Where is the aux battery located? Is it really necessary to replace? and if so how much does it normally cost
2016 LR4 SCV6

 

The aux battery is under the hood in the plastic box on the drivers side. Its a little motorcycle battery. Without it, the eco stop/start will not function. It is not clear whether running with a dead aux battery will have any effect long term. Some people have just disconnected the aux, and I haven’t seen any negative reports. Mine went dead recently, and I ran for about a week with no ill effects.

It is expensive to have it changed at the dealer. It’s easy to change yourself, but the dealer is basically the only place to buy the battery in the US (they want something like $350 just for the battery). The two alternatives are (1) use a cheaper AGM motorcycle battery and modify the battery cables to attach (the motorcycle batts have square terminals); or (2) buy the battery from an overseas vendor (sold as Exide EK151). I did the latter - the overseas vendor that a number of people have used with good success is here:

https://rover.ebay.com/rover/1/711-5...YAAOSw2tFaYckz

Takes about 5 days to get here, but the overall cost with shipping was only about $130, which is about what the motorcycle batteries cost here in the states.