Ordered the wrong controller, will it work?

[anon4]

I am upgrading my wife's bike to 48v, we have accidentally ordered a 24/36v 15a controller instead of equivalent 48v one. The battery has a BMS which should protect it, and the KT LCD should show the correct charge anyways. The question is will it even run? Anyone got experience of doing this with a KT controller?

 

[vfr400]

I'm pretty sure that the answer is no. The LCDs have a volt rating written on the back too. Some are limited to 36v, some, 48v and some 72V. Look carefully at the back. If it says 24v/36v, you'll need a new LCD as well as the controller.

 

[anon4]

I'm pretty sure that the answer is no. The LCDs have a volt rating written on the back too. Some are limited to 36v, some, 48v and some 72V. Look carefully at the back. If it says 24v/36v, you'll need a new LCD as well as the controller.

The LCD is definitely correct as it's the same listing I bought for mine. I'm reading mixed things online, some are saying if the caps inside are 63v then it will work, was thinking the controller might just throw an error though. Looks like I might have some explaining to do hehe

 

[vfr400]

The LCD is definitely correct as it's the same listing I bought for mine. I'm reading mixed things online, some are saying if the caps inside are 63v then it will work, was thinking the controller might just throw an error though. Looks like I might have some explaining to do hehe

You know it's correct when you look at the marking on the back!

 

[Nealh]

The 24/36v controller will blow at 48v, the caps aren't 63v rated.
That's why they do a 36/48v version.

 

[anon4]

You know it's correct when you look at the marking on the back!

I know it's correct because I ordered it separately from the same link I bought mine

The 24/36v controller will blow at 48v, the caps aren't 63v rated.
That's why they do a 36/48v version.

That's what I feared, we will sell it at cost and order another more carefully

 

[anon4]

The 24/36v controller will blow at 48v, the caps aren't 63v rated.
That's why they do a 36/48v version.

Well It came today and I opened it up, turns out it actually does have 63v caps. I will see if it runs, still going to order the proper one but I suspect we might get away with running this for a short time at least, have read a few success stories of people doing the same

 

[Nealh]

It pays to look sometimes, I had a 24/36v KT and it only had 50v caps.

 

[anon4]

It pays to look sometimes, I had a 24/36v KT and it only had 50v caps.

Yeah, I'm just wondering if the KT LCD 3 sets the lvc, the BMS has its own but it cuts a bit low for my liking

 

[anon4]

It's running. I had to mess with c2 as it was running rough, now it's ok. The throttle doesn't seem to run at full speed but the Pas does, any idea what's going on there?

 

[anon4]

Nevermind the limiter wire was plugged in, rode to shops and hasn't blown up yet lol

 

[Nealh]

KT lcd lvc is 30v @36v & 40v@ 48v, 24v is 20v which is low at 2.86v per cell.
C12/4 is the normal setting for 20,30 or 40v lvc you can raise lvc by up to 1.5v using value 5,6 or 7 with each value being +0.5v higher.

 

[anon4]

KT lcd lvc is 30v @36v & 40v@ 48v, 24v is 20v which is low at 2.86v per cell.
C12/4 is the normal setting for 20,30 or 40v lvc you can raise lvc by up to 1.5v using value 5,6 or 7 with each value being +0.5v higher.

So the LCD does handle the cutoff, great. On our shopping run we brought two panniers full of tins and bungeed a load of pop and beer to the rack so the motor was understandably stressed and it worked great. Better than mine actually, the 20a controller I use likes to cut out unless you limit it to 17a, her controller is tiny, wrong voltage and runs at its full 15a spot on

 

[Nealh]

LCD only sets the lvc level , the controller handles the lvc cut off.

 

[anon4]

Hmm maybe we spoke too soon about it working fine. She has complained of cutouts on the way to work. If it's anything like mine it's the crappy fets overheating, reducing the current should sort it. Maybe the c2 setting is still wrong, am I right in assuming this does the same as swapping the phase/hall wires around to get the correct combo? It seems to behave as expected with it set to 2 so I think it is a fet issue possibly because of overvoltage, any other things I should check?

 

[Nealh]

The 6 fetters run to hot in high pas level on inclines at a slower pace.
My one got so hot I couldn't hold it, the 9 fetter runs cooler it gets warm but not so uncomfortable I can't hold it.

 

[anon4]

The 6 fetters run to hot in high pas level on inclines at a slower pace.
My one got so hot I couldn't hold it, the 9 fetter runs cooler it gets warm but not so uncomfortable I can't hold it.

It seems there was a connection issue as it was intermittent when I tried it. I have melted some solder into the phase and halls to reinforce their connections then made sure everything was secure. Fingers crossed

 

[Nealh]

The phase bullet connections are often a weak link as vfr often tells all to solder directly or I use a better rated connector like MT60.

 

[anon4]

The phase bullet connections are often a weak link as vfr often tells all to solder directly or I use a better rated connector like MT60.

Nah this seems to be a bigger issue as it's just not wanting to work, it seems when it reaches a certain speed it bugs out and starts acting like the halls aren't connected right. I have repaired my old brainpower controller so she will at least have a display while we wait for a proper one. This motor is faster than mine, is it possible for a motor to be too fast for a particular controller?

 

[anon4]

Have repaired my old brainpower controller I borrowed wires from and stuck that on her bike, all is well now. Guessing it's probably because of wrong voltage, in hindsight I should have tested her old 36v battery to verify. Now what I need is a KT 48v that is pretty small as my 20a model would never fit in that enclosure