How long batteries last ?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Greggg, Sep 15, 2019.

  1. Greggg

    Greggg Light Load Member

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    If I turn off my inverter, (I have a 4.5cu fridge) and everything else in my truck, how long would my batteries last (I have 4 of them) before I would need to be jumped ?
    (My batteries usually last 12hrs with the inverter/fridge on)

    If my batteries do die can a regular small sedan jump start me ? (Even if might take a longer time ?)

    I have a 2005 freightliner can’t find the battery kill switch and don’t know if the truck would shut itself off to keep enough power for me to start it...
     
    Last edited: Sep 15, 2019
  2. RustyBolt

    RustyBolt Road Train Member

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    A small sedan, while not recommended, can jump start a truck. It can take several hours depending on how dead the batteries are. But it can do it. Jump started a Freightliner in 1990 with a 4 cylinder Buick Skyhawk. Roughly 5 hours for that one.
     
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  3. SpeedyGonzalez

    SpeedyGonzalez Light Load Member

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    One of our rigs has 4 batteries as well, with the fridge shutoff I see about .2 volts drop every night, you really dont want to let the battery get below 11.6v or itll be a pain in the behind to get started, at 11.2v mine will crank much slower and I'll get a ECM power low on the dash. I usually get 5 days before it needs to be jumped. I can jump it with my pickup in about an hour, if you've got a good set of cables when you hook up to the jump terminals you should hear the engine load up. Most alternators only make a few amps at idle, my truck puts out 160amps at 1500rpm so I just use a stick and slide the seat forward to keep the pedal depressed.
     
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  4. Greggg

    Greggg Light Load Member

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    Thanks a lot for all that info speedy. Definitely you too rusty thanks.
     
  5. HoneyBadger67

    HoneyBadger67 Heavy Load Member

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    Almost 2hrs to jump start my T660 (4 batteries, 2 of which were bad) with a Camry...LoL
     
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  6. thaistick

    thaistick Road Train Member

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    If you've got good batteries and everything is off....you could go months. How long are you going to be away? If more than a week or so, I'd disconnect the batteries, so that there wouldn't be a parasitic drain.
     
  7. Final Drive

    Final Drive Medium Load Member

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    I think key is using heavy duty jumper cables....
    With a high idle on your vehicle..
     
  8. Greggg

    Greggg Light Load Member

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    Cool that’s good to know too.

    Just in case info helps someone I’ve ran my fridge and other too long before to the point where even the inverter and fridge shut off a dually had me started in about 15 minutes I’d say with the regular jump cables they have at Walmart.
     
  9. PE_Trans

    PE_Trans Road Train Member

    I’ve been thinking another option to have a fridge in the truck and not risk damaging the batteries is to buy a mini freezer, an inverter, and an ice box. You will be freezing bottles of water or (blue) ice packs while driving. On every 10 hr break, you turn off the freezer, and move the frozen ice packs to the ice box.
     
  10. SpeedyGonzalez

    SpeedyGonzalez Light Load Member

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    The great fridge dilemma lol, we ended up going with a deep cycle battery in the side box isolated with a control relay and switching relay. If the truck isn't running the fridge runs off of just the deep cycle, once system voltage is up to 12.6V control relay trips and they're all chained together and charging. Nice part is if the main batteries are weak, the driver can hit a button on the control relay and has an extra battery for starting. Cost was $30 per truck excluding batteries and cables.
    PS. The fridges in the trucks use a peltier module which are highly inefficient, if you shop around you can usually find a mini fridge that uses a compressor that runs at 5-6 amps. Those will cool better and faster and are more efficient, and usually have a larger volume for the same power draw of the peltier ones. You can also modify them with a big capacitor to reduce the inrush current requirement if your inverter cant keep up.
     
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