UK legal rear hub 48 volt kit?

[Fordulike]

Do you already have a motor in mind?

No, any suggestions?

You know, if my spare battery was 36 volts, then I wouldn't be having this fiasco lol. The battery is still going strong with decent Samsung cells, so really want to utilise it.

 

[Deleted member 4366]

The Q128 is an excellent motor. It's light and powerful. You can get it in cassette version (Q128C) and high torque free-wheel version (Q128H). The original one (just plain Q128) was a bit gutless, but the latest ones seem to be much improved.

Slightly more challenging because it's a bit wider than a normal hub-motor is the Xiongda. It's cheap and has winch-like torque at 48v in its low gear, and if you want, it can cruise happily at 20 mph without much effort.

 

[anotherkiwi]

I also am looking at the Q128C 36 V 201 rpm version which I would like to run at 44.4 V (12S) and 22-25 Amps in a 26" or 24" rim. That is 1245 W nominal with the battery hot off the charger, 1110 W at battery nominal voltage with a 25 Amp controller.

Will it handle that?

 

[Fordulike]

Am I correct in thinking that a user adjustable cut-off speed, via a display, isn't allowed in the EAPC ruling?

 

[anotherkiwi]

Am I correct in thinking that a user adjustable cut-off speed, via a display, isn't allowed in the EAPC ruling?

That is correct.

 

[craiggor]

I think you both have just made a lot of bikes and kits sold in the UK illegal. Must say I agree, what is a mode if its not a few button presses. I think you should take your 48 battery apart and reconfigure the cells to 36v using the Vruzend DIY 18650 battery kit.

Sent from my D101 using Tapatalk

 

[Fordulike]

I think you should take your 48 battery apart and reconfigure the cells to 36v using the Vruzend DIY 18650 battery kit.

Mmmmm, maybe for the forum techie gurus, but not my cup of tea I'm afraid

 

[Deleted member 4366]

I also am looking at the Q128C 36 V 201 rpm version which I would like to run at 44.4 V (12S) and 22-25 Amps in a 26" or 24" rim. That is 1245 W nominal with the battery hot off the charger, 1110 W at battery nominal voltage with a 25 Amp controller.

Will it handle that?

Should be OK, especially as it's not too fast. It'll be running at a speed where the back emf limits the current rather than the controller most of the time, but will still give full power for climbing.

 

[Deleted member 4366]

Am I correct in thinking that a user adjustable cut-off speed, via a display, isn't allowed in the EAPC ruling?

You have to be sensible. How would anyone know how to adjust the speed apart from you. Do you think that some policeman will come along and press secret codes, then try and nick you?

The only problem will be when he sees you going along at 30 mph uphill without pedalling. If you then showed him that your bike only does 15 mph with the motor, he's naturally going to be very suspicious.

 

[Fordulike]

You have to be sensible. How would anyone know how to adjust the speed apart from you. Do you think that some policeman will come along and press secret codes, then try and nick you?

The only problem will be when he sees you going along at 30 mph uphill without pedalling. If you then showed him that your bike only does 15 mph with the motor, he's naturally going to be very suspicious.

As I want this bike to be entirely compliant with the EAPC rules, then you've got a good point there. So, as I won't be going any faster than 15.5mph uphill, then I should be pretty safe from scrutiny anyway.

 

[Fordulike]

@d8veh

I still like the idea of converting a bike using the kit in post #19. Could I ask you Dave, would you be comfortable, from a law point of view, riding a bike fitted with that kit, if the legal mode wire was connected?

 

[Deleted member 4366]

@d8veh

I still like the idea of converting a bike using the kit in post #19. Could I ask you Dave, would you be comfortable, from a law point of view, riding a bike fitted with that kit, if the legal mode wire was connected?

That's a difficult one because it's a 1000w motor, which is illegal whatever you do with it. Also, it's a bit of a waste of time because it won't be very efficient when restricted. It'll actually give less power than a decent 250w geared hub-motor. It would be much better to get something like a Q128, which at least looks like a 250W motor, and give something like double the torque of that one, especially if you choose the 48v 201 rpm version, which maxes out at 19 mph without restriction.

 

[Fordulike]

That's a difficult one because it's a 1000w motor, which is illegal whatever you do with it. Also, it's a bit of a waste of time because it won't be very efficient when restricted. It'll actually give less power than a decent 250w geared hub-motor. It would be much better to get something like a Q128, which at least looks like a 250W motor, and give something like double the torque of that one, especially if you choose the 48v 201 rpm version, which maxes out at 19 mph without restriction.

Totally agree with you there. The blurb is a bit misleading, as it makes it sound like it's totally legal once the special wire is connected. I wonder how many people have bought these, and innocently thought that it is EAPC compliant

I'll have a butcher's at the Q128

 

[Nealh]

Q128C 36V 201RPM maxs out at 19.8mph on my KT lcd2, bit is probably about 19 as these lcds have a speed over read of about 5%.

 

[Deleted member 4366]

Q128C 36V 201RPM maxs out at 19.8mph on my KT lcd2, bit is probably about 19 as these lcds have a speed over read of about 5%.

Mine's the Q128H 48v version and matches that speed. Masses of torque though.

 

[tommie]

Mine's the Q128H 48v version and matches that speed. Masses of torque though.

d8veh, but how would all that perform in a larger 700c rim??

 

[anotherkiwi]

The 201 rpm is the version for the 700c, 26" and 24" wheel. The 328 rpm is for 24" and smaller.

 

[Deleted member 4366]

Fine. It's a good motor for that type of bike. the only thing is to get the speed right;
36v 201 rpm at 36v = 15 mph
48v 201 rpm at 48v = 15 mph
36v 201 rpm at 48v = 20 mph
48v 328 rpm at 48v = 25 mph
36v 328 rpm at 36v = 25 mph.
48v 328 rpm at 36v = 20 mph

Add 7.6% to those speeds for a 700c wheel and say 15% when the battery is fully charged, but deduct 10% when it's flat.

All those speeds are theoretical. I'm pretty sure that, in practice, you can add 2 mph to the speeds.

For me, the best compromise is the 201 rpm 36v one at 48v, which gives a nice balance of speed and torque, but if you're sure that you only want 15.5 mph, then get the 48v 201 rpm one.