Hello All!

This is my 2nd Jag (2013 XJ 5.0 SC), and I'm somewhat handy with a wrench.

I was tired of the "low battery" warning everytime I the car was not running (on but not running). So i decided to get an aftermarket battery (at spec or better) and swap out with the original. Now the original was somewhat fine and I used the ctek charger to keep its life a little longer, but I had time over the weekend and figured i swap.

So I swap out the battery (pretty simple) but now i get absolutely no power to anything in the car. I even replaced the original battery back and still nothing. I'm at a loss on what to do next. Any help here would be greatly appreciated!

 

Assuming that you've checked all cables, connections and fuses, I'd recommend scanning for DTCs.
Assording to the shop manual, "The Battery Monitoring System control module must be reset following the installation of a new battery. The BMS control module reset procedure must be performed using an approved diagnostic tool."

 

Multimeter is the key for finding out how far power goes from battery terminal. Propably one of the big fuses have been failed.
Check one more time that you had terminals + and - right way around.

Battery low notification come out quite fast on any modern vehicle because when power is On and engine not running, the vehicle can take 20-30Ah. Battery Monitoring system try to warn owner not to run battery on the point of no start.