On Sat, Apr 19, 2025 at 07:20 PM, Luke Vogel wrote:
I have a Lenovo laptop that currently uses an AC power supply (135W).? I think the output is aprox 20V.
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I'd like to be able to run it from the RV batteries (typically 12 to 13V) without the need for an inverter.
So, the question you need to answer is:? Can you correctly power the circuits inside the laptop that normally need 20 V, from just a 12 - 13 V power source and no inverter?
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My first answer is "no!"? Not without an inverter to boost it up to 20 V.? But to correctly answer it, you would need to know exactly what inside the laptop gets driven by that DC input voltage, and whether or not it can accommodate such a low voltage.? If it goes directly into an internal DC-DC converter (and nothing else) and if that converter is compliant enough to accept 12 V without a hiccup, then OK.? But do you have access to the schematic and internal parts list for this laptop?
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Without that, I think the best you can say is that it is highly unlikely to work without an inverter.
I think the major issue is the current draw.?
I think that is incorrect.? Electronic circuits need certain voltages to work properly, and if 12 V is too little compared to the 20 V that it needs, then either it won't work with only 12 V, or it could let out the "magic smoke", or do something else bad.
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135W at 20V can draw 6.75A so a 12V boost converter would probably draw 11.25+ Amps.
Yes, that is a reasonable estimate - if you can use a high efficiency inverter.
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Note that your RV's battery might be as much as 15 V when charging.
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Also make sure that the laptop actually needs 20 V.? How did you determine that?? If you measured its AC-DC power supply without the laptop connected, it might not be the normal in-circuit voltage, as you probably know.
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Are we at odds over use of the word "inverter"?? You spoke of a "boost converter", but isn't that an inverter?
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Andy
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