24 volt pure sine inverter with no fan or quiet fan in the 1kw range

[Mary B]

Any ideas for an inverter that isn't going to drive me insane? The fan in my Samlex sounds like a jet engine.

[birdhouse]

i love my prosine 1800 from xantrex.  got it used on ebay for $500.  fan just quit, so NO fan noise, but thats an easy fix... 

until i find the time, i just hot glue gunned a 24v fan to the back of the unit, and turn it on as needed.  fixed it for now, but need to figure out a better solution for permanent. 

it'll run everything i've got except for a HF log splitter, and my millermatic...  it will run the MIG welder, just not at full blast. 

adam

[bob g]

i don't know your budget concerns, or what the surplus computer stuff availability is in your area, but here is a viable option.

the APC ups system 1400va units are good for 1050 watts, they are 24volts dc front end and are very clean sine wave output and hold a dead on 60hz at 120vac in my experience. their fans are quiet and long lived, the beeper is easily shut off and they are very tough units.

i would have to look at one of mine to get a model number, but the ones i have are built to have up to 10 additional battery packs attached
so they can run virtually continuous duty at full output.

i have looked at their wave form and it is very clean on a scope, there is some distortion starting inductive loads which is to be expected.

they can surge to 1800 watts or thereabouts for 3 seconds before they trip out and have to be reset/restarted, which make starting some motor loads possible.

they are available often times for 50 bucks at electronics recycle centers, usually because of dead internal batteries which you would be bypassing to your bank anyway.

efficiency is not spectacular, the come in at ~85-87% efficient, and have a no load draw of around 50watts, which might be an issue.

having said all that, i think they have a place in any system using 24vdc battery banks, because they are readily available, tough as nails, are pure sine wave, and are relatively cheap... perhaps phantom load and somewhat lower efficiency is an acceptable compromise.

i think so.
fwiw
bob g

[Mary B]

With only 520 watts of solar keeping standby  current down is a must. Lower the price the better of course.

[Frank S]

OK this might not be of any use but I have  a Triplite Onmivsint 1500Xl  that runs my factory computer
 since I'm on a generator. And when the generator is shut down I just continue on with both 32" 160 w monitors the PC with its 550W power supply the HP K7103 printer and the HP 4850 scanner running as if nothing happened. I have a Battery pack 24v @ 400AH I get hours of run time with no worries
 I know triplite is an el-cheapo around $300.00 new 4 years ago but it does the job for me as a UPS I would think it would do fine as just an inverter as long as the input volts were clean

Tripp Lite's OMNIVSINT1500XL line interactive UPS system offers voltage regulation, surge suppression and long lasting, expandable battery support for personal computers, internetworking equipment and other sensitive electronics. Internal UPS circuits support entry level PC systems for up to 75 minutes during power failures so that connected equipment can be shut down without data loss. Automatic Voltage Regulation (AVR) circuits regulate brownouts as low as 151 and overvoltages up to 282 volts back to usable 230V levels without using battery power. Offers complete desktop power protection in an attractive black tower configuration. Includes 8 IEC320-C13 outlets with battery support and AC surge suppression. USB port enables optional unattended system shutdown without data loss in the case of extended power failure, USB cable included. PowerAlert software available via free download from www.tripplite.com. Built-in single line RJ jacks protect modem, fax machine, Ethernet, cordless phone or other peripheral with a standard dialup/DSL phone connection. Built-in audible alarm and 4 front panel LEDs indicate line power status, battery power status, battery low/replace status and voltage boost operation. 1500VA power handling ability supports entry-level PCs, network workstations, point-of-sale equipment, small business phone systems, audio/video equipment and home theater systems. Offers 4.5 minutes battery runtime with a full load of 1500VA and 13 minutes with a half load of 750VA. Supports hot-swappable battery replacement via built-in access panel. Extended runtime available with optional BP24V15RT2U or BP24V28-2U external battery packs.

[Mary B]

I suspect the tripplite isn't pure sine. This is also going to be powering my solar hot air and that blower doesn't run on modified sine very well.

[Frank S]

I suspect the tripplite isn't pure sine. This is also going to be powering my solar hot air and that blower doesn't run on modified sine very well.

NO as near as I can tell it would be modified.
 but it has been running my PC for years without a hitch.

[cdog]

Exeltech??

[oztules]

If your happy with the unit you have (apart from noise), then just haul it out of it's box, and make a new enclosure with passive cooling that will remove the heat better. Even if you open board it on a sheet of alumunium with multiple fins.

If you still struggle, use a fan with voltage control to pull it down to 1/4 speed, or use a few of them in series to cool your new unit.... slower quieter.

I find it hard to believe that a quick rebuild would not sort the probem out, and your caps will love you for it too.

Currently doing this for a curtis 1204 275A controller. It will soon be open without a box, and the caps will survive much better in the cooler air.


..............oztules

[Mary B]

Thing is also horribly noisy RF wise I discovered today, wipes out the ham bands completely. Bypassed all the leads and that isn't the problem, it is coming from the internals. Time for a real inverter. Price is cheap at $350 for these but you get what you pay for I guess.

[dnix71]

I own a Wagan Elite 300 watt sine inverter. Wagan's tech and customer support is first class. I bought a cheap inverter from eBay that turned out to be an internal demo from Wagan that should not have been on the street and they gave me a gift card to replace what it cost me. I sent the demo back.

http://www.ebay.com/itm/Wagan-EL2205-Elite-2000-Watt-12-110-Volt-Pure-Sine-Wave-Inverter-/130726844915
An open box sine wave Wagan here. A new 1000 watt version isn't much cheaper.

http://www.ebay.com/itm/Wagan-Tech-2203-Elite-1000-Watt-Pure-Sine-Wave-Power-Inverter-/260984077143

The fan on my Wagan runs a lot, but it isn't annoying. Better a fan running than overheating any day. No load less than 1 amp.

[Mary B]

No mention of RFI specifications on them so pass.

[dnix71]

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25746211 an old thread with all sorts of opinions on rf noise.

http://community.enphaseenergy.com/enphase_energy_community/topics/microinverter_rf_noise_in_the_2_meter_amatuer_radio_band_144mhz This one is about Enphase panel mounted micro inverters

One of the posters admitted to not having the battery hard-wired until after being able to silence the low battery beeping under a heavy load. Another didn't use the provided case ground.

RF noise in the US is actually part of electrical specs. If your device has UL certs it shouldn't be noisy, assuming you have properly sized cables and a proper earth ground. If you don't it's your fault it's noisy.

The Samlex I own does not have any certs, and it will not trip off under severe loading, but it was cheap for the time.

I also know from trial and error that the Apple supplied laptop charging brick is horribly noisy. It's some kind of universal input voltage switching supply with a magnetic tip.

[boB]

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25746211 an old thread with all sorts of opinions on rf noise.

http://community.enphaseenergy.com/enphase_energy_community/topics/microinverter_rf_noise_in_the_2_meter_amatuer_radio_band_144mhz This one is about Enphase panel mounted micro inverters

One of the posters admitted to not having the battery hard-wired until after being able to silence the low battery beeping under a heavy load. Another didn't use the provided case ground

RF noise in the US is actually part of electrical specs. If your device has UL certs it shouldn't be noisy, assuming you have properly sized cables and a proper earth ground.

I think you probably meant FCC or CE certs as UL standards are not EMI  related. 

[/quote]

[boB]

I own a Wagan Elite 300 watt sine inverter. Wagan's tech and customer support is first class. I bought a cheap inverter from eBay that turned out to be an internal demo from Wagan that should not have been on the street and they gave me a gift card to replace what it cost me. I sent the demo back.

http://www.ebay.com/itm/Wagan-EL2205-Elite-2000-Watt-12-110-Volt-Pure-Sine-Wave-Inverter-/130726844915
An open box sine wave Wagan here. A new 1000 watt version isn't much cheaper.

http://www.ebay.com/itm/Wagan-Tech-2203-Elite-1000-Watt-Pure-Sine-Wave-Power-Inverter-/260984077143

The fan on my Wagan runs a lot, but it isn't annoying. Better a fan running than overheating any day. No load less than 1 amp.

That looks like it might be a good inverter for the price especially if the support is good as you point out.
[/quote]

[Mary B]

Looks nice but no RFI specs means I won't be going that route unless I can find a review saying they are RF quiet. Found a different model Samlex that is RF quiet and a quieter fan so may go that route unless I scrape up funds for an Outback.

[boB]

2 meter noise is rare, but just when you need it quiet there the most, the unit will be noisey.

These things are usually noisey below 30 MHz but fairly quiet above.

boB

[Mary B]

QST had reviews on a few models and the Samlex PST models were even fairly quiet at HF. A few birdies I can live with, computer monitors and TV crank out plenty already.

[Badger]

I'm shopping around for a similar setup, and I was surprised to find that even the expensive brands of inverters are only 85%-90% efficient.  That Samlex 1000w is 85%.  So, for a 1000w inverter at 85% efficient, is that thing drawing 150 watts continuous?!?  Starting to think that bigger is not better with these things.  I'm going the route of the UPS, as bob g suggested.  Great price, pure sine wave, and still around 90% efficient.  Might even be able to find a scrap one laying around at work, there are 100w ones everywhere.

[bob g]

lets be clear on this

as for APC ups units

those that are over about 700kva usually are pure sine wave

those over 1400kva are as far as i have seen always pure sine wave

none are better than about 86% efficient, all will have about 50-75 watts continuous draw,

the losses are generally not related to no load draw, so much as losses in all the related internals (iron losses of the transformer being significant, lots of switching relays, and lots of other power electronics) which always seem to add up to a bit higher losses than that of a stand alone inverter, and certainly it seems that generally speaking the better built MSW inverters are more efficient than the pure sine wave inverters.

i don't know for sure, but my bet is outback inverters (pure sine wave) are better than 90% at rated load? 

so i wouldn't use a ups as an inverter unless i could accept the lower efficiency and the higher wattage losses running under no load.  the extra cost of a quality inverter is likely going to pay off over time with the difference in efficiency, and the much lower no load current draw.

but if i only needed an inverter as a backup, then all bets are off, the difference in first cost would certainly buy a pile of batteries, or more solar panels or more of each, enough so to maybe offset the difference in efficiency and no load draw? 

ups as inverters are not right for everyone, but they certainly are not wrong for everyone either.

you be the judge

bob g

[Mary B]

Many UPS are also not designed for continuous duty so keep that in mind and derate the maximum load.

[spottrouble]

I looked at a big APC unit today, 2500 watts, I think it might even do 220V, came out of a server farm. Price is not bad . How hard would it be to add the switching so that on a cloudy no wind day a ups system could just switch to grid power? This thing could run everything in my house except AC, so what if has to suck juice a few days a month, I'm thinking of using it like grid tie with battery backup, only never feeding into the grid. Anyone ever tried this?

Kristi

[bob g]

it already has all the switching needed onboard, all you would need to do is provide a disconnect from the grid when you don't want to use the grid. basically a knife switch box between the grid/utility and the ups system. then if you open the utility knife switch, the ups internal relays will switch over and the inverter section kicks in to continue to deliver the power to your loads.

that's a basic system,

the output side gets to be a bit more complex, and depending on what all you want to power from it will largely dictate how you go about connecting to the ups to get the power to the loads.

some ups units are capable of hardwire connection to the load circuitry
i will let other expound on how best to do all that, because there will likely be code concerns involved.

if you have no code concerns, and aren't concerned with insurance issues, live in a small place where your loads are centrally located, the solution to this project can be quite simple in my opinion.

it might look something like this,

because the kitchen usually has things like a refrigerator and maybe a microwave, maybe it is the likely place to also have the ups located
to power those loads

or maybe you locate it near the breaker panel, and connect it to the house via a subpanel and also locate the switchgear there too.

the short answer is yes it can be done,

bob g

[spottrouble]

If I was standing there watching things all I'd have to do was plug it in, but I'm thinking something automatic. In normal operation a UPS senses line voltage, if it drops it switches to battery power. What I want is the UPS to sense battery voltage, and if it drops to a preset level it switches to line power. Seems like it would not be that hard to reverse things, then again I might not understand it if you did and explained it I've got odles of mag contactors with different coil voltages to control them to build the switch, its the sensing battery voltage thing that confuses me.

Kristi