Hey, Are you connecting your ground Charger wire to the Battery Negative Post? The Service manual states not to do this for the sensing wire for the BCM is on that post and it will cause charging issues. Now the manual also states when the Doors are locked for more than 8 hours the BMS will reset. But I just connect the negative to the chassis grounding point.Battery tender
The best place for a intelligent charger is directly on the terminals.
The best place for the car is the chassis ground but as stated above, its irrelevant if the car is left locked for 8 hours or more - who's going to use a maintenance charger for less than 8 hours anyway ?
I know its subjective, but I think its neater on the terminals anyway
Here is how I did mine including fitting the Bluetooth monitor :
Solder and heat shrink rather than crimps :
I fitted the sense unit behind the battery :
All the wiring and fuses are within the battery box, but enough out of the way to allow battery change :
Lid back on and a quick wipe with 303 :
Secured the pigtail :
The CTEK sense unit reports voltage :
SOC :
And not like I can do a lot about it, temperature :
At least the temp should be reasonably representative of the battery as it’s sat in the same sealed (relatively speaking) compartment.
I know both charger and monitor will have tolerances, but it reports 14.39v maximum :
Against a spec of 14.40v :
I think that’s close enough
WD
These instructions should be sticky. I use a CTEK with this set upI've been using Battery Tender chargers for years now on different cars and have always been happy.
A lot of good information here about how to install a trickle charger: https://www.mustang6g.com/forums/threads/installing-battery-tenders.73725/
I added a pigtail attached to the fuse box and ground lug on the shock tower. This seems to be the consensus as to the best way to hook up our S550s due to the way the battery monitoring system works. The positive lead is attached to the fuse box lug closest to the firewall.
