Inverter performance

adas

Aloha, I "tested" the new inverter (mod sine 3600W) with heavy transformer vs. my lighter Mod Sine "Aimes" brand 5000w......results///

I thought that efficiency of running a microwave should give me a good indication of how good the inverter is at doing some work.

The Aimes solid state boiled a certain measure of water in the micro in 4 minutes 30 seconds.

The new 3600 mod sine with heavy transformer (100# monster) boiled the same measure of water in 2 minutes 30 seconds.

Soooo...... am i to assume that the 3600 has a transformer with a higher "K factor" and is a better inverter for handling "fussy" equipment?

At lease can I assume that the 3600 will do the job in about 1/2 the time even though the large transformer may make it only 85%+ efficient as apposed to the Aimes brand that may claim 90%?

And run a power tool with less effort? thus saving power.

thanks
Frank

BB.

Re: Inverter performance

You really need to use a power meter to see how much energy you are using... Certainly the Microwave is an interesting test--but I don't design microwaves--so I am not exactly sure what it is telling you...

A true square wave at 120 VAC true RMS will be 120 volts peak (flat for 1/2 cycle, the inverter for the other half of the cycle). A sine wave will peak at 120*sqrt of 2=170 volts peak--so if the microwave (or tool) cares about the 60 Hz resonant peak your test may be telling us something...

If you don't have an AC power meter (just V*A is not enough), you could go back to the DC side of things and see how much current*voltage you are pumping into the inverter...

If the 4 minute water uses half the wattage (or DC wattage) of the 2 minute water boil inverter--then both are using the same amount of energy to boil the water--but one is running the microwave more efficiently...

If, however, when you add the transformer, your water boils faster, but you use even more than the expected 2x power--you are loosing efficiency...

In the end, if you are interested in efficiency (assuming the tools work OK on both inverters)--you would be best setting a tool up with a standard load (i.e., electric drill "beating" 5 gallons of water)--and measure the inverter DC input power... And go from there. If you notice the drill runs slower (and/or hotter) on one vs the other--you will have to decide if that is a deal breaker or not.

-Bill

adas

Re: Inverter performance

Aloha, heres the watt/time period breakdown for boiling a given amount of water in the microwave

Aimes inverter, 240 seconds at 1020 watts = 244,800 units (could not get a hertz reading)

Transformer inverter 165 seconds at 1200 watts = 198,000 units (also registered 60 -61 cycles the whole time)

Aimes inverter uses 24% more energy to boil, but we don't know yet how much more or less energy the inverter uses converting DC to AC for the 1200 w output

BTW, I heard the microwave is one of the tougher tests for an inverter and really likes a good wave. I also used a kill-a-watt meter for the test.

frank

BB.

Re: Inverter performance

Using a Kill-A-Watt meter on a square wave inverter--may be difficult to get accurate measurements (see issues with even checking frequency).

Sounds like you have an answer--it would be interesting to see if you can confirm the findings with DC input (current and voltage)... Would factor in the overall conversion efficiency of the inverter too (battery out to boiling water).

-Bill

Windsun

Re: Inverter performance

adas wrote: »

Aloha, heres the watt/time period breakdown for boiling a given amount of water in the microwave

Aimes inverter, 240 seconds at 1020 watts = 244,800 units (could not get a hertz reading)

Transformer inverter 165 seconds at 1200 watts = 198,000 units (also registered 60 -61 cycles the whole time)

Aimes inverter uses 24% more energy to boil, but we don't know yet how much more or less energy the inverter uses converting DC to AC for the 1200 w output
frank

Not sure how good the results are on the wattmeter, but it is interesting how much difference there is just between two type of modified sine wave inverters.

A long time we got an email on some tests that someone had done between their old DR mod sine (transformer) and their new Outback running a washing machine, and the Outback used about 20% less.

So, perhaps (in theory at least), you could extrapolate that to say that a good transformer based sine wave would be 40-50% more efficient running some appliances than something like the Aimes.

You would probably have to do DC usage measurements to get an exact figure for overall efficiency.

adas

Re: Inverter performance

Aloha, whats a cheap and effective dc amp meter? My watts-up just died. Anyone know of a cheap Radio shack or Mcgiver one? Automotive?

Frank

BB.

Re: Inverter performance

Are you looking for a DC Current Clamp or a DC shunt that you can just use any old mVolt DVM with?

Somebody here found a reasonably priced one (DC Current Clamps are usually not cheap... $300 or more for 400 DC amp max?).

A shunt could be cost effective solution. 500 amp for $30...

-Bill

adas

Re: Inverter performance

Aloha, I bought a few of these meters on ebay was surprised that they just came in, so will try them out. They are cheap enuf, but only 100 amps.
frank
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=250252176741&ssPageName=STRK:MEWN:IT&ih=015

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=250254420077&ssPageName=STRK:MEWN:IT&ih=015