I recently tried connecting my battery (9.6v NI-MH) and a couple minutes after running the system smoke emmitted from a little black thing right under the words EP-GW (top left of the mobo) Theres a circle thing with a blue ring around it and two things to the right there was smoke burnin away. I turned it on again but the green led started fading after about 50 seconds and it then turned off. After this i tried reconecting the battery's but there were just two big sparks on the negative and positive of the battery, and my wires melted.
Is it fried? Is there a way to save it? (I'm guessing yes so I might as well say it now: "SH!T"!)
9.6V is way to much for the PSOne to handle. And yes if smoke came out you probably fried it. Get a 7.2V battary and try shorting some of the fuses on the mobo.
6V your cutting it close. Id say a safe range is 7-8.5V... maby 9V if your feeling lucky. Any more than 9V and its gonna fry, any less than 7V and its not gonna start up.