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Dave_in_Central's avatar
Dave_in_Central
Explorer
Jun 30, 2020

Question: Truck Battery Bank for Shore Power

Based on some back-and-forth with my original post, I've redefined my problem.

1. Situation: I'm trying to use the battery bank on my truck for shore power for my travel trailer. I want to be able to use the battery bank on my truck to run low-draw AC appliances while dry camping.

1.1. Battery Bank: On the truck I have three deep cycle batteries in parallel connected to an inverter. These are not tied into the truck's alternator. I use a Schumacher battery charger to keep them topped off.

1.2. Wiring from Camper to Inverter: First, the camper's shore power cable plugs into a 30Amp RV to 15/20Amp pigtail adapter. Second, a 20-amp 10-gauge generator cord plugs into the pigtail adapter and goes to the back of the truck. Third, the generator cord plugs into a 15A to 20A adapter, and then is plugged into the inverter.

1.3. Inverter Information: My set up works with an 800W inverter that outputs 120 volts. My set up does not work with my 2000W inverter that outputs 115 volts.

2. Problem: I want to use my 2000W inverter to provide shore power to my camper. Seeing that the 800W inverter that outputs 120V works and the 2000W inverter that outputs 115V does not, is there anything I can do to get the 2000W inverter to work?

2.1. The inverter I'm asking about is a Whistler Pro-2000, it outputs 115 volts (modified sine wave). When I connect the shore power cable to it, the RV gets power for a second, then the inverter goes into alarm mode (audible alarm, light blinking red-green-red-green, and power from inverter cuts off).

2.2. Last night, I was asked whether my inverter outputs 120 volts. I looked and the labeling on the inverter clearly states it outputs 115V (the Whistler Pro-2000). I also have an 800W inverter in the house that outputs 120V. When I tried using this inverter for shore power, I was successful in using truck's battery bank to provide power to the RV.

Thanks,
Dave
  • Tom_M1's avatar
    Tom_M1
    Explorer
    Jun 30, 2020
    Some inverters do weird things with the neutral and ground. Try a two prong adapter like the one below:

  • Dave_in_Central's avatar
    Dave_in_Central
    Explorer
    Jun 30, 2020
    Answering valhalla360's questions.

    But before I do, this update.

    The inverter I'm asking about is a Whistler Pro-2000, it outputs 115 volts (modified sine wave). When I connect the shore power cable to it, the RV gets power for a second, then the inverter goes into alarm mode (audible alarm, light blinking red-green-red-green, and power from inverter cuts off).

    Last night, I was asked whether my inverter outputs 120 volts. I looked and the labeling on the inverter clearly states it outputs 115V (the Whistler Pro-2000). I also have an 800W inverter in the house that outputs 120V. When I tried using this inverter for shore power, I was successful in using truck's battery bank to provide power to the RV.

    On to valhalla360's questions...

    Question 1: Are they really deep cycle...or are they the combo batteries (which are really just starting batteries with a different label). 12v deep cycle batteries are hard to find and expensive. Most people parallel 6v golf cart batteries which are legitimate deep cycle batteries.

    Answer 1: Batteries are combo batteries.


    Question 2: What size cables and how long are they connecting the batteries to the inverter? 2000w is about 170amps, that takes a pretty thick battery cable and will kill a moderate battery bank pretty quick.

    Answer 2: The cables that connect the inverter to the batteries are 2AWG and about 30 inches long.


    Question 3: How are you replacing the power draw? The standard truck alternator will only put out the rated output for a short time and then it drops back significantly.

    Answer 4:
    I use a Schumacher battery charger to recharge the batteries. The battery bank is not tied into the truck's alternator. House current --> battery charger -->batteries.


    Question 5: Does the inverter have a fuse/breaker? That would be a simple answer.

    Answer 5: Inverter has an internal fuse, no breaker.
  • Dave_in_Central's avatar
    Dave_in_Central
    Explorer
    Jun 30, 2020
    I have a Whistler Pro-2000W inverter that produces a modified sine wave.

    Here's verbiage about this from the WhistlerPro200 owner's manual:

    Whistler inverters work in two stages. During the first stage,
    the DC to DC converter increases the DC input voltage from
    the power source (e.g. a 12 volt battery) to 145 volts DC. In
    the second stage, the high voltage DC is converted to 110
    volts (60 Hz AC) using advanced power MOSFET transistors
    in a full bridge configuration. The result is excellent overload
    capability and the capacity to operate difficult reactive loads.
    The output waveform resulting from these conversions is a
    "quasi-sine wave" or a "modified sine wave" as shown on
    below. This stepped waveform is similar to the power generated by
    utilities and has a broad range of applications.
    The modified sine wave produced by the Inverter
    The modified sine wave produced by your Whistler inverter
    has a root mean square (RMS) voltage of 110 volts. The majority
    of AC voltmeters measure RMS voltage and assume that the
    measured waveform will be a pure sine wave.
    Consequently, these meters will not read the RMS modified
    sine wave voltage correctly and, when measuring your Whistler
    inverter output, the meters will read about 20 to 30 volts too
    low. To accurately measure the output voltage of your inverter,
    use a true RMS reading voltmeter such as a Fluke 87, Fluke
    8060A, Beckman 4410, Triplett 4200 or any multimeter identified
    as "True RMS."
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 30, 2020
    Is the inverter a PSW or MSW
    DO you have any kind of "Surge Guard" or Progressive Industries EMS? or competitor's product.

    Some of those look at the wave form and will not pass MSW inverters.
  • valhalla360's avatar
    valhalla360
    Navigator
    Jun 30, 2020
    Are they really deep cycle...or are they the combo batteries (which are really just starting batteries with a different label). 12v deep cycle batteries are hard to find and expensive. Most people parallel 6v golf cart batteries which are legitimate deep cycle batteries.

    What size cables and how long are they connecting the batteries to the inverter? 2000w is about 170amps, that takes a pretty thick battery cable and will kill a moderate battery bank pretty quick.

    How are you replacing the power draw? The standard truck alternator will only put out the rated output for a short time and then it drops back significantly.

    Does the inverter have a fuse/breaker? That would be a simple answer.
  • Dave_in_Central's avatar
    Dave_in_Central
    Explorer
    Jun 30, 2020
    So it appears to be an issue with the inverter (and I would imagine the output voltage). I just tried my 800W inverter that outputs at 120V and it worked fine.
  • Dave_in_Central's avatar
    Dave_in_Central
    Explorer
    Jun 30, 2020
    Fully charged? Yes. Inverter on? Yes. 120 volts? No. I have a 2,000W Whistler inverter that outputs 115V.
  • corvettekent's avatar
    corvettekent
    Explorer
    Jun 30, 2020
    Are the three deep cycle batteries fully charged?
    Is the inverter turned on?
    Is there 120 volts at the output of the inverter?

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