Hi, can anyone help?

I have been running a 500w MXUS kit on a bike for nearly 2 years and with a couple of thousand miles on it can say its fine. Its been running 14S Lipos and a shunt soldered to give 30a peak draw. Whilst it has been fine I have tired of messing with lipos and have fitted a Samsung celled 48v 12ah bottle battery. I've desoldered the shunt back to its original 22a draw. All is fine and the bike runs great.

HOWEVER - the low voltage cut off is incorrect. Its cutting off at about 50.5v not the 42v it says on the tin. Never saw that low voltage whilst running the lipos but now of course 50.5v is a major problem.

Can anyone advise how I can adjust this or even remove the LV cut off? I know its something to do with resister values????

I have the controller stripped and will post a picture of the board when I figure out how.

Thanks

Are you sure it's the controller that's cutting off and not the battery?

 

50.5v is about the LVC for 60v. Sometimes controllers have a bridge in them that you can join with solder or an external jumper to convert between 48v and 60v. If you provide detail photos, we should be able to see it. On most controllers, the LVC voltage divider is on the near left side of the pcb if you have the FETs away from you and the wires on the right.

This may be a starting point http://www.pedelecs.co.uk/forum/threads/changing-the-lvc-of-a-controller.10243/

 

There's some links in that to a similar ES thread.

Dave beats me to it!

http://i958.photobucket.com/albums/ae62/averhamdave/Saracen%20MXUS/20150824_100455_zpssagd2izw.jpg

Hope that's come through ok.

The controller housing states 48v.

There are no jumpers to change the LV cut off

Not enough detail. Too fuzzy and we need both sides. The voltage ivider will be two or three tiny black resistors with four digits printed on at least one of them. They could be behind the blue wire at the front if that's the ignition wire.

Ill be back soon with more pics thanks

http://i958.photobucket.com/albums/ae62/averhamdave/Saracen%20MXUS/20150826_114938_zpsd19ni70h.jpg

http://i958.photobucket.com/albums/ae62/averhamdave/Saracen%20MXUS/20150826_114958_zpsachrilyu.jpg

http://i958.photobucket.com/albums/ae62/averhamdave/Saracen%20MXUS/20150826_114938_zpsd19ni70h.jpg

 

 

If still not sharp enough I'll dig my digital camera out and have another go as the phone camera obviously has its limitations. Thanks

looks like the same one as this https://endless-sphere.com/forums/viewtopic.php?f=2&t=65325

Yep that's the one Paul thanks and well spotted!

 

Are my pics clear enough for you to see the board d8veh?

No. Like I said, look or a resistor with 4 digits on it and photograph there.

Butting in, where is the shunt in that?

Is it the piece of wire on the back, top right hand corner?

You will always find the shunt/s between the black battery wire and that thick negative track that runs along the MOSFETs. You can see it in the photo in that ES link along the edge of the board. In OP's photo, you can only see the ends of the legs on the backside photo.