12v lead acid battery is hard to deal with for exact readings of energy transfer, and release. The charged battery has quantity built up of pluses + and minuses - at each end, so as being unbalanced. The discharging of battery is seeking balance of charges. A large computer capacitor is readily available and responds to electronics math formulas. See 2 manuals from Eagle Research called Energy Conserver. A quality polypropylene capacitor is NOT an electrical load, only a temp storage means. Electricity passing over wire to resistive load such as lamp bulb releases light as work done. If opposite end is connected to capacitor, the in series current is absorbed into it, held, with quantity of electrons, not passing on to end connected battery terminal. If 2 caps are in parallel (with switches) and in series with other side of source power, the light stops at point, that volts match. The 2 caps are then put in series so as with higher volts. The power source is disconnected. The storage of same used current is rerouted back through bub. The 2nd work done brightness can be measured as close same with lumens meter, and at approximately same time in seconds. Question- Does this bench test require power factor reading? This system could extend range of electric cars.