Battery is the first place to start. If it has the stainless steel "T" bolt clamps, do yourself a favor and put some copper anti-sieze on those threads so they don't gall (they will if you don't).

As for squeaky brakes, this is usually caused by the rear of the pad hitting the rotor before the rest of the pad.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual