What can be more simple and convenient than plugging an inverter into your vehicle’s cigarette lighter? When it comes to convenience and ease-of-use, I am all in. Be aware that these benefits come with limitations though.
Cigarette lighters, sometimes called power ports, are installed using small gauge wire by the vehicle’s manufacturer. To protect this thin wire a 10-15 amp fuse is typically installed inline. As a result, you are only able to get about 120-180 watts worth of power from the cigarette lighter before you blow the inline fuse.
The reason is to give you options. Inverters in the 200-400 watt size range allow you use the cigarette lighter adapter, with limitations, or to use a heavier wire directly connected to the battery for full output capabilities.
This is strongly discouraged as the cigarette lighter adapter fuse was properly sized for the gauge and length of wire installed by the manufacturer. Using a larger than recommended fuse size could result in damage to the vehicle’s wiring.
If you attempt to overload your cigarette lighter you will blow the inline fuse. Fortunately, replacement fuses are inexpensive and easy to replace. Just be sure to replace it with the same size fuse.
Here is an expert tip. If you can’t get your inverter to turn on when plugged into your cigarette lighter, check the cigarette lighter adapter. Some inverter manufacturers install a fuse in the adapter itself for additional protection. You can check for a fuse by unscrewing the tip of the included adapter.
These preinstalled cigarette lighters in our vehicles can be a great asset when using an inverter. Just keep in mind the potential limitations and you will be fully prepared for your next trip.
I am frequently asked why a fuse is required when installing an inverter. After all, doesn’t the inverter have built in protection? Yes, a quality inverter has multiple protection features that help prevent damage to the inverter. What an inverter does not protect against is a short in your battery cables.
Let’s take a moment to look at a hypothetical situation where you’ve installed a 1000 watt inverter into your work truck for recharging cordless tool batteries. You’ve taken the time to run a set of cables from the battery, through the vehicle’s firewall, and into the cab of the truck. You’ve experienced months of trouble free operation and everything seems to be fine. However, under the hood the cables have bounced around causing the protective coating to wear off where the cables rest against the metal chassis of the truck. If the wire in the center of the positive and negative cables touch, or touch the metal chassis, you will have a short on your hands. If you consider where the short has occurred, there is no way for the inverter to protect against this. Without an overcurrent device in place you could end up damaging your cables, battery and inverter. You will also have created a potentially harmful hazard.
There are other reasons to consider an overcurrent protection device as well. What if the inverter itself has an internal short and the protection features fail? What if something metal falls between the negative and positive post of the inverter? While these scenarios may be unlikely, they are possible. Why not invest a small amount of money and time to install an inline fuse to protect against these worst case scenarios? Think about this. Would you want to live in a house wired up with no protection breakers?
Even though an inverter will work without a fuse, and it may seem unnecessary to install one, I strongly urge you to install an inline fuse to protect both your installation and yourself.
Original Posts by Patrick Fallon for Don Rowe's Blog at DonRowe.com