Bafang CST and S12S controller without LCD

[RustyKipper]

Hey Guys,

I’m currently nearing fitting my new Bafang CST and S12S controller, just finishing the carbon composite battery box and saving up for the remainder of the 15Ah Headways.

So sorry if this question has been asked before but here goes.

I know the controller will function without the LCD display by linking the appropriate wires and indeed have had the motor and controller running happily on the bench. I believe if the LCD-3 controller is not fitted the controller will default to power level 2 (out of 5 levels). I haven’t been able to ascertain if this is only when using the pedal sensor or if this effects throttle also.

I don’t want to fit an LCD as I want the bike to be as stealthy as possible and it would be just something else to be shaken to pieces on my daily commute.

The idea is to use the 500W rear Bafang as an out of town boost for hill climbing, around town I am quite happy with the 250W SWXK working from the crank sensor, even with this modest power level I have fitted a switch under the saddle to switch out the pedal sensor so some of the trickier manoeuvres can be carried out on part throttle. The 500W motor will use throttle only.... I think realistically I might just end up with the rear cst on both crank sensor and throttle ultimately but riding around town and cycle lanes on 250W kind of gives me a clear conscience.

So the question is without the LCD can I use full power (the case of the S12S shows max current being 30A) or am I stuck with the lower default power. If so has anyone tried communicating with the S12S with an Arduino or similar, it would be physically very easy to construct a simple dongle if sense can be made of the data sent between the 2 devices, I’ve successfully hacked into GPS receivers before now to build speed and altitude sensors so this should be do-able.

I have seen a few of you chaps with very tidy and stealthy looking steeds without any obvious LCD’s fitted and what looks like CST’s and S12S’s.

 

[motomech]

Yes, it will be stuck in speed level 2 when pin jumped.
I think your best bet would be to get the SLCD-1 and hide it.

 

[d8veh]

You completely wasted your money if you bought a S12S without a LCD. If you don't want a LCD and PAS, the KU123 would have been better.

My advice, get a S-LCD1. It won't shake to pieces. They're very robust. Then, you can enjoy all the benefits of the S12S, in particular, the nice PAS system.

 

[RustyKipper]

Oh that's annoying.

S-LCD1 now on order, its going to be a struggle to find a location for it though, on the other hand it will give me the opportunity to look at the data and see if I can make up something to fool the controller into thinking an lcd is fitted. A small pcb will take up some of that wasted space inside the controller enclosure.



A couple of questions,

How does the power of the S12S / 500W CST on level 2 compare to a 250W SWXK? the latter motor is getting quite hot to the touch especially when the weather gets over 30 centigrade, I could likely run the above combo from my current 9Ah battery pack on level 2 without the bms cutting it, this could work until the lcd turns up.

How does the CON121 compare to the KU123, obviously they are both square wave, similar power, size ect, its just I can get the CON121 from Greenbikekit, life's just too short to deal with BMS more than I have too.

 

[motomech]

Speed level 2 (out of 5) is S-L-O-W. maybe 12 mph.
If all you want is a throttle only, small controller, why not use a 6-FET Infineon based controller, the two most common being the Grin 25A or a Lyen Mini-monster.
I've used both and they pack the most punch into the smallest package and they are bullet-proof.
Grin will get it to you fast.
Lyen can add options, but u\it takes a while.

 

[d8veh]

Speed level 2 (out of 5) is S-L-O-W. maybe 12 mph.
If all you want is a throttle only, small controller, why not use a 6-FET Infineon based controller, the two most common being the Grin 25A or a Lyen Mini-monster.
I've used both and they pack the most punch into the smallest package and they are bullet-proof.
Grin will get it to you fast.
Lyen can add options, but u\it takes a while.

It uses current control, so no effect on speed. It'll still spin to the maximum, but with less power.

A 9Ah battery isn't going to be powerful enough unless it's something special. Running a battery continuously near the point at which the BMS will trip will wesr it out very quickly.

 

[TheBeastie]

I have used the LCD1 exclusively for over a year and i stays attached fine but I recently upgraded to the LCD3 a good month ago and I think if anything i attaches on and stays on even nicer.
Because the PAS assist level buttons on the LCD3 are separate you could get a small cyclist handlebar bag or phone bike down tube bag and hide the display in that and just have the discreet PAS buttons on the handle bars that way you can get all the benefits of the LCD displays adjustment levels but still be pretty discreet.

 

[RustyKipper]

It uses current control, so no effect on speed. It'll still spin to the maximum, but with less power.

Ah, now that's interesting. My SWXK / 6 fet controller combo run out of the box at 14A I shunt modded the controller to run at 18A for hill climbing (possibly why the motor gets hot). I don't suppose you would have measured the current on level 2?

I tend to pedal quite hard, on the flat I like to keep to about 19 to 24mph, I think 19mph is about the point that the little motor tops out so in theory with the CST / S12S there will be some current / speed still available. I'm kind of thinking it could be weeks before the LCD turns up but I might be able to use the new motor in the meantime. I wonder if I could do a temporary shunt mod on the S12S. I have a 15Ah / 36V battery under construction.

Probably clutching at straws as I don't want to sacrifice hill climbing power for speed.

 

[RustyKipper]

Ignore the last post, I may have been talking out of my bottom

 

[medved]

Hey Guys,
I know the controller will function without the LCD display by linking the appropriate wires and indeed have had the motor and controller running happily on the bench. I believe if the LCD-3 controller is not fitted the controller will default to power level 2 (out of 5 levels). I haven’t been able to ascertain if this is only when using the pedal sensor or if this effects throttle also.

I have seen a few of you chaps with very tidy and stealthy looking steeds without any obvious LCD’s fitted and what looks like CST’s and S12S’s.

Can you please send the link where you found it? I found only this topic.

 

[motomech]

They were probably using a simple square-wave controller like I use. I do combine my controllers w/ the 810LED display, which is durable and not very obtrusive.

Two 810 displays.
Voltmeters in the sm. frame bag.

 

[medved]

Thanks, for my 2wd setup I will order S-LCD3 display for front controller and 810 LED in case if the rear controller refuse to work without display.