Can a lead-acid battery be defective even though it has enough voltage? Starter battery: A lot of time ago the radio off. Recently the return camera. All fuses intact, annealing and starting is problem-free. Living room battery: The light in the washroom (4×10 watts incandescent lamps) has become weaker, previously tested LED lamps are without function. The living room battery is charged by a 200W solar system. On Sunday I removed both batteries. Today I still have 12,9 V and 12,7 V. It seems very strange to me. Can a defective one still be present?