Old Giant struggles with hill.

[jarnold]

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]

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]

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]

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]

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]

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]

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]

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]

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?

 

[jarnold]

I'll do some more testing if it ever stops raining.

 

[jarnold]

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]

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?

 

[jarnold]

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?

https://amzn.eu/d/io12pGf

 

[saneagle]

https://amzn.eu/d/io12pGf

This looks like the same one. It has 13A max current written on the label. Does yours have that?

https://www.amazon.co.uk/dp/B07WYMMQTD/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07WYMMQTD&pd_rd_w=eDPYE&content-id=amzn1.sym.46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_p=46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_r=S016X68A3CTYVAHBQ77D&pd_rd_wg=rymTN&pd_rd_r=b0e496ea-b452-4ec7-8ac8-e4787b924c81&s=sports&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

If yours is 13A, that's the reason for the lack of power. Soldering 25% of the shunt will get it up to a more useful 16.5A.

 

[Peter.Bridge]

This looks like the same one. It has 13A max current written on the label. Does yours have that?

https://www.amazon.co.uk/dp/B07WYMMQTD/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07WYMMQTD&pd_rd_w=eDPYE&content-id=amzn1.sym.46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_p=46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_r=S016X68A3CTYVAHBQ77D&pd_rd_wg=rymTN&pd_rd_r=b0e496ea-b452-4ec7-8ac8-e4787b924c81&s=sports&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

If yours is 13A, that's the reason for the lack of power. Soldering 25% of the shunt will get it up to a more useful 16.5A.

On the Amazon listing the OP linked to the sticker on it said current 11a limiting 13a

 

[jarnold]

On the Amazon listing the OP linked to the sticker on it said current 11a limiting 13a

On the Amazon listing the OP linked to the sticker on it said current 11a limiting 13a

Maybe you're viewing it on a computer, I can't read that on my phone.

 

[Peter.Bridge]

Maybe you're viewing it on a computer, I can't read that on my phone.

Took a screenshot and used the Google photo editing wizardry, it's very faint on the listing

 

[jarnold]

This looks like the same one. It has 13A max current written on the label. Does yours have that?

https://www.amazon.co.uk/dp/B07WYMMQTD/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07WYMMQTD&pd_rd_w=eDPYE&content-id=amzn1.sym.46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_p=46187d6a-4306-4bc6-830c-7b2085e0e39f&pf_rd_r=S016X68A3CTYVAHBQ77D&pd_rd_wg=rymTN&pd_rd_r=b0e496ea-b452-4ec7-8ac8-e4787b924c81&s=sports&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

If yours is 13A, that's the reason for the lack of power. Soldering 25% of the shunt will get it up to a more useful 16.5A.

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]

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]

How fast is the bike moving at cut out.