# SolarPanel Calcuation For Laptop

I am having some trouble understanding if I am doing my calculations correctly when trying to calculate the battery size / solar panel wattage for our RV.

I started off small by just calculating for my laptop.

My laptop draws about 5 amps on 120V (mains) which is 600W.

So next I did the calculations for the battery and solar panels. I am assuming that because I am using a 12V battery I will need to change the amps by a factor of 10 to get the same wattage.

Battery (12V) - 50 amps * 12V = 600W (So if I use my laptop for 8 hours then I am looking at 50amps*8hours = 400 amp hours)

Solar Panel (18V) - 50 amps * 18V = 900W

This seems a very big setup for just running one laptop, can someone tell me if this is actually correct or where I am going wrong. Does the inverter affect this or is my math just way off?

This is my amp measurement while my laptop is on.

• 600 watts is a lot for a laptop; my laptop is currently consuming 6.1 watts. Granted it's not doing that much, since I'm just on this website with a few things running in the background, but I think you should double check where you got that 600 watt figure from. Jul 14, 2021 at 2:33
• @Hearth It does say 65W on my charger, but when I measured the amperage at the plug using an amp meter it says between 3-5amps. Maybe the amp reading is wrong? I'm a bit new to measuring current. Jul 14, 2021 at 2:43
• You're probably measuring it wrong, then, because 600 watts is utterly absurd for a laptop. Jul 14, 2021 at 2:44
• With your new image, can you show us what the thing you're clamping the meter around is? Some of those have multiple turns to increase sensitivity, and you have to divide the reading by the number of turns. You also shouldn't be using the 200 amp range to measure such a low current. Jul 14, 2021 at 2:52
• Edit your question to add a picture of that, just to be sure. But "x10" in this context almost certainly means "times ten". Jul 14, 2021 at 2:54