Q128C seems very slow - normal or not?

Forge Custom

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May 14, 2016
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Hi

It's been a bit of a marathon but I've finally got the 201 36v Q128C fitted to my MTB - paired with PSWPowers 20s controller and a 48v 14.5ah battery from Jimmy at Insat.

I've gone to spin it up today and take it for its first test run and I have to say - it feels pretty gutless for want of a better word. So I'm wondering if something isn't quite right?

Only got it on the thumb throttle at the moment but spinning it up with full throttle, it max's out at about 29kmh/18mph. And that's without me sat on it. WIth me on it - I'd say 15mph was about it. I'm 13.5st so not particularly lardy!

So - is that all I can expect? I have a 1000w Cyclotricity motor laced into a much heavier beach cruiser bike and using the same battery - that flies.

Are there any LCD P settings that might be wrong? I was just expecting more. Again, I tried it out alongside another heavier beach cruiser that had a 250w Panada front drive motor on, and again, that easily outpaced the Q128C.

Any thoughts, much appreciated. I'll try and upload a video somewhere of it spinning up too.

Many thanks

Matt
 

Nealh

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Aug 7, 2014
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Have you disconnected the speed restriction white wires out of the controller ?
I recently tried mine with the two whites connected :eek:, arrgh the ride was horrible so pedestrian. They came apart very quickly again :D.

36v Q128C with 36v comfortably goes up to 19mph and a bit more with good cadence, 48v should go somewhat more expect 24/25 mph.
 
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Forge Custom

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Have you disconnected the speed restriction white wires out of the controller ?
I recently tried mine with the two whites connected :eek:, arrgh the ride was horrible so pedestrian. They came apart very quickly again :D.

36v Q128C with 36v comfortably goes up to 19mph and a bit more with good cadence, 48v should go somewhat more expect 24/25 mph.

Ah - didn't know there were any! Is that standard with PSWPower controllers?
 
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Deleted member 4366

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I take it that you've set it to a speed limit much higher and that you have the correct wheel-size set? Also, there's lots of settings in the controller. Make a note of all the P and C settings and list them here.

24w seems a bit low, so it might well be hitting a speed limit. How many watts show if you run the motor under high load? Apply the brake while you spin the motor to see. That might give some clue to what's going on.
 

Forge Custom

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I take it that you've set it to a speed limit much higher and that you have the correct wheel-size set? Also, there's lots of settings in the controller. Make a note of all the P and C settings and list them here.

24w seems a bit low, so it might well be hitting a speed limit. How many watts show if you run the motor under high load? Apply the brake while you spin the motor to see. That might give some clue to what's going on.
Thanks d8veh. The bike is still in my mate's shop so not to hand. Spped limit was set to maximum and wheel set at 700c (it's actually 27.5 - is that the best setting?)

Disconnecting the white speed restriction wires has improved it apparently - he did that before shutting - but still said it didn't seem to be spinning as quick as other motors.

Are there any obvious P or C settings that effect speed limit? I have it as throttle only at the mo - no PAS fitted. Does P3 effect this?
 

1boris

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Sep 10, 2013
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i have the q128c 201 RPM 36volt version in a 700wheel with 48v 18 amp and can pedal it to ca 43 kmh.
 
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Deleted member 4366

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You need to fit the PAS! It's the best feature of that system, so I can't understand why anybody wouldn't want it.

If you're only using throttle to test, the throttle might be faulty. If the high magnet gets dislodged, you only get half-throttle. That's quite common.
 

Forge Custom

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You need to fit the PAS! It's the best feature of that system, so I can't understand why anybody wouldn't want it.

If you're only using throttle to test, the throttle might be faulty. If the high magnet gets dislodged, you only get half-throttle. That's quite common.
I wanted to fit the PAS but it wouldn't fit the hollow tech bottom bracket so abandoned it. I know there's a fettling way around it I've seen but I was hoping it would be more bolt on and play. I've seen various PAS that say they're specifically for Hollow Tech BB's but not sure. Haven't checked properly but the guy fitting it said there wasn't 'enough gap'.

Will check the throttle. Would the fact it's left hand but been fitted upside down as a right hand have dislodged the magnet maybe?
 

BornAgainCyclist

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Apr 22, 2017
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Fully charge the battery and when reconnected do a lcd reset and reprogramme. Use the LCD3 manual and set it up so that P1 is 201 and P3, 4 and 5 reflect the throttle usage.
 

Forge Custom

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May 14, 2016
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Fully charge the battery and when reconnected do a lcd reset and reprogramme. Use the LCD3 manual and set it up so that P1 is 201 and P3, 4 and 5 reflect the throttle usage.
Thanks for that. Can I ask how do I do a reset and assuming I'm using throttle only, what would be your suggested settings for P3, 4 and 5 please?

Thanks again

Matt
 

Nealh

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P1 setting has an effect on the hub timing and can cause slow/hesitant pickup under pas use, throttle is unaffected.
Try 202 - 224 the scope/range is quite wide and then use a gps to see if the lcd speeds match or are close to within 2 or 3 tenths of mph if not adjust the P1 setting up or down by 2 digits at a time to match the speed read outs.
Lowering the number gives a higher speed readout and going higher reduces the speed readout.
 
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Deleted member 4366

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The PAS should be dead easy to fit on a Hollowtech (Shimano) crank. I have them on all my bikes. They're the easiest because you don't need any special tools. Show us your PAS and a photo from underneath your BB, and I'll show you how.
 
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Forge Custom

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The PAS should be dead easy to fit on a Hollowtech (Shimano) crank. I have them on all my bikes. They're the easiest because you don't need any special tools. Show us your PAS and a photo from underneath your BB, and I'll show you how.
Thanks d8veh. Will get some pics in the week.
 

Forge Custom

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Literally not had time to look at it again yet alas. It's in my mate's shop and he's been away all over Christmas. I think he disconnected one of the controller wires - the white speed restriction one - and he said it spun up a bit quicker but he hasn't ridden it. Hoping to get it back at the weekend to investigate further. I think possibly my expectations may have been too high as I have a 1000w Cyclotricity hub in the rear wheel of a much heavier bike and that flies. Same 48v battery.
 

Nealh

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If the controller restriction white wire has been disconnected and you adjust the lcd speed to about 45km/h you should see about 22-25mph depending on gearing.
My 36v Q128C sees 19mph @36v, though when I eventually try it at 48v should see another 4- 5mph.