Hi
Whats the board you are exactly using? because kk 2 doesnt have pins for voltage sensing, but its an easy mod.

Cutoff voltage can be changed in the menu depending on which firmware you are using. For default firmware go to Misc Settings, select the Alarm option. The following video should be helpful.



An image for kk2 pinout

If he says that there are two pins for monitoring the battery voltage, then it must be a kk 2.1 board since that has pre soldered headers. I would suggest you update the firmware of the board as soon as you can. You can get the firmware here: http://www.rcgroups.com/forums/member.php?u=367321 When I first built my quad, it was flipping on takeoff until I updated the firmware.

It's best to update the stock f/w to latest before first flight,
I tried setting up and flying a KK2 with out f/w update, and what to say, that f/w has autopilot , It just flew up and up and up then witched away on it's own . Thanks to my LiPo low voltage alarm, after 4-5 Hrs It started buzzing from the top of a tree. I really thought I lost the quad. But the damage was only a prop adapter.

Then the very next day, flashed the latest f/w and there it flew fine with the default PI settings.

The kk board I have has a two pins marked as battery

For updating the firmware what sort of connector is required to the pc and where to get it?

Yes, this looks like a kk 2.1. When it powers up, you can always check the hardware and firmware version which is displayed on the screen. You will need a tool like this http://www.ebay.in/itm/261441182745?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 though you can get a cheaper one and make the 10 to 6 pin adapter yourself. You could also use an Arduino board if you have one for this. See this http://blog.oscarliang.net/flash-kk20-16-firmware-upgrade-arduino/ and this http://www.rcindia.org/multirotors/updating-kk-firmware-with-an-arduino-(on-a-mac)/msg203151/#msg203151.

It's  a KK 2.1.5 board.
Use a Arduino as ISP or USBASP tool for flashing the latest f/w. It is recommended.
still you can try and check if everything goes fine with the stock f/w, if ok, then you are ready to go.

We have all had successful stable flight with Stock firmware on KK 2.0 and programmable ESC's but after eliminating all vibrations of frame, prop and quad and after tweaking a lot on the PIDs after detailed study of PIDs Setting guide. Which in fact gave us lot of insight into how the quads behavior changes with change of each tweak of every entity of PID.

Then came the Wiz Kid "Pravesh"   .

Only after we saw how his quad flew and his level of control with it, then we realized and were hooked on to upgrades of KK firmware and SimonK firmware for ESC. 

You can definitely set up the quad in existing firmware and with programmable ESCs. But yes if are up for it then you can right away upgrade with latest firmware on KK 2.1 and SimonK ESCs. Since I doubt you can flash the ESCs you have, I recommended to go ahead with same set up.

Some videos for PID setting Guides

www.youtube.com/watch?v=0W7PiV6qvWc

This is very good video on how to set gains on KK

www.youtube.com/watch?v=I8RN8wMnQpg

Thanks for info. Just ordered some silicon wire from Kinetic Hobbies as required guage not available with the three LHS here. So planning to go out again and probably will return home next week. Hoping packet would have reached Bangalore by then.