Power Supplies and Power Inverters are something you will be involved with if you do a lot of road travel or even one good summer vacation. Power, of course is the key to everything on the road. There are many 12 Volt appliances and accessories available both online and off.
Power Supplies are units that plug into a 110 ac outlet and deliver 12 Volt dc to a set of positive and negative plugs or a cigarette lighter socket, usually located on the front of the unit. Some deliver only a few amps and the bigger units deliver 35 and more. Amps are only important in
as far as having enough. Your unit will only draw what it needs, even if the power supply is rated very high and the device only requires low amps.
Don't even think about that working the other way around. Too small an amp rating attempting to power a higher rated unit will overheat the power supply and damage it. Most quality power supplies have overload protection and fuses to prevent damage and even fire related to such a situation. Best thing to do is be aware of the required draw of devices you intend to power and the capacity of the power supply unit you have in service. Best match is where the power supply has about 10% larger amp rating than the sum of all the devices it is required to power.
Power Inverters are the other side of the coin, they attach to a battery, 12 Volt for our purposes, and deliver power as 110 ac. Worth mentioning that most units include the convenience of a 12 Volt cigarette lighter type socket or two.
The larger the battery the better the result. Often in larger vehicles or dedicated applications you will find multiple batteries connected in parallel or series parallel configuration. This can provide good power for longer periods of time.
Since power inverter applications often rely on battery power that is not being replenished as it is being used, you will discharge the battery. Two pieces of information should be brought to bear before you even get started down the inverter road.
The first; there is a device commonly referred to as a “battery guard”. The function of the battery guard is to keep track of how discharged the battery power is becoming and shut down the power inverter service while there is still enough battery power to start the engine.
The second, and this one is a little confusing, most batteries in common use in motor vehicles are not meant to be discharged and recharged. They are meant to see heavy use, such as starting the engine under most any condition, then be immediately recharged by the vehicle's charging system. This type of battery is referred to as SLI (starting, lighting, ignition). Fully discharging and recharging this type will damage the battery and you will find yourself shopping for batteries very soon.
The kind of battery that works well with power inverters, and other applications that require continuous power, that brings the battery into a near fully discharged state is called, “deep cycle” or “motive”. The internal differences in construction and materials are beyond the scope of this article. The difference in functionality is undeniable and important. Plan your power inverter applications carefully so you get longevity and service from your power investments.
I would like to add one last solution to this power profile. The more feature rich “emergency jump start units” have built in inverters and convenient 12 Volt power receptacles. With the desirable motive type battery, they provide extended life for laptop computers and recharging cell phones. Emergency jump start units are rechargeable from AC power where is it available and 12v battery power while you are going down the road. They invariably feature an air compressor for low tires and, of course, if you or a fellow traveler need a jump start, you can always use them for their intended purpose.
Happy traveling. It must be time for a cup of coffee and “more power to ya'”.