# Pure Sine Inverter



## vickers (Jan 16, 2013)

Can anyone recommend a low cost Pure Sin Inverter? Im not having much luck finding one. I know that they are more expensive than the modified sine inverter, but im really looking for a low watt (200 or so) as I have a larger modified sin inverter for other needs. Thank you.


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## LincTex (Apr 1, 2011)

What exactly are you going to power with it?

I just use an old APC brand UPS (600 watts?) with its internal batteries gutted and tied into my 12volt home solar power system to run the computer. I do not think it is pure sine at all, but will run the computer, router, modem and printer easily.


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## vickers (Jan 16, 2013)

LincTex said:


> What exactly are you going to power with it?
> 
> I just use an old APC brand UPS (600 watts?) with its internal batteries gutted and tied into my 12volt home solar power system to run the computer. I do not think it is pure sine at all, but will run the computer, router, modem and printer easily.


Thanks. Hadnt thought of that. Just looking to charge a laptop or maybe run a TV. The modified sine scares me a bit and im worried it will damage my electronics. Ill definitely look into that, as i should be able to recharge the UPS device with the modified sine inverter.

Thank you.


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## AKPrepper (Mar 18, 2011)

vickersja said:


> Can anyone recommend a low cost Pure Sin Inverter? Im not having much luck finding one. I know that they are more expensive than the modified sine inverter, but im really looking for a low watt (200 or so) as I have a larger modified sin inverter for other needs. Thank you.


Check on Amazon for the Xantec 600 or 1000w pure sine wave inverter. I just purchased the 1000 and as soon as it warms up a bit, I'm installing it in my camper to power the TV and some other 120v appliances when I'm out boondocking it. I've tested it in the garage with differnet power tools and have had nothing but good results.


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## vickers (Jan 16, 2013)

AKPrepper said:


> Check on Amazon for the Xantec 600 or 1000w pure sine wave inverter. I just purchased the 1000 and as soon as it warms up a bit, I'm installing it in my camper to power the TV and some other 120v appliances when I'm out boondocking it. I've tested it in the garage with differnet power tools and have had nothing but good results.


Great. Thank you.


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## LincTex (Apr 1, 2011)

vickersja said:


> Just looking to charge a laptop or maybe run a TV.


Both of those devices rectify AC into DC before using it, so the power can be as "choppy" as ever and they will not care.

Do not use modified sine wave inverters with cordless drill chargers, it will toast the charger.

Some say CFL bulbs become very "noisy" when using a modified sine wave, but if it gets to that we should just be using 12 volt bulbs... using an inverter is a waste of energy (inefficient).

Always power everything directly from 12 volts whenever you can (lighter socket style).


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## vickers (Jan 16, 2013)

LincTex said:


> Both of those devices rectify AC into DC before using it, so the power can be as "choppy" as ever and they will not care.
> 
> Do not use modified sine wave inverters with cordless drill chargers, it will toast the charger.
> 
> ...


Great point. Ive been doing some research and have found that as much as 20% can be lose in the DC to AC conversion process. If running from batteries, that is a huge amount.


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## Fn/Form (Nov 6, 2008)

http://www.donrowe.com/

DR has some of the best selection/experience. Drop them a line with your intended loads, frequency of use and see what they recommend. They carry decent choices for just about any budget.


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## mtexplorer (Dec 14, 2012)

Not an electronics guy, could someone explain what the differences are with inverters and why the sine inverter is better for you equipment? I would like to learn a little more about this. Thanks

M


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## labotomi (Feb 14, 2010)

The black line is a sine wave. The blue line is a pulse width modulated signal that approximates the sine wave. If you take the integral of the blue signal (area under the curve) you would have an approximation of the sine wave.










There are several advantages and disadvantages to this type of inverter.
Pros:
Inexpensive
Very efficient compared to pure sine inverters
Small size

Cons:
Can damage some types of electrical components (transformers primarily)
Certain conditions can cause a phenomenon called "standing waves" or "reflected waves" which can cause the voltage on the line to double what the output of the inverter is producing.

"Most" electrical equipment in a residential environment will not be harmed by a modified sine inverter.

If you have something with a transformer fed directly from the inverter it has the potential for damage. If you're powering a very old electrical motor or one that is located far away from the inverter itself, it could be damaged.

We use several hundred large ones where I work and we don't have any problems, but they're used to vary the speed of electrical motors. We don't power receptacles from them as it would be stupidly expensive and we couldn't guarantee the results of everything that possibly could be plugged in.


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## mtexplorer (Dec 14, 2012)

What I'm getting from this is that a pulse is similar to flipping a switch on/off every x-per second which can cause spikes or drops in voltage and can damage equipment. The sine wave gives a flowing supply of current which unlike the pulse which has a hammer effect. Is this analogy close?

M


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## LincTex (Apr 1, 2011)

mtexplorer said:


> What I'm getting from this is that a pulse is similar to flipping a switch on/off every x-per second which can cause spikes or drops in voltage and can damage equipment. The sine wave gives a flowing supply of current which unlike the pulse which has a hammer effect. Is this analogy close?


Yes, pretty darn close. The capacitance of a given circuit can cause all kinds of weird thing to happen in a modified sine wave inverter, which is why some folks complain their CFL bulbs act very weird when running on modified sine wave inverters.

"on/off every x-per second" And from what I gather, switching power supplies also do something very similar.


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## labotomi (Feb 14, 2010)

LincTex said:


> Yes, pretty darn close. The capacitance of a given circuit can cause all kinds of weird thing to happen in a modified sine wave inverter, which is why some folks complain their CFL bulbs act very weird when running on modified sine wave inverters.
> 
> "on/off every x-per second" And from what I gather, switching power supplies also do something very similar.


Capacitive loads can act funny or sometimes not at all if the switching frequency is too slow. If the switching frequency is high enough, the difference won't be enough to notice.

The damage is done to inductive components which act like a short when DC voltage is applied. That's why the damage is done to the battery chargers as they have a built in transformer (basically 2 coupled inductors). The virtual short causes high current and heat generation. Again the higher the switching frequency the less chance you have of damage.


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## vickers (Jan 16, 2013)

Fn/Form said:


> http://www.donrowe.com/
> 
> DR has some of the best selection/experience. Drop them a line with your intended loads, frequency of use and see what they recommend. They carry decent choices for just about any budget.


Thanks.


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## Viking (Mar 16, 2009)

Fn/Form said:


> http://www.donrowe.com/
> 
> DR has some of the best selection/experience. Drop them a line with your intended loads, frequency of use and see what they recommend. They carry decent choices for just about any budget.


Don Rowe is where I bought my Xantrex RS 2000 pure sine wave inverter/charger for our motorhome. They have many other sizes and brands to choose from and his prices beat all that I researched at the time. Actually pure sine wave inverters have a purer sine wave than grid electricity, they don't get dirty from everyone elses motors, lights, welders, sawmills, factories and etc., switchings that cause spikes and distortions that can travel down the lines to your home. The standard inverter is square wave even if it's modified as labotomi has shown. I've read that some motors run hotter on the square wave inverters.


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## mosquitomountainman (Jan 25, 2010)

A "pure" sine wave is only available on a generator type circuit or from the power company when they reduce the high voltage in the power lines to 110 and 220 AC current.

Pure sine wave inverters are just modified sine wave inverters with finer adjustments. A digital (electronic) inverter can only shut off and turn on electricity. A modifed sine wave inverter does it in such a way the the impulses resemble a flight of stairs. A "pure sine wave" inverter does the same thing only the "steps" are smaller. Most things function quite well on modified sine wave inverters (with the previous exceptions noted). What I was taught is that if battery chargers for tools get too hot you shouldn't use them on that inverter. Ours have all done fine.


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## Viking (Mar 16, 2009)

We're planning on developing a solar system for our home and I've looked at the Magnum Energy 4000 watt pure sine wave inverter/charger that's on Don Rowe's site. It operates on 24 volts DC and puts out 120 VAC out of phase each side of neutral and 240 VAC between line 1 to line 2. They can be stacked parallel up to four units that will put out a total of 17,600 watts. This 4000 watt inverter is 93% efficient with a 5 second surge rating of 5800 watts, surge ratings are important for starting electric motors such as fans, water pumps, compressors or any motor that draws high amperage to get it spinning. This inverter/charger and the one I have on the motor home use a very large transformer and are probably for closer to grid sine wave than the smaller all electronic units which produce the sine wave mosquitomountainman mentioned. The 2000 watt unit on our motor home weighs 55 pounds as does the 4000 watt unit. One all electronic 2200 watt unit I checked out only weighs 14 pounds.


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## Fn/Form (Nov 6, 2008)

mosquitomountainman said:


> A "pure" sine wave is only available on a generator type circuit or from the power company when they reduce the high voltage in the power lines to 110 and 220 AC current...


This was true about three decades ago. I used to repair small (280 Watt) to huge (1.1 MegaWatt) backup power systems. New and aged. Elgar UPS/GUPS, Lorain, Exide, California Instruments, PCP, Emerson, La Marche, Liebert, HDR, Powerware, blah blah blah.

It used to be that inverters or inverter sections were designed around available components. Nowadays we have specialized components--built specifically for inverters--and microprocessor control that enables much less than 3% distortion without the bulk/weight of the older "quality" models.

You still get what you pay for, but quality power choices are available to the masses. Often cleaner than the power company... and as stable or much more so than a genset.


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## Nadja (Jan 12, 2011)

A modified wave inverter will not hurt your electronics unless it is some cheap chinese type or so. Modified sine wave WILL damage motors over time, so this is where you need to draw the line.


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## Viking (Mar 16, 2009)

Fn/Form said:


> You still get what you pay for, but quality power choices are available to the masses. Often cleaner than the power company... and as stable or much more so than a genset.


The Xantrex pure sine wave inverter we bought about eight years ago cost us about $1,400 from Don Rowe and this was about $600 or so less than a RV supply catalog. You really do get what you pay for because this inverter which runs on four series/parallel 6 volt golf cart batteries charged by four 100 watt solar panels through a very good solar charge controller is far more efficient for the small amount of power we use than the propane guzzling generator that's in the motor home. I'm considering pulling that heavy generator and just develop my own small engine powered 12 volt backup charge system to charge the batteries on days that there isn't enough sun charging available.


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## labotomi (Feb 14, 2010)

mosquitomountainman said:


> A "pure" sine wave is only available on a generator type circuit or from the power company when they reduce the high voltage in the power lines to 110 and 220 AC current.
> 
> Pure sine wave inverters are just modified sine wave inverters with finer adjustments. A digital (electronic) inverter can only shut off and turn on electricity. A modifed sine wave inverter does it in such a way the the impulses resemble a flight of stairs. A "pure sine wave" inverter does the same thing only the "steps" are smaller. Most things function quite well on modified sine wave inverters (with the previous exceptions noted). What I was taught is that if battery chargers for tools get too hot you shouldn't use them on that inverter. Ours have all done fine.


Mostly true, but there are actual analog inverters that do produce a sine wave and not a pulsed digital signal. They're more expensive and much more inefficient, but they do exist and are commercially available.

The major difference in these are how the transistors are used. If they're used as on/off switches, it's more of a modified sine unit. If they're used as a modulating device. One that varies output based on input in an analog fashion, it's being used as an amplification of the actual input signal that reproduces the input signal.

One easy example is an op-amps in every iteration. They're so common that the list of electronics that don't use them is much smaller than the list that does.

Just look to car audio amplifiers for examples. There are several classes that have differing amounts of accuracy and efficiency ratings.

Class A is basically a pure sine inverter, but it suffers from poor efficiency because the transistors are conducting almost continuously.

Class AB are less accurate but more efficient because their is distortion every time the signal crosses 0V because of the turning on of half the transistors and turning off the other half.

Class D is the modified sine most people mention. It is very efficient (comparatively) but not accurate so they're only used in low frequency applications like the subwoofers because people don't notice the distortion as much and higher frequencies require higher switching speeds which drive up the cost of components.

There's many more classes, but those three cover enough to describe the differences. All the others just combine characteristics to get the best signal to efficiency based on the requirements of the circuit.

You won't find commercial inverters with the ratings of the equipment we use at my job. The carrier frequency (how often it can turn on and off) can be adjusted, but the minimum value we can use is 2kHz.

A unit designed for residential use are more likely to be limited to turning on or off at a rate of 4 or 8 time a second. Still this is fine for the vast majority of electrical equipment, but it does affect some negatively. The lower the switching frequency the higher the chance of damaging components that are susceptible to damage.

Companies such as Allen Bradley, Siemens, Square-D, Omron, and rebranded offerings from Automation Direct make modified sine inverters that have the ability to produce a signal that does a fantastic job of approximating a sine wave. The downside of course is cost. Automation Direct would probably be the cheapest. Just make sure you're looking at a DC to AC unit as many are AC to AC units that are simply used to take a 60Hz input and output whatever frequency you want.


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## labotomi (Feb 14, 2010)

Nadja said:


> Modified sine wave WILL damage motors over time, so this is where you need to draw the line.


I'll have to respectfully disagree.

If you're talking about an old motor as in pre 80s then yes, the chance of damage is higher.

Another factor is the distance of the motor from the inverter itself. The longer the distance the higher the chance of standing or reflected waves which could cause "ringing" and/or a higher "corona" effect and damage the insulation of the windings.

Personally, I've been using and designing systems using standard motors with modified sine inverters without any noticeable increase in failures. I do limit the distance to about 300ft for a comfort level and we do use shielded cables, but that's more for the motor cable affecting the signals of other devices rather than the opposite.

Since most homes aren't going to be using appliances that were built prior to the 80s or have distances in excess of a couple hundred feet, I believe any increase in potential damage is insignificant.


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## labotomi (Feb 14, 2010)

Fn/Form said:


> This was true about three decades ago. I used to repair small (280 Watt) to huge (1.1 MegaWatt) backup power systems. New and aged. Elgar UPS/GUPS, Lorain, Exide, California Instruments, PCP, Emerson, La Marche, Liebert, HDR, Powerware, blah blah blah.


I deal mostly with VFDs and we don't service our backup UPS units so my experience is different than yours, but most of the principles are the same. We currently use several Liebert backup units and I've come to despise them.

They may have some great units, but the ones we have are prone to popping fuses and SCRs whenever switching from backup operation back to normal AC input operation. Their technicians haven't been able to give me an explanation that I find satisfactory.


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## Viking (Mar 16, 2009)

This discussion has me thinking, I have a neighbor that has an Oscilloscope and when the weather gets warmer I'll have him bring it over and have a look at the waveform that my inverter puts out. I'll try to take a picture of the screen and post it here. That might take care of the question of how pure the sine wave is on upper end inverters.


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## labotomi (Feb 14, 2010)

Viking said:


> This discussion has me thinking, I have a neighbor that has an Oscilloscope and when the weather gets warmer I'll have him bring it over and have a look at the waveform that my inverter puts out. I'll try to take a picture of the screen and post it here. That might take care of the question of how pure the sine wave is on upper end inverters.


Are you putting it on a pure sine inverter or a modified sine?

A modified sine isn't supposed to look like a sine wave as it's a DC pulse with the same amplitude but varying durations. You have to take the integral of those signals to get the sine wave shape.

I'd be curious as to the shape of one claiming to be a pure sine inverter that's designed for residential use.


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## Viking (Mar 16, 2009)

labotomi said:


> Are you putting it on a pure sine inverter or a modified sine?
> 
> A modified sine isn't supposed to look like a sine wave as it's a DC pulse with the same amplitude but varying durations. You have to take the integral of those signals to get the sine wave shape.
> 
> I'd be curious as to the shape of one claiming to be a pure sine inverter that's designed for residential use.


The Xantrex model RS 2000 that we have is a pure sine inverter. In the research I did before buying the unit some of the things mentioned about modified sine inverters was that some electronics such as DVD players, Digital TV's, microwave oven control circuits and other sensitive electronics might not work properly. One other thing in considering inverters is the surge power and length of time a surge power can be had and this has to do with motor locked rotor amperage ratings which are well over the run amperage ratings. This applies to motors that have capacitor start or induction start windings such as air compressors, refrigerator/freezer compressors and well pumps. Small cooling fans don't usually draw all that much starting amps and may not need a lot of surge time or surge power. The RS 2000 has 4000 watt 5 second surge time which can start and run my small portable compressor, large drill motors or bench grinder if need be.


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## vickers (Jan 16, 2013)

Nadja said:


> A modified wave inverter will not hurt your electronics unless it is some cheap chinese type or so. Modified sine wave WILL damage motors over time, so this is where you need to draw the line.


Thanks. So much conflicting info out there. It appears that the answer is maybe modified sine inverters will damage, but to what extent and for long can they be used is the question.

For an emergency situation, i just purchased a modified-sine inverter from Harbor Freight Tools for $39.99 after coupon. 750W and 1500W startup.


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## vickers (Jan 16, 2013)

Viking said:


> The Xantrex model RS 2000 that we have is a pure sine inverter. In the research I did before buying the unit some of the things mentioned about modified sine inverters was that some electronics such as DVD players, Digital TV's, microwave oven control circuits and other sensitive electronics might not work properly. One other thing in considering inverters is the surge power and length of time a surge power can be had and this has to do with motor locked rotor amperage ratings which are well over the run amperage ratings. This applies to motors that have capacitor start or induction start windings such as air compressors, refrigerator/freezer compressors and well pumps. Small cooling fans don't usually draw all that much starting amps and may not need a lot of surge time or surge power. The RS 2000 has 4000 watt 5 second surge time which can start and run my small portable compressor, large drill motors or bench grinder if need be.


You mentioned a surge protector... I wonder if that will help to minimize the modified sine inverter effects on electronics?


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## labotomi (Feb 14, 2010)

vickersja said:


> Thanks. So much conflicting info out there. It appears that the answer is maybe modified sine inverters will damage, but to what extent and for long can they be used is the question.
> 
> For an emergency situation, i just purchased a modified-sine inverter from Harbor Freight Tools for $39.99 after coupon. 750W and 1500W startup.


The variable is actually the pulse frequency of the inverter. Ones that switch 4, 6 or 8 times a second have the most potential for damage. Higher switching frequency won't cause damage except in specific circumstances.

As an example, we've been using modified sine inverters on 100+ motors in the area I oversee. We lose approximately 5 per year but that's mostly due to heat related bearing failure (3000F furnace application). I can only think of a couple of times when we've encountered a problem with the motor windings and that's not any more than you'll see on motors that are running from the power line (non inverter).


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## CulexPipiens (Nov 17, 2010)

labotomi said:


> ... We currently use several Liebert backup units and I've come to despise them.
> 
> They may have some great units, but the ones we have are prone to popping fuses and SCRs whenever switching from backup operation back to normal AC input operation....


Is this happening in multiple units? I've got a 15KVA Liebert system in my server room and it's performance has been flawless for about 5 years now. Granted we don't switch on to it that often but ever time we had to it has worked perfectly. For longer than I wanted (during an upgrade with both the old and new systems both online) we also were running at 95-97% of capacity and it handled it like a champ. I'd be all of anything Liebert for my house... assuming I could afford it!


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## labotomi (Feb 14, 2010)

CulexPipiens said:


> Is this happening in multiple units? I've got a 15KVA Liebert system in my server room and it's performance has been flawless for about 5 years now. Granted we don't switch on to it that often but ever time we had to it has worked perfectly. For longer than I wanted (during an upgrade with both the old and new systems both online) we also were running at 95-97% of capacity and it handled it like a champ. I'd be all of anything Liebert for my house... assuming I could afford it!


Ours is on all the time, usually converting the 480V input to DC then to 480V output, but upon loss of the input power it shifts to the battery bank. We seem to have problems after restoring power and reconnecting that power to the system.

It's an older system, probably installed around 95 or so when the facility was initially built. It always works when shifting to backup operation, so it isn't a huge concern and the reason we haven't replaced it. When restoring, we're in a condition where a temporary loss of power isn't a big deal. We can just put it in bypass mode until we replace the failed components.


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## Fn/Form (Nov 6, 2008)

vickersja said:


> You mentioned a surge protector... I wonder if that will help to minimize the modified sine inverter effects on electronics?


It looks like you are talking about power conditioning. A power conditioner can help smooth out a modified sine wave, but an effective one might cost as much or more than the inverter. A surge supressor doesn't condition power like that.

A surge protector simply clamps down when the voltage rises (generally 130V for 120V circuits). The devices plugged into it really need at least 2 to 3 feet of power cord; by the time the surge suppression devices clamp, the high voltage will have traveled about 2-3 feet down the power cord to your computer, TV, etc. Also, most people have all the cables coiled up... which is also not good when a big surge hits. It's best to have the surge suppression well upstream... such as the power distribution point ("breaker box") itself. And it largely depends on the quality of your home's grounding system.

Of course, the surge suppression most of us can afford is still helpless on direct or near lightning strikes. I do prefer APC surge products for the wall plug-in types. We sold a lot of them, and APC actually paid out on a customer claim when they were struck by lightning. It was a West Texas convenience store in the middle of nowhere. Their point of sale terminal and dial-up merchant credit line were toasted.

One more thing, and then I'll shut up. Surge suppressors are sacrificial devices. They are "used up" over time by surges caused by the power company, distant lightning or poorly designed equipment connected to it. They need periodic replacement; it all depends on the power quality, storm or static activity and equipment in your locale. If you've had the same one for 6 yrs, it's probably a good idea to replace it.


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## Fn/Form (Nov 6, 2008)

labotomi said:


> Ours is on all the time, usually converting the 480V input to DC then to 480V output, but upon loss of the input power it shifts to the battery bank. We seem to have problems after restoring power and reconnecting that power to the system.
> 
> It's an older system, probably installed around 95 or so when the facility was initially built. It always works when shifting to backup operation, so it isn't a huge concern and the reason we haven't replaced it. When restoring, we're in a condition where a temporary loss of power isn't a big deal. We can just put it in bypass mode until we replace the failed components.


Lieberts of that timeframe were decent. It sounds like you're referring to a Static Switch problem. Phase mismatch during xfer? If it's happening on multiple units I'd start looking at the load, too. If I was servicing it, I'd like to put a Dranetz-BMI power analyzer on the load.


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## LincTex (Apr 1, 2011)

Viking said:


> I'm considering pulling that heavy generator and just develop my own small engine powered 12 volt backup charge system to charge the batteries on days that there isn't enough sun charging available.


I will probably not be worth it. To use your current gen, Just make sure you have a REALLY high capacity battery charger, or step down your AC output and run it through some heavy diodes (basically making your own heavy duty charger). If you just need a smaller set-up, there is that as well.

This will be very helpful if you do choose to do the "DC only" route: http://www.microcogen.info/index.php?board=12.0

http://www.microcogen.info/index.php?topic=2930.msg33137#msg33137


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## LincTex (Apr 1, 2011)

Sorry to hijack... "sort of" but I think most folks posting in this thread would be interested in something very similar to this:

Diesel driven Leese/Neville alternator project:
http://www.microcogen.info/index.php?topic=2763.0

A test was done to see if the alternator could be used to drive my inverter.
I connected the Alternator to the starting battery with #2 cables. I then connected a 2000 watt mod-sign inverter to the battery. The alternator drives the inverter with the battery in the circuit as a buffer (capacitor). Because the battery charge is not drawn down, a standard automotive battery is used. Seemed to work fine, although I have not tried any inductive "spiking" loads yet. The Alternator put out approx. 78 amps @ 12vdc to make 845 watts at the Inverter plug with the engine spinning at 1600 rpm.

The engine had no trouble at that load. In future I will try applying greater loads. If the engine labors, I can simply raise the engine speed. Being a 180 amp (2100 watt) alternator, the system should be able to drive the full capacity of the 2KW Inverter. (Although bigger cables will be needed)


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## Viking (Mar 16, 2009)

LincTex said:


> I will probably not be worth it. To use your current gen, Just make sure you have a REALLY high capacity battery charger, or step down your AC output and run it through some heavy diodes (basically making your own heavy duty charger). If you just need a smaller set-up, there is that as well.
> 
> This will be very helpful if you do choose to do the "DC only" route: http://www.microcogen.info/index.php?board=12.0
> 
> http://www.microcogen.info/index.php?topic=2930.msg33137#msg33137


The inverter has a built in 100 amp charger which is great when the motor home is parked in it's shed and it's been cloudy for so many days that the 20 watt solar charger hasn't been able to trickle charge the batteries enough and the voltage is lower than I like to see. When we were out on the Northern Nevada desert for six weeks we had one cloudy day were it wouldn't recharge the house batteries enough so I just started the diesel motor home engine and charged all the batteries, if I had charged the batteries through running the propane generator I would have used about four of the eight gallons of propane and we needed all the propane we had for the cook stove and refrigerator/freezer. It would have been nice if the generator was run by a diesel engine as they use so little fuel it wouldn't have put a dent in the 90 gallon fuel tank. The Microcogen that you have written about is about what I had in mind, just a small engine and a 12 VDC truck alternator of 150 to 200 amps and I could charge the house batteries and run low power loads off of the inverter at the same time.


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## Viking (Mar 16, 2009)

LincTex, I went to the Microcogen site and that's exactly what I had in mind. A set up like that would take up 1/3rd or less of the space and weight of the generator that's in the motor home now. Thanks for putting a link up as I think it's a great companion set up for solar charge systems that are used for charging the batteries to run inverters. At least at the 12 volt level and there are some alternators that could be used for 24 volt systems like the solar, potentially off grid, system we have in mind. Sorry, this did highjack the post a bit but there is a lot of connection to the pure sine inverter question and I'm honestly going to try and get a sine wave pic to post here when it's not so dang cold outside.


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## cowboyhermit (Nov 10, 2012)

vract: 
Why do so many people go to a higher voltage? Please think hard about the advantages of 12V before you go another way. I know it is the way that mainstream solar has been telling everyone to go. I have had to deal with many remote sites that were converted to 24V or 48V and it can be so frustrating, any little thing you want to add has to be inverter driven or through a dc/dc converter which are really expensive. The proliferation of 12V devices is amazing, you can get almost anything to run on it and it often is not overpriced. For example I picked up a 12V charger for my Makita power tools, it is much more efficient and bypasses any issue with inverters and chargers, it was the same cost as 110V.
The voltage drop issue is not nearly as bad as some would make it out to be, it is completely surmountable if planned out properly.


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## Viking (Mar 16, 2009)

cowboyhermit said:


> vract:
> Why do so many people go to a higher voltage? Please think hard about the advantages of 12V before you go another way. I know it is the way that mainstream solar has been telling everyone to go. I have had to deal with many remote sites that were converted to 24V or 48V and it can be so frustrating, any little thing you want to add has to be inverter driven or through a dc/dc converter which are really expensive. The proliferation of 12V devices is amazing, you can get almost anything to run on it and it often is not overpriced. For example I picked up a 12V charger for my Makita power tools, it is much more efficient and bypasses any issue with inverters and chargers, it was the same cost as 110V.
> The voltage drop issue is not nearly as bad as some would make it out to be, it is completely surmountable if planned out properly.


I've thought this out thoroughly and when Don Rowe added a 4000 and 4400 watt 120/240 pure sine inverters to the inverter line up I liked the idea that I could just run a transfer switch into my existing 120/240 panel, thing is the 4000 watt unit runs on 24 volts and the 4400 watt unit runs on 36 volts. And since they can be stacked if I ever felt I needed more wattage I can easily add another unit. In consideration of ohms law higher voltages draw less amps, no big deal though because I can series/parallel batteries or solar panels and the system I designed wouldn't cost any more if it was 12, 24 or 36 volt.


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## cowboyhermit (Nov 10, 2012)

Yeah, it sounds like you know what you are getting into and if you need 240 then I guess that makes sense, there are plenty of 12V-240V inverters though, surprising they don't have them.
It just has caused me a lot of frustration to have all those batteries just sitting there and no proper way to use them directly, I have access to a lot of 12V equipment. 
In my experience everything that can be run on dc easily should be but others feel if you have the inverter you might as use it.


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## labotomi (Feb 14, 2010)

cowboyhermit said:


> vract:
> Why do so many people go to a higher voltage? Please think hard about the advantages of 12V before you go another way. I know it is the way that mainstream solar has been telling everyone to go. I have had to deal with many remote sites that were converted to 24V or 48V and it can be so frustrating, any little thing you want to add has to be inverter driven or through a dc/dc converter which are really expensive. The proliferation of 12V devices is amazing, you can get almost anything to run on it and it often is not overpriced. For example I picked up a 12V charger for my Makita power tools, it is much more efficient and bypasses any issue with inverters and chargers, it was the same cost as 110V.
> The voltage drop issue is not nearly as bad as some would make it out to be, it is completely surmountable if planned out properly.


It's much easier for an inverter or amplifier to produce the output with a higher input voltage without generating as much internal heat. It really isn't about efficiency but rather physical limitations on heat generation.

I don't see much benefit for home distribution, but for certain applications it has it's purpose.


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## cowboyhermit (Nov 10, 2012)

I am well aware of the reasons for using a higher voltage, I just don't think it is worth giving up the ability to have a battery bank at 12V. It is not that I think that 12V is somehow superior, it is just the proliferation and cost effectiveness of the components available to the general public.
There are certainly many things like circuit boards and cameras that run off of higher dc voltages, particularly those with power over ethernet so 12V is not the only way to run off of dc.


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## labotomi (Feb 14, 2010)

cowboyhermit said:


> I am well aware of the reasons for using a higher voltage, I just don't think it is worth giving up the ability to have a battery bank at 12V. It is not that I think that 12V is somehow superior, it is just the proliferation and cost effectiveness of the components available to the general public.
> There are certainly many things like circuit boards and cameras that run off of higher dc voltages, particularly those with power over ethernet so 12V is not the only way to run off of dc.


If you ask, expect a reply.

In my field, 24V is the standard voltage that components are designed to run on. I could go into technical reasons but they aren't necessary in a residential setting.

Having a battery bank at 24, 36 or 48v is not more difficult than 12v.

There are more 12v appliances available not because of a superiority of 12v, but rather the availability of 12v supply systems.

A system designed for higher voltages does offer advantages over lower voltages. 12v systems offer the availability of more off the shelf appliances.

Its all opinion of the designer as to what is more important. Some go one direction, some go another.


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## Viking (Mar 16, 2009)

If I was to build a new home I would more than likely also wire for 12 volts as well as 120 AC, pretty much like my old travel trailer that had light fixtures with 12 VDC and 120 VAC bulbs in each fixture. As to the system I'll be installing if I use the 24 volt system I'll be series connecting 12 volt batteries so if I ever need 12 volts I can just tap into the jumper between the batteries.


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## cowboyhermit (Nov 10, 2012)

Sure you can always tap 12 volts off a bank but it is not really the right way to do it. Probably won't cause any harm if the load is small but you will not be draining/charging the batteries evenly. Some old machinery we had was 24V but of course they just put 12V lights because of availabilty and cost, the batteries were much more prone to failure. So all these companies, John Deere etc made "upgrade" kits where you switch out the starter, alternator etc, cost a bundle but was money well spent, battery problems solved.

Sorry Labotomi I thought it was clear my question was rhetorical. All your points are valid, I just have a lot of experience with a wide variety of systems and imo 12V is the way to go, like I said not because it is superior but because it is so ubiquitous. That is my opinion.


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## LincTex (Apr 1, 2011)

cowboyhermit said:


> ... and imo 12V is the way to go, like I said not because it is superior but because it is so ubiquitous. That is my opinion.


The merit to 12 volt is simply the availability of 12volt items, and simplicity. It is so easy to get 12 volt items because of the market to so many RV'ers and truckers.


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## labotomi (Feb 14, 2010)

Fn/Form said:


> Lieberts of that timeframe were decent. It sounds like you're referring to a Static Switch problem. Phase mismatch during xfer? If it's happening on multiple units I'd start looking at the load, too. If I was servicing it, I'd like to put a Dranetz-BMI power analyzer on the load.


It's not during any type of paralleling operation, just when restoring AC to the converter. It's not as often as when I first came here so I guess the service techs have made some progress.

I don't have a model number but it's a 150KVA unit. I'm not sure how many differing models are in their lineup.


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