I was using this car charger to charge my MacBook Pro from past two months without any issue in my Swift Dzire 2012 model. Today, I connected two laptops at the same time using a multi socket extension. It worked fine for 15 minutes and then cigarette lighter fuse blown.

I took car to service centre and they replaced the blown fuse with another one of same capacity (15 AMP). When I again plugged in the charger into cigarette lighter socket then it blown again in few seconds. This happened a couple of times.

Finally, they used another car charger which looked like this and this time fuse was not blown.

Is it possible that the charger that I am using is the culprit and blowing up fuse repetitively? And is there anything that I can do to test and fix it?

Note - I was using this charger from two months without any issue but with a single laptop.

  • 1
    Your charger is blowing the fuse - that's already been tested by the service centre. I'd suggest getting a different charger.
    – Rory Alsop
    Commented Nov 20, 2020 at 15:22
  • Did you consider charging 2 laptops at the same time is the issue?
    – Solar Mike
    Commented Nov 20, 2020 at 15:24
  • @SolarMike Definitely, this issue is caused after charging 2 laptops at the same time as earlier I was able to use it fine for hours with one laptop. Carger/Invertor was rated with output of 150 Watts and the combined usage from two laptop chargers was around ~180. So perhaps, it stressed the invertor. I am wondering if there is something that I can do to fix the invertor.
    – conetfun
    Commented Nov 20, 2020 at 15:26
  • @RoryAlsop I was interested in knowing the internals of inverter/charger to understand what could have happened when I plugged two laptops. Like something inside inverter is gone bad due to which now it is pulling more than 15AMP and causing blown fuse
    – conetfun
    Commented Nov 20, 2020 at 15:30
  • 1
    The carger is now broken as he is constantly shorting the supply. Either get a new (and better) one, or try to ask the guys on electronics.stackexchange.com on how to fix it
    – Martin
    Commented Nov 20, 2020 at 16:27

1 Answer 1


So that inverter is a 150W output model. Assuming it's 90% efficient (that's probably a high guess) that means it takes 167W input. At 12V that is 14A.

What's the fuse capacity on your lighter outlet? Most are in the 10-15A range so at 14A you are really close and it makes sense that you will blow the fuse after some time. Fuses are not able to handle their rated capacity for an extended period of time.

You need to either:

  1. Only charge one laptop at a time since the full capacity of the inverter is not needed to charge one of them.
  2. Plug your inverter in somewhere else. That may require installing a second power outlet in your vehicle.
  • That will be sure thing - charging one laptop a time with the new inverter that I get. But is there any explanation what could have happened to existing inverter which is blowing fuse even when there is no laptop charger connected to inverter.
    – conetfun
    Commented Nov 20, 2020 at 16:18
  • Perhaps the inverter is failing. I'm sure it's a cheaply made Chinese device. These things don't stand up to much stress. No way of knowing without taking some measurements but more than likely it drawing more current than it's supposed to and the fuse is doing what it's designed to do, protect your car.
    – jwh20
    Commented Nov 20, 2020 at 16:25

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