12V DC Outlets on Inverters
The Ac outputs are regulated and at the proper voltage and frequency (120 volts 60Hz). The 12 volt DC output is not regulated. With no load I measure 19.4 to 25 volts dc depending on low or high idle. With the output connected to a battery I get 17.2 to 20.4 volts DC depending on low or high idle. I have called tech support a few times about this.
Yes, with no resistance on the outlet, the voltage will be this high. If you connect an automotive or power sport battery to the outlet for example, the voltage will drop down to about 17V DC. If you are using a portable charging device to charge a phone for example, the adapter will have the proper resistors to supply appropriate voltage and amperage to your devices for charging.
This outlet is unregulated which means it can be used for automotive style batteries, but is not intended for deep cycle batteries for example. You would need to connect a converter to the regular AC outlet on the machine and the converter will charge the deep cycle batteries in the proper regulated stages.
In the owner’s manual, they have this to say about the 12V DC outlet:
"12V DC Outlet
The 12V DC outlet can be used with the supplied charge cable and USB charger and other commercially available 12V DC automotive style plugs. The DC output is unregulated and can damage some products. Confirm your accessory input voltage range is at least 12-24V DC. When using the DC outlet turn the Economy mode switch to the “OFF” position."
If you look at most automotive phone USB chargers for example, you will see they have an input voltage of 12-24V DC.