Samlex S Series InverCharge Pure Sine Wave Inverter Chargers.
Once in a great while a line of inverter products comes along that sends its competition back to the drawing board. The InverChargeTM line of inverter products is that product.
We recently received our first sample shipment of the Samlex S-2012A Pure Sine Wave Inverter Chargers. I immediately picked up the phone and called our service center manager, asking him to stop by the warehouse to pick up one these units and put it through his usual field effect transistor popping, output transformer smoking, burn in tests. When I use the word burn in I mean it in the literal sense because very few of the new inverters that we test before they're offered on our website survive even the first few minutes of his evaluation.
I stood by in the warehouse so that I could catch the look on his face because I knew that he would be expecting another typical 8 pound, 2,000 Watt, high frequency throwaway inverter that usually comes from overseas. I chuckled when he tried to pick up the inverter and immediately set it back down, opting instead for a for a dolly to wheel the inverter over to the service center.
As I walked over, he asked me if there were two inverters packed in the box. I said "No, we only ordered a single sample." He then said "I take it that this this is not a high frequency unit" I replied with a blunt "nope"
You see I had already seen the Samlex S-2012A Inverter Charger at a recent solar energy trade show and I already knew a little about this inverter's specifications but nothing could prepare me for how well this inverter was to perform during our service center manager's grueling tests.
Besides the weight of this heavy duty unit (Over 51 pounds) we were impressed with how well this inverter was packaged. With over 11 years worth of shipping inverters all over the world, the one thing that is lacking in most inverters is the packaging. In fact 2 out of 6 inverters that leave our warehouse usually arrive with a few dings and dents that result in a UPS claim. Not this inverter, we probably could have dropped this unit in its box from a height of 5 feet and it wouldn't have been phased.
After removing the inverter from its packaging, we were still amazed at how heavy this unit was for a 2,000 watt inverter. The fit and finish of this inverter surprised us. The level quality represented by the S-2012A was not what we typically see from an overseas manufacturer. If it was simply up to the looks of this inverter, we could see how this inverter could easily out sell many of its competitors.
Upon removing the inverter's cover, we immediately discovered why this unit weighed so much, the output transformer and the driver heat sink, two of the most important components in any inverter, were simply massive. I could tell by the look on our service center manager's face that he was impressed and so was I.
Further examination revealed a very well laid out design. There were grommets at every potential abrasion point to protect wiring. We found no evidence of cold solder joints, the main control and FET board (field effect transistors) were well laid out. There were no after thought revision jumpers or components that were soldered in a haphazard fashion. We found two cooling fans, one for the FET board and one for the transformer which was controlled by a heavy duty thermistor. The inverter also included two high quality built in circuit breakers to protect both the inverter and the charger's output as well as 40 amp automatic AC transfer relays with an fast 16ms transfer time which is sufficient for the prevention of data loss in most computers.
Upon completion of our visual inspection, we both concluded that this machine appeared to be well deigned and loaded for bear. But looks can be deceiving in the world of high power electronics so we weren't holding our breath. Very few inverters survive what was coming, but to be honest, we were so impressed with our visual inspection that we would have been disappointed if the inverter smoked like so many inverters had in the past.
We connected the inverter to the 4/O heavy duty inverter cables that were connected to our 810 amp hour battery pack. Next we hooked up our oscilloscope and a true RMS multimeter and finally we hooked up our 4kW resistive load bank and variable inductive load.
We turned on the inverter and checked for the quality of the pure sine wave. The oscilloscope displayed a perfect sine wave with no visible distortion. Next we began adding progressively increasing resistive loads. 100 watts, 500 watts, 1,000 watts, 1,500 watts, 1,800, watts, 2,000 watts and virtually no distortion in the waveform. The cooling fans gradually came on as they were designed to do and we did not feel any unusual heat radiating from the inverter. It should be noted that several 2,000 watt inverters that we had tested in the past started displaying a corrupted waveform at about 1,800 watts but not the Samlex S-2012A. We cranked up the load to 2,300 watts and still no distortion.
Next we backed the resistive load down to 1,500 watts and turned on our variable inductive load which consists of 500 Watt Variac which is attached to a large transformer that has had it's primary winding short circuited. We cranked the Variac's dial back and forth from zero to maximum voltage and nothing, this didn't even faze the inverter. It should be noted that several inverters that have undergone the variable inductive load test actually fried after a few seconds of this test taking out the FETs.
Next came the Achilles Heel for most inverters, the dreaded short circuit test. Despite the fact that many inverters advertise that they are short circuit protected, this test has killed 2 out of 5 inverters that we've tested in the past. I stood there with my fingers crossed as our service center manager reached for the short circuit switch.
Before I tell you what happened next I want to describe this switch. It's this massive 3 inch diameter 3 phase device with 3 separate contacts that are all wired in parallel so we don't burn the thing up. There's this big label that surrounds the switch with big bold capital letters that read CAUTION SHORT CIRCUIT TEST ! in other words this is one of the worst procedures that you can put any inverter through and you had better have your safety goggles on and a fire extinguisher handy because a short circuit can not only cause FETs (Field Effect Transistors) to start exploding like popcorn but it can also start a small fire in your output transformer.
Needless to say, I stood way back because I've dodged my fair share of molten FET casings. As I closed my eyes, the service center manager flipped the switch and...... nothing. The load bank shut down and everything went quiet. For a few seconds I wondered if we finally killed the inverter ? No FETs had popped though and I didn't smell any insulation burning so maybe the inverter shut itself down like it was supposed to.
The service center manager reset the inverter and there it was, a perfect sine wave on the oscilloscope. We cranked up the load to 2,000 watts and again a perfect sine wave. I left the inverter on with a 1,000 watt load for the next 8 hours and came back to the service center that evening to test the battery charger. I set the charger to it's maximum setting, plugged the inverter into the AC outlet on our test bench then watched as the inverter's built in battery charger started pumping amps into our battery pack as displayed by our test bench's DC ammeter. At that moment I knew without a doubt that I had a winning product on our test bench.
Since we opened our service center back in 2000 we've tested lots of inverters that were shipped to us as samples. We have shelves that are lined with once brand new inverters that were dead on arrival right out of the box even before the tests began and inverters that miserably failed our tests releasing smoke and fire. We've been saying for years that we're going to repair them someday.
Even if an inverter survives these tests we usually find
something negative that merits a rating that is lower than the maximum 5 stars for what
we consider an ideal product but that was not the case with the Samlex S-2012A.
This is one of those rare occasions where we've decided to undeniably give the
Samlex S-2012A our highest 5 star 
rating for its quality, performance, durability, warranty and value.
Here's some pictures that I took of this incredibly well built machine:
Note the massive output transformer. A quarter was placed next to transformer to show scale.
Note the huge heat sink with the row of high output Field Effect Transistors (FETS). Also note the large Thermistor mounted on top of the heat sink to the left and the large cooling fan.
Note the nicely designed control board. The latest in DSP (Digital Signal Processing) technology is employed to reduce the complexity of the control board which dramatically increases reliability due to the reduced parts count when compared to older analog designs.
Here's another shot of the massive output transformer. Note the large industrial grade output circuit breakers on the right.
Note the large heavy duty terminal strip for easy wiring. Above left are the easily accessed resetable circuit breakers.
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