Power Save 1200 Capacitor

SteveK

Re: Power Save 1200 Capacitor

john p wrote: »

Steve K what exactly do you mean by "the battery monitor" ?

John, Yes like Bill said above. I have a Victron battery monitor that measures all the current flowing in and out of the batteries as well as the bank voltage.

On the AC motor I monitored with a Kill-A-Watt meter.

There was no difference in current draw or voltage at the bank with or without the caps. A large percent reduction in current used at the motor with the caps installed.

I was happy with that. I'd like to save some AH in the batteries too if possible though.

Steve

niel

Re: Power Save 1200 Capacitor

so are you guys in agreement on the not saving any power usage from the batteries or any other power source in using the caps?

also are you guys in agreement the cap could possibly allow more items to be run from an inverter that has a finite amount of va capability or at least run what it has more efficiently?

BB.

Re: Power Save 1200 Capacitor

Technically, the motor does not use less current--The point at which the Caps and the Motor connect add the Cap+Motor loads to reduce VA ("out of phase" current) in the branch circuit.

As I understand, there will not be a savings in energy used by the inverter (other than some relatively minor savings in losses from I^2*R heating)--But, as Niel says, it should allow the inverter to run other loads because the VA usage is now less.

And, always make sure the capacitors switch on and off with the motors--Otherwise, there would be the poor power factor of just the capacitor(s) without the motor(s) to balance out the lead/lag current.

By the way, the $30 Kill-a-Watt is not a lab quality power meter... So don't take the readings as gospel down to three decimal places.

-Bill

SteveK

Re: Power Save 1200 Capacitor

Right, I'm with you. The Kill-A-Watt does infact read-out as reduced Amps, Reduced VA but the Watts stay the same. I could connect the Prema bench meter but thought it to be overkill for this. Plus then I'd need a calculator...

john p

Re: Power Save 1200 Capacitor

i think you guys are all missing something .. the trouble the missing part is small.
its a fact there will be less drain on the batteries with the caps for 2 reasons, one the inverter will run slightly more effeciently . this can be proved the inverter will be slightly cooler when using the caps. and because the motor is running more effecient there will be a slight reduction of current drawn from the batteries,, it likely the shunt between the battery and inverter is not sensitive enough to register that,, I dont know that monitor but if it has a 200a shunt it may not show a difference. we not talking about a 30a difference between caps and no caps.
but it can be a difference to some people with a small solar battery system to get the most from the system as even 1/2 an ahr makes a big difference if having to run on batteries for 2 days as no Mr Sun.

BB.

Re: Power Save 1200 Capacitor

Generally the issue with accurate measurements is not usually the shunt but the ability of the meter to properly measure the area under the curves for the current and voltage wave forms.

The meters typically need sample the wave forms vs the standard measure the peak and use 1/root(2) as the conversion factor for sine waves (the difference between a cheap meter and a True RMS meter). And why "cheap" meters do not properly measure the voltage/current on a MSW inverter--because of the non-sine wave output.

For a DC Battery Monitors--They probably only sample the wave form and not nearly fast enough to do a true RMS reading. But, it is probably close enough in with the 120 Hz riding on the DC current wave form that inverters typically have--That it should be able to distinguish the difference between a 0.95 and a 0.6 AC power Factor if it were present...

And for a 2 amp 120 VAC load vs a ~3.3 amp 120 VAC 0.6 PF load--that would be (if the full PF issue carried through the inverter to the DC side) would be a ~20 vs 33.3 Amp difference at 12 volts--Something that I would assume would be apparent with virtually any DC battery monitor.

Maybe we are misunderstanding each other... The capacitors are making almost no difference on the DC side of the inverter (same current, voltage, power).

The difference is purely on the AC side of the inverter and a pretty significant reduction in VA--which can allow other loads to be operated at the same time as the motors as the motor circuit is now (more or less) close to 1.0 PF.

And, if somebody added more loads, the DC input current to the inverter would rise appropriately.

So, we are agreeing that the power savings of the capacitors (and the ability of the battery bank to last longer) is pretty much having no effect on battery current/power draw.

-Bill

mike95490

Re: Power Save 1200 Capacitor

niel wrote: »

so are you guys in agreement on the not saving any power usage from the batteries or any other power source in using the caps?

also are you guys in agreement the cap could possibly allow more items to be run from an inverter that has a finite amount of va capability or at least run what it has more efficiently?

This is what I understand.

SteveK

Re: Power Save 1200 Capacitor

john p wrote: »

i think you guys are all missing something .. the trouble the missing part is small.
its a fact there will be less drain on the batteries with the caps for 2 reasons, one the inverter will run slightly more effeciently . this can be proved the inverter will be slightly cooler when using the caps. and because the motor is running more effecient there will be a slight reduction of current drawn from the batteries,, it likely the shunt between the battery and inverter is not sensitive enough to register that,, I dont know that monitor but if it has a 200a shunt it may not show a difference. we not talking about a 30a difference between caps and no caps.
but it can be a difference to some people with a small solar battery system to get the most from the system as even 1/2 an ahr makes a big difference if having to run on batteries for 2 days as no Mr Sun.

The monitor (from what I've experienced) is certainly able to pickup an 8W LED light bulb John. It has a 500A shunt too. As far as intrinsic accuracy, stability and repeatability goes I know it is not near NIST traceable but it does a great job at relative measurements.

The Kill-A-Watt does great for what it is. Quick and easy.

I love this BMV-602 monitor but always trust the hydrometer ultimately.

So far the only thing that has greatly reduced consumption of battery power (as the Power Saver 1200 here seems to stake a claim to) has been to step away from the Exeltech 1100W inverter and step into the Victron Phoenix 24 - 350 inverter. By doing this it saves me ~5-6AH per day. The Exeltech was vastly underutilized.

So to keep this on topic, the Power Saver 1200 seems to be a scam in my opinion. It would do nothing for me as my inductive loads are below the minimum levels to allow it to operate effectively in any fashion. And would never save me a nickel on the poco bill.

john p

Re: Power Save 1200 Capacitor

well I cant give an answer to what has been said, but its the first time ive had someone tell me the battery current did not go lower when thepower factor was improved by adding caps on motor or using better quality better power factor CFLs,, as I always have shown people a battery drain reduction. and as I have said now a few times some of it is because the heat generated by the inverter is lower.. and that means less power consumed(wasted).
As i dont know that battery monitor cant realy say much about it.or how it actually measures the current.. as there are many ways to do it.

john p

Re: Power Save 1200 Capacitor

lets all think about this before typing something,, This was the original claim..Like you said it did not reduce the amount of current from the batteries but there was large current savings after the inverter.

I sourced 2x2MFD and 2x3MFD run caps at my local Grainger. 2x3MFD in parallel reduced my current draw at the combustion motor (24/7 operation) from .49A to .27A, PF from .61 to .95.How can that be possible.. its like saying you have 10x10w lamps connected to the output of an inverter you turn one off the battery current remains the same?? Is someone going to tell me that is possible? If the output current of the inverter dropped then why does the inverter still draw the same current from the batteries?? if it does where is that not used (on the inverter output) current going.???,, or am I just getting so old as to not understand this??

BB.

Re: Power Save 1200 Capacitor

I believe you are missing the AC math part of the equation. AC power based on driving inductive or capacitive loads is:

Power = voltage x current x cosine (lead/lag of current vs ac voltage sine wave)

You can equate this to pulling on a rope when towing a car.

Stand in front of a car, cosine of zero degrees is 1.0 (aka power factor)

Stand 60 degrees to the side and cos 60 is 0.5 -- or you have to pull twice as hard on the rope to move the car the same distance. Still the same amount of work because you are moving the same direction as the car so the force pulling side ways has no relative motion to the car.

-Bill

john p

Re: Power Save 1200 Capacitor

i am missing something .. In all cases I have seen where the power factor has been improved by whatever means the inverter runs a little cooler.. .OK? Now explain how that took no battery power to make it run "hotter" with a poor power factor ??

BB.

Re: Power Save 1200 Capacitor

I do agree that the inverter can run cooler, but the power savings is not that great.

A typical inverter with 85% efficiency probably only has something like 5-8% loses as I^2R loses, which means that you may be looking at a 2 to 4% reduction in dc input current.

This is getting pretty close to the measuring limits of the standard solar re metering equipment.

Also there is a lot of variables based on loads as a percent of inverter rating.

An inverter running at 100% va rating saving 40% current flow vs an inverter running at 10% rated va and saving 40% of that when much of the losses at low power are capacitive switching losses which are relatively independent of load.

Lots of variables and assumptions in my attempt at an explanation.

-Bill

john p

Re: Power Save 1200 Capacitor

BB in other words in all the posts trying to give explanations that there is no reduction in battery current with improved power factor are incorrect.
I see in your last post you now state yes there will be a reduction admittadly a small one.. Isnt that EXACTLY what ive been posting in the last few posts??/If you are getting no reading of a reduction of reduced battery drawn current then there is a problem with how either the measurement is being done or the way the device is measuring the current.
I f you have poor power factor you MUST be getting reflected power waste back into the inverter and its disipated as heat,, As I already said.. You reduce that reflected power loss the battery current MUST then go lower.

The problem is not my not understanding the AC maths,, My test has always been simple . connect a 50a shunt in series with the inverter use a good multimeter to read the voltage(current) across the shunt.. Connect 10x14w low quality (poor power factor) CFLs in parallel to the inverter . Note the reading on the multimeter,now connect 10 x14w good quality CFLs across the inverter now measure the current drawn from the battery IT WILL BE LOWER..

BB.

Re: Power Save 1200 Capacitor

John,

Perhaps I misunderstood this post...

john p wrote: »

lets all think about this before typing something,, This was the original claim..Like you said it did not reduce the amount of current from the batteries but there was large current savings after the inverter.

I sourced 2x2MFD and 2x3MFD run caps at my local Grainger. 2x3MFD in parallel reduced my current draw at the combustion motor (24/7 operation) from .49A to .27A, PF from .61 to .95.

How can that be possible.. its like saying you have 10x10w lamps connected to the output of an inverter you turn one off the battery current remains the same?? Is someone going to tell me that is possible? If the output current of the inverter dropped then why does the inverter still draw the same current from the batteries?? if it does where is that not used (on the inverter output) current going.???,, or am I just getting so old as to not understand this??

Stevenk is only looking at 30 watt motors or so (~50 VA)... So if he has a 600 watt+ inverter--the amount of I^2*R losses saved are very small compared to the (guessing) 6-12 watts of the inverter's switching losses with the inverter running very light loads (either outside the accuracy of the equipment or buried in other losses).

From my post almost a week ago:

In theory, the poor power factor does not cost you any battery energy. The inverter only uses battery power to run the 0.6 of the current that is doing real work.

In practice, this costs you in two ways.

First, most off grid inverters have a watt output rating that is the same as their VA rating. The end result is that the motor with poor power factor is "using/wasting" current that could be used to run other devices.

Second, heating loses are equal to I^2 * R... So if you had a power factor of 0.5 , that device is using 2x the current but causing 4x the wasted energy as heat.

So, I guess I was misunderstanding what you where looking for--Any current reduction vs a 40% reduction in current by changing from 0.6 to 1.0 power factor... There will not be a 40% reduction in DC input current to the inverter with this level of PF correction (even with large motor loads).

If we are looking at the RMS AC current reduction (by correctly power factor) reduces losses (possibly at an unmeasurable level at low inverter loading)--Then I don't think we are disagreeing.

-Bill

SteveK

Re: Power Save 1200 Capacitor

john p wrote: »

Connect 10x14w low quality (poor power factor) CFLs in parallel to the inverter . Note the reading on the multimeter,now connect 10 x14w good quality CFLs across the inverter now measure the current drawn from the battery IT WILL BE LOWER..

John, How much lower is it? What size inverter and at what % capacity? At what percentage of the load is the inductive load?

Bill, I'm using 31W at the one motor on a 350W cont. sine inverter.

If I need to go to lab equipment to see the savings they would amount to nil. The BMV has resolution to to a hundredth for V and A. Calibrated? Definately not but I'd see movement there switching the caps in and out.

So at these levels, like I said above, nada.

Thanks!

SteveK

Re: Power Save 1200 Capacitor

Ok I bit the bullet and tested battery current using my Prema bench meter. This meter is an upper mid-end piece and has been calibrated to NIST standards and was traceable 2 years ago. Here's what I found.

Inverter idle current .22A
DC current with caps installed on motor 1.32A
DC current with caps removed from motor 1.345A

This means that the:

Inverter uses 5.2W in idle current.
Inverter is 92.2% efficient while running a 31W load.
Capacitors saved .025A of DC current draw.

On the setup with inverter losses included the caps saved 1.85% in DC current.

This is the equivalent of .625W @ the 25V bank voltage.

So yep there seems to be a savings.

niel

Re: Power Save 1200 Capacitor

if one doesn't have good sized dc wires the extra current could make things a bit worse, but it would seem to be the overall loss represented here is too small to bother with in most cases. what i don't know is what the ac load was that you were using and what its pf was.

BB.

Re: Power Save 1200 Capacitor

Niel,

Way back:

SteveK wrote: »

Hey guys just checking in on this. It works great!

Like you said it did not reduce the amount of current from the batteries but there was large current savings after the inverter.

I sourced 2x2MFD and 2x3MFD run caps at my local Grainger. 2x3MFD in parallel reduced my current draw at the combustion motor (24/7 operation) from .49A to .27A, PF from .61 to .95.

The two 2MFD in parallel raised the feeder motor for .54PF to .74 PF, I need a better combo here.

Not too shabby I thought!

Thanks again!

Stevek,

Thank you for the testing. It is always nice to have real numbers to backup the discussions.

In the end, remember where Stevek save lots of energy was to go from a ~1,100 watt inverter to a 350 watt inverter to power the 30 watts of 24x7 motors--The smaller inverter using less idle current (less switching losses) and is more efficient at the loads Steve needed to run.

-Bill

SteveK

Re: Power Save 1200 Capacitor

Niel,

Yes right. It is not worth fussing with caps for me. It will take 67 days to save a 1 KWH and the payback will be around 19 years on a $12 investment at local poco rates....:p. 38 years if I only count the winters...

Bill,

Glad to do it! I'm not sure to say this is I^2 R losses but it sure fits the bill from what I know... One thing for sure, I like this Phoenix inverter much more now. It was the alternate for the SureSine that I couldn't use.... Wish they would make it in 24V!!!

Thanks again to all, I learn so much here...

System2

Re: Power Save 1200 Capacitor

Hey russ,

I loved Adair. Have you used them yet or did you get a consultation? Someone on here says you can save money doing your own install and adding glazed windows... yikes! I knew people who did this in NJ and ended up having to scrap everything and get a real co. in there to install. You just don't know what you're getting into if your not an installer I think. Adair did my consultation for free and were fast to install and still check in with me to see how my equipment is doing. Overall very pleased.

f5f9

Re: Power Save 1200 Capacitor

Hello.

I see this is an old topic.

Does the Power Save 1200, Electric Saver 1200 or any of its kin help with brown-outs for heavy draw items like a pump?

Would it be better to add a capacitor to each heavy draw induction item?

Really not into it for the "savings".... just the little boost when I need it. Hate the "electric chair" dimming effect when the pump comes on.

TIA!

niel

Re: Power Save 1200 Capacitor

no.
they won't act like mini-batteries to store power for such things. we are talking about ac here and not dc, but if it were possible it would've dumped that little bit of power in a matter of a split second.

if such a thing were possible then we would not be seeing backups with batteries and inverters.

levent

Re: Power Save 1200 Capacitor

Hi steveK,

Is it true that It will take 67 days to save a 1 KWH ? How did you know it?

BB.

Re: Power Save 1200 Capacitor

Yep... He just measured the DC input power to his AC Inverter--Once with the capacitors, and a second time without the capacitors.

Are you familiar with Power Factor and AC circuits? It is not a straight forward subject and takes a bit of time (and math) to understand.

-Bill

inetdog

Re: Power Save 1200 Capacitor

bradturner32 wrote: »

Anyone seen or tested these systems?

http://www.power-save.com/1200.html

They look inexpensive and the power surge protection alone would be worth it; I've spent well over $300 in UPS and Surge protectors for my audio/video and computer equipment.

It still seems to be basically a scam. No change there over the last few years.
If you are not an industrial/commercial customer your utility will not not penalize you for low power factor, even though it costs them more.
Any "Surge Protector" which does not provide ratings in terms of max voltage and energy capacity in Joules is not worth looking at. Check the ratings on your current equipment and then try to get the corresponding numbers from PowerSave.

For the situation where you DO pay for low power factor (like when you are using an off-grid inverter) it might make some sense, but the best thing would be individually sized capacitors on the load side of the control switch for each large motor load. You do not want to overcorrect into capacitive loading with some inverters!

swmspam

Re: Power Save 1200 Capacitor

BB. wrote: »

...Stevek save lots of energy was to go from a ~1,100 watt inverter to a 350 watt inverter to power the 30 watts of 24x7 motors...

...67 days to save a 1 KWH...

So SteveK was saving 1kWh over 67 days running a 30 Watt motor. That's tiny!

Pretend my reactive load is 900 total watts of refrigerators, HVAC, motors, CFLs, etc. Now the calculus changes dramatically. My situation is 900W/30W = 30 times as large. SteveK's time to save 1kWh becomes (67 days / 30) = 2.23 days for me. The total savings would be 163 kWh/year. At $0.50/kWh (I made that up), that's $82/year. The $299.99 magic box would take 3.65 years to pay back. And I consider my mathematics optimistic. Be forewarned: your mileage may differ. I assumed SteveK's numbers were a good starting point. My refrigerator and new technology such as CFLs may be different. Note: don't discount the power factor of CFLs. There is a lot of misunderstandings about Watts and VA (volt-amps) when discussing reactive power. The average CFL has sufficiently bad power factor that some European utility operators (such as Vattenfall) have taken action. Instead of monitoring power factor for each individual residence and billing accordingly, Vattenfall simply raised the overall rate for everybody:

to compensate for reactive effect from home electronics and CFLs with poor power factor, a generalized extra fee is included in the standard price per kWh

So in Europe, the utility company is already charging you for your poor power factor. If you purchase a Power-Save box, you'll be paying twice for your poor power factor. This won't change unless utility companies start monitoring power factor for each individual residence, like they do businesses.

As mentioned in a previous post, it's not a good idea to load your expensive inverter output with a heavily reactive capacitive load unless you talk to the inverter design engineer first. All this math says I'd rather hang another $300 of solar panel than buying the Power-Save box, or perhaps buy some weather stripping or extra insulation somewhere. Otherwise, donate canned goods to your local food pantry with the money.

BB.

Re: Power Save 1200 Capacitor

And capacitors will not "correct" bad power factor for a typical CFL or computer power supply.

Inductors and capacitors "shift" the phase of the current relative to the voltage (current "leads" voltage for capacitors; current "lags" voltage for inductors--Put both together, correctly, on the same wire, and they cancel each other out).

"Non Linear" loads like "inexpensive" power supplies in many CFLs and computers only takes a "spike" of current near the peaks of the AC voltage sine wave. A capacitor will not materially affect or smooth out the current spikes--It will still be a poor power factor.

-Bill