A system comprising: - a controller, - a lamp comprising a passive network comprising multiple groups of passive components, the multiple groups being couplable in parallel between two terminals of a battery, the passive components of each group respectively comprising resistors and LED diodes, each group comprising multiple subgroups, each subgroup consisting of a different number of LED diodes in parallel connections, each group comprising multiple resistors coupled in parallel, the passive network forming a network of voltage determined variable resistances carrying different currents when a terminal voltage of the battery is different due to a change in the remaining electrical energy in the battery, - an energy consumption routing circuit configured to route electrical power from an electrical energy source (110, 120) comprising the battery to the passive network; wherein when the energy consumption routing circuit routes electrical power from the electrical energy source (110, 120) to the passive network, the passive network is configured to decrease the amount of electrical power consumed by the lamp when the terminal voltage decreases, said decreasing being a function (301, 401) of the terminal voltage of the battery such that reduction in the terminal voltage (110, 120) causes a disproportional smaller reduction in luminosity of the lamp compared to the reduction of the terminal voltage, the passive network routing current through the passive components such that when the voltage at an input of the passive network is higher due to a higher value of the terminal voltage of the battery, more LED diodes in the passive network are actively emitting than when the voltage at the input is lower. - a controller, - a lamp comprising a passive network comprising multiple groups of passive components, the multiple groups being couplable in parallel between two terminals of a battery, the passive components of each group respectively comprising resistors and LED diodes, each group comprising multiple subgroups, each subgroup consisting of a different number of LED diodes in parallel connections, each group comprising multiple resistors coupled in parallel, the passive network forming a network of voltage determined variable resistances carrying different currents when a terminal voltage of the battery is different due to a change in the remaining electrical energy in the battery, - an energy consumption routing circuit configured to route electrical power from an electrical energy source (110, 120) comprising the battery to the passive network; wherein when the energy consumption routing circuit routes electrical power from the electrical energy source (110, 120) to the passive network, the passive network is configured to decrease the amount of electrical power consumed by the lamp when the terminal voltage decreases, said decreasing being a function (301, 401) of the terminal voltage of the battery such that reduction in the terminal voltage (110, 120) causes a disproportional smaller reduction in luminosity of the lamp compared to the reduction of the terminal voltage, the passive network routing current through the passive components such that when the voltage at an input of the passive network is higher due to a higher value of the terminal voltage of the battery, more LED diodes in the passive network are actively emitting than when the voltage at the input is lower.