Yk85s controller 36v mode

So I have the yk85s controller on a bike working with 48v through a dcdc stepup off a 54.6v server power supply. Now this controller is supposedly both a 36v and a 48v controller and my new batteries are all 36v so I'd like to run this yk85s at the 36v but I cannot work out how this is done. Any people here running this controller at 36v?

Does it not run at all on your 36v packs?

If you have a variable voltage PSU you could try using that to power it off-ground no-load to see exactly where the LVC on yours is. If the PSU isn't high enough voltage on it's own you can series it with a lower voltage battery to just vary the smaller amount with the PSU.

If it's like this one
https://www.aliexpress.com/store/product/36V-48V-250W-350W-16A-Electric-Brushless-Motor-Controller-Electric-Scooter-Ebike-Tricycle-Speed-Controller-36V/2502036_32764330398.html
it says it has a 42LVC, which would make it not really a 36v controller (as a 36v pack might be *full* around that voltage).

I did some poking around and have found references to people with 36v packs that run this controller, and found at least one that mentions a problem with an SLA setup after the first km or two with cutouts till he lets it sit; there's no further info from him about it beyond that. If he was charging to 14.4v per SLA that'd be 43V+, just above the LVC, so it could've been cutting out from that if the pack was big enough to not sag much from load. But I couldn't find any further info from him about it, or other issues like that for this controller.

I feel like it might be a jumper inside on the PCB which is populated or not to switch between 36v and 48v mode but this is a guess. I have a faux sine wave 36v BMS battery controller that works so I might swap that over. It's annoying since this controller is small, neat and does the job. Another option is running the battery via a boost dcdc so giving it the voltage it wants to see. Problem with that is the mess.

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Some dual voltage controllers and LCDs are fully automatic. It's a mystery how they decide what battery have, but they normally get it right, though it helps that your battery voltage is unambiguous when you first connect. Others have to be set by a setting in the LCD. A few years back, there were some with jumper wires, but I haven't seen one like that recently.

There is no LCD nor wires to connect it. Theres a couple of white wires which switch the wheel direction when you momentarily short them but I haven't open it up to look at the PCB yet. I think my voltage at 36v was under the 41.5v lvc for 48v so if it were doing it automatically it should have just worked.

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Some controllers do indeed work on multiple voltages, but in your case, the implied 36v/48v compatibility might just be a bad translation of Chinese to English. It could be intended to work on a specific voltage.

To eliminate the need for multiple iterations on these controllers, there might be a jumper on the circuit board that sets the working voltage.

I have one (non-KT) that was available in either 36V or 48V, versions, but it came with an LCD so I assumed I'd could buy the 48V model and run both. Well, I was wrong. I initially set it up on 36V and wasted several hours going thru all 36 Hall combos but the motor just stuttered. LCD worked though, and I could set LVC to 30V. Then I tried 48V and it spun up my motor as advertised. Later, I opened it up and spotted a bare pad marked "36V". When I jumped it to ground, I had both 36V and 48V operation. Maybe all it does is override a hard wired LVC, and the LVC on the LCD is meaningless.

I've found that sometimes there is enough residual charge in my KT controllers that they get confused when I change from a depleted 48V battery to a fresh charged 36V battery. They power up with a low battery icon. Unplug. Wait. Reconnect. Then they sense the proper voltage.

Found another 36v ku93 controller lying about in my parts bin. Will test that out later. Nothing on the PCB which definitely read 36v but were a few pads designed to be jumpers to ground one labeled 12/6 which was an interesting candidate. While I have this one working at 48v and another that I can test to work at 36v i will refrain from breaking it via randomly shorting pads I don't understand.

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whereswally606 said:

one labeled 12/6

Click to expand...

probably 120/60 degrees for the halls.

That makes sense

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Mounted the KU93 yesterday and after lots of faffing managed to get the bike working on the 36v Macalister b&q battery. At first I thought I'd broken something and then after a full throttle on and off I saw the wheel move a smidge. I did it again saw abit more movement. Then I did this repeatedly and saw that the wheel was spinning nicely backwards. Realised I was simulating Pedal assist sensor and then looked for the throttle input. Different connector so went and found a spare throttle to avoid further soldering. Hooked it up, then swapped two phases to reverse it. There was no handy wires on the ku03 unlike the yk85s to swap the wheel spin direction via a momentary jumper. So now the bike is not far off a maiden 36v journey. My aim is to convert all my bikes to this system and 3d print all the mounts. That way I can sell / recycle the old ones and consolidate all the new batteries into this form factor.

Should probably start a new thread as the topic is now defunct in that I now use a different controller on the bike. The update is that I managed to get both my Scott ransom and Norco team race bikes running on the Macalister b&q batteries now with my custom 3d printed mount which is also houses the terminals to mimic the batteries natural home in say a strimmer or mower. This involved reflashing my golden motor controller to lower the lvc for 36v. So today my wife and I took my Husky\samoyed cross and son on 5mile run. Used 1.8ah which was less than 1 full battery and we have 4 working 2.6ah one and two which need new cells. Pictures to follow when I next get on my computer