Power Inverters

Discussion in 'Trucking Electronics, Gadgets and Software Forum' started by rdubill, Jan 25, 2007.

  1. Buster

    Buster Light Load Member

    Nov 4, 2008
    Kingston NY
    I installed a Cobra 1500 / 3000 watt inverter in the Peterbilt. I followed the instructions found on this page. But, I have 2 questions.

    1; If I leave the inverter "on" but nothing is connected to it at that moment, will it drain the battery down or draw any power from the battery?

    2;I connected the "hot and ground" to the same battery. Should I have connected the hot or the ground to another battery??

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  3. outerspacehillbilly

    outerspacehillbilly "Instigator of the Legend"

    May 28, 2009
    The Who's Your State
    1. You should always turn it off when not in use. It will drain juice from the batteries but it would take a while to run them down with nothing running but it will drain them.

    2. Doesn't matter.
  4. Hardlyevr

    Hardlyevr Road Train Member

    Jul 30, 2009
    Mapleton Depot,PA
    some inverters also have a seperate ground lug or post on the outside of it's cabinet, that one you should try to wire to the frame or steel section of body panel that is grounded, not the negative post of the battery.
  5. newly crusin

    newly crusin Medium Load Member


    I'm no expert on inverters, I do have some electronic knowledge.

    If the inverter is powered up and on, but with completely no load( not even those square little transformers) when powered up, the circuit that is energized is the electronics so the inverter is ready to go when needed to supply the wattage output that is needed.
    If the DC/AC bus thermistor temperature increase's the fan ( if yours has one) will come on to decrease the temp. of the heat sinks and the thermistor.

    When powered up the DC/AC bus is still powered but with out any load.
    This milliamp draw can be measured with a good quality multi-meter,
    ( the meter MUST be set to mA and the correct range and be placed in series with either the negative or positive lead to the power supply),any measurements below .750 mA
    ( similar to a cell phone charger when it is charging a cell phone) and I don't think you will have problems.

    Contact Cobra and ask them first before you do anything.

    I had two in the same truck and powered on( with no load when parked) for about 3-4 years,had newer,better batteries and never had any problems.

    One other thing, if your rig is not used and parked for a long time , then yes power down the inverter.It will slowly absorb voltage from the batteries.I drove my truck everyday,inverter powered but with no load at night and never had any problems.


    Last edited: Jan 26, 2010
  6. IROCUBabe

    IROCUBabe Road Train Member

    Apr 9, 2008
    Dallas, TX
    Hey since this is here, I have a inverter question too.

    We have some weird yellow one of which the name of eludes me and its in a hard to glance at the name place so I can only really say the brand seems to only be sold at Pilots, and its yellow. Ours is 1000 watt one with a display that displays current watts drawn.

    Anyway, I hooked a vacumn to it and it began to smoke, not a house vacumn one of those smaller handheld ones. I took that one back got another, it did same thing. Tried a different brand of vacumn had better luck except randomly it would like go nuts. Well I have a desktop pc now in the truck and I wanted to protect it so I got a Uninterrupted Power Supply for it. I hooked it up and it refuses to run on the inverter, it says the inverter is pushing too much power, between 150-260 volts, instead of 120.

    My logical side says thats probably not what its supposed to be doing (and explains the issues before), but before I rush out and spend 150 on another one, is this normal for inverters? Or is mine defective?
  7. newly crusin

    newly crusin Medium Load Member


    Well this is a good one,first thing you have to do is :
    1) Always check the wattage out put of the inverter, peak and nominal. It seems you chose a good one that gave you a readout of wattage used, it might not supply enough wattage though.
    2) Always check the wattage of the device you are plugging into the inverter, never exceed the wattage as this will overheat the electronics/ DC to AC bus.

    Your problem of plugging in a ( I guess) a household UIPS to the inverter is a good one, I'm no inverter expert.

    Probably doing this because the inverter is supplying a higher voltage(with no load) so when a load is connected to it, the inverter thinks the voltage will decrease when a load is applied.
    The UIPS tolerence is low when powered up , most are 10%( example, 120volts +10%= 132 volts, 120 volts - 10%=108 volts.)
    This also might be due to the harmonics caused by the inverter you have and the UIPS you have might not like this,causing it to shut down.Also you have to remember most UIPS's like to see a high voltage supply of 120volts,+/- 10% of nominal AND CONSISTENT 60hz (similar to a house). The hz from your inverter can be measured with a good quality meter while idle and while it is powering the UIPS, measure on the high voltage side of thr inverter,carefully.Please don't get electrocuted.
    As the high voltage,120 v, flucuates so does the wattage consumption on the other end, and the 12 volt amperage that the inverter consumes to supply the high voltage.

    My suggestion is try to locate a decent quality 3000 watt inverter, perminatly mount in your truck, fused correctly at all power sources, basically they are all the same, the difference is the electronics, the harmonics output
    ( smoothness of the supplied simulated 60hz, as would be seen on an oscilloscope, to 120 volt devices).

    Again I'm no inverter expert.

    Try eBay,I just checked there is over 3000 of them of all sizes on ebay right now.

    Belkin is a good manufacturer.
    copy/ paste this link:


    Try to do some surfing on eBay, Google,etc.

    Hope this helps,

  8. IROCUBabe

    IROCUBabe Road Train Member

    Apr 9, 2008
    Dallas, TX
    I was told I needed a pure sine wave inverter to safely run the ups so I found a good deal on one...

    On eeebbaaayyy!
  9. kajidono

    kajidono Road Train Member

    Jun 1, 2009
    I power my inverters down when I park the truck for a while. My batteries aren't that great and the power drain from starting the truck can and will damage the inverters.
  10. whisky

    whisky Light Load Member

    Jun 9, 2009
    Hi all, I'm new to trucking and want to put an inverter in my truck that I will be getting Sunday but don't know how many watts I would need. Just want to run my laptop , and maybe a cooler fridge or something like that. Also can I get the kind that plug into the lighter ?

  11. lovesthedrive

    lovesthedrive Is here to help

    Nov 11, 2008
    Sorrento Maine
    go to radio shack and buy a 12 volt cord adapter for your laptop. Most newer trucks 2005 and on have 1500 watt inverters on board. Otherwise 1500 is safe but you will need to tally up your planned watts to know what you are going to need.
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