bdog Posted January 21, 2014 Report Share Posted January 21, 2014 Bad voltage drop with a 270 amp mechman. i tried replacing all batteries, belt and running two 0 gauge front to back with double grounds to frame . So the only thing left i can think of is the truck is messing with the alt or the alt got damaged in shipping as it came with cracked plastic . ive got 2 group 31's and two group 78's overkill on the wire 1 mechman 270 , 1 saz-3500 on a 250 amp fuse. i get bad voltage drops right off the bat. hitting 12v in less that 30 seconds then it takes ten minutes to get back up to 14.4 also the alt shuts off completely at idle in gear/500 rpm. If anyone could tell me how to bypass the truck so i can find out if its messing with me that would be great. any other suggestions would be great too. Quote REP Link to comment Share on other sites More sharing options...
slamingsuburban Posted January 21, 2014 Report Share Posted January 21, 2014 is the belt slipping and hows your ground. did you do the big 3. and what are you idling at rpm wise Quote Link to comment Share on other sites More sharing options...
slamingsuburban Posted January 21, 2014 Report Share Posted January 21, 2014 sorry just read the double grounds did you ground the alt also and where are you grounded to in the back Quote Link to comment Share on other sites More sharing options...
bdog Posted January 21, 2014 Author Report Share Posted January 21, 2014 grounds from alt to frame from front batt to frame 2 grounds from rear batts to frame . voltage reading at alt is only 0.1v higher than rear batts. Quote REP Link to comment Share on other sites More sharing options...
slamingsuburban Posted January 21, 2014 Report Share Posted January 21, 2014 clean the throttle body that should bring your idle up in gear at least it did for mine i have 03 suburban so close to yours. not shure whats going on with the alt taking forever to get back up to 14s tho you replace the idler arm recently i know you need a tight belt for the smaller mechman pully, maybey even a lil bit shorter. are you hearing any slip when the alt is under full load? Quote Link to comment Share on other sites More sharing options...
bdog Posted January 21, 2014 Author Report Share Posted January 21, 2014 im not hearing anything. old idler arm/ new 1 inch shorter gates belt Quote REP Link to comment Share on other sites More sharing options...
slamingsuburban Posted January 21, 2014 Report Share Posted January 21, 2014 Well do you still have the stock alt if so put that back in and see what the voltage is like with it and how fast it goes back to 14s Quote Link to comment Share on other sites More sharing options...
slamingsuburban Posted January 21, 2014 Report Share Posted January 21, 2014 other then that i would just call mechman in the morning and maybe they can troble shoot it for you they have good cs so they should get you up and running Quote Link to comment Share on other sites More sharing options...
MECHMAN Posted January 21, 2014 Report Share Posted January 21, 2014 Bad voltage drop with a 270 amp mechman. i tried replacing all batteries, belt and running two 0 gauge front to back with double grounds to frame . So the only thing left i can think of is the truck is messing with the alt or the alt got damaged in shipping as it came with cracked plastic . ive got 2 group 31's and two group 78's overkill on the wire 1 mechman 270 , 1 saz-3500 on a 250 amp fuse. i get bad voltage drops right off the bat. hitting 12v in less that 30 seconds then it takes ten minutes to get back up to 14.4 also the alt shuts off completely at idle in gear/500 rpm. If anyone could tell me how to bypass the truck so i can find out if its messing with me that would be great. any other suggestions would be great too. How old are the batteries? What voltage do the rest at ? Resting voltage can only be measured if the batteries sit disconnected for 24 hours. What is the voltage output on the alternator? Quote 1-888-MECHMAN www.Mechman.com [email protected] Link to comment Share on other sites More sharing options...
bdog Posted January 21, 2014 Author Report Share Posted January 21, 2014 Brand new batts . No better than the batts that were in there a week ago. Voltage at alt range from 14.2-14.9 when batts are fully charged no acc on Quote REP Link to comment Share on other sites More sharing options...
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