Are 12v cigarette lighters bad for my laptop?

[Goofygiggles]

So I'm considering buying a 12v power inverter for some trips in a car and obviously I only would use it on trips and not much else.. But I'm wondering if its bad for laptops and other electronic equipment because I heard it is. The inverter I'm looking at is https://www.amazon.com/SNAN-Power-Inverter-Outlets-Charging/dp/B01DNV30HM/ref=sr_1_2?ie=UTF8&qid=1472169715&sr=8-2-spons&keywords=12v+power+inverter&psc=1
because I don't have much money for it. Thanks!

 

[ledhead11]

It's a tricky thing.

1. You also should know what rating your alternator or cigarette lighter is. Some vary quite a bit on the amperage. Inverters will try to draw whatever they're rated for and this can damage a car's electrical system(usually just blowing a fuse but it can be far worse). Cars with v6's or v8's are normally more powerful in this respect but its not a given. The overall maintenance and quality of the car's electrical system can play a factor too. Believe me, I've seen many a blown fuse, fried alternator, fried voltage regulator, melted wires/short circuits to know this is true.

2. Even if the car is up to par. . .inverters may not always provide the steadiest/cleanest of power. The psu/brick can become stressed and eventually blow its fuse or worse. The motherboard of the laptop may become stressed overtime and eventually fry.

The lower the wattage and amperage on the inverter and the laptop psu the better. I did look at the one you posted and it looks nice but I'm still nervous about these things(they wouldn't put so much effort into talking about all the protections if it wasn't an issue).

Bottom line is to say, I wouldn't recommend it. I've done it and been alright but I know plenty of others who weren't.

 

[Goofygiggles]

It's a tricky thing.

1. You also should know what rating your alternator or cigarette lighter is. Some vary quite a bit on the amperage. Inverters will try to draw whatever they're rated for and this can damage a car's electrical system(usually just blowing a fuse but it can be far worse). Cars with v6's or v8's are normally more powerful in this respect but its not a given. The overall maintenance and quality of the car's electrical system can play a factor too. Believe me, I've seen many a blown fuse, fried alternator, fried voltage regulator, melted wires/short circuits to know this is true.

2. Even if the car is up to par. . .inverters may not always provide the steadiest/cleanest of power. The psu/brick can become stressed and eventually blow its fuse or worse. The motherboard of the laptop may become stressed overtime and eventually fry.

The lower the wattage and amperage on the inverter and the laptop psu the better. I did look at the one you posted and it looks nice but I'm still nervous about these things(they wouldn't put so much effort into talking about all the protections if it wasn't an issue).

Bottom line is to say, I wouldn't recommend it. I've done it and been alright but I know plenty of others who weren't.

Yeah thanks for the reply! I see what you mean and I feel like running one laptop off the inverter (about %60 load on the inverter) once in a blue moon wouldn't be a big deal, Do you agree? Thanks again by the way.

Except for the fact that I just looked it up and the lighter in the car I was planning on using it in is only 10 amp oops 😛

 

[bigpinkdragon286]

As long as you stay reasonably below the rating on the inverter you plan to purchase, you will be fine. They have both a peak and a continuous rating. You need to stay below the continuous rating. The peak rating is for starting up equipment, when power draw will be highest, and can be sustained momentarily.

The circuits in your car are fused for good reason. Only if modifications to your car have been made should any of your circuits be unfused. This is your responsibility to determine. If you overload your 12V accessory outlet, it'll blow it's fuse. If you overload the inverter, it'll blow it's fuse or trigger it's circuit breaker.

While a lot of inverters do not produce the cleanest power output, as in, a clean sine wave, most laptop power adapters are quite tolerant of what will be produced and will run just fine. The power adapter for the laptop will buffer any bad power from the laptop. That's it's point. To take the input power and output just what the laptop requires to run. If the inverter cuts out, the laptop will automatically run from it's battery, so it isn't as though you are unprotected in that regard.

When starting the car, it's possible the inverter will lose power momentarily. Also, an alternator in the charging circuit of an automobile can not supply peak power when at idle, so if you manage to have a high draw through your inverter, it may not be able to supply the rated output at idle. Being that the particular inverter you are interested in is powered from a 12V accessory outlet (cigarette lighter adapter), the draw should be low enough you don't encounter this problem. I've usually only seen the issue with inverters that were large enough you had to wire them directly to the battery.

If your 12V accessory outlet in your car is always on, don't forget to turn your inverter off, or unplug it, when not in use and the car is not running. Your inverter will consume power, even with nothing plugged into it, and will eventually drain your car's battery if left unattended.

I've run laptops for years off of various inverters and see no major concerns there. It's nice to have some 120V outlets on hand wherever you are, as not every device has a 12V option.

 

[InvalidError]

I have two "XPower" inverters (75W and 300W, came as a pair kit) and their output waveforms are similar to typical consumer UPS, so they shouldn't be any better or worse than "stepped approximation" UPS.

 

[Goofygiggles]

As long as you stay reasonably below the rating on the inverter you plan to purchase, you will be fine. They have both a peak and a continuous rating. You need to stay below the continuous rating. The peak rating is for starting up equipment, when power draw will be highest, and can be sustained momentarily.

The circuits in your car are fused for good reason. Only if modifications to your car have been made should any of your circuits be unfused. This is your responsibility to determine. If you overload your 12V accessory outlet, it'll blow it's fuse. If you overload the inverter, it'll blow it's fuse or trigger it's circuit breaker.

While a lot of inverters do not produce the cleanest power output, as in, a clean sine wave, most laptop power adapters are quite tolerant of what will be produced and will run just fine. The power adapter for the laptop will buffer any bad power from the laptop. That's it's point. To take the input power and output just what the laptop requires to run. If the inverter cuts out, the laptop will automatically run from it's battery, so it isn't as though you are unprotected in that regard.

When starting the car, it's possible the inverter will lose power momentarily. Also, an alternator in the charging circuit of an automobile can not supply peak power when at idle, so if you manage to have a high draw through your inverter, it may not be able to supply the rated output at idle. Being that the particular inverter you are interested in is powered from a 12V accessory outlet (cigarette lighter adapter), the draw should be low enough you don't encounter this problem. I've usually only seen the issue with inverters that were large enough you had to wire them directly to the battery.

If your 12V accessory outlet in your car is always on, don't forget to turn your inverter off, or unplug it, when not in use and the car is not running. Your inverter will consume power, even with nothing plugged into it, and will eventually drain your car's battery if left unattended.

I've run laptops for years off of various inverters and see no major concerns there. It's nice to have some 120V outlets on hand wherever you are, as not every device has a 12V option.

Oh ok! So does that mean running one laptop off of it would still be fine? I mean the power adapter for my laptop is RATED for (Input)100-240v ~2.5 amps and 130watts so the inverter shouldint pull near 10 amps right? I dont think so but I feel its better to ask and be safe then not and blow something up. Also thanks for the well thought out answers, I appriciate it.

 

[Goofygiggles]

I have two "XPower" inverters (75W and 300W, came as a pair kit) and their output waveforms are similar to typical consumer UPS, so they shouldn't be any better or worse than "stepped approximation" UPS.

Ok, Thanks!

 

[InvalidError]

Oh ok! So does that mean running one laptop off of it would still be fine? I mean the power adapter for my laptop is RATED for (Input)100-240v ~2.5 amps and 130watts so the inverter shouldint pull near 10 amps right?

Simple math says the input current will be at least 10A if your adapter ever does draw 130W: for the inverter to output 130W, it needs to draw more than 130W from its input - that's basic conservation of energy. P = V * I, so I = P / V = 130 / 13 = 10A assuming 100% efficiency.

Nothing is ever 100% efficient, so you can bump that to 11A at a more realistic 90% efficiency.

 

[bigpinkdragon286]

Because your inverter is running on a 12V system, you can easily get high amperage requirements. Your 12V accessory outlet should be good for in the neighborhood of (10A x 12V) / 1.1 or approximately 109 watts of power.

Most laptop power adapters are under 100 watts, which would fall below the limits on your 10A 12V accessory outlet.

The numbers you supplied off of your power adapter don't really help. The output power is a bit more useful here, rather than the input power. If your output power is 19V at 3.42A then your adapter can supply up to approximately 65 watts of power, and say it's only 70% efficient then it will draw in the ballpark of 85 watts to get you those 65 watts out. Make sense? So, with numbers like that, you're below the rating on your 10A 12V accessory outlet and would be fine.

Edit: LOL, I missed the 130 watts. That clearly won't work on the 10A fused outlet. Either find another outlet, wire your own outlet that is rated higher, or direct wire an inverter to the battery. The only other option is to use a laptop that doesn't draw as much power.

 

[InvalidError]

Edit: LOL, I missed the 130 watts. That clearly won't work on the 10A fused outlet.

A 10A fuse will usually be able to sustain 13-15A for 60+ seconds before blowing open, so that shouldn't be an immediate issue unless the laptop is under full gaming/compute load on a half-dead battery and the adapter needs to supply full system power while the battery charger is attempting to put all remaining power in the battery.

There is also that bit about the alternator's output voltage typically being 13-13.5V while the car is running to float-charge the battery.

 

[bigpinkdragon286]

Yes, there is definite wiggle room in there, but if it were up to me I would just do it right rather than fight the 10A fused circuit.

Are there more than one 12V accessory outlet in the vehicle? Are they all attached to the same fuse? Perhaps just run two accessory outlets to the inverter instead, if it's an option?

 

[InvalidError]

Yes, there is definite wiggle room in there, but if it were up to me I would just do it right rather than fight the 10A fused circuit.

I'd simply measure how much power the adapter is pulling from the plug while the laptop is under the intended on-the-road workload and go from there. Most of the time, electrical specs for devices that have a wide power requirement range are aligned with the worst case and actual power draw is considerably lower under typical use. Few laptops will draw anywhere near 100W even under full load.

 

[Goofygiggles]

Because your inverter is running on a 12V system, you can easily get high amperage requirements. Your 12V accessory outlet should be good for in the neighborhood of (10A x 12V) / 1.1 or approximately 109 watts of power.

Most laptop power adapters are under 100 watts, which would fall below the limits on your 10A 12V accessory outlet.

The numbers you supplied off of your power adapter don't really help. The output power is a bit more useful here, rather than the input power. If your output power is 19V at 3.42A then your adapter can supply up to approximately 65 watts of power, and say it's only 70% efficient then it will draw in the ballpark of 85 watts to get you those 65 watts out. Make sense? So, with numbers like that, you're below the rating on your 10A 12V accessory outlet and would be fine.

Edit: LOL, I missed the 130 watts. That clearly won't work on the 10A fused outlet. Either find another outlet, wire your own outlet that is rated higher, or direct wire an inverter to the battery. The only other option is to use a laptop that doesn't draw as much power.

Yeah thats because I forgot to add the wattage and updated it xP - Yeah if you need more PSU Info I have the Dell Inspiron 7559

 

[Goofygiggles]

Oh ok! So does that mean running one laptop off of it would still be fine? I mean the power adapter for my laptop is RATED for (Input)100-240v ~2.5 amps and 130watts so the inverter shouldint pull near 10 amps right?

Simple math says the input current will be at least 10A if your adapter ever does draw 130W: for the inverter to output 130W, it needs to draw more than 130W from its input - that's basic conservation of energy. P = V * I, so I = P / V = 130 / 13 = 10A assuming 100% efficiency.

Nothing is ever 100% efficient, so you can bump that to 11A at a more realistic 90% efficiency.

I feel like my laptop will never draw more then 100 watts, Dell (I have the Inspiron 7559) wouldn't push the power adapter that hard. Thanks!

 

[Goofygiggles]

Yes, there is definite wiggle room in there, but if it were up to me I would just do it right rather than fight the 10A fused circuit.

I'd simply measure how much power the adapter is pulling from the plug while the laptop is under the intended on-the-road workload and go from there. Most of the time, electrical specs for devices that have a wide power requirement range are aligned with the worst case and actual power draw is considerably lower under typical use. Few laptops will draw anywhere near 100W even under full load.

So are you saying it would be OK? Just thought I'd mention, Im 14 and I cant wire up my parrents car.. xP. I also dont feel like blowing a fuse for them.

 

[InvalidError]

So are you saying it would be OK?

I cannot say for certain without measuring first. As long as you aren't planning to play games while connected to the inverter, it should be fine. If you want to run games while on the go, you may need to select the battery-saving power management profile first to reduce the likelihood of pulling over 100W. An i7 + GTX960M + LCD + charging battery + everything else could certainly get to 130W.

 

[Goofygiggles]

So are you saying it would be OK?

I cannot say for certain without measuring first. As long as you aren't planning to play games while connected to the inverter, it should be fine. If you want to run games while on the go, you may need to select the battery-saving power management profile first to reduce the likelihood of pulling over 100W. An i7 + GTX960M + LCD + charging battery + everything else could certainly get to 130W.

I don't have anything to measure with, but after I reply to this Im going to look up how much this laptop draws. What am I looking for how many amps, or wattage it draws?

 

[bigpinkdragon286]

You want to know the wattage that the laptop is going to be drawing.

Blowing a fuse should be generally harmless. Of course, you will need to find and replace it if you cause it to blow, but any auto parts store, or even big box store will sell replacement fuses.

 

[Goofygiggles]

You want to know the wattage that the laptop is going to be drawing.

Blowing a fuse should be generally harmless. Of course, you will need to find and replace it if you cause it to blow, but any auto parts store, or even big box store will sell replacement fuses.

Ok! Hey, Thanks so much for the help!

 

[bigpinkdragon286]

Another option you have is to get an inverter that won't draw over 10A and just live with that. It will probably get hot, might poop out on you when if your laptop draws over 100 watts, but it won't overload your 10A accessory outlet in the car.

 

[Goofygiggles]

Another option you have is to get an inverter that won't draw over 10A and just live with that. It will probably get hot, might poop out on you when if your laptop draws over 100 watts, but it won't overload your 10A accessory outlet in the car.

Thats True

 

[Goofygiggles]

Another option you have is to get an inverter that won't draw over 10A and just live with that. It will probably get hot, might poop out on you when if your laptop draws over 100 watts, but it won't overload your 10A accessory outlet in the car.

Do you know of any inverters that dont draw more then 10 amps for under $30 though?

 

[InvalidError]

Do you know of any inverters that dont draw more then 10 amps for under $30 though?

Take any inverter with a user-replaceable fuse and put a 10A fuse in it. There you go, it won't be able to draw much more than 10A for very long.

 

[bigpinkdragon286]

I like your idea better than mine, InvalidError. You can use a larger inverter and rate it to the system it's paired with, provided it's got a user replaceable fuse.

 

[ledhead11]

Another thing to consider when popping car fuses. Their usually part of a circuit. I.E. a cigarette lighter isn't likely to be the only thing that will stop working if the fuse goes. Good news they're usually paired on the 'accessory' type circuits. So if it goes, you might also lose ceiling/cab lights or some other non-essential option in the vehicle. I'm not sure if it was Bigpink or Invaliderror, but one mentioned sometimes there are different cigarette plugs in a car. For newer, post 2000 vehicles this is often true. They sometimes have a dedicated plug just for things like this with higher amperage ratings. In either case, just be aware that when a fuse goes in a car its rare that just one, single, item stops working.

You may also want to check the dell site. Some manufacturers actually make their own car adapters for their laptops. It makes a lot more sense to send DC to DC since the PSU is actually re-converting it back into DC. No need for an inverter and probably safer for all.