Power has been cutting out for a few seconds when going up hill

[Bachgen_o_Gymru]

How do you intend on running a 35a controller output to only draw 20a ?

As far as I'm aware, I could do this by reducing the C5 setting on the lcd to a lower value, or by crimping the shunt on the controller.

 

[anotherkiwi]

As far as I'm aware, I could do this by reducing the C5 setting on the lcd to a lower value, or by crimping the shunt on the controller.

You said the controller was warm, that rules out thermal cutoff.

We need to know if the battery sags before you make any rash decisions.

C5 can only go down to -1.5 IIRC which would be 23 A with a 35A controller.

 

[Bachgen_o_Gymru]

You said the controller was warm, that rules out thermal cutoff.

We need to know if the battery sags before you make any rash decisions.

C5 can only go down to -1.5 IIRC which would be 23 A with a 35A controller.

Do you know if it is possible for a controller to momentarily cut a high current due to something other than thermal cutoff?
I suppose you're right that I need to check if the battery is sagging before I make any other decisions. I'll take a look at the voltage next time I ride up the hills.

 

[anotherkiwi]

Do you know if it is possible for a controller to cut a high current due to something other than thermal cutoff?
I suppose you're right that I need to check if the battery is sagging before I make any other decisions. I'll take a look at the voltage next time I ride up the hills.

No, if you feed too many volts the capacitor will blow other than that they are pretty bullet proof.

 

[Bachgen_o_Gymru]

I just have one more question: If the problem was being caused by the battery, would it be expected that the LCD would shut off rather than stay on? It would seem to me that the fact that the LCD stays on while power is being cut indicates that the issue is being caused by the controller.

 

[anotherkiwi]

I just have one more question: If the problem was being caused by the battery, would it be expected that the LCD would shut off rather than stay on? It would seem to me that the fact that the LCD stays on while power is being cut indicates that the issue is being caused by the controller.

The battery can be supplying the tiny amount of current required for the LCD. Some LCDs have a battery so are self powered.

The controller doesn't have enough volts to send to the motor, that is your cut off we have to find why.

I thought of another type of cut out that you can have with a mid-drive, back EMF but in my experience it doesn't last 5 seconds just a short "burp". Back EMF is caused by spinning too fast. I fixed it by upping the voltage only to have thermal cut out by the controller...

 

[Nealh]

C5 only allows 5a max reduction, each # from 10 to 00 is 0.5a reduction and not a % one.

LCD only need 5v so unless power is completely off it will still function.

Another factor could be wiring if you have used incorrect awg spec wiring, if too thin will cause a bottle neck and not be able to deliver required amps or poor wire connectors.

 

[Nealh]

The likely hood is the battery as AK mentioned isn't up to delivering the required high load needed to see 900+w.
For this the cells need to be v.good rated ones of at least 10a, the best buck for your money for a 10a rated cell is a Panasonic PF.

 

[Bachgen_o_Gymru]

Thanks for your replies.

Yeah I suppose it probably is that the battery isn't able to deliver the high wattage that I've been using. I'll check the voltage next time I go up the hills to see if the battery is sagging. If I am able to discover that this is the cause of the issue, I'll try running the bike at a lower current from then on and see if the problem stops occurring.

 

[Bachgen_o_Gymru]

I went for a ride today which included a mile-long hill that was moderately steep. I kept an eye on the voltage display on the LCD as I went up the hill. The resting voltage was 52.5 at the start of the hill. The voltage dropped under load, but I don't think there were any sudden drops of 3 or 4 volts. The voltage gradually went lower the further up the hill I went. At the end of the hill, the voltage under load was 48.2. I think it then went up to 50 or thereabouts when I went downhill and wasn't pedaling. Near the top of the hill, I had to stop the bike to put the chain back on after it had fallen off. When I pressed the throttle to restart the bike, the power cut off, and it stayed off for 15 seconds or so before going back on. This was the only time the power got cut during the trip. The controller got warm during the ride, but not hot.

 

[Nealh]

Do you use pas ?

The fact the cut out happened using throttle suggests a battery issue and it can't handle the instant load, could be a weak cell string or the cells in general doesn't like it.
Have you tried C5 setting, adjusting it lower and see what happens. There should be appoint at which the battery is happy to handle a load, just a case of finding it's threshold.

 

[Bachgen_o_Gymru]

Yeah I use pedal assist most of the time. I just use the throttle from standstill.
I'll reduce the C5 setting to number 8 and see if that stops the problem.
Are you sure that the C5 setting goes down 0.5a from one level to the next? On the kt-lcd3 manual that can be found online, it says that the C5 setting goes down as a percentage. According to that manual, the C5=9 level should provide 91% of the current that C5=10 provides, and C5=8 should provide 87% of the C5=10 current.

 

[anotherkiwi]

Yeah I use pedal assist most of the time. I just use the throttle from standstill.
I'll reduce the C5 setting to number 8 and see if that stops the problem.
Are you sure that the C5 setting goes down 0.5a from one level to the next? On the kt-lcd3 manual that can be found online, it says that the C5 setting goes down as a percentage. According to that manual, the C5=9 level should provide 91% of the current that C5=10 provides, and C5=8 should provide 87% of the C5=10 current.

It depends on the software version I think.

 

[Nealh]

Yeah I use pedal assist most of the time. I just use the throttle from standstill.
I'll reduce the C5 setting to number 8 and see if that stops the problem.
Are you sure that the C5 setting goes down 0.5a from one level to the next? On the kt-lcd3 manual that can be found online, it says that the C5 setting goes down as a percentage. According to that manual, the C5=9 level should provide 91% of the current that C5=10 provides, and C5=8 should provide 87% of the C5=10 current.

Try all C5 settings down to 0.
I browsed yesterday and noticed they now appear to use a % level as AK has said it is likely down to software versions used. The later % revisions certainly offers more adjustment scope.