Off Grid Home Forums Technical Discussion Inverters for Computers Reply To: Inverters for Computers


Hi ttab,

OK, first of all most electronic devices today run on low voltage DC. The AC that you supply them is converted to 12v, 5v, 3.3v to power the IC’s on board. The power regulator in the device will drop the voltage and regulate it. Since most electronics today are very sensitive to voltage drops, the regulators have filter capacitors used to smooth out line noise so a MSW inverter is no problem.

As for the furnace blower motor, that could be an issue. Either inverter style would work, but the thing to remember about inductive loads (motors) is that they have a heavy start up surge. If the blower motor is say 3/4 hp then the running wattage will be around 575 – 600 watts; however, the surge may be 2,000 watts or more. That is an expensive PSW inverter. And yes, a 1,000 watt inverter may claim to have a 2,000 watt surge capacity, but don’t believe it. Read the fine print for the specs, the surge capacity may be 2,000 watts, but the surge duration will be less than one second (if it’s listed at all). This is not long enough to start most motors. Now I’m not trying to talk you out of a PSW, just be sure you buy a large enough inverter to power your load. That is the only regret I have about my system, 1,000 watts is just a tad too small for some loads. I would like to run a small 700 watt microwave, but the 700 watts of cooking power requires 1050 watts to produce. A 1,500 or better yet 2,000 watt inverter is what I really would like to have. (It’s on my wish list now)

An option to get around this is to get a DC motor for the blower. 12v and 24v motors can be had that run at 1,800 RPM to match the 1720 RPM of most AC motors. There is no surge issue with the DC motor since you don’t run it through the inverter anyway. The only down side to that is the wire will need to be a heaver gauge wire to handle the higher current load. But wire is a lot cheaper than inverters.

One last thing, if I where you I would consider using a laptop rather than a desktop. Laptops use a fraction of the power of a desktop computer, and believe me, using 30 – 40 watts is much easier on your battery bank than a few hundred watts for the desktop. I don’t even use a laptop, I use a netbook. Granted the 10.1″ display is a tad small, but I can use it 24/7 if I wanted to as it runs at around 10 watts or less most of the time, and has never spiked over 26 watts when burning a DVD on the USB powered external DVD drive.