I thought the battery was t shaped and fit under the car between the driver and the passenger? I also thought the battery was liquid cooled to maintain an even temp to reduce overheating while discharging and charging? Do not know about overvoltage. You might be thinking of too much current which can cause overheating which can cause the battery to have an exothermic chemical reation (runaway fire). But I am an aerospace engineer not an electrical or chemical engineer.