rx trouble

[PaliGap27]

hey guys
im a fairly new owner of an 82 rx7 gs.it works great and its fun to drive. The other day i drove my friend home and i waited outside as he went in to grab something, so i shut the car off. When he got back i turned the key, had power but when i turned to start it, the power was gone and i had nothing. The only power i had were the interior lights which were really dim. I grabbed a volt meter and the battery was a little low at just under 12 volts.Potential can also be felt between the positive terminal and the chassis. I got kinda pissed off so i left it a while and when i got back, i turned the ignition and i had power....but again, i turn all the way to start and the same thing happened....nothing, all the power was gone....has this happened to anyone or if you have some good troubleshooting tips, please share...thanks

[L-Spec]

Mmm happened to my FC. It was because my battery terminals were shit. At first, I thought i was a poor battery, so I got my friends to boost me each time to start it, but then I realised that my terminal was a *bit* loose. So I wedged it on as low and as tight as possible to the battery and it worked ..for a while. I soon noticed that the terminal just looked like shit, so I replaced it with gold plated terminals and it runs every time now. When I ran my voltmeter, it read somewhere around 12 too I believe, not 100% positive. I can check tomorrow.