Solar battery chargers

We have two cars parked in a secure driveway (Ford Kuga and Lexus SC430) and are planning on being out of the country for the whole of December and into early January. Would it be wise keep the batteries trickle charged while away? Rather than removing the batteries from the cars my garage suggests using a couple of solar powered chargers which seem to abound at various prices but I'm just wondering if they are likely to be any good in winter? Added to which, I'm planning on keeping the Lexus under its cover which will exclude sunlight.
Whether they will work depends partly on whether the car batteries are hardwired to their accessories sockets, because if the battery won't charge through the accessory socket you need to connect the chargers directly, or build in charging points. And partly how much sun we get over December and January because if the car is covered in snow (or a cover), no sunlight will get to the charger. There is also a slight risk of fire. Depending on what codes you lose by disconnecting the batteries it might be better to remove them and keep them in a warmer place than the cars. If the batteries are healthy, if there are no draindowns in the cars and if you take both cars for a 40 mile run before leaving them standing there is a chance that will put enough in the batteries to last for 5-6 weeks without being disconnected.
Answered by Honest John on

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