Both the rms and peak output voltages of the Trace were very stable. We measured a low rms voltage of 118.5 and a high of 121.9 vac rms. The peak voltage of the Trace's waveform varied from 161 to 172 vac peak. This degree of stability is better than the utility grid delivers to most homes.
The power efficiency chart speaks for itself. Our overload tests showed us this machine really has lots of snort. After loading up the 4024 with our 3850 Watts of resistive loads long enough to bring on one of the internal cooling fans, we started a 1/2 HP split-phase grinder. With the grinder and the other loads running, we started a 1/2 HP air compressor. Finally, with all of that going, we started a 7-1/4" Skilsaw. The Trace still had more to give, but our 250 Ampere input circuit breaker popped off at 274 Amps input!
We didn't have the capability at the test site to adequately test the charger features, but data observed from other SW4024 installations indicates it will do as specified at around 75% efficiency (117 vac in to 24 VDC out). This is a big improvement over the Trace 2500 Series chargers which run at about 55%-60% efficiency.
Here are some comments from other SW4024 users.
"The table saw starts much faster, even with the electric water heater on."
"Wall cubes don't buzz (some cheap compact fluorescents still do)."
"The three general purpose relays are great! I have simply been plugging/unplugging the electric water heater (dump load which also serves a useful function). Now I can use one of the relays to control a power relay."
"I like being able to use power tools while someone else is microwaving without dumping the computer."
Warts, or, Ya Can't Please Everybody...
The lowest search threshold is 16 Watts. We'd like to see it a little lower. Over the years, many of us have trained ourselves to eliminate all phantom loads and replace our energy sucking incandescent lighting with low wattage compact fluorescents. I've heard of folks having to insert a phantom in a circuit just so their favorite 7 or 11 Watt CF reading light will stay lit.
The pushbuttons on the control panel sometimes don't make contact and you need to punch them a few times to change the display. The menu items under the menu headings are not necessarily grouped intuitively. We'd like to see two copies of a control panel flow chart, one with the manual and one loose to tack up on the wall next to the machine until you can find your way around.
While the SW4024 is pretty quiet on its power output, the inverter itself emits a very audible hum, especially at high output power. For most applications and installations this should be no problem at all, but if you have to live or work in close proximity to the inverter, then the noise will be irritating.
The stickem on the battery temperature sensor needs some help. It's come unstuck from the sides of several battery banks I've seen.
If this sounds pretty picky, it is! We had to hustle to come up with these! Given the incredible versatility of the SW4024, these are pretty minor flaws.
The SW4024 is also available in a 48 VDC input version. It also comes in a 3kW, 234 vac, 50 Hz export version, the SW3024E. Trace plans to release a 2500 watt, 12 VDC model by this fall. Options for either the 4024 or the 4048 include a conduit ready enclosure for
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