FedEx. The only restrictions on carriage for us is that the batteries cannot be loaded on the same pallet or container as Accessible DG (DG that must be located in crew accessible locations and crew inspected prior to departure). The batteries can be loaded in the position
right next to the class 1 explosive pallet - just not mixed in with them....so, we got that going for us.....which is nice.
The batteries do not have to be crew accessible (and frequently are not) and can even be loaded in belly positions if properly blocked/secured.
In the past few years, we started being notified that they are on board. They are identified as class 9 miscellaneous which is the same category as dry ice and magnetized material. So, we do at least know which pallets have the potential to burn through the bottom of the aircraft.