Things that Work! Home Power tests PowerStar's UPG1300 Inverter Richard Perez and Bob-O Schultze Some devices set new standards for performance and value. This new PowerStar inverter is such a device. The UPG series inverters are the slickest way to make 120 vac out of battery power that I have ever used. It is powerful- 1,300 Watts continuous with surge capacity to 6,000 W. It is very quiet- both to the human ear, and to radios & TVs. It is efficient- between 89% and 98% by our testing. The PowerStar UPG revolutionizes inverters. Shipping & Documentation The PowerStar UPG1300 arrived in fine shape in a small box. Most inverters this powerful weigh between 25 and 50 pounds and require a special shipping carton. This five pound inverter can go in a shoebox. The UPG in very small about 3 inches by 3 inches by 11 inches. The documentation is simple to understand, direct and to the point. It gives the user all the information needed to install and effectively use the inverter. The UPG's Specifications The inverter we tested is the largest of the UPG line. PowerStar's UPG line begins with a 400 watt model, which is upgradable to 700 watts, which is upgradable to 1,300 watts. This is in itself revolutionary. This is the first expandable inverter. It allows the user to start small and add more watts as they are needed or can be afforded. These rating are CONTINUOUS, not time de-rated like the specs on virtually every other inverter. The surge rating on the 400 and 700 watt model is 3,000 watts. The 1,300 watt model surges to 6,000 watts. The UPG series is a modified sine-wave inverter. It uses a high frequency (÷ 30 kHz.) DC to DC switching power supply rather than a large transformer running at 60 cycles per second. The high voltage DC is then chopped by field effect transistors into the modified-sine wave 120 vac. This accounts for its tiny size and light weight. At five pounds, it is less one-sixth the weight of any other inverter in its power range. The UPG series operates over a wider voltage range than any other 12 Volt inverter. It happily makes power anywhere between 10.5 VDC and 16.5 VDC. This makes it ideal for nickel-cadmium or nickel-iron battery systems. This is possible because the UPG uses the high frequency DC/DC switcher technique rather than the 60 Hz. transformer technique. The Test System I installed the UPG1300 on Agate Flat in our PV/nicad test system. This system is sourced by two photovoltaic modules (one ARCO 47 W. and one Solarex 55 W.) through a photovoltaic regulator (a Heliotrope CC20). The PowerStar UPG inverter is wired directly to a 12 Volt, 100 Ampere-hour battery (ten series connected Alcad nickel-cadmium cells). The UPG has all electrical connections and the on/off switch located on one end of it's 3" X 3" square tube. A fan is located at the other end of the eleven inch long square tube. The high quality, color coded 12 VDC connectors are large enough to accept #2 wire and are tightened by an allen wrench supplied with the inverter. The 120 vac output is by a single three prong female receptacle and via a strip of connectors. The UPG can also be remotely activated via this connector strip. The UPG powered a variety of 120 vac loads during the "user" phase of our testing. We non-technically used it to power whatever we needed. Some of the appliances we powered are a satellite TV system, a one hp ShopVac, a microwave oven, an AM/FM/Short Wave radio, a plethora of Osram EL series fluorescent lights, several "wall-cube" power supplies for flashlight battery recharging, and a coffee grinder. "User" Test Results" The first thing we noticed was how quiet this inverter is. In the audio spectrum, the only noise the inverter makes is when the fan operates. This inverter is very quiet. When we were doing the technical testing, Bob-O couldn't believe it was operating and had to put his ear on the inverter to hear anything at all. In the radio spectrum, the UPG is the quietest high frequency DC/DC switcher inverter we have ever used. This is not to say it is totally without radio frequency interference (RFI), there is still some. The UPG is two to five times quieter than any other type we've ever used. It produces less glitches on the satellite system, less noise on the AM radio, and less noise on the shortwave receiver. We successfully operated all the equipment listed above. Of particular note is the ShopVac. This one horsepower cannister vacuum is a large and demented load. It has already killed two inverters that couldn't cope with it's surge demand and inductive feedback. Not only did the UPG run this vacuum, but it did it better than inverters twice its size and cost. The ShopVac's motor was very happy with the UPG's power. The motor ran as quickly as it does on grid power and it ran cooler. I also noticed that the small wall-cube power supplies put out more power than on any other inverter. Most of these supplies would only recharge small batteries at about half power on other inverters. With the UPG, these supplies put out just like downtown. Since the inverter only consumes about one Watt on idle, we left it on all the time. This inverter doesn't have to put itself to sleep to save power. It can stay awake all the time and make power for small 120 vac devices like wall-cube power supplies. In the past, it has been very inefficient to keep an inverter operating all night just to power a phone answering machine or other small 120 vac load. The UPG inverter is going to change the way systems are designed and operated. Technical Testing After such a successful user test, we couldn't wait to stick it to this inverter. Bob-O Schultze came to Home Power central to witness the event. We lined up all the monster loads, broke out the two Fluke 87 meters, and proceeded. We used a 0.5% precision shunt (50 mV. at 200 Amperes) in series with the battery/inverter cable. What follows below is a spreadsheet showing the raw data of an afternoon's rigorous testing. INSERTSPREAD Notes on this data Watts are calculated fields for both 12 VDC and 120 vac wattages. This was done by multiplying volts times amps. Efficiency is the output wattage divided by the input wattage. The hard facts are in the spreadsheet, no editorial verbiage here! Conclusions from the data and tech tests This is one fine inverter. It powered up its rated output of 1300 watts. It survived overloading of 1500 Watts output for five minutes and thirty seconds, then it shut itself off. No damage. It survived overvoltage on its input. Here I disconnected the battery and left the inverter on line with the open circuit PV array. The voltage went to over 19 VDC and the UPG shut itself off with no damage. The low voltage shut down function works at 10.5 VDC as specified. The UPG series has a smart fan. Most inverters use a thermal switch to turn on the cooling fan. The UPG uses current operated logic to activate the fan. This means the fan turns on BEFORE the inverter gets hot, instead of after. All very slick and effective. Efficiency The efficiency of this inverter is very high. Especially at low output wattage. While 60 Hz. transformer based inverters have this same high efficiency around full power, they are very inefficient at low output power. The PowerStar UPG is uniformly very efficient. For example, consider the 25 watt lightbulb's test data on the spreadsheet. Here the UPG is 98% efficient. With a 25 watt load, most 1,000+ watt inverters are less than 30% efficient. We are so impressed with the uniformly high efficiency of the UPG that I have graphed it below. This graph uses our actual data from the spreadsheet. INSERTEFFICIENCYGRAPH Peak Voltage Output The reason that our ShopVac and wall cubes work so well on the UPG is because it maintains high peak and root-mean-square (rms) voltages. Ideally the peak output voltage should be about 164 vpp and the DC equivalent voltage output at 117 vrms. This is what the power grid strives to maintain (and often doesn't). The output performance of the UPG is head and shoulders above other DC/DC switcher types. Output voltage is more stable and in a more useful, higher range than any other type. This means better performance from electric motors, microwaves, wall-cubes, and virtually all 120 vac appliances. Once again, we're amazed and provide a graph of out data on the PowerStar's output voltage performance below. INSERTVOLTAGEGRAPH UPG Cost The price of the 400 watt UPG model is $399. The 700 watt UPG model costs $499. The 1,300 watt model we tested costs $799. At about 62› per continuous output watt, the UPG 1300 sets a new low price record for inverters. PowerStar warrantees the UPG inverters for two years. Conclusions We really like this inverter. The unique operating features of this inverter will revolutionize how we design and use our systems. We most highly recommend it to Home Power readers. Access: Authors and Testers: Richard Perez and Bob-O Schultze, C/O Home Power, POB 130, Hornbrook, CA 96044 ù 916-475-3179 or 916-475-3401. Manufacturers: PowerStar Products Inc., 10011 North Foothill Boulevard, Cupertino, CA 95014 ù 408-973-8502. A Note on this particular "Things that Work!" "Things that Work!" is just that. We don't waste your time, our time, and all this paper with negative reviews of equipment that doesn't work. These reviews are good reviews by definition. Products that don't work are not mentioned at all, but instead consigned to the oblivion they deserve. Only problem is that every so often a product comes by that is outstanding even among other "Things that Work!". This inverter causes me to reach deep in my bag of superlatives. Nuff said. RP.