Suggestions for small inverter
Plowman
Solar Expert Posts: 203 ✭✭✭✭✭
I've tried a few cheap MSW inverters for the year and a half or so I've been living off grid, they work OK for a while but lately I've been having problems with them shutting down unexpectedly, usually at the most inconvenient moment. Time to buy a decent inverter.
I don't need a big inverter, 300W is fine. Not powering any motors, just lights, electronics, small battery charging. I keep my inverter on 24/7, so low no-load draw is highly desirable. I turn my main power strip off at night and much of the day when I'm at work, but the inverter itself is kept on all the time.
I keep the inverter in a cargo trailer that gets cold during the winter (sometimes down into the 10s F, but rarely that cold) and hot during the summer (up to 110 F, but rarely that hot). Climate here in western Oregon is fairly mild, but the inverter will need to deal with the occasional extreme. I don't care how noisy it is, cargo trailer is well away from living area.
I'm looking at the following:
--Morningstar SureSine 300---spec sheet says no load draw on "stand by" is 55mA, but "inverter on (no load)" rating is 450mA. Not sure what the difference is. High voltage disconnect is 15.5V, which concerns me, quite close to my equalization voltage. I've got two cheap Xantrex MSW inverters that don't appreciate higher voltages. One shuts down at absorption voltage (14.8V).
--Samlex 300W pure sine---spec sheet says high voltage disconnect is 16.5V, which would work fine for my system. No load draw is <500mA, a bit on the high side, but acceptable.
--Xantrex ProSine 1000W---bigger than the others, don't need that much wattage but could use it if I had it---spec sheet says no load draw in “search” mode is <1.5W (0.125mA @ 12V) but in “idle” mode it's <22W (1.83A @ 12V)---not sure what the difference is between search and idle, but a no-load draw of 1.83A would be unacceptable for my little system.
I'm leaning towards the Samlex, given the price and the high voltage disconnect. Any other suggestions? I don't need pure sine, but these seem to be rated for continuous duty.
I don't need a big inverter, 300W is fine. Not powering any motors, just lights, electronics, small battery charging. I keep my inverter on 24/7, so low no-load draw is highly desirable. I turn my main power strip off at night and much of the day when I'm at work, but the inverter itself is kept on all the time.
I keep the inverter in a cargo trailer that gets cold during the winter (sometimes down into the 10s F, but rarely that cold) and hot during the summer (up to 110 F, but rarely that hot). Climate here in western Oregon is fairly mild, but the inverter will need to deal with the occasional extreme. I don't care how noisy it is, cargo trailer is well away from living area.
I'm looking at the following:
--Morningstar SureSine 300---spec sheet says no load draw on "stand by" is 55mA, but "inverter on (no load)" rating is 450mA. Not sure what the difference is. High voltage disconnect is 15.5V, which concerns me, quite close to my equalization voltage. I've got two cheap Xantrex MSW inverters that don't appreciate higher voltages. One shuts down at absorption voltage (14.8V).
--Samlex 300W pure sine---spec sheet says high voltage disconnect is 16.5V, which would work fine for my system. No load draw is <500mA, a bit on the high side, but acceptable.
--Xantrex ProSine 1000W---bigger than the others, don't need that much wattage but could use it if I had it---spec sheet says no load draw in “search” mode is <1.5W (0.125mA @ 12V) but in “idle” mode it's <22W (1.83A @ 12V)---not sure what the difference is between search and idle, but a no-load draw of 1.83A would be unacceptable for my little system.
I'm leaning towards the Samlex, given the price and the high voltage disconnect. Any other suggestions? I don't need pure sine, but these seem to be rated for continuous duty.
Comments
Search Mode--Inverter turns on for 1/2 to 1/1 cycle around once per second. If the inverter "sees" a load >~6 Watts, the inverter turns on full time until load is below ~6 Watts.
Search Mode is great for things that have on/off switches (lights, fans, larger than ~6 Watt loads). Not so useful for small loads like cell phone chargers, smaller LED bulbs, etc.
Another neat thing about the MorningStar--It has a remote on/off input (something like 12 volt circuit, close = on; open = off (or similar)).
I have not looked at the Samlex in detail yet--But they have some remote panels that may give you some of the options (like remote on/off). Much nicer than having to flip a large DC breaker (or 12 VDC switch) on/off.
If you are in cold weather--The 15.0 to 15.5 volt limitation is a pain. All three inverter families have a good following (have not heard much specifically about the Samlex, but a good/low cost TSW inverter from what I have read).
-Bill
My panels and other components are 100+ feet away in a locked cargo trailer. I rarely find the motivation late at night and/or first thing in the morning to walk over there, unlock it, and flip a switch. I wish there was a way to turn an inverter on/off wirelessly. but I haven't seen that solution as of yet.
Not much info on the Samlex I've been able to find. Our host sells it, but they don't seem to popular here on the forum. The price is right for me, though.
I hadn't even thought of winter charging. As it is the 15.5V limit is right where Trojan recommends I equalize. One of my Xantrex inverters has a digital readout, it doesn't always agree with what my other meters says. I assume Morningstar's inverter might be a bit more accurate, but I'd rather not crank my equalization voltage down.
I've heard nothing but good things about the Morningstar (except this thread). The equalization thing does give me pause, though. I don't equalize all that often, though (probably not often enough), so it's possible I could work around it. I equalize manually, so I suppose I could switch to one of my cheapo inverters that can handle the voltage when I equalize.
Do you think the solid state nature of the Morningstar would be a problem when it's hot? 110F (43C) or so. My most reliable cheapo inverter has been an old Sima 150W car inverter, but it overheats pretty badly when it's hot out.
As to heating up - - the two I had only barely got the chill off them, they NEVER got hot, so I would not expect problems running them in hot weather.
Good to know about the lack of heat generated by the Morningstar. That was my other concern, besides the high voltage disconnect.
I wasn't too worried about that negative thread, just cited it since it was the only bad thing I've heard anyone say about these inverters. I'm leaning towards the Morningstar now. Before I posted this thread I narrowly lost an auction for one on eBay, brand new for $220 shipped. Got sniped 2 seconds before the auction ended. Oh well. Guess I'll have to pay full price LOL
They are heavy, solid and on my 1600va one, I can even power a small fridge with no problem.
Sold a 350w one to my friend for his lights, works very well for his needs.
I have run an inverter type refrigerator off the suresine without issue. I really like the sealed nature of the suresine. Great for corrosive environments as well as dusty ones.
I am a fan of less moving parts. Has a really good surge ability for a rated 300w inverter. Probably due to the large toroidal transformer that is inside. Also reason for low standby losses. Vs el transformer
Two thumbs up for the morningstar inverter. I only wish they made a 24v version.
In terms of the search/sleep mode current draw, I dont think there is anything that comes close to how little the morningstar uses.
Thom
Oh? That is exciting. I hear midnite is working on one too. I think there are big gaps in inverter offerings. I would love to see a version of the morningstar for 24 and 48 volts, and perhaps one a little larger too. Also in my fantasy world we would have large inverters with less idle and sleep draw - seems there is room for improvement here.
-Bill
One tip: my installer had the good judgment to test the first Sure Sine before we treked out to the cabin and it was dead. Morningstar expressed a replacement right away (without waiting to receive the bad one as I recall) and we were good to go.
-John