I need help taking out stripped battery screw (tri-wing)

If you are getting desperate, remember that the screw itself is expendable.

You can take a regular drill, at least as large as the shaft of the screw, and drill into the screw-head until it parts from the screw shaft or is turned into shavings. Then the part will come out. The screw shaft can easily be removed when the part is out.

A mechanic would call this, "drill out the stuck screw".

Hi,

I don't know if these will work on a screw head that small, but you might want to give them a try: Vampliers Mini - Screw Extraction Pliers - - Amazon.com

When screws get stripped, you figure out pretty quickly that only the friction of the head against the substrate is what is keeping the screw in place. if you could magically remove the screw-head, the part would be removable, even with the body of the screw still in place.

The screw itself is expendable -- you can replace it with a different screw later.

The cylindrical barrel of the screw is under very little pressure and could easily be teased out later, or attacked with tiny pliers.

In car repair, they sell some things called "easy-out", that consist of a left hand twisted spiral tapered thing like a screw, but not sharp. You drill out part of the item to be removed, press the easy-out into the hole, and press while twisting to remove.

They also make a similar thing that has an easy-out on one end, and a small left-hand drill head (sharp this time) on the other end. Drill in reverse into the screw-head until either the easy-out starts to fit, or the screw head is obliterated and you are done. You may not need a power drill for these -- sometimes just pressing and twisting the drill bit by hand allows you to make (slow) progress.

This set of four must be very common, and in small sizes, because there were tons of picture to grab on google images. The barrels are standard quarter inch. I got mine from Sears in the US, but others outlets will have them as well.

The last thing in the world you want to do is cut into a Lithium battery. The inside contents may be flammable when exposed to air.

A machinist might try, on a larger screw, to "drift" it out. Take a small punch or pointed object or a chisel and place it into the head at an angle, then tap on the end with a hammer, providing sudden rotational force in the remove direction. A blunt metal piece kept lying around the shop for such purpose might be called a "drift" when used at an angle, but suddenly turn into "punch" when used perpendicular to the work.

Those pliers are designed to work with the head of the screw sticking out. That said, I wouldn't know if they'll work with a head that small. I think the only way to find out is to try.

That is one "back yard" method used to extract screws/bolts, but these screw heads are so small, I doubt it would work.

You can try a regular pliers, but I highly doubt it will work. The pliers I linked have a special jaws designed exactly for this purpose.