Forum Discussion

roamlab's avatar
roamlab
Explorer
Aug 25, 2017

Charging A Laptop on 12V?

In reading about charging laptops off 12V, most people seem to advise using an inverter. However, we'd like to avoid the wasted power when converting from DC to AC and back to DC. I see some cigarette lighter style chargers, but hear mixed responses to those re: fried batteries.

Is anyone charging their computer directly from 12V with a cigarette lighter converter or a USB C?

EDIT: For context, my traveling companion has an Dell Inspiron 7737. Dell sells an auto adaptor for this build. Inconveniently, I have a MacBook Air which takes 14.85 V. I know 12 V batteries in practice don't put out exactly 12 V but would they handle 15 V?

19 Replies

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  • GordonThree's avatar
    GordonThree
    Explorer
    Aug 25, 2017
    Laptop will want either USB type C charging (2016 model and newer) or proprietary charging at least 16 volts DC some as high as 19 depending on model.

    A laptop with a 2S battery may operate as low as 12v.
  • Sam_Spade's avatar
    Sam_Spade
    Explorer
    Aug 25, 2017
    roamlab wrote:
    Thanks for the input, guys! Both of our computers are pretty old, so we may be upgrading soon to ones with USB C. Being 12V compliant sounds like a major selling point!


    Be very careful with this.

    I don't quite understand the theory that you can charge a laptop via a USB port.......since the USB voltage standard is only about 4.5 volts......and I doubt that the laptop would have a 4.5 volt battery.
  • roamlab's avatar
    roamlab
    Explorer
    Aug 25, 2017
    Thanks for the input, guys! Both of our computers are pretty old, so we may be upgrading soon to ones with USB C. Being 12V compliant sounds like a major selling point!
  • time2roll's avatar
    time2roll
    Nomad
    Aug 25, 2017
    I have used both. Inverter is far more handy than a dedicated DC/DC converter. I don't buy into converter damaging the laptop battery. If this little bit extra to run an inverter drains your RV battery.... you need a better RV battery.
  • sch911's avatar
    sch911
    Explorer
    Aug 25, 2017
    Most laptops have vehicle chargers availlable even if they require more than 12v. In those cases the charger brick includes a DC to DC converter. Check with your laptop manufacturer.
  • 2oldman's avatar
    2oldman
    Explorer II
    Aug 25, 2017
    You don't any kind of converter if you need 12v. But as said above, if it's 19 then it's inverter time. The 'wasted' power is of little consequence.
  • mr__ed's avatar
    mr__ed
    Explorer
    Aug 25, 2017
    I may be mistaken, but I think the laptops I've used required 19 VDC from the charging unit. If that's the case, 12 volts may be insufficient. Maybe someone else can chime in here with the proper answer.
  • Sloop_Smitten's avatar
    Sloop_Smitten
    Explorer
    Aug 25, 2017
    If your using a laptop cable, provided with the laptop, that utilizes USB you should be good with a 12V outlet USB Adapter. The time it takes to charge may be slower (or faster) but the adapter should convert the 12VDC to the proper USB voltage.

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