Most Efficient sub-100W DC➡AC Inverter and 120V Light Bulb

[LEDAdd1ct]

Greetings, Fellow Fans of Photons!

I have a few questions/thoughts/considerations about both the efficiency of DC ➡ AC inverters as well as the most efficient 120V light bulb.

1) I plan to acquire a high capacity 12V LiFePO4 battery.

2) I plan to acquire the most efficient/reliable 100W equivalent 1600 lumens LED light bulb.

a) I have intensely researched 12V bulb options, and the only models I can find out there are poorly reviewed with suspect build quality

b) Additionally, while there is certainly an efficiency penalty to converting 12V DC to 120V AC, it would provide the greatest degree of flexibility in being able to swap out bulbs

3) Does anyone have a recommendation for the "most" efficient 120V 1600 lumen LED light bulb?

a) The best that I can find is the IKEA Solhetta, which is rated at

2700K
10.5W
1600 lumens

4) Can anyone provide information about the efficiency costs for a 50W, 100W, and 150W...DC ➡ AC inverter...with especial respect paid to this bulb, i.e., a 10W to 25W draw?

5) I would prefer an inverter "Made in U.S.A." if possible, but barring that, something from a name brand, established company would be ideal.

6) Does anyone know of a more efficient way to get 1600–2000 lumens in this format, i.e., a very high efficacy 12V fixture?

a) I can't find anything more efficient than the 10.5W IKEA bulb
b) Staying with 12V DC and cutting out the inverter...would be nice

Thank you!

 

[KITROBASKIN]

You should really consider getting a Morningstar 300W inverter. American made, employee owned last time I looked.

We have had the Classic for 27 years: very quiet, barely audible under significant load (designed to not need a fan) if you are close to it. Efficiency may be better with the new generation of Morningstar inverters, but it is plenty sufficient for us.

Like so many of us, we find other uses for AC, so 300W may end up lacking in the future for you...

Off-Grid Solar Inverters | Reliable Remote Power

Discover Morningstar Corp's high-quality Off Grid Inverters, perfect for providing clean and stable power to your off-grid solar systems.

www.morningstarcorp.com

 

[LEDAdd1ct]

Thank you very much!

1) I had never heard of this company before but I will be researching them thoroughly; thank you so much!

2) I actually just discovered that Philips now has a P.D.E. (Pretty Darn Efficient) series of 60W equivalent and 100W equivalent LED light bulbs:

8.5W draw
1540 lumens output
3000K CCT
90CRI
Efficacy = 181 lumens/watt

Link

3) Now the question is "Which inverter will throw away the least energy to go from DC to AC...?"

 

[KITROBASKIN]

diysolarforum has information about Morningstar, but a wealth of other products.

 

[Ocelot808]

Here's an inexpensive and simple solution for the DC to AC inverter problem. For $17 this Amazon find can provide 150W of 110 VAC, enough to run ten of the excellent Philips PDE bulbs plus it has 2 dedicated USB outputs as well.

150W Power Inverter 12V DC to 110V AC Car Plug Adapter Outlet Converter with 3.1A Dual USB AC car Charger for Laptop Computer Black https://www.amazon.com/dp/B08YTH66FN?tag=cpf0b6-20

 

[Dave_H]

A 150-300W invertor driving a 10W bulb? Besides overkill, efficiency at such low end is very likely to be dismal, which sort of defeats the purpose. I'd consider a 50-75W inverter but suspect even so the efficiency will not be good. I would check into this.

OP may want to consider automotive "auxiliary" LED lights which typically run from 10-30vdc Most would not pass automotive standards for in-motion use but they have plenty of other uses. The issue for many of these is the form factor: not a screw-base bulb. Something might be rigged with a small spot/flood with attached diffuser.

Some other downsides are limited CCT choice (usually 5000K-6500K) and lack of dimmability, if that matters.

Dave

 

[orbital]

+

Having straight DC bulbs is an option. ..Save that 15% DC~AC conversion
I have a number of DC bulbs, fun hobby stuff

do need to get light socket(s) to hook up pos. / neg.

12V filament led

Amazon.com

www.amazon.com

 

[KITROBASKIN]

Good luck finding a nice quality, efficient, reliable pure sine wave inverter in the lower wattages being discussed here. Please report here if you do.

I did not want to muddy the waters by going into more detail about the massive advantages of having clean, reliable AC power for other needs than a single light bulb.

When the power goes out, having an AC source to charge phones and other communication devices is priceless. Years after getting that Morningstar inverter, we got a 600W Xantrex. It is used daily to power our Viasat system. It can charge the battery for our Stihl chainsaw…

Couple years ago we purchased as a back up to the home off-grid system a Victron Phoenix 24V 1200VA (~1200W). It is used in a mobile setup during fire season and stationary otherwise, as a source to cook with an induction cooktop and a small toaster oven as well as a parabolic dish personal heater when it is cold.

Victron is very popular for maritime and road uses. A lot of it is built in India but based in the Netherlands. They are known for efficient inverters and charge controllers. Reliable but not always perfect of course.

 

[Dave_H]

Good luck finding a nice quality, efficient, reliable pure sine wave inverter in the lower wattages being discussed here. Please report here if you do.

I did not want to muddy the waters by going into more detail about the massive advantages of having clean, reliable AC power for other needs than a single light bulb.

When the power goes out, having an AC source to charge phones and other communication devices is priceless. Years after getting that Morningstar inverter, we got a 600W Xantrex. It is used daily to power our Viasat system. It can charge the battery for our Stihl chainsaw…

Couple years ago we purchased as a back up to the home off-grid system a Victron Phoenix 24V 1200VA (~1200W). It is used in a mobile setup during fire season and stationary otherwise, as a source to cook with an induction cooktop and a small toaster oven as well as a parabolic dish personal heater when it is cold.

Victron is very popular for maritime and road uses. A lot of it is built in India but based in the Netherlands. They are known for efficient inverters and charge controllers. Reliable but not always perfect of course.

I don't doubt that what you have works for you. For OP's case we are short some information such as battery capacity, expected/minimum runtime, and converter efficiency at expected current.

Why would someone need pure sine wave (versus "modified" sine wave which admittedly looks a bit ugly) to run lighting?

Dave

 

[KITROBASKIN]

Other needs when power goes out, plus it is so convenient once you jump in, to use it for other purposes. LED bulbs have electronic circuitry that may not play well with lousy square sine wave.

 

[aznsx]

Re: sine wave AC...

I can understand why one would wonder 'why would a light bulb care?', and in most cases it probably doesn't. However, the reason I would want to stick with proper sine wave AC power is harmonics. I do not want nasty, harmonic-ridden signals, conducted or radiated, fouling my electronic environment. Unless one is using them for something specific, harmonics are, more often then not, a potential problem / liability, and thus best avoided.

Some may be unaware that a square wave is essentially equivalent to the sum of a sine wave at the same fundamental frequency, plus all the odd harmonics thereof. Do a net search on 'square wave harmonics' sometime if you'd like to learn more.

EDIT: If you want to know how nasty it 'sounds', turn your audio amp up until it starts clipping;-)

 

[aznsx]

If you want to know how nasty it 'sounds', turn your audio amp up until it starts clipping;-)

PSA - On second thought, don't do that, at least not for long. That will overheat the voice coils of your speakers (which tells you how much speakers like that garbage). You can imagine how much some other things like it. I didn't mean to provide a case in point involving destructive testing though

 

[Macgravy]

Just thought I would chime in...Some tweeters do NOT like clipping at all and will burn out upon even the smallest amount of clipping. Another word of caution.

 

[Dave_H]

I understand and agree, crude modified-sine is not good for some purposes, but OP is asking about running low-power lighting from battery source, at best efficiency. A large inverter at light load is unlikely to be optimal. A small convertor closer to load current may be OK. No inverter with 12v lamps would be better.

As for LED bulb reaction to modified-sine wave, depends on the driver, particularly what these super-high efficacy bulbs are using. Most ordinary cheap LED bulbs directly convert ac to dc which feeds a linear regulator with some headroom, probably OK.

OP would ultimately need to decide if particular inverter efficiency is good enough. Some testing might be in order if feasible, especially if spec is not available (possibly borrow something before buying).

The 12v filament bulbs linked to are in the right direction but at 6W are not going to put out anything close to 1600 lumens; but they don't claim to (in fact don't specify). I'm not nixing these, just leery about some stuff which is "light" on key specs. It does say runs on 12v and 24v, interesting what's inside for driver, may be similar to other 12/24v lights which use buck driver such as PT4115E, pretty amazing for what they can do.

Dave

 

[Dave_H]

I ran some informal tests on a couple of older modified-sine inverters, 150W and 175W,
using 100W eq. LED bulb rated 15W (measured 14W on power meter).rto

Both drew about 1.6A at 13v input (20.8W) so efficiency looks like 67%, not surprising
down at 10% of maximum load. A really good bulb (8.5-10.5W) will be even further down.

With no load, both drew 0.1-0.2A, not bad, one was spec'ed at 0.25A.

I have a 75W inverter somewhere but I expect it would not show much better efficiency.

Best option seems to be 12v lamps directly off the battery.


Dave

 

[snakebite]

Time to roll your own dc fixtures.
Running from an inverter probably incurs more losses than the load consumes.
There are plenty of 12v in led drivers on ebay around 900ma.
So 3 high quality power leds in series.
Example is 3 nichia 219c in a lamp here.
280lm ea at 700ma
Around 1000lm at 900ma.
2 drivers and 6 leds to hit your target.
And you get to chose color temp and cri vs settling for whats available in a mass produced bulb.
Start with a metal fixture as a heatsink

 

[snakebite]

Example

 

[Dave_H]

Here is a spreadsheet of some bulb scenarios with and without inverters at different efficiencies. Light outputs are not the same, but can be scaled. I have assumed the 6W 12v filament bulb is 600 lumens based on similar products, as is not spec'ed. Most efficient 120v option (line 3) would be small inverter at 90% efficiency. with Philips bulb; but likely most expensive.

Dave

 

[Dave_H]

Example

Hard to tell exactly from image, but I see what appears to be four diodes at the input. White wires indicate polarity does not matter. A diode bridge adds up to 10% loss depending on diodes used (silicon or Schottky). If the rest of converter has (say) 90% efficiency (but it is not spec'ed), it would go down to 85% or 80%. I wonder which IC is used, could look up its datasheet if I could read its markings.

I found my 75W inverter. Test results were similar to 150W, standby current was 0.2A, current for 14W bulb was around 1.5-1.6A. Interesting that it did not vary much between 11v and 13v input, and dropout was around 11v. Seems to indicate nothing is gained going above 12v input, but LiFePO4 4-cell if that's what's used would be 13v or so.

Dave

 

[Dave_H]

OP still hasn't stated whether a roll-your-own approach is the way to go, or more of plug-and-play. I am not discouraging it, just that acquiring LEDs, mounting on a proper PCB, heatsinking, enclosure, optical (diffuser etc.) can be a lot of work. "Star" PCB with 3 per would be OK.

Using shown driver, maximum power available to three series LEDs is nominally 8.1W (3v x 0.9A). Output range 9-12v means 3 LEDs, four would be iffy depending on input voltage and LED Vf.

Assuming 80% driver efficiency, total power is 10.1W. Getting 1600 lumens from 8.1W requires efficacy around 200 lumens/W which at this power level is in question, but some get close (ideally). 150 lumens/W is achievable but still only yields 1200 lumens. Doubling up (6 LEDs) will consume around 20W for double the output.


Dave