This is what you need. This dual 12v plug wire link has several functions. It charges, it holds 12v for vehicle and can raise the requirements of a low battery whilst starting a vehicle. It gives digital voltage and led display.
I have had this for years.

You're making this more complicated than you need to. Just disconnect the battery, put the new one in, reconnect and reset the windows. Simple! Landrover - turning owners into mechanics since 1948

2014 Orkney grey Freelander SD4 GS.
2004 Zambezi silver Discovery 2 Td5 (Gone)
1963 Surf blue Morris Mini Minor Super de Luxe (my little toy)

I'm with Bob ......... as above.

It isn't that you are the first ever to do this ........

.

The radio is coded to the ECU. Just reconnect battery, reset the windows, adjust the clock. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

If you don't feel competent to do the job, find a professional that can. Best way.

We changed the battery on our FL2 by just er......changing it, never knew about all this special precautions stuff, as far as I can tell everything has been working fine ever since, didn’t even reset the windows, although I have needed to do this on other vehicles in the past. Regards

David

Lovely i6 has now gone, but not me......

Please let me know if anything in my post offends you, as I may wish to offend you again......

Same here.
Remove old battery then fit new one.
Nobody died and car did not explode.


Too much knowledge can be dangerous.

Automotive rating for ECUs is 9.7v to 16v, and JLR do test to the 16v, so your 15v supply shouldn't damage anything.

The OBD port has a 5amp fuse, if you happen to turn the ignition on or wake the CAN bus (open or close a door/bonnet, press a button on a key) you'll blow the fuse.

The battery supply wires to the OBD port are 0.5mm^2 so can take more than the 5a they are fused to, but not a lot more.

Flanagan wrote:

Simon J - did you not lose the radio, or did you have the code (I don't)?.

As others have said, no radio code. You’ve probably spent more time questioning how to do it than it would have taken you to reset the windows