we have a 2016 F350 with 30,000 miles on it. The truck has been through 5 batteries and an alternator!! Ford can't seem to figure out what the issue is!! They keep putting new batteries and telling us the problem is fixed. Its not fixed and this keeps happening over and over again. If anyone has any suggestions it would be appreciated!! Thank You

Sounds like an alternator or voltage regulator issue, voltage spikes can kill batteries quick. Also sounds like a lackluster dealer not putting any effort into their repairs. Someone should check voltage across the terminals before, during, and after starting and watch for any spurious spikes. I've read on Ford trucks a large number of complaints related to how poorly grounded F350's are, especially the cab, and some members suggest running an additional ground strap from the alternator to prevent spiking (it can damage gauges and modules too, in fact the instrument cluster has a 16V breaker to prevent damage). Try a web search on your Ford truck and "voltage spikes" and you'll find more symptoms and suggested solutions. Too bad your dealer isn't investigating this a little more thoroughly. I have a new E350 van that was also killing batteries, I added 3 additional grounds and haven't had the problem since - one ground at body to frame, one engine to frame, and alternator mounting bolt to neg battery. Good luck.

Have they check for a parasitic draw? Why are the batteries dying? Overcharging or from being drained?

I'll have to ask my mechanic what he did exactly on my E350, for now I'll try and go off memory - your vehicle has a battery management system, and it'll set a charge level as well as a cutoff level. In fact if charge drops below a certain point some accessories will cut off. So there is a computer module governing how battery is charged. There's a section in the owner's manual on the BMS. I forget the name of the module (it may even be a part of the BCM, body control module). Anyhow, one of the devices that allows the module to monitor the battery is a hall effect sensor, part of the ground circuit - it's near the neg batt post but not directly connected. The voltages you measure across the terminals is slightly different than what the hall effect sensor reads (by design), and if you have a bad ground, the sensor will be even further off, so it's possible the battery is being overcharged. (That was my case, weak grounds). There is a whole diagnostic procedure on resetting the BMS with a scan tool, that might be beyond a DIYer. I'd keep on the dealer and mention the BMS to them. A parasitic draw will drain a battery but not kill it, overcharging or voltage spikes will kill it.