I have a 2001 Prius, and a hybrid fault came up on the screen. I took it in and was told that #4 cell had a fault and it needed a need battery. Has anyone else heard of this and is there a fix, I dont want to speed $3650.00 for a new battery!!

Is this the first time that the battery has had a problem? If so you have gotten a good run.with the unit. I guess external testing could confirm that you have a bad cell/bank, butthe on board diagnostics are probably right on. and a new battery is the fix.

I would not mess with it yourself, it isn't just any battery but a series of batteries that add up to like 275v and a rediculous amount of amperage. Screw up and you will die, no joke. Have the dealer do the work, it isn't worth it unless you've been properly trained.