How Many Amps Does The Cigarette Lighter Put Out?

[GoVikings!]

My father in law needs to run his O2 machine in the car and I need to know how many AMPS the cigarette lighter puts out. Any one know? If it's under 15, any idea where I can get a good power inverter? Please help...

[RhoXS]

The label on the caps on some of the cigarette lighters states 120 watts. This is 10 amps max at 12 volts.

In my opinion, the conductor sizes in most if not all vehicles seem marginal for a continuous 10 amp load. A continuous 10 amp load will probably cause a significant temperature rise in the wiring harness and at connections. That does not mean it cannot safely handle 10 amps for brief period of time (like using a small 12 volt air pump to press up a tire). However, I would not even think of applying a 10 amp load continuously on any of my cars.

The correct method of supplying a large DC load in a vehicle is to run a fused wire (probably minimum #14 conductor depending on length) directly to the battery. The wire not only needs to be able to handle the current without an undue temperature rise, but the voltage drop across the wire must be no more than a volt or so at maximum load. Ohm's Law gets you two ways with low voltage DC high current circuits. The so called "I squared R" losses can produce a lot of heat and the "IR" voltage drop can be significant if the wire is not properly sized.

Search for "12 volt power inverters" using Google. Also, check your local marine supply stores for a good inverter.

One last but very important consideration. Installing an inverter for in a car for a critical load gives you many "single point vulnerabilities". In other words, there will be many single failures that can easily leave you without power for the O2 machine. If loss of O2 cannot be easily tolerated for enough time to get to another source, then this might not be such a good idea. Think about a likely scenario, of a failure on say an Interstate, twenty miles or more from the nearest exit, in heavy rush hour traffic.

We have a close relative with COPD. She requires continuous O2. She has an O2 machine that is intended for portable operation. It allows her to travel by vehicle. I believe it is battery operated. I do not know if it is designed to use and/or charge on a cigarette lighter. I strongly suggest you do not try to adapt a 120 volt machine to work in a vehicle but instead use a machine that is intended for this type of service. Your health care provider can probably suggest equipment specifically intended for portability and it may even be covered by your health care insurance.

[GoVikings!]

Great feedback, thanks. Luckily we would only use the cigarette lighter if the battery pack went out. I had an idea that running it for a long period of time wouldn't be a good move. I appreciate the help.

The label on the caps on some of the cigarette lighters states 120 watts. This is 10 amps max at 12 volts.

In my opinion, the conductor sizes in most if not all vehicles seem marginal for a continuous 10 amp load. A continuous 10 amp load will probably cause a significant temperature rise in the wiring harness and at connections. That does not mean it cannot safely handle 10 amps for brief period of time (like using a small 12 volt air pump to press up a tire). However, I would not even think of applying a 10 amp load continuously on any of my cars.

The correct method of supplying a large DC load in a vehicle is to run a fused wire (probably minimum #14 conductor depending on length) directly to the battery. The wire not only needs to be able to handle the current without an undue temperature rise, but the voltage drop across the wire must be no more than a volt or so at maximum load. Ohm's Law gets you two ways with low voltage DC high current circuits. The so called "I squared R" losses can produce a lot of heat and the "IR" voltage drop can be significant if the wire is not properly sized.

Search for "12 volt power inverters" using Google. Also, check your local marine supply stores for a good inverter.

One last but very important consideration. Installing an inverter for in a car for a critical load gives you many "single point vulnerabilities". In other words, there will be many single failures that can easily leave you without power for the O2 machine. If loss of O2 cannot be easily tolerated for enough time to get to another source, then this might not be such a good idea. Think about a likely scenario, of a failure on say an Interstate, twenty miles or more from the nearest exit, in heavy rush hour traffic.

We have a close relative with COPD. She requires continuous O2. She has an O2 machine that is intended for portable operation. It allows her to travel by vehicle. I believe it is battery operated. I do not know if it is designed to use and/or charge on a cigarette lighter. I strongly suggest you do not try to adapt a 120 volt machine to work in a vehicle but instead use a machine that is intended for this type of service. Your health care provider can probably suggest equipment specifically intended for portability and it may even be covered by your health care insurance.

[code58]

The label on the caps on some of the cigarette lighters states 120 watts. This is 10 amps max at 12 volts.

In my opinion, the conductor sizes in most if not all vehicles seem marginal for a continuous 10 amp load. A continuous 10 amp load will probably cause a significant temperature rise in the wiring harness and at connections. That does not mean it cannot safely handle 10 amps for brief period of time (like using a small 12 volt air pump to press up a tire). However, I would not even think of applying a 10 amp load continuously on any of my cars.

I did Code 3 outfitting for a major law enforcement agency for the last 8 years before I retired. I have always believed in erring on the side of caution- hence I wired at 150%-200% of draw a lot of the time (depended on what the potential for long term continuous operation was). I wondered about the small gauge wire that is used almost exclusively in vehicles anymore. The Ford rep for the factory code 3 packages they sold said that they use a different copper wire and a different insulation in order to keep the size of the looms manageable. I have seen engine looms with over 100 wires in them. Can you imagine if those looms had all 14 and 16ga. wire. They would be as big as one of the pistons. He named what the wire was but I don't remember now. I think that is the reason it looks like they have downsized or cheapened the the wiring. It actually is fully capable of carrying what the larger wire used to. The manufacturers would be pretty stupid to engineer an unsafe condition (potential fire) just to save a few bucks on copper.