2016 579 low voltage disconnect

Discussion in 'Peterbilt Forum' started by Edjahman, Dec 12, 2016.

  1. Hdrider201

    Hdrider201 Bobtail Member

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    Jul 4, 2017
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    I purchased a 2019 389 in January with LVD. I run an Espar bunk heater on cold nights, trying to avoid idling that might harm the engine's emissions. Since I run in northern Wisconsin I also installed an Espar coolant heater which is set with a timer to run for an hour or two, depending on how low the ambient temperature is, to avoid engine cold starts. I also removed one of the four batteries and installed a Maxwell ultra capacitor in it's place to handle the duty of starting the engine. This was the set-up I used on my 1998 379 and it worked perfectly - warm cab all night, warm engine at start-up.
    Enter LVD. The system would sound an alarm about eight hours into my break; in other words, about one hour before I intended to wake up! When I switched on the key the volt gauge would read approximately one needle width below 12 volts.
    The Peterbilt dealer informed me they could change the setting on the LVD to 11 volts. Perfect! My hotel power loads have never caused the battery voltage to drop that low. Still, morning after morning - BEEP BEEP BEEP arousing me from sleep to find the battery voltage just under 12 volts. I even went to the trouble of dressing, leaving the cap, opening the battery box and checking the voltage at the batteries where I found a surprising reading of 12.6 volts!
    Peterbilt has come up with a few theories:
    1) The Maxwell ultra capacitor is backfeeding current into the system. (Huh?)
    2) The system can't function properly on three batteries because the truck came with four batteries. (One battery was removed to make room for the Maxwell.)
    The 1998 379 that I purchased new came with three batteries and did a great job for the 2.3M miles I drove it. I would be interested to hear from anyone with a Paccar product which uses three batteries and an LVD system.
    Any ideas?
     
    Slowmover1 Thanks this.
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  3. pushbroom

    pushbroom Road Train Member

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    Sep 1, 2012
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    Cecu controlled lvd or separate Lvd module? Post the last six of your s/n if you are unsure.

    First guess would be the parameter was not correctly changed. Maxwell is separate and only wired to the starter motor, should not affect LVD operation, neither should only 3 batts, unless the capacitor was installed incorrectly. We usually just disable the LVD for our customers. Less hassle that way.
     
    spsauerland Thanks this.
  4. Hdrider201

    Hdrider201 Bobtail Member

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    Jul 4, 2017
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  5. Hdrider201

    Hdrider201 Bobtail Member

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    Jul 4, 2017
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    Thanks for the response. And no, the Maxwell, installed by myself, as it was on my 98, is installed correctly. I included that detail in my post to indicate how entirely lost this Peterbilt service department is regarding this issue. They are grasping at straws at this point.
    I'm going to say it's cecu controlled as I have heard them describe making settings changes to the cecu in an attempt to lower the disconnect threshold to 11v instead of the current 12v setting.
    As another poster commented, the LVD is a nice feature if I want to leave the fridge on over the weekend. Having the Maxwell to rely on to start the truck allows me to rely on the LVD to a lesser degree. But I paid a lot of money for this truck and I have a right to expect all of it's features to perform as advertised and it's my head and I can beat it against this wall as long as I like. Or as long as the warranty lasts.
    But seriously, I'm going to install 3 AGM batteries next week and replace the Maxwell with one of the 6 month old flooded lead batteries. Just for two weeks, just long enough for Peterbilt to recognize their theory was incorrect.
    I'm very interested to hear the experiences of others and their LVDs. Thanks again
     
  6. pushbroom

    pushbroom Road Train Member

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    Sep 1, 2012
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    Lvd can be cecu controlled or a seperate module. If its a seperate module, thats why changing the cecu settings did nothing.
     
    spsauerland Thanks this.
  7. popcorn169

    popcorn169 Road Train Member

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    Sep 5, 2011
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    I posted this in the Apu thread a couple weeks ago and no response so hopefully someone can help me with this issue.

    15 Pete 579 Cummins isx and an older Thermo King Apu. When batteries get low the Apu used to come on automatically now it does not do that. As a matter of fact it won't come on.

    The Apu will run the AC and charge batteries if I turn the AC on.
     
  8. 6mmrem

    6mmrem Bobtail Member

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    Sep 16, 2018
    Neepawa,Mb. Canada
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    I'll have to get dealer to check my lvd settings. Just park for a few minutes and it comes on with just the cab lights on. Digital display shows 13.3 volts.
     
  9. Edjahman

    Edjahman Medium Load Member

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    The LVD eventually died and that was really great because I hated it anyway.

    I've since got a different tractor!
     
  10. DavidK57918

    DavidK57918 Bobtail Member

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    Sep 27, 2021
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    What's the solution. I have a 2018 Peterbilt 579 , and as soon as I turn the truck off, the LVD comes on and cuts my power off. I have a small frigde. No lights or power in the sleeper.
    I was thinking about buying a inverter, but will it even work with no power. Pff.
    I don't have a apu. Winter is around the corner.
    And my truck idles at 650rpm.
    .7 a gallon per hr.

    What's the solution, do I buy better batteries?
    Change the setting to cut all power off at 12v?

    Will it even start. I need a permanent solution to this. I driven Frieghtliners, Internationals, Volvos, KWs ,and this is the first time I have no power. And I cook in my truck. I need help.
     

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  11. Goodysnap

    Goodysnap Road Train Member

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    Jul 12, 2017
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    You need to perform a battery service, clean all cables and connections and load test the batteries, first. The LVD voltage is low and the bunk power is being disconnected so that you have sufficient voltage to start the truck. The more loads running, CAB, SLEEPER or otherwise reduce voltage and cause the LVD to shut off early.
     
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