Without an alternator, a fully charged race car battery starts at 12 volts and discharges down to about 10.5 volts when it is completely exhausted. However many of the electrical systems on a race car (ECU, Dash, etc..) will stop working properly long before the battery is fully discharged. The TDC 30 will draw up to 30 amps from the battery, boost and regulate it to any desired voltage between 13.5 and 17 volts (in ½ volt increments) until every single amp-hour of energy is drawn from the battery. It is perfect for short races (one hour or less) where there is enough charge in the battery to meet the energy needs of the car but not necessarily at a high enough voltage for modern ECU’s. Even on race cars with an alternator (engine or differential driven) it can stabilize the voltage during cranking or when the car is not moving.