Factory installed Hyundai positive clamp... gots to love them when they seized... need to take them off once in a while and keep the guts lubed so they dont freeze up..

Dont crank them down super tight too, snug it up good and be done.

 

Although I don't have this problem I would suggest that you remove the top nut and try to get some penetrating oil down into the interior of the socket. Another thought might be to drill a couple of small holes in the top to allow access to the oil. Be sure to remove the negative terminal before using a grounded (3prong) AC drill. If the car is grounded in any way and you drill the positive terminal there will be BIG sparks if the negative terminal is still connected. The "lead oxide" expands the post's size and also reacts to the terminal's metal composition.. The oil should help along with some "lite" tapping on the terminal to free it.
Dave

 

OK Thanks for the reply! Now I know it is a factory poriginal.
I still don't know how the clamping mechanism works but I will spray some PB Blaster on the terminal and see if it loosens up.

 

Ok finally got the terminal off since my battery is starting to show signs that it is on its way out. What size costco battery will fit in my 2005 Elantra? The Kirkland catalog does not list a size for this vehicle or the size listed is not in stock. Will a group 24 battery fit?

 

Any of the parts stores should be able to tell you the "group" size for your battery. You can also measure (H,W,D) the battery and have that info available when you go shopping for a replacement. Just make sure the replacement has the same or a higher cold cranking rating. That rating is usually marked on the top of the battery. The parts guy will be able to get you squared away.

 

Did a search and found that a group 35 battery should fit .

 

Yeah mine seized up like that too. Hit it with PB Blaster and everything else I could think of. Finally ruined the battery by breaking the post trying to twist the connector off with channel locks.

I hate this design.