We charged our 12v recarchable battery, but every time we plugged it into our NXT, it would read that the 12v recarchable battery is at 0 volts.We charged the battery using the standard battery charger .The battery packs are about two years old would that affect the power of the battery or its ability to hold a charge.
The NXT batteries are rated for a huge amount of recharges, enough that even the way FLL and FTC teams use it, they should last for more than 2 years. (Even if your team goes to April for both those years.)
From the information you gave, I am not sure what the problem is, can you explain some more? Also, you should call Lego Edu support, they are amazing at figuring out what the problem is and fixing it. You might have to wait till tomorrow, but it will be well worth it. They do this for a living, and know stuff a lot better than the FIRST community.
Sorry, I could not help more!
It is a known fact that charging NiCad battery packs like the NXT, when hot will cause sufficient problems to eventually kill the battery. Repeated charge discharge cycles on warm to hot batteries will cause premature failures of some or all of the cells within the pack. There is also a temperature fuse in some of the packs that will open under these conditions.