Built-in trickle charger connector!

[PaulGover]

Like several members, I've wondered how to connect a trickle charger, as the X350's cigar lighter sockets all disconnect with the ignition. My charger is a Maplin solar cell I could leave on the dash, but how to connect it to the battery? I thought of running the cable through the ventilation grill at the bottom of the rear screen, but to get further requires removing the seat, leaves cables wandering across the boot, leaves clips on the battery terminals, and you have to remember to unplug it before starting off. All in all, a right faff.

Delving on t'Internet turned up devices using the ODB-II diagnostic socket. Sounds a bit scary, but no, the relevant SAE J1962 specification says pin 4 is chassis earth and pin 16 is an unswitched connection (possibly fused) to battery +12V that rated at 4A. That makes it an ideal connection for the purpose. I found a seller in Leeds on eBay doing a plug kit for less than £5. I've only ordered the kit, so can't vouch for the seller or product, but it looks just the part.

(I've just checked the wiring diagrams for my 2008MY car: pin 16 is connected via a 5A fuse in the passenger junction fuse box to the 100A megafuse and thence to the battery.)

A bit of cut-and-paste between the plug and the cables that came with my solar charger, I'll have a panel to plug in whenever I leave the car for an extended period, and can't forget to unplug before driving off. Given the current COVID-19 hiatus, the battery will need topping-up!

[Popsjag]

I have an AA solar battery charger that does the same thing. I always use it if I'm not using my XJR X350 for longer than a couple of days.

[PaulGover]

Just installed my charger. For info, all the diagrams of the pin placements I've found show the socket from the plug side, i.e. the plug from the cable side. Chassis earth pin 4 (end electronics earth pin 5, but don't use that for a charger) are both seated a bit further out in the plug, so as to make earth contact first (much like a 13A mains plug), so don't be concerned when they look out of line.

I'll have to see how it goes over the next week or so. My battery's already showing just under 12V after 10 days idle. If it doesn't rise much, it will need the use of a mains charger.