Solar charger via cigarette lighter on Fiat Ducato

I am thinking of buying a small solar panel to keep my battery charged up whilst in the storage compound over winter.   My problem is that there is not enough room in the battery compartment to use crocodile clips with which the panels usually are fitted.   Does anyone know whether it would be safe to run a cable from the battery terminal clips into the caravan to a cigarette lighter socket?   If it is, would it have to have a fuse in the cable between the battery and the cigarette lighter socket?

The cigarette lighter socket will be fused but provided it is live with the ignition off then it should be feasible to back feed. I don’t believe in saying something is “safe” without inspecting what you are doing but I would certainly consider doing this myself and I am sure it is an accepted method. I imagine the solar panel controller is already fused? 

At the risk of sounding obvious, make sure you wire the plug up correctly with the right polarity otherwise there will be a Big Bang!

The cable from the battery  positive terminal to the cigarette lighter must be protected from a short circuit that could melt a small cable and cause a fire. The fuse should be mounted as near to the battery terminal as possible. If this is not practical then you must be confident that the short length of cable (no more than a few millimetres) between the terminal and the fuse is run in such a way that there is no possibility of it shorting to the negative terminal or any cable connected to the negative terminal. If I was installing the cigarette lighter I would fit a fuse to both battery terminals. I know many solar panel are supplied with croc clips to connect them to a battery but this arrangement is inherently unsafe and since the vehicle will be unattended for long periods of time its essential that the installation is safe to leave.

I believe the OP is proposing using the cigarette lighter socket in the cab or in the habitation area. In both cases the socket will be fed from a fused supply either from the engine battery (cab) or the habitation battery (caravan or habitation area) and he will be back feeding it. That’s fine in principle but I would want the solar panel controller to be protected by a fuse which it probably is.

plug something in , easy check

They normally only work with the ignition key turned to accessory or with the engine running, don't you have a phone charger adapter to try it

8 years ago  I'm sure he's been waiting for these replies and will be along shortly to thank you.

Just noticed date !

Further to Dave Nicholson's response above, I am not sure whether he is responding to my query or to the owner of the Fiat vehicle.   For the sake of clarity may I explain more fully what I would like to do.   The battery compartment on my caravan is almost completely taken up by the 115Ah battery and the sprung clamp-on battery connectors.   I was considering purchasing a TP-solar 10w 12v solar panel (which comes with a regulator) in order to keep the battery trickle-charged during winter at a storage site about 10 miles from home.   As I could not use the croc clips which come with the solar kit I would have to permanently clamp the cable into the battery connectors.   I would then run the cable through the wall of the battery compartment (duly sealed around), across the floor of the under-bed storage area to a socket to be mounted on the wall of the storage area next to existing 13 amp and TV aerial sockets.   This would be a convenient place to plug in the solar panel when required. I had thought of a cigarette/cigar lighter socket for this but now wonder whether a 12v DC plug and socket would be just as suitable?    

I don’t think it makes any difference, either setup would do the job, suitably fused or your regulator/controller might already incorporate a fuse?