Hey guys I just fitted my bike with a juicy bikes 250 watt kit, bafang front drive motor and 36volt 10amp battery. it is derestricted for off road use. I currently get around 15mph without pedalling. If I upgraded my motor to a 350 watt motor, would I get more speed derestricted and what would the implications be on my range. Anybody have any experience with this kit? Would I need a different controller for the 350 watt kit or could I just swap the motor and use my current controller and battery.
Juicy bikes kit/Bafang 350/500 watt motor, faster than 250?
- Thread starter BATFINK
- Start date
Hi there is no such thing as a 250 or 350 watt motor volts X amps = watts
bigger controller will give you more amps but the battery management in the 36 volt battery will also be to small and the cells to small output = low cost controller low cost battery
You could try just the controller but my experience is the battery will shut down when you try to draw more amps
Answer New controller + 48 volt battery = 500 watts +
KU123 500W 12Mosfets High Speed Controller - BMSBATTERY
48V 10Ah Li-Ion Alloy Shell EBike Battery Pack - BMSBATTERY
Hope this helps
Just a note There is nothing wrong with the kit juicybikes sell it is all designed around the UK 250 watt legal speed and power and a Budget price
Frank
bigger controller will give you more amps but the battery management in the 36 volt battery will also be to small and the cells to small output = low cost controller low cost battery
You could try just the controller but my experience is the battery will shut down when you try to draw more amps
Answer New controller + 48 volt battery = 500 watts +
KU123 500W 12Mosfets High Speed Controller - BMSBATTERY
48V 10Ah Li-Ion Alloy Shell EBike Battery Pack - BMSBATTERY
Hope this helps
Just a note There is nothing wrong with the kit juicybikes sell it is all designed around the UK 250 watt legal speed and power and a Budget price
Frank
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Depends on the motor, some members have swapped out the 250W Bafang motor for the 350W BPM and reported an increase in the top speed using the same battery and controller as before. Range worked out to be similar if a little less than before so yes its possible.Hey guys I just fitted my bike with a juicy bikes 250 watt kit, bafang front drive motor and 36volt 10amp battery. it is derestricted for off road use. I currently get around 15mph without pedalling. If I upgraded my motor to a 350 watt motor, would I get more speed derestricted and what would the implications be on my range. Anybody have any experience with this kit? Would I need a different controller for the 350 watt kit or could I just swap the motor and use my current controller and battery.
The speed increase is probably due to the RPM wind of the 350w motor being different to that of the 250w...the 250w also comes in different RPM versions so you can go faster with this motor but at the expense of hill climbing ability.
Another way to get more speed is to increase the voltage on the motor by changing the battery but you have to be careful not to exceed the top voltage rating of the controller...if you do, you will let the magic smoke escape and it wont work afterwards!
no such thing as 250 - 350w motor ????????????????????????
Don't really know what your trying to say when they are all advertised as 250, 350 or 1000 watt motors...
And can someone answer Mr Batfinks question as to the range he will achieve..........
break it down into english please frANK
Hi FrankHi there is no such thing as a 250 or 350 watt motor
Frank
Don't really know what your trying to say when they are all advertised as 250, 350 or 1000 watt motors...
And can someone answer Mr Batfinks question as to the range he will achieve..........
break it down into english please frANK
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Hi
I did tel him what to do and and links on where to buy as for range that is a Question for another posting
Simple all motors the watts are calculated by a simple equation Volts X amps
36 volts X 9 amp controller 320 watts into the motor
48 volts X 15 amp controller 700 watts into the motor
Then you deduct the electrical watt conversion into mechanical power
most motors are good for 80% at doing this so minus 20%
To convert Watts (W) to a horsepower rating (HP) simply multiply the Watts by 0.00134
320 W - 20% = 256 watts X 0.00134 + 0.35 HP
700W - 20% = 560W X 0.00134 = 0.75 HP
W x 0.00134 = HP
now there is a power symbol you will recognize HP
Hope this Helps
Frank
I did tel him what to do and and links on where to buy as for range that is a Question for another posting
Simple all motors the watts are calculated by a simple equation Volts X amps
36 volts X 9 amp controller 320 watts into the motor
48 volts X 15 amp controller 700 watts into the motor
Then you deduct the electrical watt conversion into mechanical power
most motors are good for 80% at doing this so minus 20%
To convert Watts (W) to a horsepower rating (HP) simply multiply the Watts by 0.00134
320 W - 20% = 256 watts X 0.00134 + 0.35 HP
700W - 20% = 560W X 0.00134 = 0.75 HP
W x 0.00134 = HP
now there is a power symbol you will recognize HP
Hope this Helps
Frank
Last edited:
Hi
Simple all motors the watts are calculated by a simple equation Volts X amps
36 volts X 9 amp controller 320 watts into the motor
48 volts X 15 amp controller 700 watts into the motor
Then you deduct the electrical watt conversion into mechanical power
most motors are good for 80% at doing this so minus 20%
To convert Watts (W) to a horsepower rating (HP) simply multiply the Watts by 0.00134
320 W - 20% = 256 watts X 0.00134 + 0.35 HP
700W - 20% = 560W X 0.00134 = 0.75 HP
W x 0.00134 = HP
now there is a power symbol you will recognize HP
Hope this Helps
Frank
Simple all motors the watts are calculated by a simple equation Volts X amps
36 volts X 9 amp controller 320 watts into the motor
48 volts X 15 amp controller 700 watts into the motor
Then you deduct the electrical watt conversion into mechanical power
most motors are good for 80% at doing this so minus 20%
To convert Watts (W) to a horsepower rating (HP) simply multiply the Watts by 0.00134
320 W - 20% = 256 watts X 0.00134 + 0.35 HP
700W - 20% = 560W X 0.00134 = 0.75 HP
W x 0.00134 = HP
now there is a power symbol you will recognize HP
Hope this Helps
Frank
...but this is watts going into the motor it is not the same as the continuos wattage rating of the motor that the OP was referring too.
Also Franks 80% efficiency figure is for top RPM running, the motor will not draw a lot of current near maximum RPM.
Peak motor power will occur around half the unload RPM or less. At this point motor efficiency is around 60~70% at best.
Plus with higher amps drawn the losses in the controller, wiring and motor will be greater.
If we take a 65% efficient motor at peak power with 15amp controller and 36v battery, peak watts from the battery will be 540w, losses may amount to somewhere around 60w, maybe less, so 480w x .65 = 312w electrical power at the motor. Then there are mechanical losses due to the Bafang reduction gearing so the actual power, HP or whatever is quite low...
Also Franks 80% efficiency figure is for top RPM running, the motor will not draw a lot of current near maximum RPM.
Peak motor power will occur around half the unload RPM or less. At this point motor efficiency is around 60~70% at best.
Plus with higher amps drawn the losses in the controller, wiring and motor will be greater.
If we take a 65% efficient motor at peak power with 15amp controller and 36v battery, peak watts from the battery will be 540w, losses may amount to somewhere around 60w, maybe less, so 480w x .65 = 312w electrical power at the motor. Then there are mechanical losses due to the Bafang reduction gearing so the actual power, HP or whatever is quite low...
Simple question, possibly complicated answer.
If I have a controller that is limited to 15a, would it be limited to 15 regardless ofthe voltage - i.e. wuld it still be limited to 15a irrespective of whether I used a 36v or 48v battery (assuming the controller can take a 48v battery).
If so, does that then mean the amps would stay the same but the watts would go up?
I.e. 36v @ 15a = 540 watts
or 48v @ 15a = 720 watts
If I have a controller that is limited to 15a, would it be limited to 15 regardless ofthe voltage - i.e. wuld it still be limited to 15a irrespective of whether I used a 36v or 48v battery (assuming the controller can take a 48v battery).
If so, does that then mean the amps would stay the same but the watts would go up?
I.e. 36v @ 15a = 540 watts
or 48v @ 15a = 720 watts
For the experts and the long termers in this forum you all may have an idea what NRG is going on about. But for us beginners/non ebike technically minded, try it again in lay man's terms please.
Efficient motors etc why are they not efficient in these modern times, for goodness sake it's 2011, Motors should be 100% efficient, if not why not..... or are we the punters being made fools out of just like the IPODPADPEN industry, new release of version 1 in March by august version 2 is out rendering your initial outlay for version 1 useless, happens every year in the elctrionics industry, for instance I could get a Blue ray player for £100 there or about, blue rays release prices 8 months earlier were £600-800. OR is that plain old capitalism showing its nostrils again..
yes am having a rant today it seems
IS the Ebike world trying to follow suite........?
Efficient motors etc why are they not efficient in these modern times, for goodness sake it's 2011, Motors should be 100% efficient, if not why not..... or are we the punters being made fools out of just like the IPODPADPEN industry, new release of version 1 in March by august version 2 is out rendering your initial outlay for version 1 useless, happens every year in the elctrionics industry, for instance I could get a Blue ray player for £100 there or about, blue rays release prices 8 months earlier were £600-800. OR is that plain old capitalism showing its nostrils again..
yes am having a rant today it seems
IS the Ebike world trying to follow suite........?
Well sod off effciency etc there are ways to go faster :-
Keeping the same Motor + Battery
Buy a larger amp controller - This will increase Torque. More amps more torque. The limiting factor will be the battery and eventually the brushless motor will burn out with heat. But you'll maintain a higher speed constantly. (Decrease in range) - Cheapest
Keeping Battery + Controller
Buying a newer faster RPM motor - This will increase speed at the cost of hill climbing (Torque) ability
(Decrease in range) moderate cost
Keeping Controller + Motor
Buying a higher voltage battery - Increase in volts = increase in speed (maybe a little in torque but its offset by the additional speed and also increases the speed at which peak torque is achieved). Same range depending on amp hrs you buy. Most expensive
Please note the ratings of motors whether they be 250 / 350 / 500 / 1000 are rated watt's that the motor can handle without taking any damage. The BPM for example is rated at 350watt with a peak of 750.
Keeping the same Motor + Battery
Buy a larger amp controller - This will increase Torque. More amps more torque. The limiting factor will be the battery and eventually the brushless motor will burn out with heat. But you'll maintain a higher speed constantly. (Decrease in range) - Cheapest
Keeping Battery + Controller
Buying a newer faster RPM motor - This will increase speed at the cost of hill climbing (Torque) ability
(Decrease in range) moderate cost
Keeping Controller + Motor
Buying a higher voltage battery - Increase in volts = increase in speed (maybe a little in torque but its offset by the additional speed and also increases the speed at which peak torque is achieved). Same range depending on amp hrs you buy. Most expensive
Please note the ratings of motors whether they be 250 / 350 / 500 / 1000 are rated watt's that the motor can handle without taking any damage. The BPM for example is rated at 350watt with a peak of 750.
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Thanks for the information. I see now where the power increases come from with regards to the volts x amps but then that would surely mean you would also have to upgrade your motor to match the output from the battery and controller. I.e. If running the following setup:
48volts by 15 amp = 700watts with a 250 or 350 watt motor = burnout?
Ideal set up would be 48volts by 15 amp = 700watts with a 700watt motor.
My current setup is 36 volts with 10amp controller which is 360 watts output minus 20% will give me around 290 watts output and I have a 250 watt motor, so I'm running the motor above the rated wattage?
48volts by 15 amp = 700watts with a 250 or 350 watt motor = burnout?
Ideal set up would be 48volts by 15 amp = 700watts with a 700watt motor.
My current setup is 36 volts with 10amp controller which is 360 watts output minus 20% will give me around 290 watts output and I have a 250 watt motor, so I'm running the motor above the rated wattage?
Hi
There is no such thing as a 250 Watt motor Add more volts and amps if you overdo it yes it will burn out
Not from 36 to 48 volts maybe if you give it 72 /92 volts
Our motors will run on 36 volts to 72 volts before the insulation on the motor windings will break down
So from 250 watts at 36 volts to 3600watts at 72 volts same motor
the reason the motor losses are approx 20% they are converting Electrical energy into Forward motion onto the road like all conversions there are losses
Frank
There is no such thing as a 250 Watt motor Add more volts and amps if you overdo it yes it will burn out
Not from 36 to 48 volts maybe if you give it 72 /92 volts
Our motors will run on 36 volts to 72 volts before the insulation on the motor windings will break down
So from 250 watts at 36 volts to 3600watts at 72 volts same motor
the reason the motor losses are approx 20% they are converting Electrical energy into Forward motion onto the road like all conversions there are losses
Frank
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Very clear answers and thanks to Scotty for the simple but laymen termed answer. Makes it easy for me, il probably update my motor first and see what sort of difference it makes to my top speed then I can worry about the rest. anybody know a good 350 watt motor that is compatible with my front wheel and disk brake?
Hi
If you buy a kit from BMS it comes with the right controller
Bafang BPM 36V500W Rear Driving Bike Conversion Kit - BMSBATTERY
Frank
If you buy a kit from BMS it comes with the right controller
Bafang BPM 36V500W Rear Driving Bike Conversion Kit - BMSBATTERY
Frank
Scottf you said sod off efficiency am afraid my feelings are hurt are you telling me to sod off.Well sod off effciency etc there are ways to go faster :-
Please note the ratings of motors whether they be 250 / 350 / 500 / 1000 are rated watt's that the motor can handle without taking any damage. The BPM for example is rated at 350watt with a peak of 750.
Arghhhh now i understand, many thanks Frank but some of us need LAY MAN TERMS, and Scottyf hit the nail on the head.....
Whats the waiting time for a kit from China and can anyone recommend a reputable dealer to do business with????
The only one I know of and spoken to are BMS battery, there must be like for like competitors out there....
cheers all
B0331e, feeling better now
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Eh!? Of course there is such a thing as a 250w rated motor as there is a 350w, 500w or whatever. Its the safe limit the manufacturer places on the motor for its continuos operation. The limit imposed either by heat dissipation or a mechanical limitation. The 500w BPM motor is physically larger and mechanical stronger than the 250w version and so can produce more continuos and peak power.Hi
There is no such thing as a 250 Watt motor Add more volts and amps if you overdo it yes it will burn out
Not from 36 to 48 volts maybe if you give it 72 /92 volts
Our motors will run on 36 volts to 72 volts before the insulation on the motor windings will break down
So from 250 watts at 36 volts to 3600watts at 72 volts same motor
the reason the motor losses are approx 20% they are converting Electrical energy into Forward motion onto the road like all conversions there are losses
Frank
Why are you ranting?For the experts and the long termers in this forum you all may have an idea what NRG is going on about. But for us beginners/non ebike technically minded, try it again in lay man's terms please.
Efficient motors etc why are they not efficient in these modern times, for goodness sake it's 2011, Motors should be 100% efficient, if not why not..... or are we the punters being made fools out of just like the IPODPADPEN industry, new release of version 1 in March by august version 2 is out rendering your initial outlay for version 1 useless, happens every year in the elctrionics industry, for instance I could get a Blue ray player for £100 there or about, blue rays release prices 8 months earlier were £600-800. OR is that plain old capitalism showing its nostrils again..
yes am having a rant today it seems
IS the Ebike world trying to follow suite........?
No one has yet invented the perfect machine.
Losses in electric motors are well known and understood, IE: Mechanical losses, copper losses and iron losses, there's loads of papers and web pages available on the internet all you have to do is use Google.
Sorry I wasn't telling you to sod off. I was jsut saying for the question you primarly asked forget the effciency loss. Its niot applicable when building your own ebike as a majority of motors will all have similar losses. Trying to improve the effciency is much harder than just say increasing any of the three things I've listed.
To improve your own bike effciency is much easier. Keeping your wheels in good form and correct tire pressure. Low friction tires etc... Reducing your own physical size by loosing some weight you chunky monkey ;-)
Please note than most batteries can deliver 1c which at a 15ah battery even with the cheap cells it will delivery a continous amp of 15, with a max of 30amp in bursts.
most people use around the 10amp mark for a decent current and range given that most ebikes have anything from 13 to 20 amp controllers as standard.
Cheapest option really is to improve the motor to a faster wind and increase the amp's on the controller. This will get if you already have a battery you dont want to change increase in hill climbing and top speed.
I went down this route. But you could just put a booster pack onto your original battery and keep the motor and controller. This will give more speed. Similar range and similar hill climbing ability.
Theres lots of tweaks you can do butsometimes you can over do it going with larger motors and batteries making it cumbersome on the handling front. Balance is important on a push bike and some people do like to pedal and keep fit.
Others are just lazy and want a moped that looks like an ebike.
To improve your own bike effciency is much easier. Keeping your wheels in good form and correct tire pressure. Low friction tires etc... Reducing your own physical size by loosing some weight you chunky monkey ;-)
Please note than most batteries can deliver 1c which at a 15ah battery even with the cheap cells it will delivery a continous amp of 15, with a max of 30amp in bursts.
most people use around the 10amp mark for a decent current and range given that most ebikes have anything from 13 to 20 amp controllers as standard.
Cheapest option really is to improve the motor to a faster wind and increase the amp's on the controller. This will get if you already have a battery you dont want to change increase in hill climbing and top speed.
I went down this route. But you could just put a booster pack onto your original battery and keep the motor and controller. This will give more speed. Similar range and similar hill climbing ability.
Theres lots of tweaks you can do butsometimes you can over do it going with larger motors and batteries making it cumbersome on the handling front. Balance is important on a push bike and some people do like to pedal and keep fit.
Others are just lazy and want a moped that looks like an ebike.
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