Used Trace Inverter

UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
Hello Everyone,
I have a recreational cabin in Northern Minnesota that I have been building for several years. My current system is 48v 200ah agm battery, 1000w panels, and a small 250w inverter. We have been getting by, but we am looking to upgrade my inverter to something larger and also need to include a battery charger. This is a weekend cabin, so the system doesn't see heavy daily use.

I found a older Trace SW5548 1998 model for sale. The seller wants 400$ for it plus shipping.
Is this unit near its useful life?
Can a person still get replacement parts?
Common worn out parts?

Any comments would be appreciated.
 Thanks Ed


1000W panels Kid CC 184 ah battery bank @ 48v
Weekend cabin, 250w inverter.
Looking to upgrade inverter!
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Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,323 ✭✭✭✭✭
    Trace made good stuff, but I usually plan to replace electronics at 15 years and consider additional years a bonus. I would be a bit uncomfortable with a $600(?) 22 year old inverter. I think it would have to ship freight. 


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,403 ✭✭✭✭✭
    edited September 13 #3
    No parts except scavenged from used inverters. No networking makes it hard to see things in your power system. Today, inverter/chargers are networked and can give a visual aide in system operation.  The Trace/xantrex SW's are great if they are not used hard at this age and were protected by SPD.

     You might expect to have problems with the generator relay which would be a major issue at a cabin with need of a genset. 

    Example of a networked power system below.

    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Thanks for your replys. I was concerned about the age and replacement parts mainly. It sounds like I may have to pass on it. Networking isn't a large concern of mine. Off grid, remote cabin with minimal cell coverage. I have a MN Kid and it takes care of most of my charging needs. Only long visits with company in the cloudy months give us some concern.

    I've been waiting for the new MN inverter stuff to get done. I don't know what the prices exactly will be. I was also looking at a Cotek Sp-2000-148 with the auto transfer switch and a Mean Well Pb-1000-48 battery charger. I have some time, but am in need of something bigger.
    Ed
    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,403 ✭✭✭✭✭
    Offgrid is especially useful to see what the battery did in the last 24 hours. If you really did complete charge or did clouds or loads pull you out of the set-point. Same with an EQ.  Even better if you can go back months and find what started the problem in an unattended cabin.
    Definitely do not need the internet for this either.

    You would be smart to stay with the same brand also. Seeing is believing, especially offgrid. A battery charge and then an EQ below.


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • PhotowhitPhotowhit Solar Expert Posts: 5,323 ✭✭✭✭✭
    I believe the Midnite Kid the 'Whiz-bang Jr' shunt based battery monitor, will chart most of what Dave would like to show on their Dashboard/local app.

    Here's a screen shot of the minute by minute battery and input voltage.



    Here's a link to a video of their data logging software app;

    https://www.youtube.com/watch?v=9x2eD56nwlY
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    I believe the Kid does in pc mode. I have 2 concerns though.
    1)Finding a small computer with low power consumption.
    2)The bigger concern. It routinely gets -40F to -50F (-40C to -46C) every winter. Which means,it can be colder than 0F (-18C) in the cabin when we arrive for a weekend stay. That can complicate things. If I had a lot in invested in my system, I would consider some redundant heating system for my electronics and a cell phone based system to give me updates.

    I do have to work with these parameters. Right now my agm's are somewhat sheltered from the extreme cold in the cabin. They also have a max volt per cell value. If my next set of batterys are flooded, I will need an inverter that can really handle the volts.  I've been keeping my eyes open for one that has both higher voltage rating and low idle power consumption.

    My current inverter is a Victron model.  My cabin and generator are wired for 120v. I could easily change the cabin to 240v. The generator is firm at 120v.  Finding a reasonable priced 48v inverter with around 2000 watts is the problem I am running into. A lot of what I am finding would be around 3500$ with the fuse box, programming controller, and extra guarding. I'm not trying to be cheap, but the inverter will cost more than the rest of my solar system combined and it is for a weekend cabin.

    I am open to any suggestions.
    Ed
    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • PhotowhitPhotowhit Solar Expert Posts: 5,323 ✭✭✭✭✭
    My current inverter is a Victron model.  My cabin and generator are wired for 120v. I could easily change the cabin to 240v. The generator is firm at 120v.  Finding a reasonable priced 48v inverter with around 2000 watts is the problem I am running into. A lot of what I am finding would be around 3500$ with the fuse box, programming controller, and extra guarding. I'm not trying to be cheap, but the inverter will cost more than the rest of my solar system combined and it is for a weekend cabin.
    Not sure what your end goals are, or what you are powering with the need for 2000 watt inverter, a fridge?

    Interestingly, I'd recommend a 48 volt system normally for a use in a cabin that would someday be a primary residence. If the 'end game' is a 2000 watt inverter, and a weekend use, with a fridge and pretty much everything but air conditioning and water heating... You might consider a 24 volt system. This might be the first time I ever suggested reducing battery voltage. Certainly since I had to move from my cabin, sized for a 24 volt system, into a larger place which really needs a 48 volt system.

    Samlex makes a nice unit at 24 volts, 2200 watt inverter/Charger with an internal transfer switch for running a generator (not sure if you need that) For around $1500. It's UL1741 for home use. You could continue to use your Midnite kid with 1000 watt array on 24 volt system (if your batteries could be reconfigured that way.) It draws about 25 watts in 'normal' mode and 8 watts in 'save' mode.
    Samlex EVO-2224 2200 Watt 24 Volts DC Inverter  Charger with Transfer Switch
    https://www.solar-electric.com/samlex-evo-2224-inverter-charger.html

    Spec's here;

    https://www.solar-electric.com/lib/wind-sun/Samlex_EVO_Specs.pdf
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Photowhit,
    My wife and I are still building this cabin and it probably won't be complete for a few years. It is well insulated and a.c. wired similar to a modern home. This year, we were up there for the 4th of July week. It was the hottest week of the year. It was 90F in the cabin when we went to bed and only 80F when we got up. Two box fans on low in the windows. I see a small window ac unit in my future, probably more panels also. A ac relay operated by the Kid load feature to turn on the ac once the batteries are full.  Other items on the list are a small fridge (found one, 1.5a draw), the wife would like a small 700 watt microwave for short occasional use, we have a small chest freezer for longer stays with many guests, and a vacuum cleaner. I also have some ideas on a waterless water heater or something that will be heated when we are away. I'm concerned about the winter freezing. That is my long game. We are still quite young and not sure what our future will bring. We are planning on spending as much time there as we can there. I do see us expanding in the years to come.

    The 48v is probably going to stay. I have 8 12v agm  batterys. 4s 2p. They were to good of a deal to pass up. And for a first set, they are holding up well. I see all kinds of options for 12/24v systems, but 48v is probably the best choice for our future.  Once the battery technology takes this current leap and inverter manufacturers address the more common 48volt and larger systems. I see more option in the future. I was also looking at the Victron 48v 1200va Phoenix inverter. The 1200va scares me, not sure if it's big enough. I like the blue tooth and efficiency of the smaller 250va one we have. I just don't want to run it at max with the previous mentioned loads. I don't think they are stackable. I haven't verified that yet.

    I still need a battery charger. Would be nice to have a inverter/charger. I am willing to separate them.

    The only manufacturers that I am aware of that fit my parameters are Outback, Schneider Electric, Cotek, Victron, and some time in the future Midnite Solar. If I missed one,please let me know. I need -20F (-29C) min operating temp, 48v, around 2000watt min., true sine, and prefer 64v + upper limit. Tougher conditions, but realistic requirements in my situation. Please let me know if I missed a manufacturer. I will update my list.

    Ed
    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,403 ✭✭✭✭✭
    The Schneider CSW inverter/charger is 40v to 64vdc. Their Mppt is 0 to 80vdc. They also can be networked and you can see the big picture as well as all of the usual charts, graphs, and data. Monitor it any where there is internet or cell. CSW will charge from a 120vac genset or 240vac.

    https://solar.schneider-electric.com/product/sw-na/
    https://solar.schneider-electric.com/wp-content/uploads/2020/09/DS20200909-Conext-MPPT-60-150.pdf
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • PhotowhitPhotowhit Solar Expert Posts: 5,323 ✭✭✭✭✭
     This year, we were up there for the 4th of July week. It was the hottest week of the year. It was 90F in the cabin when we went to bed and only 80F when we got up. Two box fans on low in the windows. I see a small window ac unit in my future, probably more panels also. A ac relay operated by the Kid load feature to turn on the ac once the batteries are full.  Other items on the list are a small fridge (found one, 1.5a draw), the wife would like a small 700 watt microwave for short occasional use, 
    I used a small 1000 watt array in a tiny home on a much smaller battery system. I don't think you would have any problem with weekend use of a window air, a fridge  and microwave on what you have now if you added another 1000 watts of array and a larger inverter.

    I used a Xantrex/Schneider/Prosine 1800 watt inverter, the same one that I continued to use until this year since 2005. I powered all those things though only minimal air conditioning into the night as I only had 5 kWhs of storage (4 golf cart batteries). The system started at 1000 watts of array in 2004 and ended with about 16-1700 watts of array 5 years later. I only ran both the fridge and air conditioner 2 summers. This was daily use, I suspect weekend use you would be fine. Considering your near double the storage. The golf cart batteries lasted 5 years, 1 year before I started running the window air over the summer and 4 years running the window air, so reasonable battery life from 4 Sam's club golf cart batteries.

    I would question the small fridge. It's always nice to find the energy star rating for fridges as the momentary draw of 1.5 amps (need a watt measurement, could be 48 volt or 120 volt AC) isn't a good indicator of how much energy the fridge will use over time as it will have a compressor that turns on and off while in use. My 4' 2 door fridge, likely used nearly as much as modern apartment sized fridges. Indeed I would look for a modern  apartment size fridge with a rating around 1 kWh a day. Inverter fridges are even more efficient, though a bit more costly.

    I really don't worry about on line monitoring. In 18 years I've built my systems to reasonable standards and they have pretty much worked. Early on I did 'cheap out' with an inexpensive inverter that more or less died (fried it's parallel fuses, I replaced and it worked, but I replaced it with the Prosine. I also had a charge controller fail (Integrated in the power center) but had a spare and a inverter fan die (in the Prosine It worked but would over heat above 4-500 watts in use, I replaced the fan and it's still working. None of these would have been helped by online monitoring, it might be somewhat more desirable in a remote cabin, but then it's the difficulty of communicating with the system.

    I've also used Exeltech which are wonderful, but expensive in a 2000 watt version. It's not a inverter charger, but when I moved to my new location, I had intended to stay at 24 volts since I had purchased a 24 volt forklift battery in 2011, still works nice... Until it needed replacing. I found a 24 volt Magnum 4024 inverter used and verifiable working at a reasonable price, so I'm likely going to stay at 24 volt. Samlex also makes some 48 volt inverters, but not inverter chargers. I like their EVO design, I've always designed my system to run without back up sources of power, but the integrated transfer switch in a nice feature. Perhaps they'll make a 48 volt version...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,403 ✭✭✭✭✭
    A reason also that small systems have problems is there often is not enough solar or the genset is not set-up correctly. Large systems like wits above and mine do not need to "see" the system.  There is such overkill in the solar power or the user has a ton of experience with this stuff.  

    Or, it is overkill for winter where people live full time. Or the new one in the west, it is designed to provide enough power in summer during wildfires.

    Many more battery size (stored KWH) options for you at 48v.  MANY !
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Looks interesting. I'll do some research. One quick question. Is it either 120v or split 240v? Meaning it has to be specified at time of purchase. Is there any drawbacks to using only 120v?
    Thanks,
    Ed
    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,403 ✭✭✭✭✭
    120 or split 120 / 240 inverters for North America. Some 120 inverters can be stacked or stepped up for 240. Be careful you do not buy something for a non north american application.

    The drawback of using 120 only is there are some loads that are better at 240, will use less energy, will cause less flickering of lights when big loads come-on. 240vac loads do not require the balance act an electrician does when splitting 120 loads to both sides of a split home panel.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • mike95490mike95490 Solar Expert Posts: 8,961 ✭✭✭✭✭
    A well pump or a sewage ejector are better at 240V. Air conditioning/heat pumps other than window units, would be better on 240V  Most main electrical panels are set for 120/240 split phase, with alternating breakers on the busses
    and if you bought a large backup generator, it's likely to have split phase 240 output.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    The reason for the higher inverter watts is mainly for motor startup surges and the small microwave. I read somewhere that the actual draw on the microwave is approximately 2x the wattage rating. I haven't verified It, and I'm not sure if it's more on the startup. It would be interesting to know. All with other appliances plugged in and possibility running. We currently typically charge around 1.7kw  per day. Very small usage. And the freezer gets run with the generator for a couple hours, 2x per day. So I'm very satisfied with the size of my system and believe the addition of the fridge ect will have little effect on my system capacity. The ac may, and at that point, I'll have to add some panels to compensate. My killawatt is at the cabin and I am planning to verify it's 24 hr  usage.

    I never thought of the split phase benefits. So thanks!! That sounds like a direction I should ultimately be headed in. My ac panel is a split phase type. It's currently setup with a jumper to make it all 120v. So it isn't a problem to switch to split phase.

    Really great info and advice from your experiences! Thanks everyone!

    Ed

    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • mike95490mike95490 Solar Expert Posts: 8,961 ✭✭✭✭✭
    With motors and microwaves, Power Factor is the problem.  The inverter has to be large enough to be able to stable when supplying large unbalanced PF loads.   Ordinary wall plugs are 15A  @ 120V = 1800w restive load, but with weird power factor, the inverter sees much more (oddly, the batteries don't, the inverter works extra hard to supply out of phase voltage and current)

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    edited September 16 #18
    Mike,
    I do have one device that makes my 250va  @48v and my in-laws 500va @24v inverters scream unhappy sounds. Both inverters are Victron. My wife has a medical grade transformer (120v ac to 12v dc) for her cpap night breathing machine. It can't stabilize the 120 voltage, it jumps all over the place. It is rated for 65w  output. It never see that, since she doesn't use the onboard heater on high. I even bought a replacement oem style. I think it was a Meanwell brand. The replacement was better, but still won't work. I ended up buying a 64v to 12v buck converter and a cigarette lighter plugin. Then the cheap 12v inverter and a long extension cord. I figure it's better to blow 25$ then 200$. Besides,the rest of the cabin doesn't like the unstable voltage. I would love too plug it into the wall like everything else. None of the cellphone chargers mess with it. I don't know if there is a different style transformer, I don't believe it needs a medical grade transformer other than because it is one. It originally had an option to use a 12v battery.

    Any thoughts or suggestions?

    Ed

    I looked up the oem replacement. Meanwell p/n GSM90B12-P1M

    Desktop AC Adapters 80W 12V 6.67A Medical Adaptor



    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • mike95490mike95490 Solar Expert Posts: 8,961 ✭✭✭✭✭
    I don't think a medical grade power brick ( this is a brick shape power supply in the middle of 2 cords ?  ) of such low wattage, would upset a properly functioning inverter.   I suspect your inverters are getting "tired".  <My washing machine makes my 6kw inverter moan, as does the well pump, but it's just working and power is quite stable.   You might research what the idle draw is on your 2 inverters, and compare to the latest Schneider XW series ( 26-28W).  Going with a quality inverter would likely make those troubles go away.   My CPAP and assorted household gizmos have a pretty steady 200w draw (air pumps, water filter pumps, USB chargers, laptops, microwave....) and I found the easiest way to deal with it, was an extra PV panel, instead of being anal about switching off outlet strips.  May not be the answer for you.


    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Thanks for your insight. Both inverters were less than one year old and the CPAP was the only item drawing power at the time of the test. The best I could tell it was around 40w draw. It was jumping around so much. I think I'll chalk it up to the design/size of the inverter. Below is a screenshot of inverter specs.The idle power is very low.

    Ed


    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • BB.BB. Super Moderators, Administrators Posts: 30,939 admin
    It sounds like a classic Control Theory issue...

    There is a controller in the AC inverter that tries to output 120 VAC at whatever current the load needs. And there is the load that takes whatever voltage is supplied and then pulls the current to supply its load. Both are (more or less) "constant power" devices.

    For example, say the load needs 70 Watts. At low and high line voltage, current wise, that would be:
    • 70 Watts / 105 VAC low line = 0.67 Amps
    • 70 Watts / 132 VAC high line = 0.53 Amps
    The "load" (CPAP) machine is "happy" at either of those two points, and anywhere in between. It will simply take more or less current as needed to maintain 70 Watts.

    You have the AC inverter trying to hold ~120 VAC regardless of load. When the load takes more current, the voltage falls, and the load takes more current to make up for the drop. Then the AC inverter pumps out more voltage to make up for the "extra load current". The "load" sees the higher line voltage, and takes less current (P=V*I, higher voltage, less current needed). The AC line voltage rises above the 120 VAC set point, and the AC inverter cuts back on the high line voltage and brings the voltage back down. And the whole thing repeats.

    Effectively, the two (or more) control circuits (AC inverter, "power brick", and the CPAP load) are all resonating against each other.

    Short of trying to figure out where each component has "resonance" points, There are only a couple of things that I could see that might make the situation better...

    One would be to put an additional small load (like a 10 Watt filament bulb) on the AC line. Another thing to try would be to put a power resistor in series with the CPAP (a >1 Watt rated resistor, say 1 Ohm @ 1 Amp CPAP load). Either may take the devices out of their resonance zone of operation.

    Otherwise, different brands of devices (inverters, CPAP machines) or other solutions (DC to DC converter driving DC CPAP adapter) are probably the only easy solutions (which was your final solution).

    The "big issue" is probably is the CPAP power brick causing the overall problems. But this can be still very difficult to solve. Power supplies are becoming so "interactive" with their loads--They have no "extra storage energy' (like larger high voltage storage capacitors between AC input and load output), that simply adjusting the controller's internal feedback loop may not doable. With everything "small" and inexpensive as possible, the power brick is relying on the AC mains to supply zero to max current "instantly" (within the 60Hz AC frequency, or even adjust current draw during the individual voltage sine wave--Basically the pump motor to keep it at its exact needed RPM/Torque)--Transmitting the loads instantaneous power needs to the AC main with little "buffering" between load and AC mains.

    Years ago, I was getting into the issue with computers and their power needs. The PFC (Power Factor Corrected) power supply designs react very quickly to changes in load--And that affects the AC current draw--Which makes for AC current "harmonics"--Which make it more difficult to pass certification tests (variable frequency CPUs for power saving vs software requirements, varying processing needs vs programs, I/O, etc.). 

    I would be neat to get the two companies' systems engineers to talk to each other and see if they can fix the problem--But that may not be easy either.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Bill,
    One would be to put an additional small load (like a 10 Watt filament bulb) on the AC line.

    If I understand it correctly, 10w filament night light in the same outlet to possible provide a buffer the power supply. Easy enough to try.

    Otherwise, different brands of devices (inverters, CPAP machines) 

    I could see if there is a different power supply available. Maybe one that isn't quite as efficient/ different grade.

    Both solutions seem easy enough to try. I'll respond with the results as they come available.

    Another thing to try would be to put a power resistor in series with the CPAP (a >1 Watt rated resistor, say 1 Ohm @ 1 Amp CPAP load). Either may take the devices out of their resonance zone of operation.

    Not sure how or where to get the resistor. I definitely not afraid of doing it, just haven't done it before.

    Ed

    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
  • BB.BB. Super Moderators, Administrators Posts: 30,939 admin
    Here is a quick link to power resistors


    You can try 1/2/3 power resistors in series and see if it helps or hurts.

    Adding a bit of resistance is like adding a shock absorber to a car axle. Instead of the car bouncing after a bump, the shock absorber turns the excess motion into heat.

    Or adding "dampening" to a control system.

    Not sure it will do anything... Cheap and fun to try.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • UpNorthManUpNorthMan Registered Users Posts: 10 ✭✭
    Bill,
    Thanks for your insight and the link. I will be headed to the cabin this Friday. If the light bulb doesn't work, I'll bring the CPAP home and do some testing with my in-laws inverter. They aren't the same size, but both suffered from the same problem. 

    I'll keep everyone posted.

    Ed
    1000W panels Kid CC 184 ah battery bank @ 48v
    Weekend cabin, 250w inverter.
    Looking to upgrade inverter!
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