Franklin from IndoorGenerator sent this unit over for me to play with, and I’ve found it to be very good. The unit combines a 3000 watt modified sine wave power inverter, automatic transfer switch, and 30 amp smart charger all in one nice, compact, lightweight package.
Yesterday I beat the holy splunge out of it with various test loads including a portable air conditioner and large 1/3 horsepower AC motor, and ran it at 2.8KW output for the better part of an hour. It barely even got warm to the touch.
From my testing, I found that the inverter only has two weaknesses to it.
First, like any high frequency switching type inverter, it can sometimes run out of power and turn off suddenly while trying to start loads with a large inrush current. This includes large halogen/incandescent lights, large motors, and compressors. If you’re starting such a beast off a switching inverter, it should be the first thing to be turned on, and any other loads should be removed before attempting to restart the large motor/light.
Second, the transfer switch isn’t instantaneous. The power goes off for about a second during the transfer from battery to AC or AC to battery.
A very useful little LED meter is present on the end of the unit next to the outlets. By pressing the button next to it you can select whether to view the battery voltage, DC input amperage, or AC output wattage in Kw. While AC power is present and the unit is charging the batteries, the output Kw and DC amperage both show as zero. I would have liked to have a DC current measurement visible during charge like the Xantrex TR series provides, but I’m not gonna complain much about it.
When the inverter goes into overload, the LED display on the end shows “E01″. I also managed to get the inverter to glitch a couple of times – weird things happened like the battery voltage reading coming back as ” 0.4″, or the inverter shut down and showed “Err”. Both of these problems went away as soon as I replaced a 1 AWG battery cable in the test setup which was becoming stinky hot! Oops. Too much voltage drop!
As the inverter begins to get near maximum power output, the peak to peak voltage begins to fall a bit. The unit compensates by shortening the 0-volt pauses on each cycle to maintain 120Vrms through manipulation of the duty cycle. Lights will not change brightness, but some AC induction motors may become weak as the wave approaches being a 120V peak to peak square wave. I noticed this only after applying around 2.7KW of load. The Daewoo portable air conditioner I was running did not show any problems with this, but a large industrial fan (of doom) began to slow down a little.
The charger is rated at 30 amps output. I clocked it at 33-34. It is, interestingly, built on its own board inside the top of the unit. This is a lot different than the charge system in the Xantrex Freedom series units I’m used to refurbishing, on which the same (massive) transformer and transistors are used to convert and regulate the current for charging. The internal 3-stage charger works fine on flooded cell batteries, but the absorption voltage got too high for a gel battery. I measured 14.82VDC. This may be in range for AGM batteries, however — check your battery manufacturer’s recommendations!
Today, I popped the top off and started looking around inside.
The build quality is very nice. It appears that the lower board is in charge of converting 12VDC to 170VDC. The board at upper right contains the AC transfer circuitry, a current sense transformer, and an H-bridge to chop the 170VDC into modified sine wave. The board at upper left is the charger.
The charger board has a jumper (JP1) located on it. Removing JP1 and turning on the charger activates equalize mode (about 15.3VDC). The small green LED located near JP1 comes on when the charger is in absorption or equalize mode. Unfortunately, significant disassembly of the unit is needed to access JP1, and activating any function of the unit while it’s open like this will expose lethal voltages to the user… so let’s just say that until a switch is brought out to the end panel of the unit, this feature is not Ready For Prime Time. AIMS didn’t even know the jumper was there! I only figured this out as I tried toggling the jumper to see if it was there to reduce the voltages for use with gel batteries.
The cooling fans at the end of the unit run whenever the charger is active, and otherwise… very rarely. It barely gets warm at all while in invert. All of the transistors that have any significant amount of current across them are heatsinked to the extruded, finned alumimum chassis. This is a design borrowed from high power car audio amplifiers, which have to put up with being wedged in all sorts of weird ways into hot car trunks with little air circulation.
My final verdict: If you’re looking for a good low-cost, lightweight modified sine wave inverter/charger, this is probably just what you’re looking for. If you’re running any large motor loads, however, be prepared to go over and reset the inverter when they fail to start.
If the cost and weight aren’t that much of an issue, I’d step up the Xantrex Freedom or Xantrex TR series; they cope with starting large motor loads by just throwing everything they’ve got at it, current limited only by the inductance of the transformer. The motor makes hilarious sounds and the inverter output voltage dips during the ordeal, but it’ll start the motor, whereas a lightweight switchmode inverter like this will just go “Noooo! OVERLOAD! Now you get to come over here and reset me! HA HA!” Plus, the Freedom and TR have a much stronger charger.