E70+ need to have a batteries characteristics defined to the x5 otherwise it doesn't know exactly how to charge the given battery. The battery needs to be a ago type.that can better handle the discharge.recharge cycles the x5 design will do to it. The x5 only.charges using the alternator when coasting. So if you do a.lot.of.short runs on level land you can discharge.the battery... the car will.get crazy as.the voltage of battery runs low. A fully charged battery with the car on but not.running should be over 13.volts not under. So I advise.you recharge.the battery.with a ago approved charger and.see how.the car.acts. fyi the charging.design is.crazy.bad .... do a search on Google using n63 hearing batteries and read ... n62 design is.the same just doesn't have a electrical discharge.of.fans.cool I g.turbo.