Help me please jumped started by hooking battery up backwards
Check the diodes in the alternator on your Nissan
I had a car that would whine and the pitch would vary with the RPM. It was one bad diode out of the matrix. Depending on how your regulator is constructed you may be able to replace just the diode.
88 300E 225K Sold
2000 C230K Totaled @103K
2003 ML320 140K Granddaughters Limo
2009 E350 4Matic Sport 37K Sold
2011 ML350 44K