I had two optimas crap themselves instantly one time. Was running two smaller ones in paralell in the boot of my ED, drove home from the city no problems, parked at the night owl to grab some milk on the way home, went back to the car and it was completely dead - not even the central locking would work. Took them to an optima dealer and they said they'd test them and get back to me.....waited a week, rang them, they said they were waiting on an OK to replace them under warranty...waited another week, they said they'd been sent back to wherever they go for testing....waited another week and they'd "lost" them. I gave up and bought a sealed lead acid and never had another problem.