You need to get a battery charger charger.
If that doesn't work you'll need to get a battery charger charge charger.
If that doesn't work, buy a new car.
That's all well and good, but if you have a power cut you'll need a battery, or a generator.
As luck would have it most cars have an electricity generator on board and as if by magic, they're 12 volt, perfect for charging car batteries.