Picture the scene: you’ve woken up to a frost-covered winter scene and biting, sub-zero temperatures, but you’ve still got somewhere to be. You head outside, scrape the ice off your car, plip your keyfob to get in and… nothing. A dreaded flat battery. Winter can be tough on cars in all sorts of ways, but one of the most vulnerable components is its battery, which is liable to essentially turn your pride and joy into a giant four-wheeled paperweight until you can get it sorted. Thankfully,...