Flickering LEDs when i use my laptop HELP!

[Sonic98]

I have a similar problem. I bout a 100W power inverter from a company called MicroSpec. I noticed the first time I used it, it seemed to blow the fuse to the lighter in my work truck. I took it back to my car. It was working, but it started off popping and other things that made me think it was faulty. I took it and exchanged it. It has worked fine in my car ever sense. I've been waiting for them to come change out the fuse in my work truck for months. Finally they sent someone out who couldn't get the fuse out. Later I found my pliers as was as the spare fuses. I can actually charge my phone and iPad at work without having to go to my car. I can't, however charge my laptop. I plug in the inverter, and it seems to work fine. But was soon as I plug it into the laptop, the power light starts to flash. The light on my charger barely stays lit. It works fine in my car but not in the truck. It's a 15A fuse. I looked up what fuse would be in my car. It says my car has a 20A fuse going to the lighter. I really don't have the electrical specs on the laptop at this time, but the laptop is a Dell Latitude 5540 I think. I would change it out and get a pure wave inverter, but it works fine in my car. Not sure if it would be a waste of time.

 

[Gavin A]

you need to allow for the losses in conversion from dc to ac to dc, with cheap kit they're probably 20% losses each conversion, so an 8A charge to the laptop would take 8 x 1.2 x 1.2 = 11.5A, then allow for the voltage, which is often around 19V on laptops, so 11.5 /12 * 19 = 18.24A actually being drawn from the battery by charging a 19V laptop battery at 8A through a cheap inverter.

And batteries don't really like being drawn from at those sorts of levels, which are approaching C5 levels of discharge - ie full discharge in 5 hours, which significantly reduces the battery capacity.