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Help Needed- Volt monitor has jumped 0.5 volts to 14.7 - Alternator Problem?

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  • Help Needed- Volt monitor has jumped 0.5 volts to 14.7 - Alternator Problem?

    For years I have monitored voltage from my head unit (always 14.2V average) and from my Cigarette output monitor (always shows 13.9 average). Over the past month I have noticed that on start up the voltage has jumped to 14.7 v on the head unit and after warm up drops to around 14.4 on average. Have just bought a new starter battery (dual batt setup with simple idolator and switch). The new battery label says that charge rate should note exceed 14.7 Volts!

    Last edited by Subbo; 24-06-2018, 11:00 AM.
    2004 120 - 1KZ Diesel, Custom Ironman 45710FE 436-569mm with Dobinon C59-352, Custom Ironman 45682FE 383-618mm with Dobinson C59-627, 30mm extended Roadsafe links,, Recaro Drivers Seat, ARB Delux Bull, LED Driving Lights, 1200lb winch, BF02's, LED's all round, Cage Rack, Duel Batts., Airtek Snorkel, Awning, Black Widow drawers and barrier, 40L Engle Fridge- all fun!

  • #2
    It sounds ok to me. Slot your old battery back in if it drops back to 14.2 itís just the new battery probably has a bit better capacity
    2018 VX Prado

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    • #3
      Might be worth having your Alternator tested. That's getting quite high. A larger battery capacity doesn't affect the power being output by the Alternator. 14.7 is very close to battery boiling territory.

      Do you have a booster diode in?

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      • #4
        No booster Diode.
        Put in new battery because the old one was 5 years old (and needed top up with water??), and also preparing for upcoming 4 week trip in Central OZ. (Brrrrr! - Cold ). I put in my spare new alternator just to compare and found just the same voltage, with a bit more fluctuation. Looked at operating specs in manual and found that the voltage can fluctuate upwards to point 5 of a volt in cold weather. So top charge rate still remains at around 14.7 volt in Melbourne winter. I now have security of new battery and alternator for trip so all should be OK. Will report back if anything untoward happens. Thanks for your response - much appreciated
        2004 120 - 1KZ Diesel, Custom Ironman 45710FE 436-569mm with Dobinon C59-352, Custom Ironman 45682FE 383-618mm with Dobinson C59-627, 30mm extended Roadsafe links,, Recaro Drivers Seat, ARB Delux Bull, LED Driving Lights, 1200lb winch, BF02's, LED's all round, Cage Rack, Duel Batts., Airtek Snorkel, Awning, Black Widow drawers and barrier, 40L Engle Fridge- all fun!

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        • #5
          First off if it is always around 14.2V their is something wrong, generally the voltage in with the temperature around
          24C it will start off around 14.4V and drop t around 13.8V after 20 minutes or so.


          Cold day like today maybe start around 14.7V but should again drop to around the 14V, if it doesn't try removing the "ALT-S"
          fuse, if the charge light doesn't come on the alternator is probably not the OEM mode, did you purchase the car from new?
          HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others

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          • #6
            Hi Leigh, The removed alternator was original Toyota OEM (330,000) k's. The new one was purchased from Repco (80amp "Bosch Type" model). With new alternator at around 10degree temp it starts at about 14.7 volt and is then settling down to around 14.4 to 14.5 after vehicle warm up . I am assuming this is reasonable. I do note that there is now fluctuations occurring with new alternator but the old one was always at around 14.2 static.
            2004 120 - 1KZ Diesel, Custom Ironman 45710FE 436-569mm with Dobinon C59-352, Custom Ironman 45682FE 383-618mm with Dobinson C59-627, 30mm extended Roadsafe links,, Recaro Drivers Seat, ARB Delux Bull, LED Driving Lights, 1200lb winch, BF02's, LED's all round, Cage Rack, Duel Batts., Airtek Snorkel, Awning, Black Widow drawers and barrier, 40L Engle Fridge- all fun!

            Comment

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