I just bought a new laptop. I had purchased an inverter for my car to charge things with that has a 3 prong plug, usb port etc. It says it’s 100 watts. I’m trying to figure out if I can use it for my laptop - the manual says it’s18.5 volts, or 19.0 volts. Then it says 3.5, 4.74 or 6.50 A - what does this mean in terms of 100 watts? Please help this electrical ignoramus!
watts is Amps X Volts.
19 volts at 6.5A is roughly 120W (nominal…actually wattage is usually slightly different than VxA, but is’ not relevant for this discussion). So, you may, depending on when it is pulling 6.5A vs when it pulls 3.5A, overload the inverter. I assume the inverter is a 120V output, which means it will put out a little less than one amp at that voltage. Your computer’s 19V is the DC voltage, I’m sure, after the AC adapter converts the 120V AC power to 19V DC. You’ll pull far more amperage on the low voltage side of the adapter for the same power as on the high voltage side.
Basically, for this, though, you’re looking at watts only, as the voltage should be irrelevant for you…so use VxA for the load and compare it to the rated wattage of the inverter. If you overload the inverter, it will probably shut down the laptop (or force it to battery), so it’s worth a shot. I would imagine just for charging it will not be an issue, though.
Worst case power is 19v * 6.5A or 123.5W, which exceeds your inverter’s capability.
However, I’ve never heard of a Laptop charger which took that much power, so I’m guessing that your are misinterpreting the spec.
I would just try it. The worst that will happen is that it will cause the inverter to trip, and then you will have to wait until it resets.
The maximum power draw for your laptop would probably be when it’s both running hard and recharging the battery at the same time. If it’s just sitting there doing nothing while it charges, then it should be a lot less.
Thanks! I don’t care about hurting the converter. It’s a cheapie I bought at Walmart. I do, however, care about hurting my new laptop 
The converter says: AC output: 110-125 volts AC, 60 Hz, 100 Watts continuous. Is knowing this helpful?
What that means if you continually run the converter at over 100 watts its live will be shortened. And for recharging if your computer’s battery is completely flat then it will probably staart at the 123.5 wattts. Which will mean the voltage out put may be a little low. As the battery begins to charge the output will decrease and the voltage output will increase.
The dammage will be to the converter.