Some questions about using a 12-volt-to-110-volt power inverter on board a vehicle.

Discussion in 'Mobile Radio Systems' started by KC0BUS, May 31, 2019.

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  1. KC0BUS

    KC0BUS Ham Member QRZ Page

    I need a power inverter and I've never owned or used one before and had a few questions about them. I need to power a few 110-volt AC device's in my 12-volt vehicle while on road trips. How long can I safely power things with one without draining my vehicle's engine starter battery? Also, does it matter which one to choose or are they all pretty much the same? How much is a good one versus an 'El-cheap'O' one made in China or Taiwan? Would I be better served buying used or new? Where's a good place to get one? Thanks for any help
  2. KD8DEY

    KD8DEY Ham Member QRZ Page

    Depends on the wattage rating of the inverter, it's efficiency, how much power you plan to draw, battery capacity, etc etc etc....
    I think they are probably just about all pretty much made in Taiwan or China,....
  3. KC0BUS

    KC0BUS Ham Member QRZ Page

    I'd like to be able to power two hand-held FM 2meter/440 transceivers along with two laptop PC's running windows 8 and/or 10. That would be the ideal scenario for my current needs.
  4. KD8DEY

    KD8DEY Ham Member QRZ Page

    I would try checking to see if there is a "Lighter Socket" type battery eliminator available for the laptops and HT's, or maybe build a small regulator to supply the HT's, and try to ditch the idea of an inverter...(less wasteful)
  5. AC0GT

    AC0GT Ham Member QRZ Page

    If it's laptops you are running then I'd suggest avoiding the use of an inverter. There are 12 volt chargers for most any laptop today, especially if they are capable of charging from USB-C.

    I see @KD8DEY beat me to it.
  6. WB2LBV

    WB2LBV Ham Member QRZ Page

    Agree with the above, using an inverter for those devices is very inefficient as you're converting DC-AC then back to DC. Also the inverters, especially the cheaper ones, are likely to produce a fair amount of RF hash.
    It only makes sense to use an inverter for equipment that runs directly on 120AC with no DC option.
    As for draining the battery, anytime you're taking power from it without the engine running you need to be mindful of not draining it too much. With a few low-power DC devices and the ignition in the "ACC" position to energize the power sockets you should be ok for quite some time, while a higher power inverter will drain the battery more quickly. If you plan to do this often it would be a good idea to add a DC voltmeter to the accessory circuit so you can monitor the voltage and avoid having it drop too low to start the vehicle.
    Also consider replacing the battery, if it's a conventional "wet" cell type, with an AGM battery which is better at tolerating repeated discharges without damage.
    Last edited: May 31, 2019
  7. K8ERV

    K8ERV Ham Member QRZ Page

    Some (Dell) laps check for their brand of power supply and won't work with others. Their connector has three circuits. Check the connector carefully.

    TOM K8ERV Montrose Colo
  8. K8ERV

    K8ERV Ham Member QRZ Page

    Also many if not most 120v converters do not put out a good sine wave and could harm or not work properly with some equipment. A good sine wave converter is expensive.

    TOM K8ERV Montrose Colo
  9. AG6QR

    AG6QR Premium Subscriber QRZ Page

    Both points are true. But in my experience, anything driven by a switching power supply is very tolerant of the stepped output from even the cheapest inverters. Some devices with transformers or motors are not so forgiving.
  10. VA3VF

    VA3VF Ham Member QRZ Page

    These things are noise generators, and the output is far from a sine-wave.

    Depending on the current draw, do not use the cigarette lighter, a direct connection to the car battery may be required.

    Lastly, quality is not always the best, considering how much they sell for. I have one that cost me $10 on sale. It's a low wattage one, for connection to the cigarette lighter only.

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