Old Giant struggles with hill.

jarnold

Pedelecer
Oct 2, 2024
44
5
71
Gloucestershire
I mean it's not like it's a really steep or long hill. For anyone who has some fancy cycling map app, the bottom of the hill is ///irrigate.absent.tornado and the top is ///landed.stun.caveman

Trouble is, it's winding, potholed and has cars on it. In an ideal universe, I'd find a nice quiet empty gradient, and do some experiments...
 

Peter.Bridge

Esteemed Pedelecer
Apr 19, 2023
1,300
601
I mean it's not like it's a really steep or long hill. For anyone who has some fancy cycling map app, the bottom of the hill is ///irrigate.absent.tornado and the top is ///landed.stun.caveman

Trouble is, it's winding, potholed and has cars on it. In an ideal universe, I'd find a nice quiet empty gradient, and do some experiments...
Just had a look on street view, doesn't look that steep. I think it's worth trying it on Level 1 or 2, please let us know the results
 

chris_n

Esteemed Pedelecer
Apr 29, 2016
744
443
63
Niedeau, Austria
0.5km with average gradient of 4.2% so not really steep. Suggests your controller is way under powered. A KT 17A controller would get you up that at 15 mph withoutany actual effort from you.
 

jarnold

Pedelecer
Oct 2, 2024
44
5
71
Gloucestershire
0.5km with average gradient of 4.2% so not really steep. Suggests your controller is way under powered. A KT 17A controller would get you up that at 15 mph withoutany actual effort from you.
The thing is, I'm happy to supply some of the effort...
I will try on level 1 and level 2...
But just trying to get my head round how these cheap controllers work, because when I was testing this setup, with the driven front wheel off the floor, it seemed like the power to the hub motor cut off when I braked the front(powered) wheel to a standstill.
And no, I don't have any brake switches fitted(although it's on my list, if I get to the point where I think it's all viable...
 

chris_n

Esteemed Pedelecer
Apr 29, 2016
744
443
63
Niedeau, Austria
The way they work is that they give full power until they reach the speed that has been programmed. If level 1 is set at 10 mph you will get full power until you get to 10mph then it will reduce the power so you can maintain that speed, level 2 might give 12mph, level 3 15mph. If you don't have enough power to reach that speed on an incline then you will quickly get voltage sag. That is why a lower setting may actually help as it isn't trying to reach a speed it can't achieve.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,927
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Telford
It will always get more power from the controller on the highest level, so don't waste your time trying the lower levels. The only difference between the levels is the speed at which the power starts ramping down, which is lower for the lower levels. Your best solution would be to run a blob of solder up one leg of the shunt, with the aim to cover about 25% of the length of the whole shunt and no more. That will give you 25% more torque.

Doing things on the cheap gives you a cheap solution. You should never buy a controller unless it tells you its max current. Now, the only way to find out is with an £8 wattmeter from Ebay.
 

jarnold

Pedelecer
Oct 2, 2024
44
5
71
Gloucestershire
It will always get more power from the controller on the highest level, so don't waste your time trying the lower levels. The only difference between the levels is the speed at which the power starts ramping down, which is lower for the lower levels. Your best solution would be to run a blob of solder up one leg of the shunt, with the aim to cover about 25% of the length of the whole shunt and no more. That will give you 25% more torque.

Doing things on the cheap gives you a cheap solution. You should never buy a controller unless it tells you its max current. Now, the only way to find out is with an £8 wattmeter from Ebay.
Are you saying that the reported wattage on the display isn't accurate?
 

Peter.Bridge

Esteemed Pedelecer
Apr 19, 2023
1,300
601
I wondered if the fact that this is a 24v motor with a 36v battery would make the *no load" speed 50% higher, so at low speeds it would take this motor out of its efficient operating zone. I wondered as you approached the level 1 and 2 limit speeds, does a speed controller reduce the voltage or reduce the current ? If it reduced the voltage the "no load" speed would reduce and the motor speed might fall into the efficient zone and provide more power. I suspect from what @saneagle says that it is the current that reduces, that wouldn't help.
 

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,896
1,368
The display and any wattmeter you might add can only measure the power taken from the battery, not the power delivered by the motor. At low speeds the efficiency of a hub motor drops off badly, so delivered power can be much lower than that displayed.

Going back to the hill, are you able to maintain constant speed up it, and is the gradient even, or does speed drop off as you go up, or is gradient steeper at the top? The motor casing remains cool: what about the controller?
 
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jarnold

Pedelecer
Oct 2, 2024
44
5
71
Gloucestershire
The display and any wattmeter you might add can only measure the power taken from the battery, not the power delivered by the motor. At low speeds the efficiency of a hub motor drops off badly, so delivered power can be much lower than that displayed.

Going back to the hill, are you able to maintain constant speed up it, and is the gradient even, or does speed drop off as you go up, or is gradient steeper at the top? The motor casing remains cool: what about the controller?
The controller is screwed to a flat metal plate that is welded to the frame, so I doubt that it's getting hot, but hard to check without taking the covers off.
I could attach a temperature sensor, but there are already too many cables and connectors vying for space.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,927
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Telford
Are you saying that the reported wattage on the display isn't accurate?
It's not definitive, neither does it say whether it's a maximum or rating. Most controllers are definitive. They say something like "Max Current 15A, Rated Current 7A".

Is there a specification in the listing from where you bought it?
 

Peter.Bridge

Esteemed Pedelecer
Apr 19, 2023
1,300
601
On the Amazon listing the OP linked to the sticker on it said current 11a limiting 13a
 

jarnold

Pedelecer
Oct 2, 2024
44
5
71
Gloucestershire
It's not like a lack of power, it feels more like it just cuts out. At the top of the hill everything's fine again...
 

matthewslack

Esteemed Pedelecer
Nov 26, 2021
1,896
1,368
It's not like a lack of power, it feels more like it just cuts out. At the top of the hill everything's fine again...
It doesn't seem like a long/steep/high enough hill to trigger low voltage cutoff or thermal cutoff, no brake switches to go wrong, cadence sensor working fine, I can't see an answer from afar!
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
How fast is the bike moving at cut out.