Changing the LVC in a 72v generic controller

i just read this thread for the first time.

does anyone understand that the three 1500R resistors in parallel are there to reduce the voltage input to the voltage regulator? they have nothing to do with setting the LVC.

for a generic processor, expect the pin on the microprocessor that gets the LVC voltage to be #1 or #2 in the upper left. it may be different on some.

but you want to find the resistor divider bridge between Vcc and ground which has a trace coming out from the middle of the divider and running up to the micro. that's why looking at those pins on the micro can help you find the bridge.

if it is a 72V controller on the label then it will have a 60V LVC since they are all set up to use SLA.

if you need to reduce the LVC then find the resistor in the divider bridge between the trace that goes to the micro on one side and to ground on the other side.

if you have a 16S lifepo4 pack, then the LVC can be set as low as about 35V.

so you would want the new resistor below the trace to be 35/60 of the original. so about 7/12 the original value. so if the resistor is now 1k ohm, you can solder another surface mount resistor right on top of the old one so the new equivalent resistance is 7/12 of the old value and you would then have a 35V LVC. no cutting or drilling or anything insane. just add a new resistor in parallel with the old and of a value such that the equivalent resistance of the two in parallel will get you to the new LVC you want.

for example. current resistor 1kR, you wanna go from 60V LVC to 54V for 20S lipo. 54/60=.9

so the equivalent resistance will be .9 R1 where R1 is the original resistor. add R2 in parallel and solve

.9R1=(R1xR2)/(R1+R2) solve for R2

can anyone do that?

if you can solve that, then you can simply add another resistor in parallel. if not then buy another controller of the LVC you need.


ps: it actually is more complicated than this, in that you really have to add the in the value of the resistors in the divider network above the trace to the micro and use that to find the ratio of the lower resistor to the total resistance and then change that ratio by the amount needed. but those resistors above are much larger values so the ratio is essentially the same. so this is a simple way to solve for the new LVC without too much math.

if you can solve that, then you can simply add another resistor in parallel. if not then buy another controller of the LVC you need.

Click to expand...

Or just club out one of the resistors with your caveman tools, and use a volt meter instead. :wink:
Really that sounds a lot easier to me.

parajared said:

Does the LVC serve another function other than battery protection?

Click to expand...

Yes, it controls regen braking function. Set too low regen won't work. That's why i raised my lvc to 88V when I went to 24s rc lipo. It may also have other effects that I don't know about.

dnmun said:

for example. current resistor 1kR, you wanna go from 60V LVC to 54V for 20S lipo. 54/60=.9

Click to expand...

That's backwards. You need to lower the resistance to increase LVC. You lower resistance either replacing the stock resistor or putting another in parallel with it. I chose to leave the stock resistor and add a 0-12k variable resistor in parallel so I could easily adjust it. Original resistor was 2200 ohm for 60V lvc. Lowering it to ~1200 ohm increased LVC to ~88V, which is where I wanted it.

Spacey said:

I bought a couple of controllers that were supposed to be 36v but turned out to be 72v controllers grrrr

Hooked up one of them to the programming cable to PC and changed the LVC back to 36v.

The other one I can not do this as I gave my programming cable to someone and it's now gone, would love to just cut or does older something to have no LVC....that's what my BMS is for.

Click to expand...

How easy is it to reprogram one of these Hua Tong controllers?

Is it possible to change the current li it at all?

Thanks

There's pads on it for a usb connection, but I don't know where you'd get the software for it. Manually changing LVC is easy.

That's backwards. You need to lower the resistance to increase LVC. You lower resistance either replacing the stock resistor or putting another in parallel with it. I chose to leave the stock resistor and add a 0-12k variable resistor in parallel so I could easily adjust it. Original resistor was 2200 ohm for 60V lvc. Lowering it to ~1200 ohm increased LVC to ~88V, which is where I wanted it.

Click to expand...

So removing a resistor would lower the resistance right? You would have to solder in a bigger resistor to lower the LVC?

HypnoToad said:

Spacey said:

I bought a couple of controllers that were supposed to be 36v but turned out to be 72v controllers grrrr

Hooked up one of them to the programming cable to PC and changed the LVC back to 36v.

The other one I can not do this as I gave my programming cable to someone and it's now gone, would love to just cut or does older something to have no LVC....that's what my BMS is for.

Click to expand...

How easy is it to reprogram one of these Hua Tong controllers?

Is it possible to change the current li it at all?

Thanks

Click to expand...

I managed to find a usb programming cable but it's from a different controller...having no luck programming it so far.

Will have to change the wire order around a bit until it sends the changes over to the controller. Programming software included with this post

Removing a resistor will increase resistance in a paralleled resistor network. Adding a resistor will lower resistance. One 5K resistor is uh, 5K of resistance. Parallel another 5K with it and resistance will drop to 2.5K Parallel in another 5K resistor and the resistance will drop even more. Increasing the resistance value in the divider circuit will lower LVC. Lowering it will increase LVC

Well this is just great. I finally found this thread, read through it a couple of times while waiting for my controller to arrive. It arrived today. It shipped out on 09/07/2012. I opened up the case, since I have just about memorized all of the pictures in this thread and guess what - it does not look like any of the pictures - not even close. So whoever said they change designs constantly was spot on.

I was planning on using a 20s lipo, so the stock LVC of 60V would mean cutoff at 3V per cell, which is a bit low in my mind for any protection. Of course I could just watch the volt meter and quit riding whenever I choose. I guess my question is would the regen work with the stock LVC and a 20s lipo pack? I know Wes said it worked fine with an 18s lipo.

The good news is that it does have 100v caps and FB4410 fets. It does have some more wires on it. It came with two pages of instructions in Chinese, but they are translated - if you want to call it that. It's actually a hoot to read. I can post what they describe and say if anyone is interested.

I think there is enough info here that would enable me to track down the location of the voltage divider if I need to change the LVC. Not that I really want to do that.

The heat sink is straight with good case contact. The board looks really good.

WTN

After further inspection it has the same connections as shown on page 1 of the "72V 1500W 40A Hua Tong Generic controller connections " thread. It threw me because the Alarm 5 pin connector is separated into two connectors - one has the red and black wire - and the other has the blue - yellow - grey wires. On page two are instructions in Chinese and also in English. Here is the English translation:

Phase choice: the two yellow line docking for 60 degrees. not pick up for 120 degrees.

Cruise line: no plastic interface that a fine line: take root orange negative extremely cruise function, and take a moment, remove cruise.

(the two orange wires for alarm setting)

Two of the orange line into one fine after fine line to root orange: if alarms open (lock) alarm, tire constantly forward or backward sliding, explain motor signals and controller does not agree, this time the built-in signals to two of the docking with the fine orange line, then check is normal or not.

(this threw me - but they are talking about the throttle below)

Turn to the line: turn black and red two head, measure whether have 5 V, if have, normal, no word that is not normal.

WOW - is this how their communication works in their brain. No offense. My daughter in law is Chinese. Extremely smart folks.

The board looks nothing like the pictures posted. Heck, I cannot even find the pads for low speed and regen braking (the ones you would ground to activate said function)

WTN

OK. I have found a thread that has pictures of my controller. Now I am getting somewhere. Jeez this takes forever to track down.

WTN

Can you copy the link of where you bought that 100V fets and caps controller ?

http://www.dhgate.com/72v-1500w-brushless-speed-controller-for/r-ff80808131bbd38d0131bbda55e40253.html

It shows sold out at the moment

WTN

Is there a number on the board. If it's ca08x8m06ad_p04.1 then it's the same as mine and instructions to change LVC are in this thread.
http://endless-sphere.com/forums/viewtopic.php?f=2&t=26306&start=105#p603158

Wes,

The only marking on it is FL25 right smack dab in the middle. It looks nothing like your board. I thought I found a picture that matched it in the thread you mentioned to go to to see what type of board one had. It was close but still not a match. The build date is 08/20/2012. It also says 35A+-1 on the case. I see they keep lowering the amp rating on the sticker. This board has a total of 12 electrolytic caps on it - (the 3 big 100v being included in the count). It only has one processor chip. I can see the pads for regen, reverse, but I have no idea (yet) where the voltage divider is where one would change the resistor to alter LVC. I will take a picture later today and post it. Surely someone here has one of these "newer" boards. There is so much info to wade through on this site and if you do not use the right search, you will never find it. I did a search for Hua Tong and never found what I was looking for. Then I searched for OT100 and bingo, that led to these threads. Very frustrating. Oh well, I am retired, so I have plenty of time to search. Pics later.

WTN

OK Pics of the FL25 Board. I had to shrink them down for forum use. It would be nice to load them up full blown, so folks could + in and take a closer peek - whatever.





Great - basically useless. One cannot + in. I can take closeups.

Like I said I have not waded through the 44 pages of the thread I was on ( hell, I forgot what thread I was on). So maybe I will find some info.

WTN

So, I will call this the FL25 board. Gee, maybe I should search for that.

WTN

This really sucks. The dad blasted chinese change their boards at will. No docs. Trying to figure out how to alter LVC, regn, etc, is a PITA. Have to wade through 40+ pages of posts hoping for clues. I will persist.

WTN

If you upload directly to the forum, rather than imageshack, it'll take some pretty large pics--they just wont' display inline, rather as links.

Alternately, you could use MSPaint or whatever other photo editing software you have, and crop the original sized image down to just the PCB area, whcih will reduce the filesize, and you can also save it as sections, whcih would be a lot smaller and then uplaod eaiser.


it is unfortunate for us that companies change their products all the time; sometimes it is to make them better, sometimes to make them cheaper. Sometimes it might even be to prevent certain types of hacking into them (or making it harder, at least), though I doubt that is the case here.

The most likley thing is that you will end up having to experiment to find the right spots, tracing out parts to see where they connect electrically, despite their different physical placement on the board.

Amberwolf,

I woke up this morning thinking the same thing. That I could get closeups by zooming in at the 3Meg version, saving that, and then down convert to 640X480. I am using GIMP so I will give it a try.

WTN

Gee, should I start a new thread - something like "Chinese FL25 72V Controller Board"

Anyway, here are some closeups:





This is my first shot at closeups. I need to really zoom in on the pads.

If someone could tell me what the label name on the processor is where the LVC signal connects, I can trace it down.

If that did not make sense, the processor has an acronym for each connection. What would that be where the voltage divider connects for LVC sense?

Also, the third cap from the left along the bottom first pic does not look like a cap to me. More like an inductor of some sort - vertical wrap in heat shrink casing.

WTN

Hey WTN, any discoveries on how to change LVC on your board ?
Wesnewell, did you hook up you brake lever to the "X" pad or you left it as it was ?
To get regen working at 24s, raising lvc will do the trick ?

PeeHell said:

Wesnewell, did you hook up you brake lever to the "X" pad or you left it as it was ?
To get regen working at 24s, raising lvc will do the trick ?

Click to expand...

On the ca08x8m06ad_p04.1 version board, regen needs ground on "x" iirc. That's a small x not a capital X. Although it's been ~ 1.5 years now. Info in original thread. Regen was working using 18s rc lipo. When I went to 24s it quit until I changed LVC from the 60V default to 88V.

PeeHell said:

Hey WTN, any discoveries on how to change LVC on your board ?
Wesnewell, did you hook up you brake lever to the "X" pad or you left it as it was ?
To get regen working at 24s, raising lvc will do the trick ?

Click to expand...

I think I found the resistor. It's not that hard if you have a schematic of the processor.
I am in no big rush. Don't even have a bike yet. I bought the controller because they keep going up in price. I paid $47 for it. I will be getting the yescomusa 48V 1000W kit eventually. Probably go with a used trek 820.

WTN