LiPoly is still lighter and more powerful than other chemistries at this time, but perhaps he meant to say(I don't want to put words in his mouth), is the "Plug and Play" batteries are getting better all the time and the Li-Ion packs are light enough, and given reasonable discharge rates, powerful enough.
And his point about using two huge motors w/ 2WD is valid. Not needed for normal street riding.
You need to establish your goals first, how fast, how far, what hills will you be climbing, etc., and then design the build based on that. By picking components that are not well matched, you are placing the "cart before the horse"
Many of us like BMS Battery for their batteries and motor selection. Something like a 2WD with mid-sized geared motors like the Q128, could provide all the power that one would need.

 

[macribs]

Here is the q128 motomech was mentioning. They got motors, batteries etc. 99$ for the q128 motor.
https://bmsbattery.com/ebike-kit/775-q128h-36v800w-rear-driving-ebike-hub-motor-ebike-kit.html

 

[d8veh]

modern ebike batteries will weigh half as much and last twice as long without costing much more.

To my knowledge, it's the other way around, can you post a link to those modern ebike batteries that outperform LiPo?

Avner.

One of these will drive a BBSHD about 10 miles

https://lunacycle.com/52v-mighty-mini-cube-ebike-battery-pack-panasonic-ga-7ah-3-pounds/

This one gives 1.3 kWh and 50 amps at 12 pounds

https://lunacycle.com/triangle-52v-panasonic-ga-18650-24ah-pack-high-power-long-range/

We'll be seeing a lot more of these shortly at 224Wh per kg:

https://www.orbtronic.com/20700-panasonic-sanyo-ncr20700b-battery-rechargeable-li-ion

Em3ev.com also have some nice batteries.

 

[ferret]

I've made a table comparing the Luna packs to Hobbyking LiPo Packs (see links).
I think that although they are not the best solution to everyone, LiPos cost much less, deliver more current and only weight slightly more.

https://hobbyking.com/en_us/turnigy-graphene-10000mah-6s-15c-w-5-5mm-bullet-connector.html
https://hobbyking.com/en_us/multistar-high-capacity-6s-20000mah-multi-rotor-lipo-pack.html



Avner.

 

[d8veh]

Nobody's saying that lipos aren't cheaper to buy; however, if you look at overall costs, the pendulum swings the other way. To use lipos, you need a lot of additional paraphernalia - chargers, balance boards, leads, connectors and monitoring system; then you include the cost of the lipos that you brick (everybody does it some time); then you consider that lipos have a life cycle of about half that of 18650s. Considering all that, it doesn't make economic sense to use lipos, and with Multistars at something like double the weight of 18650s, they don't make such a good choice for an electric bicycle anyway, where weight is a significant characteristic. What they're good for is giving you flexibility on overall voltage and capacity, which is good for experimenting and testing. On a bike that I want to just ride, it'll always be 18650/20750s for me until something better comes along. Each year, the 18650s have become significantly better.

 

[tln]

Nobody's saying that lipos aren't cheaper to buy; however, if you look at overall costs, the pendulum swings the other way. To use lipos, you need a lot of additional paraphernalia - chargers, balance boards, leads, connectors and monitoring system; then you include the cost of the lipos that you brick (everybody does it some time); then you consider that lipos have a life cycle of about half that of 18650s. Considering all that, it doesn't make economic sense to use lipos, and with Multistars at something like double the weight of 18650s, they don't make such a good choice for an electric bicycle anyway, where weight is a significant characteristic. What they're good for is giving you flexibility on overall voltage and capacity, which is good for experimenting and testing. On a bike that I want to just ride, it'll always be 18650/20750s for me until something better comes along. Each year, the 18650s have become significantly better.

I agree that TCO makes lipos less attractive. I spent $150 shipped on two 6s 16Ah multistars (cheap!) but $150 on a 12s charger + power supply for instance. And then more on other random things like connectors etc.

I don't agree on the weight of 18650s vs multistars. If you use finished battery weight and capacity under a 1-2C load I think you'll find the multistars win or it's close. And less than 10% either way, ie less than 1lb.

The pace of improvements on 18650s is pretty awesome.