I have a 1988 Jaguar XJSC with the 5.3 V-12. I have done a lot of mods over the Winter which included getting rid of the 60 amp original alternator and adding a 6N 130 amp alternator. The original alternator was a single or dual wire system depending on how you want to look at it. Battery Cable and wire to the light & gauge.. The 6N has three wires plus the battery cable. I wired it as the plug instructed but that has to be wrong. my Optima battery only lasts 4 days of light driving. To complicate matters, using a volt-ohm meter with negative to ground and positive to the battery cable on the alternator I get a negative read. (i.e. -12.6V) The read with the engine running is also bizarre to me, especially with the original alternator wire reading much higher than the battery cable. Can't figure out where I went wrong.