Where can I buy a Hitch for my Tesla 3 to carry my bikes---Also why is it better (Per Tesla) to charge your battery only 85 % in town and 100% when you are going to be on trip. All battery co. I have talked to say batteries will last longer if you charge them to 100% all the time. Gene Wakefield
It's better for the batteries to be charged to 85%. The difference is not large, however, so for trips when you need the range it's okay to charge to full. But when you don't need the range, 85% is better.
The advice you are getting about always charging to 100% is for different kinds of batteries. Different batteries have different chemistries, and different chemistries have different characteristics. Lead-acid batteries, like you have in a regular car, should be charged to full. Ni-Cad batteries should be fully discharged before being charged. Lithium-Ion batteries last longest if they are charged to 85% or thereabouts and not discharged below about 10%. On your phone or your laptop, these limits are built in to the software, so when your phone says it's 100% charged, the battery is really at 85% or 90%, and when it shuts itself off and says it's empty, the battery is at 10%. This is to protect the phone or the laptop from users. Tesla tells you what's good for the battery pack but gives you the choice to use more of the battery's capacity in order to get the additional range that you might want occasionally.
Different kinds of batteries require different kinds of care.