alternator

I recently installed a snorkel on the Bronco Badlands and wanted to see if anyone has extended the rear axle breather lines. It appears to go up and behind the driver side wheel well splash guard. Any input on this or anything else needed to be done before some serious water crossings happen...

Has anyone ran a dual battery system, using the oem or upgraded alternator ? I know there are other options like self contained batteries etc but I'm very set on building this aux bat system with the/an alternator being the only charging source for it. Thanks in advance!

Buddy went off roading with me in his Badlands. Got himself into way too deep of a puddle.. turns out it was like a 30” deep mud hole. Got stuck, and I had to winch him out. he was in there for maybe 5 minutes. totally fried the alternator. Truck had to be towed to a dealer. I know, I know...

2.7 OBX has been showing battery voltage anywhere from 14.5 - 15.1V on my gauges the majority of the time. Seems excessive compared to normal ranges when searching for the answer (couldn’t find anything specific to the Bronco) Is this a typical range for this battery/alternator?