Okay, that does bring it in much closer, so let's look a bit as these are "calculated" values on specs and they can have some sloppiness to them. Things work slightly different due to simple things like the wiring and components, temperature and all kinds of weird little things we often have to guess at knowing.
The idea is that we are well off to not run too close to the edge---just because we are never too certain where that edge may be!
These are a couple conversion sites that I often use to see how close to the edge:
https://www.rapidtables.com/calc/ele...alculator.html
https://www.rapidtables.com/calc/ele...alculator.html
Amp and watts are both close to the same thing but used at different times. So when you ask if a 300 watt inverter can be used on a lighter plug, I know that the plugs are often fused at 5 amps and the draw for 300watt is near 30 amp, so the answer was a pretty easy "NO".
But when we get down to how much of that potential 300 watts we might actually be using, it gets a little more muddy as some energy is used internally by the inverter so we have to add that to what we think the overall power used will be. And they often don't tell us those details about the inverter, so we need to leave some slack in our thinking.
So if we take the 9 watts that the laptop is expected to use and run it through the conversion to see if it will draw too much power for the outlet to hold, we get a much better answer.
The calculator shows 9 watt at 12 VDC as being near .75 amp!
So if we plug an inverter with "potential" to put out 300 but we only use 9watt and the outlet is the normal thing fused for 5 or 10 amps, we see we have a lot of slack between the .75 the laptop uses plus some for the internals of the inverter before we reach the limits of the plug!
The folks who get really heavy into the thinking can point out there are some factors involved which makes the answer less precise but we have so much extra room for guessing that I would say go for it as a pretty good bet to work!
When looking for the edge, I'm okay with seeing the numbers show.75 plus a bit when we are thinking near 60 watts as safe for a plug fused even at the lower number of 5 amps. Sorry that I can't say with certainty, so if I were doing it, I might look for an inverter that I could try in the real world and return if a total bust!
I'm much bolder when the worst that can happen is I have to return the inverter and replace the fuse on the outlet!
Linear Mode
