Motor power consumption..

[Homet]

Can anyone tell me if a 750w motor running at 12mph consumes more power (from a battery) as a 350w motor also running at 12 mph?
The speeds are arbitrary, just asking about the power consumption of the two motors at the same speed!

 

[harryS]

At 12 mph, which is my typical ebike speed, both my 250W and 500W hubmotors are loafing along and use about the same amount of power. There's a little difference. The 500W is slightly higher, but it's not 2X higher. more like 5-10%,

It would be a different result at higher speeds, where the smaller motor might operate in a less efficient range.

And then my wife comes around with her 250W motor, same one that's in my little ebike, and she uses 40% less battery than me because she weighs 50 pounds less (used to be 40 pounds, but I've been pretty lazy).

 

[Homet]

Thanks, I’ll watch all this but I should have probably explained myself first!

I have a 350w bike with a 10AH battery that I use to ride around where I live. It’s usually the same routes, around 20 miles a few medium hills, just to help keep a little fit. I usually do the ride and come back with one or 2 bars left, out of 5.
Id like to get a new bike but the one I want has a 750w motor and a 13aH battery. I’m still going to do the same routes but I don’t want to be in a position where the extra battery is used up with the bigger motor, doing the same speeds as before.

My old bike is 36v but the new one is 48v. Not sure this makes a difference.

Hopefully my original question makes more sense now!

 

[Captain Slow]

Compare your current bike to the one you want. How much of a difference in weight is there? As Harry says, weight is a big factor in power consumption.

I have two electric bikes, one that has a 240 watt motor that is a low power motor and a 320 wh battery. I use very little battery and regularly ride 70-80 km's and use between 1 to 2 wh/km travelled. But some rides I've used as little as 0.5 wh/km.

My electric commuter weighs double and going 80 km's on the same route that bike will use almost all of it's 614 wh battery. Generally that bike uses about 6 to 7 wh/km.

Big difference in power consumption and for my two bikes, the lighter one has far greater range despite having a battery not much more than half of the bigger, heavier and more powerful bike.

Not completely an apples to apples comparison because the heavier bike doesn't allow me to tune power levels. I have to use one of the 5 preset levels. Whereas my electric road bike allows me to tune the power in 5% increments.

 

[Homet]

Both bike are nearly the same weight - around 28kg. Would the fact that one motor is nearly twice the power of the other one not make much of a difference?
Also, at some point in the future, if I wanted to upgrade the battery to a 17aH or bigger, could I do that without changing all the electronics, providing I stay at 48v, of course?

 

[Homet]

VTUVIA Electric Bikes | Buy Best E-Bikes For Adults

Discover VTUVIA eBike, the leading brand for electric bikes! Browse our selection of e-bikes and accessories and start your eco-friendly journey today.

vtuviaebike.com

 

[Gionnirocket]

That's Reention Kirin.

You can get 52V 17.5Ah

52V x 17.5Ah = 910Wh capacity

And yes, as mentioned in one of the videos, 48V controller can handle 52V just fine because the voltage is so close.

US $422.0 |Reention KIRIN 48V 1000W 1200W Sanyo GA cells battery pack 52V 17.5Ah side release electric bike battery with charger|Electric Bicycle Battery| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

318.5US $ 9% OFF|Reention Vtuvia Sn100 48v 500w 750w Battery Pack 52v 13ah 14ah 15ah 17ah Side Release Himiway Electric Bike Battery With Charger - Electric Bicycle Battery - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

True... But I'd stick with the 48v battery and increase capacity over voltage for my dollars.

 

[Homet]

That’s $100 for an extra few volts, doesn’t seem the best value!
I’d be tempted by the 48v and keep the rest for BEER!

 

[Homet]

$422 vs $329?

 

[harryS]

Hornet, your current pack is rated at 360 WH. The 48V 13AH pack is rated at 624 WH. At a given speed, you burn WH/mile. Fat knobby tires waste energy, so you burn a little more going the same speed. DItto for weight differences. Higher speeds burn more, and then you get into the power/efficiency thing at higher speed.

If you really could ride those two bikes at the same 12 mph, I predict they would be within 10% of each other on smooth tires, maybe even with the knobbies.

When I put in a 48V battery in place of my usual 36V, I tend to go faster for the same level of pedal effort. The 48V uses 120W in PAS 1 whereas the 36V uses 100W. But when I'm riding with my wife, we average 12 mph anyway, so I pedal less, coast a bit, and end up using the same WH.

 

[Homet]

Thanks Harry, my current bike has fat tyres too but they’re 20” as opposed to 26” on the new one, so hopefully the difference in consumption will be pretty minimal!

 

[Gionnirocket]

To increase the capacity, you either have to up the voltage or amperage.

In this case, the capacity is 910wh

Yes, and I would up the amperage. Upping the voltage makes no sense to me, especially if your display/controller is now off a bit.

 

[Homet]

Sorry, my mistake, it’s actually only $15 extra!

 

[Gionnirocket]

How so?

Your display will show you higher voltage. (if it comes with voltmeter)

A lot of people get 52V for their 48V bike because it's an easy upgrade to get more power and top speed.

Yes I understand that but unless you are engaged in competitive racing the increase is negligible. I think you'd be better served increasing capacity.
And while the display may be able to read the voltage.. if not designed and calibrated for 52v I think you sacrifice accuracy. There's a reason you need to select the voltage in the display settings and it's just not a voltmeter.

 

[Leadfeathers]

Since I see so many informed, educated answers about this, I'm hoping I might get an answer to something I'm wondering about. (If I'm unduly hijacking the thread, I'll start another topic.)
My bike is a 750W, 48V Bafang rear hub drive, 13 AH battery. (Shown in my profile pic.) A neighbor is the West Coast rep of this company. After I bought mine, he got another shipment; the same model, with same battery and motor size is noticeably more powerful: quicker acceleration, initial and sustained. From pedal assist, and throttle.
So my question is what gives it more power? I think its the same motor at 750W. Could it be the controller? Mine is a Lishui with 21A max current. Don't know what the what the newer bike might have. Would a controller with greater max current have more power?
Thanks for any input. Hope I haven't distracted from the original discussion.

 

[Gionnirocket]

I think you might be confused about battery capacity.

By going 48V to 52V, you are NOT sacrificing the capacity.
For example, which batteries have higher capacity?

52V 19Ah

or

48V 20Ah

The answer is, 52V 19Ah (because of higher Wh rating)

If you go up to 52V, you are adding the power.
If that's too much power, just lower the assist. (more range)

I understand that... I'm just saying it is something that I would not do.
For the cost of the cells required, I would add them in parallel, not series.
Just my preference

 

[Homet]

This is pretty interesting and pretty much shows that Bafang motors are frequently not what they claim to be:

ELECTRIC BIKE HUB MOTOR REVIEW AND COMPARISON. BAFANG, DAPU SHENGYI AND HENGTAI

The reason we conduct such test is as market is full of false claimed electric bikes and motors and sorry to say there isn’t any exception to it. Before getting into further details I need to explain some basics here.

ebikereviewer.com

 

[Leadfeathers]

What kind of motor does it have?

As mentioned, just because it says "750W", it doesn't mean it has real 750W motor.
Motors can be overvolted relatively safely, you might have overvolted 350W motor.

I believe you have Bafang G060, however, they had different variants.

As you can see, when you open up the motor, it is completely different.
Externally, they all look like this:

But once you open it up, Bafang had different variants of G060.
It will usually say G060.350DC, G060.750DC, etc..

The "real 750W" motor has heavy duty magnet, coil, stator, etc.

Wow! that is one thorough response. I double checked the number on the motor and it is indeed the G060.750D 07. And for accuracy, the amp rating on the controller itself states 21Amps, not the 22 stated on the bike specs.
It sounds to me that you're saying that the motor itself is mostly responsible for the "oomph" on acceleration and take-off?
Thanks.