350w 48v rear hub motor with 36v battery

[Kelp]

I am looking to purchase a Bafang Kit from BMS Battery which is their 350w 48v rear motor kit but want to use the 36v bottle style battery. How will that combo work?

I ride predominantly on the flat but in 20knot headwinds often and would like to maintain 25kmh for my 20km commute. I'll be installing on a 700c size bike and chose rear motor for its more discrete look. Does the lower voltage drop the effective power to 250v or something?

Also frustrated that I can't seem to find anyone selling the black versions of the Bafang motor kits [ie not just rim but black motor too] which I know are on 8fun/Bafang site but know one seems to sell them.Anyone out there know where I can find them?

 

[Kelp]

I am looking to purchase a Bafang Kit from BMS Battery which is their 350w 48v rear motor kit but want to use the 36v bottle style battery. How will that combo work?

I ride predominantly on the flat but in 20knot headwinds often and would like to maintain 25kmh for my 20km commute. I'll be installing on a 700c size bike and chose rear motor for its more discrete look. Does the lower voltage drop the effective power to 250v or something?

Also frustrated that I can't seem to find anyone selling the black versions of the Bafang motor kits [ie not just rim but black motor too] which I know are on 8fun/Bafang site but know one seems to sell them.Anyone out there know where I can find them?

 

[DAND214]

Yes the power will be down. You might also have a early lvc in the controller. Why don't you get the 36v kit?

Is it cause the 350w or because it's cheaper.
I would get the 36v 500w and be done.
Dan

 

[dnmun]

yep, it won't run because the LVC will cut off at 40 1/2 volts. and slomo.

 

[d8veh]

You could ask them to swap the controller for a 36v one, which I'm sure that they'd do.

That doesn't help much because the bottle battery won't give enough power for the motor, so the BMS will trip-out every time you pull away or go up a hill. you need a battery that's rated at about 15amps and can provide 30amps max. That means Headway cells, A123 cells, Lipos, or any other battery of at least 15aH capacity.

 

[Kelp]

Thanks all, I am starting to get it now. I will try get a 36v unit. Have actually always preferred the SWXH units [36v 250w]but they are not available in a kit.
http://www.bmsbattery.com/hub-motor/42-qswxh-rear-drive-brushless-hub-motor-for-ebike.html
I assume BMS sell all the part separately anyway and I can get the rim built here. If buying all parts separately, anything I should look out for like cabling/ connectors etc that may easily be missed. What types of connectors and cables do I need?

 

[motomech]

Just get the Cute Q100 36V/350 watt 201 kit.

A least two Ebike owners here who have used both the SWXH and the Q100 prefer the Cute, stating that it is both quieter and slightly more robust.
It also has an advantage for your intended install[at least as much as I can glean from the sparse info. you have provided[too much about what you want to do is better than too little].
It will accept up to a 9-speed freewheel[very nice if your donor bike uses a 8 or 9-speed cassette].
With a 700 cc wheel, a mini geared motor and stiff headwinds, some gears to pedal assist will be nice.
You need a battery with some reserve, at least a 36V 10 Ah. I would recommed LiCoMg.
Also, the wires on the Cute exit on the left, the non-chain drive side. A nice touch.
There is a lot of reading you could do, here, or maybe better, at Pedelecs UK.
You might consider subsituting the BMS 9-FET controller for the 6-FET. It's something you should research.
You can paint the hub black.

 

[Kelp]

Thanks Motomech
I recall mixed reviews for the Cute- some seemed to fail quickly but will research more. I do agree that it otherwise does suit my specs so I hope I am wrong. Also investigating the MXUS kits from cell man. Seems to get good reviews and good service also. I am waiting on his response.

Thanks.

 

[dogman dan]

You need 30 amps of 36v to run a 350 w gearmotor kit? WTF? The kit will run on the bottle battery just fine, provided the controller LVC is not set too high for it. 350w divided by 36v is about 10 amps. A battery able to provide 15 amps of 36v should be plenty.

It's true though, that if your controller is a 20 amp one, the bottle battery might struggle on a steep hill. I do recomend a stronger battery for 500-800w.

 

[d8veh]

You need 30 amps of 36v to run a 350 w gearmotor kit? WTF? The kit will run on the bottle battery just fine, provided the controller LVC is not set too high for it. 350w divided by 36v is about 10 amps. A battery able to provide 15 amps of 36v should be plenty.

It's true though, that if your controller is a 20 amp one, the bottle battery might struggle on a steep hill. I do recomend a stronger battery for 500-800w.

I don't know why they call it a 350w motor: The controller that BMS battery supply in that kit is 25amps for the 9FET and 40amps for the 12FET.

If you only want 15 amps, surely there's not much point in having a motor that runs up to 40amps (the BPM). Wouldn't he be better getting the SWXU or Cute100 which both run nicely at 17amps?

Those bottle batteries do not have very strong cells and only 8.8aH, so it's not a good idea to push them.

 

[boppinbob]

Forget the "wife bike kits". You will never be happy. Start with 1000w rear hub at 72v @ 50 amps and go up from there. It is the only way to achieve nirvana.

 

[Austintx]

I really like this subject! - Question- If my bike is a rear hub motor 350 W and a 750 peak (Rmartin R10-H). Will a better controller make me get a little faster 18 MPH? Magnetic sensor was removed) It's a 10 AH at 36 Volts.

thanks!!

 

[motomech]

I really like this subject! - Question- If my bike is a rear hub motor 350 W and a 750 peak (Rmartin R10-H). Will a better controller make me get a little faster 18 MPH? Magnetic sensor was removed) It's a 10 AH at 36 Volts.

thanks!!

In a word, no. But you can see for yourself.
Go to the simulator at Ebike CA, use the BMC V1 motor @ 92% throttle and plug in various controller ratings and batt. voltages and view the results.

If you "like" this thread, you will absolutely LOVE the sim.

 

[dogman dan]

48v would be faster than 36v.

But yeah, you want more performance more motor is the real starting point. Which means buying stronger c rate batteries in most cases as well. $$$ start over, but it's what really works.

Something like the Mac 6t that hits 30 mph on 48v, or the clyte HS model. If you want hill performance, then same motors but lower speed windings. Less top speed but better ability to tolerate steep hills. Even a generic 9c kit with 48v battery will give you true 1000w.

These watt ratings retailers give are such a joke. Somebody asks me what it will take for 350w, how the hell am I to know the stupid "350 w" kit comes with a 40 amp controller? Hell,that would be 40 amps at 12v!

Ask me about 350w, I give you the answer for 350w.

 

[Kelp]

Thanks all, this discussion has really gone beyond my needs. Will start a new post seeking more technical info on XMUS hubs and comparing to the Cute 100's.

 

[d8veh]

Thanks all, this discussion has really gone beyond my needs. Will start a new post seeking more technical info on XMUS hubs and comparing to the Cute 100's.

You need to make sure that you ask the right questions, then you will get better advice. You need to state clearly what you are trying to achieve:
How fast do you want to go?
How far do you need to go?
Do you have a lot of steep hills where you ride?
Do you like to pedal?
How heavy are you?
Bear in mind that to go fast and far requires big, heavy, expensive batteries.