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new alternator still over charging

ckinser1 ยท 2015-03-31 13:03

So I had a bad alternator on my 590sl. It is a bosh style self regulating alternator. I replaced it last friday n But it put out 17.9 volts after it went beyond idol.The second one came in today and it also is putting out over 17 volts. Made sure the contacts to my battery and to my alternator were clean. Anyone have any ideas?

Replies9
  1. #1rmllarue912015-03-31 13:59

    Hey ckinser1 have you double checked the gauge or your volt meter?

  2. #2Delmer2015-03-31 14:26

    And where are you checking the voltage? Check the continuity of the big wire on the alternator to the positive battery terminal?

  3. #3ckinser12015-03-31 14:43

    Rm guage is working fine. There is no resistance from the alternator to the positive battery terminal. Checking voltage at the alternator

  4. #408 Ford Roush2015-03-31 20:01

    Load test the battery as you might have a bad cell causing the alternator to overcharge. Remove the caps and when load testing check for bubbling in a cell or two ....just DON'T SMOKE while doing the test

  5. #5ckinser12015-03-31 20:13

    Ford I will try it with a different battery. I have a new one I got two weeks ago.

  6. #6Delmer2015-03-31 21:15

    Check the voltage at the battery terminals, positive battery terminal to negative battery terminal, stopped and then running. A bad ground might do the same thing as a bad connection on the positive side. Check the engine to chassis ground too. Any chance this is a 24V alternator? How was it looked up? matching the old numbers? Case online? Kid at the parts store? Sorry, nothing specific here, just shooting in the dark.

  7. #7Shimmy12015-03-31 21:38

    Good call, Delmer. Most older Case hoes were 24 V.

  8. #8ckinser12015-03-31 22:02

    The backhoe was made in 1997. I just got it last week so bear that in mind as I am just learning about the machine. The manual calls for one or two batteries. This one was set up for one battery so I am sure it is a twelve volt system as my meter on my dash reads in the green with the machine at idol. The alternator was picked by matching the outside as it is a very distinctive alternator and I believe it had a 12 volt sticker on it but I will check on that tomorrow.I will also check on the ground.thanks for all the help guys

  9. #9ckinser12015-04-01 06:08

    You guys were right about the 24 volts. But it is the alternator that is the issue as my system is definitely a 12 volt but they sold me a 24.thanks for all the help.