riding range/motor upgrade

Hi

I have a city fat bike (20”) powered by a rear 250W motor with the 36V/21AH battery. My average riding range is 50-60 km.

Now, I am planning to upgrade my bike and install a rear 750W motor with the 48V/17.5AH battery.

I wonder if my riding range changes significantly or will I achieve more or less the same range?

Anyone is able to compare these 2 set-ups (250W + 36V/21Ah and 750W + 48V/17.5Ah) in the sense of riding range (on a same bike, with the same rider) please?

Thanks in advance.

Basic math:
36 volts x 21 Amp Hours = 756 watt hours
48 volts x 17.5 Amp Hours = 840 watt hours

So you are gaining approximately 80 watt hours (+10%).
And you will be able to burn it up 3 times as fast.
The temptation to go faster is hard to resist.
The faster you go the less efficient your conversion is (energy per distance).
I would place my bets on a decrease in range.

While I agree with LewTwo, the Grin motor simulator is fun to play with for these kinds of comparisons. Click on "Open system B" to add a second motor to the graph.

https://ebikes.ca/tools/simulator.html

I’ve had an experience similar with this. I went from,
48v 30ah = 1440wh
To
72v 20ah = 1440wh
The conclusion for me is I got more range with the 72V battery because It gave me the extra speed without having to go full throttle nearly as much. With my 48v I was always smashing the throttle because it was slow LOL
So in my situation I got more range but "if” I was going full throttle all the time I would get less range with the 20ah.
Just based on this one experience it seems to me depending on how you ride will determine if you get more or less range with the smaller amp hour even though you’re increasing the watt hour.

But with this being said I’m assuming you’re using the same controller?

Eastwood said:

But with this being said I’m assuming you’re using the same controller?

Click to expand...

No. A new, 48V-compatible controller will be needed if decide to go for this upgrade (from 250W+36V/21Ah to 750W+48V/17.5Ah) .

According to the the battery seller, my current controller (https://bit.ly/3t47KCH) would not work fine with the new set (750W+48V/17.5Ah).

radvi said:

No. A new, 48V-compatible controller will be needed if decide to go for this upgrade (from 250W+36V/21Ah to 750W+48V/17.5Ah) .

Click to expand...

Well in that case you might get slightly less range. Shouldn’t be significant and you also could possibly, possibly get better range if you’re less aggressive on the throttle with the higher voltage set up because you will have a faster running speed.