You have a positive cable and a negative cable. If you buy the correct battery, the two posts will be in the same locations as on the old battery. A lot of people seem to be switching the cables. That can cause as little as a bunch of blown fuses, but usually a lot more severe and costly damage, including destroying the many computers on the vehicle. Most battery stores will install a new battery for you for free. That way you can be sure to avoid a costly mistake.
May, 20, 2011 AT 9:13 AM
Hi Thanks for the reply, my problem is a little more difficult as there are 2 batteries and as they were missing when we purchased we can not be sure how the wiring goes
May, 21, 2011 AT 6:31 AM
OHHH! Sorry to take so long to reply. The site isn't working on my regular computer. Don't want you to think I'm ignoring you.
I don't know exactly what an NPR is so I'll just assume it is no different than most other vehicles. If your batteries have the normal posts on top, you will see a minus and plus sign next to the two posts. Those are the negative and positive posts. It's hard to see unless you look closely, but the negative post will be smaller in diameter. If you try to mix up the cables, the positive cable will be real loose on the negative post or the negative cable won't fit on the positive post unless you stretch it open a bunch. In case you're tempted to try that, do it with just one cable at a time. If you connect both of them backwards you will blow lots of fuses and you can damage numerous computers. Nothing will happen if you only connect one cable.
Besides the size difference, you can identify the cables by where they go. The easiest ones are the negative cables. They will have a fat wire that bolts to the engine block and a smaller one that bolts to the body sheet metal. The positve cables typically connect together when there are two batteries, one of them will also go down to the starter, and there is often a smaller one that bolts to an under-hood fuse box.
On U.S. Domestic vehicles, the positive cables are always red and the negative ones are always black. On many imports, the positive cable is black with a yellow stripe and the negative cable is often bare but it could be black too.