EDIT: This article is out of date. The new recommended battery for the R32 GTR is this AC Delco battery. The Optima Yellowtop referenced is now discontinued.
The battery in your R32 GTR was dead when it came into the USA. That's not really a surprise - nine out of ten of the cars we get in have a bad battery when they finally arrive stateside.
The best replacement we've found from a cost to quality ratio is the Optima Yellowtop for the Prius. Click the link and you will be brought to the Amazon page for the battery. Prime members get free two day shipping, and the battery has a three year warranty from the date of delivery. It weighs 26 pounds and is rated at 450 CCA. These are now discontinued - the remaining stock can be found randomly on ebay: (Alternate ebay link here)
If you want something lighter, you can go with the Odyssey PC680 and a set of JIS terminals. The PC680 is only 170 CCA, but weighs just 15 pounds. If you decide to go this route, be very careful with the battery and keep it on a tender as often as you can. Once this battery goes dead you will not be able to revive it.
For something with more power, you can go with the Optima Redtop. It weighs an extra 5.5~ pounds, but comes with a 720 CCA rating. If you live in a really cold climate this might be a better option than the Yellowtop and certainly better than the Odyssey. The R32 GTR doesn't really need that much in terms of cranking amps to get started, but in extra cold climates all the extra CCAs help.
Why can't I just buy something from a local auto parts store?
You can't buy a direct replacement battery for your R32 Skyline because the positive and negative terminal posts on a Japanese battery are different than that of the ones that are sold in the USA. The Japanese units are smaller and skinnier, and the American ones are larger and bigger around. And yes I typed it that way deliberately to make a that's what she said joke. That's what she said.
The Toyota Prius came from the factory with the thinner battery terminals known as the JIS terminals that we see on the Japanese batteries, making them plug and play.
Note that you can buy a replacement Toyota Prius battery battery at an auto parts store, but they are upwards of $200. We recommend purchasing them from Amazon to save $50 and a core charge. Some of the stores will give you a hard time about the core charge due to the size of the battery and terminals.
Why was my battery dead?
That's a combination of things - mostly that transit companies leave the key in the ignition to keep the steering wheel from locking, and partially that they're rarely started for about two months straight. Car batteries aren't meant to die completely and be recharged like marine batteries are, so if the battery goes fully dead a few times that's usually the end of its life.
How can I keep my battery from dying in the future?
The easiest answer to this is to drive your car regularly. Usually an R32 GTR is someone's second car, so that's not always possible. If you don't drive your car regularly, consider investing in a battery tender. I purchased the one from the link three years ago and it's still running strong to this day. A battery tender keeps your battery from draining when the car is off.