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    #31
    You will want a marine alternator and not one for a car. Also check input voltage to the blue box. It should be the same as alternator output which at high idle should be 13.6 volts or higher. Check the voltage at the outputs of the blue box at high idle. They will typically be .7vdc less than the alternator voltage if they are significantly less it could be the culprit.

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      #32
      OK, I charged the batteries up this past week in preparation for this weekend. They were both at 13v fully charged (probably had a little surface charge when I tested) and we headed out on Sunday. I waited for about 2hrs on the water before testing and the Cranking read 12.4v and House read 12.2v after the 2hrs and that was with the boat running. I then proceeded to test where the POS cable exits the alternator. I was only getting a reading of 0.4v when idling and at 1500-2000rpm the output read 1.4v. These were DC readings as I couldn't get anything to show up for AC. Should that be DC coming off the alternator?

      I couldn't reach my arms back into test the blue distributor box while the engine was running as I felt like the belts would have torn my arm up. If I need to check that box I'll have to rig some loose wires up so that I can access them from away from the belts. Based on the numbers above, I think the alternator may be the culprit. I checked the manual and all it said was a 100amp min. alternator. It wasn't much help. Does anyone know of a specific type I should be looking for? Also, how do I install it?

      Thanks for all the help guys. Clearly I'm new at this.

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        #33
        Yes, the boat's electrical and charging system is DC. Seems clear that the alternator is not charging, but dont condemn it yet as a failed alternator. Need to make sure theres not any wire issues causing it not to charge, especially it its anything thing other then a 1-wire alt.

        No need at this point to test directly at the blue diode isolator. Tasting at the alt and at the battery serves the same purpose.
        Mikes Liquid Audio: Knowledge Experience Customer Service you can trust-KICKER WetSounds ACME props FlyHigh Custom Ballast Clarion LiquidLumens LEDs Roswell Wave Deflector And More

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          #34
          Here is a picture of the bow facing side of the alternator. Looks like there is a main NEG (#1 below) & POS (#2) cable on the left side and there appears to be two other connections (#3 & #4) on the right side. I cannot physically get my head down there to look at those connections so no idea what they are. What do I need to do next?
          Tige Alternator Mark-Up.jpg

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            #35
            Put positive of volt meter on post 2 and negative of volt meter on a good ground and see what you get with the engine running.

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              #36
              After some digging today, I found the parts manual for the 5.7L PCM EX343 engine off of PCM's website. It's the latest version I assume but is dated 2008. In the parts manual is the alternator illustration and part #. The unfortunate part is that I found it online and it's ~$300 new OEM or ~$100 new aftermarket. How easy is this to replace? Looks like I'll have to re-tension the belt too as the whole assembly has to come off.
              Link...New OEM Version
              Link...New Aftermarket Version

              2015-08-17_16-34-06.jpg
              2015-08-17_16-34-34.jpg

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                #37
                Originally posted by lee View Post
                Put positive of volt meter on post 2 and negative of volt meter on a good ground and see what you get with the engine running.
                I checked that and I'm getting 0.4v at engine idling and 1.4v at engine w/ 1500-2000rpm.

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                  #38
                  Poked around again this morning and found that #4 from the picture in post #34 above was a dead end POS cable with a dead end on the opposite end as well, so that has nothing to do with alternator. I traced the ground and it was anchored to the opposite side of the motor at the cranking battery ground. I disconnected the harness at #3 and it looked good as well. This must be an input cable not output. There are 2 pictures below of the harness @ #3 and a picture of the ground. I plan to take this to the dealer tomorrow to get the alternator replaced.

                  20150818_074810.jpg

                  20150818_075849.jpg

                  20150818_080232.jpg

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                    #39
                    All fixed! It was the alternator. Local dealer replaced it quickly and this weekend I retested. Was getting 14.92v off the alternator with the engine idling and 14.25v at the battery with engine idling. House battery would run down some with engine off playing stereo then would charge right back up after engine startup.

                    I want to thank everyone on here for the help especially Mike. Lots of good help thank you so much.

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