What watts?

[RobF]

I am more and more drawn to the idea of a converted crank drive mountain bike for winter/trails.

But what kit?

I had a brief go on an 8Fun 250W and liked a lot about it - neat, quiet, reasonably smooth power delivery.

It was only a short ride, but I was expecting to feel more grunt.

I take it the 500W version would be noticeably more powerful.

The child in me says go the whole hog and get the 750W, but I don't want to end up with something that's peaky in use.

I also wonder about power consumption.

Assuming I'm bowling along steadily, do the higher power kits use much more power?

Looks like the 750W demands 48V, which means a 10ah battery - 480W/h.

Would that last about as long as 36V/14ah battery which gives about the same W/h?

The proposed donor bike would have 26" wheels.

 

[Deleted member 4366]

If you have high power, you can always turn it down. The levels in the BBS01/2 are programmable from 0 to 100%. If you set the levels low, you won't use as much battery. The 48v batteries have 13s2p (52 cells). The 36v ones have 10s5p (50 cells), so you get 4% more capacity with the 48v one - assuming it's the same type with the same type of cells.

Power = volts x amps = watts. You can set the amps to whatever you want at 36v or 48v, so battery usage will be the same on either system if you set the power the same. Obviously, if you set the power to 750w on one and 250w on the other, the former will use up the battery a lot quicker than the latter.

 

[RobF]

Thanks, so I can sip power on any of my proposed set ups.

Or put another way, either of the new batteries would have useful extra capacity over my Bosch ones.

Still can't decide about kit power.

I still have this notion the 750W motor will be great fun for short bursts, but wearing to ride over a longer period.

Hope I'm wrong about that.

 

[Deleted member 4366]

There's seven levels iirc. You can select level 1 if you want. You don't have to use level 7 all the time, but it might be more fun.

 

[Nealh]

I have 18amp model and you can set speed max to 50kmh and there are 9 assist levels, most of my road use is on the level with a few inclines 7 is my set assist.

 

[RobF]

Seems I may be worrying about nothing.

Seven/nine levels sounds good, I've always thought the Bosch could do with a couple more.

 

[Alan Quay]

Seems I may be worrying about nothing.

Seven/nine levels sounds good, I've always thought the Bosch could do with a couple more.

You need one that goes all the way up to Eleven. That's one more than ten.

 

[flecc]

The German e-bike industry carries a lesson on power choices. On their S class e-bikes they are permitted up to 500 watt ratings, but the majority of manufacturers have settled on 350 watts.

I'm not saying 350 watts is right for you, just that the optimum is often a better overall choice than the most you can have.
.

 

[RobF]

The German e-bike industry carries a lesson on power choices. On their S class e-bikes they are permitted up to 500 watt ratings, but the majority of manufacturers have settled on 350 watts.

I'm not saying 350 watts is right for you, just that the optimum is often a better overall choice than the most you can have.
.

Food for thought from those pesky Germans.

"Optimum" is what I would like, but the only way to establish that would be to test each motor, which is not realistically possible.

Who knows, if I tested a few powerful hub motors as well, I might find I preferred one of those.

Not that I am complaining about too much choice, we are lucky to live in a land of plenty.

 

[flecc]

"Optimum" is what I would like, but the only way to establish that would be to test each motor, which is not realistically possible.

Who knows, if I tested a few powerful hub motors as well, I might find I preferred one of those.

I'm looking at this a little differently Rob. All the e-bike powers you mention are inadequate for transporting you in any circumstances without your assistance. On that basis you might indeed prefer the most powerful to cover almost all eventualities since you don't always have to use that power.

So since you have to assist to some degree whatever the motor, I think the considerations of range and e-bike weight to decide the optimum are at least as important, if not more so.

In effect those German makers and their customers have done some of the research for you. When the change to a maximum of 500 watts was introduced, most of them immediately introduced 500 watt models, but experience has lead them to back off to 350 watts or run the two in parallel, and 350 watts has proved to be the clear market winner in the S class. The collective view of not just the makers but tens of thousands of customers.
.

 

[Deleted member 4366]

Nice theory, Flecc, but do you think that the fact that most of their 350w versions are identical to their 250w ones apart from software, might have something to do with it?

 

[flecc]

Yes, I agree on the availability, indeed the BionX started as a 350 watts, only later producing 250 and 500 variants. But the 350 watt options seem to have been much more popular in the S class market than the 500 watt ones. I can only guess at the individual reasons, but they were probably considering the same factors as Jonathan when making their choice.
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[mechaniker]

I think 350watt is enough for a ebike as the best mixture for weight,consumption and the feeling to ride a bicycle and not a Motorbike.

But It´s just my personal opinion and other user´s maybe come to a different conclusion

I´ve tested a lot of different motors/bikes from 150Watt up to 4000watt.
Of course sometime you have fun with the high-powered but all in all
350watt it´s for my feeling the best choise

 

[flecc]

I think 350watt is enough for a ebike as the best mixture for weight,consumption and the feeling to ride a bicycle and not a Motorbike.

But It´s just my personal opinion and other user´s maybe come to a different conclusion

I´ve tested a lot of different motors/bikes from 150Watt up to 4000watt.
Of course sometime you have fun with the high-powered but all in all
350watt it´s for my feeling the best choise

.
Good to see you posting in here again Frank, last time in 2011 and we've missed you and your product knowledge!

regards, Tony
.

 

[mechaniker]

Hi Tony,

thank´s for your warm welcome after such long time ;-)
sometime is good to take a brake to bring thing´s back into focus and I was very tired of the chinese quality. Even all my friends, wife and my daugther are chinese I always try to convince them take more effort on quality not on the price then I would have more fun on selling the product´s .

To "RobF" and the thread issue
if you want a bafang with high-power then choose the 36v 500Watt.
Why not the 750watt? because the 48v 750Watt develop this 750watt at around 120-130rpm at the pedalarms. This is simply bull.... for normal bikerider´s
If you please have a look to the crankbearings´s, they cant handle this crankspeed for a long time. Please check the photo. This wretched needle-bearings including the chinese low precision.....

 

[D8ve]

I suspect that one major issue here is the confusion caused by the labling.
The law requires that the motor is RATED as 250 watts. We therefore have motors that can almost pull the skin off a rice pudding and others that can shove a fat man up a steep hill at 17 mph. They are both 250 watt legal. I suspect that often with 250 to 500 watt motors the change is the controller and labling not the copper and winding.
At the other end when power is a selling point the sales team want the motor rated as high as possible. I don't know but suspect that the max output ratings may also be a little dubious ie 750 watt at 120rpm.
Who would pay for harmonisation? Why would manufacturers subject there products to it.
If the motor ratings are unreliable then the grounds for discussion are also shaking.
(Welcome back Frank,I agree it's a bike)
Rob as to your question
As the motors are all 8fun the ratings should step up. I think you would regret not getting the 750 watt motor. And apart from extra weight and eating chain, it would have no real mechanical downside.
Yes it may be childish fun too but personally I am against. If you want a motorcycle buy one.

 

[RobF]

Frank,

Thanks for your interest.

What you say makes sense, and I couldn't spin the cranks at 120rpm even if I wanted to.

Like D8ve, I also wonder how meaningful the ratings are.

However, we have to work with what we have.

Best choice for me probably is 500W.

 

[mechaniker]

..... I suspect that often with 250 to 500 watt motors the change is the controller and labling not the copper and winding....

some motor is truely only the lable changed and not more, proove of this suspect is that I cant see any difference between the 250Watt BBS and the 350Watt BBS only the controller is different. Bafang send ones a package with overpainted housings, if you looked good you could see the 250lable under the 350lable . The 500Watt BBS has a stronger Motorhouse

Btw,one´s I had a problem with a BBS because this Motor was weaker then others and I could´nt find the reason beause all seems normal. I changed the pedalsensor and then the motor works fine. I could not realy explain why the motor now runs fine.
Only short time ago I get this photo from a user in a german forum, under a special lens you can see the funktion very well. I assume that the magnetic field was just damaged on the magnetic-disk but you can´t see it without this lens.


Hi D8ve and also thanks for welcome me back ;-.)
In germany we also have discussion about what is still a bicycle and where starts the Motorbike. For me, more than 500watt is a Motorbike.
Even 500watt is not my thing because it offers a continius Power I could never produce by myself and thats for me the difference between electricbicycle and a Motorbike but I understand the fun-factor

regards
frank

 

[Deleted member 4366]

Welcome back, Frank. Hopefully. you can inform us of any exciting or interesting things going on in Germany.

 

[Croxden]

I just love the signature line that mechaniker has.

If you're dead, that's not bad for yourself because you´re dead. Bad it is for others. Just as it is if somebody is stupid .......

Just brilliant.