If car sits 2 or 3 days battery is too low to start car. Replaced negative ground cable twice. I don't use negative post when charging battery. Any suggestion? 2010 XFR
Thanks,
EZED

 

I have the same issue. Mechanic couldn't find a gremlin, so if i know its going to sit for more than a few days I use a battery tender

 

Thanks for the info. I will try that. If I find a solution I will pass it on.
Thanks,
EZED

 

A good auto electrician can test the circuits to see where the parasitic drain is. Clearly something not shutting down properly or still running. Any aftermarket electronics (dashcam, chargers, audio, devices plugged into OBD or power sockets etc)?

I have a 2010 5.0 SC and it can sit for 3 wks and still starts perfectly first time.

 

The dealership couldn't solve problem and to have each line probed for a load could take days. The best estimate on cost was to leave a blank check.
Thanks,
EEH

 

We had a 2010 in the shop for a while chasing a battery draw. Boss swapped out the BCM and got the draw down a bunch but finally traced the biggest draw down to one of the middle vents trying to turn down but not succeeding completely. Kept the car “awake” (hazard triangle staying lit).

 

Ouch, Parasitic draw is one of the most annoying things to track down. My 2010 XF NA had a similar issue and if I didn't run it within a week, it would not have enough power to turn over the engine. I would spend days trying to track down, I changed the battery, read the draw from the fuses after letting it sit for an hour and then I tried the 12v light method bridging it between the negative connection and the battery (Disconnecting the negative clamp and bridging the light to indicate draw, now I know more about these cars, this was not such a great idea.)
I really thought my BCM was going as it was showing as an intermittent problem and soon I would have to replace it. As I procrastinated, the starter failed, had it switched out and this also fixed the draw.

Not saying that this is your issue but just putting it out there that it can be anything and it will take time to track, there is not any simple solution unless your lucky. Key thing is to let the car go through its normal power down cycle before looking for the draw, normally it is 20 minute but I usually leave the car for an hour and I do not touch doors and hoods when testing. I might get some feedback on this but not sure if your connecting the positive first and negative last when installing the battery. Electronics do not like surges and altered current flows.