Need some advice on configuration for DIY electric bike.

lowriderzzz

lowriderzzz

10 µW
Joined
May 16, 2018
Messages
5
Location
Varna Bulgaria
Hi there. I'm new to the forum yet I read many discussions and watched some videos.

For quite some while I have wanted to convert my standard bike into a electric one, yet I always postponed to do so. This summer I'm already committed to do so.

I'd be glad if you give me an advice on what do you think of this configuration.

Mid drive motor Bafang 500W 36V - LINK ->https://goo.gl/RUuQUZ
And Silver fish battery 36V 12Ah LINK -> https://goo.gl/oN7TeH

What do you think of that as a configuration and of a first DIY bike.

My aim to get transported around the town where I live - low to modest hills terrain.
If I could do about 100 kilometers range that would be great and top spread of 45 - 50 kmh would be more than enough.
Do you think that battery would do or I would need a more powerful 18Ah one?

Your replies are much appreciated.
Thank you!
 
For the speed and kilometers you desire, you would need a bigger motor and bigger battery.

If you want to go 45-50 kph, (25 - 31 mph) you will probably need a 48v motor unless you pedal really hard.
Around here we use 25 watts per mile as a reasonable bench mark. For you that would be 1.6 kilometers per 25 watt hours of battery usage. So, 100 kilometers at 48 volts you would need a battery capacity of about 33 amp hours.

These figures are general and you might be able to pedal enough to reduce your battery capacitance needs by some degree.

But remember, once you convert your bike to an e-bike the weight increases due to motor and battery weight so the pedaling becomes harder due to the weight.

Realistically, what you propose is not what is normally and practically done around here. The weight of large batteries makes long distance e-biking impractical. Although, some around here, those who take long road trips sometimes use trailers with extra batteries in the trailer.

It is possible to go 100 kilometers on the setup you proposed, but the motor would only be able to supply about 1/3 of the power needed to go 45-50 kph. You would have pedal hard to provide the rest of the power needed.

Have you ever ridden a heavy bicycle 100 kilometers using only your human power?

:D
 
e-beach said:
Have you ever ridden a heavy bicycle 100 kilometers using only your human power?

:D
Click to expand...

Truth to be told - no. I see now I might have given an unrealistic number for speed.

So with the stated configuration what speed and range do you think would be realistically to achieve?

Is this motor actually compatible with that battery?
 
My bike is in the range of what you are asking. I run a 1000 watt direct drive hub and have about 20 lbs of battery that supply about 32 amps at 36 volts for about 1200 watt hours of energy storage. My bike will go just over 30 mph which is right around your top speed specification. But at that speed it won't go the distance you want. My bike weighs about 60 lbs which is pretty heavy IMO.

On my normal commute I travel at between 20 and 25 mph or about 30 - 40 km/hr most of the time. At those speeds I use about 20-22 wH/mile or 13-14 wH/km. That gives me nearly your range of 100 km, but I tend to pedal a fair bit when I ride. You'll do better or worse depending on whether you pedal more or less. I can ride even longer distances if I exercise discipline and keep my speeds below 20mph (around 30km/hr) - and much longer if I go even slower. Wind resistance increase exponentially as you increase speed.

Motor size won't affect range much. How hard you drive the motor will. So the bottom line is that for the 100 km of range you'll want your battery to be in the neighborhood of 1200 wH of storage. So that's more like two 13ah 48v packs.

I'm not familiar with that motor or mid-drives in general. But in general, if you want to go fast or kinda fast, you'll want to lean toward a higher voltage. So 48v would be the place to start IMO. It isn't like there is generally a premium on batteries running at higher voltages. They are all the same basic thing, just wired up a bit differently to yield higher voltages and lower amperage given the same or similar amounts of cells.
 
wturber said:
........but I tend to pedal a fair bit when I ride. ......
Click to expand...

A fair bit seem a polite way to say "A Lot." :lol:

:D
 
e-beach said:
wturber said:
........but I tend to pedal a fair bit when I ride. ......
Click to expand...

A fair bit seem a polite way to say "A Lot." :lol:

:D
Click to expand...

Not "a lot" from the standpoint of degree of effort. But from a quantity standpoint, sure. I pretty much always pedal with effort.

But that effort probably averages out to only about 100 watts (150 watts at most) based on what I can infer from the Grin Simulator.

http://www.ebikes.ca/tools/simulator.html?bopen=false&motor=M2706&batt=cust_54_0.2_20&hp=100&axis=mph&throt=65

Back when I commuted only 9 miles one way on my road bike I'd estimate I was putting out around 200 watts on average. So these days it doesn't seem like that much effort. The calculator, my subjective impression, and how much I sweat and ache all seem to jibe with my effort being about half what it was on my regular road bike. I'm going twice as long now with about half the effort per mile. ;^)
 
wturber said:
... So 48v would be the place to start IMO. It isn't like there is generally a premium on batteries running at higher voltages. They are all the same basic thing, just wired up a bit differently to yield higher voltages and lower amperage given the same or similar amounts of cells.
Click to expand...

Thanks! I still don't quite understand something. If my motor is for 36V then if I power it with 48V batter (no matter ho much Ah) will not that damage the motor, since I'm supplying it with more voltage.

* the desired parameters I stated in the original post are the ideal, but I'd be glad too for less as long as they are optimal for the system (motor + battery). And in that line what would be the optimal battery for a 500W 36V motor in your opinion?

Thank you.
 
Generally 36v motors can handle 48v if the motor is not being stressed like going up a long hill. When one over-volts a motor they run the risk of over-heating the motor and burning it out.

However, I am not familiar with the motor you posted so I can not guarantee it will not burn out with 48 volt input. I have a 36v hub motor that can handle 48v without problem around here because I ride on mostly flat streets. And, the hills I climb are short, generally not longer then 1/4 of a mile.

Also, if you go with a 48v battery you will need a 48v controller and an applicable charger.

:D
 
Ok after a bit of more research on this motor, 48v should be fine, however you may need need to keep the amps low so not to burn out the controller and the battery voltage setting low to keep the motor from stopping due to the controller thinking the battery is drained as the battery gets low.

From this website:https://electricbike-blog.com/2015/06/26/a-hackers-guide-to-programming-the-bbs02/

........The biggest problem with the BBS02 is when it is turning under too much load at too low of a speed. The best way to keep the motor spinning fast is to get a smaller chain-ring and to make sure you are in the right gear for any hills you want to climb. The surest way to blow your controller is to use full throttle in too high of a gear on a hill where the pedals are turning too slowly. If you use a large chain-ring on your commuter (mine is a 52T because I like to go fast) make sure you shift down into a lower gear before coming to a stop even on level ground so you are not repeatedly trying to start moving in too low of a gear. Your pedaling cadence should always feel normal to fast, especially on hills............

.....If you are running a 48v nominal pack you’ll want to set this a lot lower (like 38v) to keep the drive from shutting off when the pack still has a little juice in it.

Limited Current(Amps): 25/25/18/18 to 20/25 This sets the power level that the drive unit will pull from the battery pack. Be aware that just because it is set lower, does not mean that it will not draw more amps for brief periods. If you don’t want to stress the BMS you may want to set this number lower than you think it should be by 2-3 amps then slowly increase it over time if your $15 watt meter shows that it is not pulling too much power on a regular basis. This variable will be set lower than 25 if you have a BBS01 or a BBS02 with a lower power level rating than 750W. If this is set lower than 25 from the factory you CANNOT RAISE it safely unless you are sure it is a 750 Watt unit & controller and your battery can handle the draw (it should say on the bottom of the unit). Matt from Empowered Cycles has this to say:

“I recommend 18 amps in most cases. You still get amazing performance, prolonged controller life, more charge cycles from your pack, more range on your rides. If you have an internally geared hub, I recommend 15 amps and changing the “start current” on pedal assist and throttle all the way down to the lowest setting of 1. Even at 18 amps the 750 watt motor keeps up with an 8T geared MAC hub motor that is pulling 1500 watts. You do not need 25 amps for this motor to perform.”

Kepler has this to say

“ I agree that 18 amps is a good all-round setting. I then rely on the Limit Current Assist level to fine tune the max power best suited to bike.”
Click to expand...

I am now of the opinion that the setup you are thinking about will require A LOT of pedal power to get anything close to what you envision and probably won't get there. You should lower your expectation on both speed and distance with this setup.

:D
 
Thanks for the info and shared link.

So what in your opinion is the best fit for the motor I posted from the batteries presented in this store.
https://www.aliexpress.com/store/604490?spm=2114.12010615.0.0.65f25e3f3pnovI (under the products tab)
 
Quite honestly, I don't know that company and would recommend sticking with known and trusted companies like
http://www.ebikes.ca/
or https://em3ev.com/
or http://www.pingbattery.com/
or https://lunacycle.com/

There might be other trustable places but if you sending your money to China is always a gamble.

What I would say is if you want speed you need volts. 36v won't give you high speed. 35 kph more or less. If you want range, you need amp hours, as many as you can fit on your bike before it gets too heavy. I am a big advocate of putting the batteries in the triangle of the bike for best weight distribution. However if you get a 20 amp hour battery, it might be too big to fit in the triangle and then it has to go some were that would destabilize the bike somewhat, like the rear rack.

Which brings up the question, what kind of bike are you going to convert.

And make no mistake, e-bikes are heavy.

:D
 
e-beach said:
Quite honestly, I don't know that company and would recommend sticking with known and trusted companies like
http://www.ebikes.ca/
or https://em3ev.com/
or http://www.pingbattery.com/
or https://lunacycle.com/

There might be other trustable places but if you sending your money to China is always a gamble.

What I would say is if you want speed you need volts. 36v won't give you high speed. 35 kph more or less. If you want range, you need amp hours, as many as you can fit on your bike before it gets too heavy. I am a big advocate of putting the batteries in the triangle of the bike for best weight distribution. However if you get a 20 amp hour battery, it might be too big to fit in the triangle and then it has to go some were that would destabilize the bike somewhat, like the rear rack.

Which brings up the question, what kind of bike are you going to convert.

And make no mistake, e-bikes are heavy.

:D
Click to expand...

Those are nice links but I don't live in the states. I'm from East Europe, so the Chinese items work for me, since all of the stuff offered here on the market is initially bought from China too.
 
lowriderzz, I'm not sure that the 36V Bafang BBS02 kit can handle 48V. There might be a high voltage limit in the controller circuitry. I have a 48V BBS02 kit and it will not run on a 36V battery. I get a low voltage alarm. I noted that the low voltage limit appeared to be programmable, but was told here that its fixed in hardware at 43 volts.

Also, on 48V the max speed of my BBS02 (750W) kit is around 28 mph on flat ground. My aluminum bike with BBS02 weighs around 55 pounds with battery. I once pedaled mine almost 20 miles with a non working battery. It wasn't bad.





.
 
I you need to order out of China,
https://em3ev.com/
and
http://www.pingbattery.com/ are both in China.

If you really want to order from that company, get a 48v setup with the 18ah battery and know that you will not get the speed or range you desire without a lot of pedaling.

:D
 
California eBikes sells batteries and has a good warranty.
 
tomjasz, Good to know about California E-Bikes, I usually think of

Em3ev.com

Lunacycle

and

Grin Technologies

for batteries,

However lowriderzz says he is living in Eastern Europe, so it does not make sense for him to buy from the U.S. or Canada , that leaves buying from China , in that case Em3ev.com is the high rated company for high quality battery packs there in China .


tomjasz said:
California eBikes sells batteries and has a good warranty.
Click to expand...
 
Doug at California eBike can ship to Europe.
 
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