One thing is true.. it is a pain in the rear and likely different than many cars you may have change the battery one. The basics are the same... getting the battery out and the new one back in and everything reconnected... that is the trick.
So here is the process on my 2002 New Beetle GLS. The process is different than older cars and may differ from newer versions as well.
Must have tools:- 10mm and 13mm socket
- long (12inch) extension for the socket wrench
- absolutely, a telescoping magnet pickup tool (to pull up and place the screws and battery holding bracket)
On the 2002, there is only on plastic shell that covers the inside edge and front of the battery (and the battery is surrounded by a padded blanket.
Process
Pop up the lid. Just pivot it back, it can stay on .. no need to remove it.
10mm socket will loosen the nuts on the battery terminals so you can slide the battery cables off of the posts (work them side to side to loosen the clamps from the posts). Remove the negative (fender side) first, then the positive.
You need the extension to the socket... 12in or so.. because the other screws are down in there.
There are two small screws to remove (10mm socket) - one long (the left one that holds the power steering reservoir on) and a short one (the one screw that holds the 2 sided hard plastic jacket around the battery (which also holds up the power steering reservoir):
You should loosen the screws and then use the telescoping magnet to pull out the screws. Careful!.. if you drop them, they drop down, probably to the splash guard under the front bumper... where you can tap/hit the plastic and bounce it off onto the ground usually, but don't go there if you can avoid it.
On the 2002 GLS, that one screw on the corner is the only screw holding the plastic cover down. The other two corners of the cover are held in place by friction - a 3/4 circle that slides over a pin on the tray. So you should be able to pull up on the plastic shield that surrounds the front and inside edge of the battery.. pull up on the corners to unsnap from the pins (red arrow below):
The yellow arrow is the bigger screw (13mm socket) that holds the battery down via the metal clamp plate.
Unfortunately, I didn't discover the simplicity of removing this thing until after I had the battery out, but you can remove it before the battery. That makes removing the clamp and hold down bolt (yellow arrow above) much easier. ALSO, its easier to put the hold down clamp and bolt back on without the cover.. so once the new battery is in, put the clamp and bolt back in BEFORE you put the cover 2 sided shield back in ... otherwise the odds of dropping the hold down clamp is likely to fall down into the engine bay multiple times and your frustration will rise.
So removing the battery (in my picture the 2 sided hard plastic cover is still in there, is lifted up by the left side, to a 45 degree angle. You can then get your right hand under the right side and slide it out. This will be tight, scratch up your hands and maybe hurt a bit (if you have big hands like me).
Once the battery is out, you remove the padded blanket around the battery by just pulling it up from the battery (lift up on the blanket and work it off).
Then slide the cover on the new battery (note the position of the battery posts, where the + and - are on the original.. they need to be on the back side facing the rear of the car).
Insert the new battery again by angling it in. Once its back in there
carefully put the hold down clamp and bolt in (MUCH easier if that hard plastic shield is NOT in there yet!).
Use that telescoping magnet to your advantage to place the bolt if need be.
Then place the hard plastic cover back around the battery - pushing the two ends to seat the openings on the pins, and the middle hole over the hold on the base. Use the telescoping magnet to place the short smaller (10mm) screw and then tighten it down with the socket.
The final bolt, and the hardest on, is that last long 10mm bolt that holds the power steering reservoir on. There are 3 things to line up. The threaded hole on the bracket that is fixed, into which the bolt goes. A bracket that goes above that to hold a hose, and then the reservoir itself. Seating and aligning those three hole AND then getting the screw in there is the tricky bit. The telescoping magnet is key here at placing the screw. Then tighten it down with the 10mm socket and the extension. Note: when placing the power steering reservoir, there are arms on the reservoir sides that slide into slots on the hard plastic shield between the reservoir and the battery.. so you need to get those back in there.
Then its a matter of reconnecting the battery terminals (+ first, then the -).
Now close the lid again. Thats it.
The final steps. The radio SHOULD not need the code (for MY 2002) because the radio sees which car its in and doesn't ask for the code. If it does need the code, you will need the radio card.
Power windows need to be reset for the instant up and down process. To reset this, you need the key in the drivers door (the windows must be up and both doors shut. Use the key in the lock to lock the drivers door. Then unlock the door (keep it closed). Then lock the car again..... and HOLD the key in the locked position for at least 1 second. You should now be able to unlock the door, get in, start the engine, and run the two windows up and down with the one-touch system.
Now return the old battery and reclaim your core charge. And wash all of that grime and grease off of your hands and bandage the few cuts you probably have.