minimum load, Xantrex PROWatt SW 2000

carilchasens · December 2015

I am considering ProWattSW 2000 to replace our old Trace inverter in our off-grid system. From time to time, I need to run a very small load, say the power supply for my laptop. Would the ProWatt have any problem with this? (Someone, who may or may not have known what he was talking about, told me that big-or-medium load inverters won't detect, won't work with a very small load)

BB. · December 2015

Tell us a bit more about your battery bank (AH and voltage) and your solar array wattage.

Larger inverters may take 20 Watts just to "turn on". Smaller inverters are closer to 6 watts. For large systems, it is a "don't care" For smaller system, losses like this can be very significant (i.e., if you run your larger inverter 24 hours per day for fridge/loads--Then a second small inverter does not save you anything).

A smaller inverter may turn on with 6 watt AC load... A larger inverter may take 10-15 watts to "turn on"... Obviously charging a cell phone with a 3 Watt AC usb converter will not turn either on.

For 24 and 48 volt systems, it is usually very difficult to find a "small" (few hundred Watt) AC inverter...

-Bill

vtmaps · December 2015

carilchasens said:

Someone, who may or may not have known what he was talking about, told me that big-or-medium load inverters won't detect, won't work with a very small load

I have never heard of a large inverter that could not power a small load. You are thinking of 'standby mode'. In standby mode the inverter shuts down when there is no load. On most name brand inverters the threshold for standby mode is adjustable.

BB. said:

A smaller inverter may turn on with 6 watt AC load... A larger inverter may take 10-15 watts to "turn on"...

This refers to coming out of standby mode. If the inverter is set to "on", rather than "standby", you will not have the issues you are concerned about.

--vtMaps

westbranch · December 2015

unless you have a need for that mid range inverter, btw it is a bit one the large size if your system is 12V, I would go for a smaller < 400W. A power supply for an older laptop would only be in the ~ 80W range...

carilchasens · December 2015

We turn our inverter on only when using AC... our lighting is 12 volt LED. Batteries are a half dozen large Trojans wired series-parallel to 12 Volt. The inverter we have now won't even run the food processor. It would be very convenient if I could use at least some of the medium-sized power tools for smaller jobs without firing up the generator. We want the 2000 watts, but do need to know that small loads will also work.
On our old Trace, I did adjust the threshhold.

westbranch · December 2015

Define medium tools? is that a drill , skill saw, table-saw or cutoff saw for example?

carilchasens · December 2015

According to Xantrex customer service, and several other sources, there should be no problem: the ProWattSW 2000 according to them does not have a standby/ search mode at all; it is on when it is on and will supply any load. That is fine for us, because we only turn the inverter on when we need it.

carilchasens · December 2015

westbranch said:

Define medium tools? is that a drill , skill saw, table-saw or cutoff saw for example?

Skill saw, grinder, etc. I do have the option of firing up the generator but it would be very convenient to use the inverter for small jobs.

westbranch · December 2015

Skil saw and up have , sometimes, a very large surge demand and that is the tipping point for inverter gens and inverters, as long as the surge demand over time can be covered you will be happy... my 1500 W inverter has a 3000W surge capacity

BB. · December 2015

If the tools are used on a long extension cord (and a "standard duty vs heavy duty) cord--The resistance of a 100 foot extension cord is sometimes enough to prevent an inverter or generator from shutting down (extra resistance of extension cord limits starting surge current).

Make sure you have short/heavy DC cabling from battery bank to DC inverter input.

-Bill

Resthome · January 2016

I use that inverter and have no problems with small loads or large loads (microwave pulling 150A @ 12V). The only issue with it is starting things with large motors. I have a large shop vac that it will sag the AC before starting. Once it starts it can run it fine. The sag reboots the DISH TV receive and I have to go through the whole search and guide download sequence. Not a problem unless the first mate is watching something.

2manytoyz · January 2016

I have that same inverter also. Mine has been running 24/7/365 for a few years now. It doesn't have a standby mode, like my Xantrex Prosine 1800W model. Therefore, it doesn't care whether it's powering a cell phone charger, or a 1500W heatgun. Just like a home outlet, it provides 120V 60Hz power. As long as you don't exceed it capabilities, it'll run most anything you try to run. My SW2000 won't run my large air compressor, or my 1969 Radial Arm Saw, but all my other shop tools work fine. Bandsaw, belt sander, bench grinder, shop vac and 10" tablesaw at the same time, drill press, etc. I also have it running my office. Computers, lights, radio equipment, etc. Great product, especially for the $325 price I paid.

oil pan 4 · January 2016

I would run larger tools like a skill saw at reduced voltage with a varrac and bumping the trigger once or twice before letting it go up to full speed.

Now I have the 2,000 watt samlex, it doesn't care. I still bump start the saw out of habit.

Anything with a series wound DC motor that over loads the inverter on start up can be soft started at reduced voltage with a varrac. The dish TV and shop vac problem could likely be cured if the shop vac was started and ran on say 100 volts, or started on say 70 to 90 VAC then turned up to full power.

minimum load, Xantrex PROWatt SW 2000

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