If you park your car for any extended period of time you need this little unit to keep the battery charged. Plug it in and you're all set! 1.25 Amp battery charger designed to fully charge and maintain a battery at a proper storage voltage without the damaging effects caused by trickle chargers. The new BTP micro-chip technology applies the correct peak charge, then automatically maintains the battery at the perfect float voltage which virtually eliminates battery destroying sulfation! Temperature compensation ensures optimal charge voltage even in extreme weather conditions. Powder coated aluminum chassis. Spark Proof! Reverse polarity protection ensures safety. Built in 72 hour timer will protect a marginal battery from over charging.

This item fits the following BMWs:
1984-1991 E30 BMW 318i 318is 318ic 325e 325es 325i 325ic 325is 325ix M3
1992-1998 E36 BMW 318i 318is 318ti 318ic 323is 323ic 325i 325is 325ic 328i 328is 328ic M3
1999-2005 E46 BMW 323i 323ci 325i 325ci 325xi 328i 328ci 330i 330ci 330xi M3
1976-1981 E12 BMW 528i 530i
1982-1988 E28 BMW 524td 528e 533i 535i 535is M5
1989-1995 E34 BMW 525i 530i 535i 540i M5
1997-2003 E39 BMW 525i 528i 530i 540i M5
1982-1989 E24 BMW 633csi 635csi M6
1981-1987 E23 BMW 733i 735i
1988-1994 E32 BMW 735i 735il 740i 740il 750il
1995-2001 E38 BMW 740i 740il 750il
1990-1999 E31 BMW 840i 840ci 850i 850ci 850csi
2004-2010 E83 BMW X3 2.5i X3 3.0i X3 3.0si
2000-2006 E53 BMW X5 3.0i X5 4.4i X5 4.6is X5 4.8is
1997-2002 Z3 BMW Z3 1.9 Z3 2.3 Z3 2.5i Z3 2.8 Z3 3.0i M Roadster M Roadster
2003-2008 Z4 BMW Z4 2.5i Z4 3.0i Z4 3.0si Z4 M Roadster M Coupe
2000-2003 E52 BMW Z8