Question about Bafang 36v 500w vs 48v 500w motor

[tomtom123]

i got 3 mains questions:

1) What's the difference between the Bafang 36v 500w motor vs the 48v 500w motor? the 48v just provides more speed right? and it is even worth it cause i can technically get to 36v to run at 48v without really damaging it and achieve the same speeds right?

2) The reason i'm asking is because i want to get the 48v motor, however getting a 48v battery with higher AH is expensive compared to getting a 36v battery with higher AH, and i want more range and torque. i'm thinking of getting the 48v motor and get a high AH 36v battery. However, several posts in the forum mentions that it won't work cause the 48v motor has a voltage cutoff rate of about 41v and so i can't use the 36v battery on the 48 v motor? this would mean i need to get the 36v motor instead?

3) is it worth it for someone who lives in NYC to buy a 48v 500w motor or should i get a 36v 500w and get a 36v battery with 20ah that would provide me more range and torque and cost around the same as a 48v 12ah battery. Would the 36v motor with 36v battery provide with me enough speed? i would like to be around 20 mph if possible on flat roads and i weigh 200 lbs and the mongoose bike is around 40 lbs

an answer to any one of these questions would suffice, and answers to all 3 would be great :lol: thanks in Advance!

 

[nukezero]

i got 3 mains questions:

1) What's the difference between the Bafang 36v 500w motor vs the 48v 500w motor? the 48v just provides more speed right? and it is even worth it cause i can technically get to 36v to run at 48v without really damaging it and achieve the same speeds right?

2) The reason i'm asking is because i want to get the 48v motor, however getting a 48v battery with higher AH is expensive compared to getting a 36v battery with higher AH, and i want more range and torque. i'm thinking of getting the 48v motor and get a high AH 36v battery. However, several posts in the forum mentions that it won't work cause the 48v motor has a voltage cutoff rate of about 41v and so i can't use the 36v battery on the 48 v motor? this would mean i need to get the 36v motor instead?

3) is it worth it for someone who lives in NYC to buy a 48v 500w motor or should i get a 36v 500w and get a 36v battery with 20ah that would provide me more range and torque and cost around the same as a 48v 12ah battery. Would the 36v motor with 36v battery provide with me enough speed? i would like to be around 20 mph if possible on flat roads and i weigh 200 lbs and the mongoose bike is around 40 lbs

an answer to any one of these questions would suffice, and answers to all 3 would be great :lol: thanks in Advance!

1. The difference is in the motor windings. The 48V motor windings is stronger and is designed for more watts at those voltage levels. You could say yes more volts will get you more speed. Some people do over-volt the 36V to 48V, but you need to change the controller for this.

2. You can get the 48V motor with a 36V controller and run it with a 36V battery. But if you use a 48V motor with a 48V controller and stick in a 36V battery, then it won't work.

3. I ridden 36V and 48V and even a chain-driven 24V. 36V is plenty of power for up to 20mph but if you live in wide-open areas like sunny southern california, it may seem a bit slow. This is where the 48V will take you to 25-28MPH. All this depends on your wheel size too, but typical for 26" wheels. A 36V 20" wheel bike will be plenty torquey because the wheels are smaller but it won't have the higher top speed.

based on your weight, bike, 36V should get you to 20MPH but probably not much more. When the battery sags (juice is drained), then you may slow down a bit to 16-18MPH and even more so on the hills.

The reason why many companies sell 36V is to stay in line with federal and state laws of 20MPH for ebikes. Anything faster than 20MPH is no longer considered a bicycle but rather a motorized 2-wheeler.

 

[d8veh]

Both the 48v and 36v motors can be run at the other voltage. It only affects the speed, so you use this effect to get the speed you want. The 36v 201 rpm one, will run 33% faster at 48v, or the 48v 201 rpm one will run at 25% less speed at 36v. Some controllers, like those from BMSBattery, are dual voltage, so they can work with both.

It's not amp-hours you need to go a long way, it's watt-hours. A 15Ah 48v battery has about 750 watt-hours, and a 36v 15 Ah battery has about 800 watt-hours, so not a lot of difference.

 

[dogman dan]

I can't say I know enough about the bafangs to tell you which motor has which winding. Some have different windings, that result in differing no load rpm at full throttle. But in general, the motor itself will have the same ability to tolerate a specified wattage. Changing the winding of highly similar motors does not mean one can take more watts than the other per se. But one motor may be better suited to a particular rider and terrain, leaving it a more efficient setup for a specific riders weight, the grade of the hill, and the rim size. Gets real complicated at times which winding might be best.

Most ready to go kits sold in the USA tend to hit a top speed, based on that 20 mph rule in the USA. If a kit is rated 1000w, it's likely to go faster than 20 mph for sure. Buying from outside the USA, kits might be tailored to other laws in other countries.

The real wattage difference between the two kits is mainly determined by the controller and the voltage it is fed. So for example, a 20 amps controller at 36v will put out about 800w, while at 48v 1200w is seen on a watt meter. Smaller motors often come with a 15 amps controller, or smaller.

As for battery capacity, a 36v 20 ah battery and a 48v 15 ah battery have the same capacity in watt hours. Thinking in watt hours, you get a direct comparison of capacity between batteries of differing voltages. 48v 12 ah is smaller than 36v 30 ah.
48v 20 ah, would be 25% bigger than 36v 20 ah, and should cost about that much more.

FWIW, lifepo4 packs get pretty hard to fit and carry well on bikes by 48v 20 ah. 48v 15 ah weighs less and fits better, so for lifepo4 batteries I tend to recommend 48v 15 ah as the max. Range is 20-30 miles for that size, generally plenty.

 

[rp3]

It's not amp-hours you need to go a long way, it's watt-hours. A 15Ah 48v battery has about 750 watt-hours, and a 36v 15 Ah battery has about 800 watt-hours, so not a lot of difference.

Not quite.
Ignoring the actual usable Wh's you'll get out of a pack. A 48V 15Ah pack is ~720Wh while the 36V 15Ah pack is only ~540Wh.

 

[tomtom123]

thanks guys, i thought the amount of ah on the battery affected the range and capacity of the battery, i did not know that it was WH. So i just i might just settle with a 48v 10ah battery then.

just another question, a 48v 15ah battery, in theory, should provide the same range but more power if needed than a 36v 20ah battery right?