Rechargeable batteries are very suitable for electrical storage, as the energy stored is not converted into mechanical energy, giving a simple system with no moving parts. This also yields a good round-trip efficiency. Batteries themselves do not give any limitations on response time, meaning that the battery can be discharged and recharged instantaneously. Properties like ramp time and frequency response are limited only by the pre-programmed grid response characteristics of the power electronics module. Due to the internal double layer capacitor in most batteries, the batteries may be „overloaded‟ for a short period of time (few seconds). Power density of the battery pack is limited by the internal resistance of the battery pack, as higher currents leads to higher internal heating of the battery pack – which can lead to degradation and ultimately destruction of the battery cell. Energy content of the battery storage usually has a linear correlation between energy content and physically size/weight of the battery and cost, as long as you design within the same technology. If, on the other hand, the energy content is changed towards a very large storage system, it may be feasible to reconsider the selected battery technology. It that case, the correlation between size, weight and cost will follow the trend of the selected technology.