eatrocks
Registered User
I’m sure this has been covered but I could not find anything on it. I have been traveling the last week driving my 2005 LJ cross country. And what should happen but the alternator fails, well not dead, it works when it’s cold, then stops after it warms up then it stops for an hour or so then works some then stops. As it’s the OEM and has 108K miles on it I don’t understand. Note to self replace the water pump next week.
Looking closer I found that the alternator is putting out 16 volts when it’s cold but the reading at the battery end of the charging wire is 13.8 volts. Turn the jeep off and the charging wire is 10.5 at the alternator end, but the battery end is reading 12.3. That meant a 2 plus volt drop though the fuse link. So I replaced the wire with some 4 gage from the alternator to the battery, no more drop. But the alternator is still not working all the time.
I had done some surfing on bigger alternator for the TJ and found some very poor information. I did find that the alternator is the same for the 2004 to 2006 TJ and it’s a 117 amp unit. There are 2 others that will have the same mounts and plug on them one is a 136 amp the other is a 160 amp both fit a 2004 dodge Durango with the 4.7 V8. Now here is the fun part. The most costly is the 117amp at about 155.00, the 160 amp is 140 and the 136 amp is 109. The 136 amp looks to be in the same case as the 117 is. The 160 is in a bigger case. As I have OBA they all bolt is with no problems. I will find out what is need, if anything to use them with the OEM alternator mounts. The 136 and 160 amp cases do have a 3rd mounting point that is not used and does not create any problems. I now have a 160 amp alternator installed with 2 gage wire from it to the battery, At idle the voltage reads 13.9 to 14.1 and does not flicker much even with all the lights on. As my head lamps are H4 130 watt. And the fogs are 100 watts I’m happy. Friends asked why if this is so great Jeep did not just use the bigger alternator in the first place. I’m sure that the 160 amp takes more power to turn and I will know, but will not see a loss of power.
Looking closer I found that the alternator is putting out 16 volts when it’s cold but the reading at the battery end of the charging wire is 13.8 volts. Turn the jeep off and the charging wire is 10.5 at the alternator end, but the battery end is reading 12.3. That meant a 2 plus volt drop though the fuse link. So I replaced the wire with some 4 gage from the alternator to the battery, no more drop. But the alternator is still not working all the time.
I had done some surfing on bigger alternator for the TJ and found some very poor information. I did find that the alternator is the same for the 2004 to 2006 TJ and it’s a 117 amp unit. There are 2 others that will have the same mounts and plug on them one is a 136 amp the other is a 160 amp both fit a 2004 dodge Durango with the 4.7 V8. Now here is the fun part. The most costly is the 117amp at about 155.00, the 160 amp is 140 and the 136 amp is 109. The 136 amp looks to be in the same case as the 117 is. The 160 is in a bigger case. As I have OBA they all bolt is with no problems. I will find out what is need, if anything to use them with the OEM alternator mounts. The 136 and 160 amp cases do have a 3rd mounting point that is not used and does not create any problems. I now have a 160 amp alternator installed with 2 gage wire from it to the battery, At idle the voltage reads 13.9 to 14.1 and does not flicker much even with all the lights on. As my head lamps are H4 130 watt. And the fogs are 100 watts I’m happy. Friends asked why if this is so great Jeep did not just use the bigger alternator in the first place. I’m sure that the 160 amp takes more power to turn and I will know, but will not see a loss of power.
