#151367  by StephenD
 Mon May 13, 2019 4:20 pm
Is anyone using a Step up Buck Converter to charge a Macbrook Pro? Does this produce the same result as a Pure Sinewave inverter.. and is this a more efficient use of energy.. 12volts to 16.5 volts for the laptop .. have to connect to a catching cable I guess,.. Rather than 12volts up to 240v and back down to 16.5volts
Or am I completely barking up the wrong tree.. ?
 #151370  by Mark
 Mon May 13, 2019 5:17 pm
I used a step-up DC to DC (12 - 18V) to power an HP laptop for a few years with no adverse effects.
 #151375  by scubadoo
 Mon May 13, 2019 7:58 pm
It will depend somewhat on your PC usage times. We have 3 notebooks all powered by a single 15A 19VDC step up converter. From past experience with mains inverter operation expect about a 20% average overall energy saving.
For 2 of our notebooks that would be a relatively insignificant issue since they typically are used for a couple of hours daily and average about 1.5A each. That totals perhaps a 10Ah daily consumption from the battery while the sun is not shining. A couple of Ah extra draw from mains inverter operation may not be important for most users
The other notebook can draw 4.5A 24/7 for a week at a time. The maths would soon demonstrate that the buck conversion method offers a substantial 30 or 40Ah daily saving.
The step up converter method is also a much tidier option for us. Just grab a lead and plug it in. :TU
 #151377  by StephenD
 Mon May 13, 2019 8:11 pm
Thanks Neville.. so does the Buck Converter not have the same problems I hear can occur with Modified wine wave inverters?
Also, as I asked Mark.. How did you wire it up? Direct connect to 12v battery?? What about to the laptop? Did you just cut the adapter off and use just the cable direct from Buck converter to laptop?
 #151380  by scubadoo
 Mon May 13, 2019 8:31 pm
What type of DC plug powers your Macbook? It may well be easier to power it from a small PSW inverter and live with the losses. At least it will be a straightforward installation.


Never had any issues in 4 years of full time travel.
Originally I used 3rd party DC plugs but I now just cut the DC leads about 150mm from the original power bricks and although they are not designed for high current use I fit an RCA plug/socket to the join maintaining mains operation when required. I am still on the original RCA plugs. Quality plugs and sockets are available from Jaycar.
They also stock other DC plug/socket combinations that may be more suitable for others.

I have run a 12V fused lead from the battery junction box to a dedicated wall plate at shin level in our living area with switched 3x 19V, 2x 5V USB, 2x 12V DC and 1x 12V cigarette lighter sockets. They are occasionally all in use. :?

Establish that the DC supply leads are a 2 wire setup before you cut if you decide to go that way. I have seen for example an HP notebook with a 3 wire lead apparently with a feedback loop of some kind.

A much easier option would be one of the many available 12V cigarette plug powered step up notebook power supplies if you can find a suitable model with the right voltage, current and DC plug requirements. Or you could fit you own plug. ;)
 #151381  by Mark
 Mon May 13, 2019 8:47 pm
The (settable voltage) power supply that I used had a cigarette socket plug on one end and a range of plugs on the computer end, one of which fitted the HP laptop.
A later HP laptop had a proprietary socket that no DC power supplies, that I could find, would fit - and so for that I had no choice but to go through an inverter.
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