Search with n63 eating batteries a road and.track article describes the design problem. Fyi I ordered a 12 dollar digital volt meter with two sub phone charge ports so I can monitor.the battery charge via.small.voltage.level variance Learning small voltage levels like maybe 13.4 battery fully.charged.and.maybe 13.0 battery half.charged.Will help us manage.the battery ..... sad we must.do.this. I will use.agm capable battery tender.charger to charge.the battery.if.I.discover.we.need.to rather than see.the battery.harmed by significant.discharge or.risk having.the battery not.having the charge.to operate.the car. I will make an plug.in adapter.to.front.of bmw.grill.to.plug.car.into.charger.if.I.discover.t hat.is sometimes.needed. yep.it.is nuts