In enquiry LED strings… Powerpacks, Solar Panel, Inverter

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In enquiry LED strings… Powerpacks, Solar Panel, Inverter

Postby griffen » Tue Aug 10, 2010 2:48 pm

In enquiry into the power usage of LED strings… Powerpacks, HaborFreight, Kill-a-Watt, Solar Panel, Inverter

I ordered 8 Sets of LED all look and run perfect. ( I also have some Solar backups)

http://www.amazon.com/Commercial-Grade- ... B003T0LZRU
http://www.amazon.com/Commercial-White- ... B003T0IF1Y

2 Strings of Cool White top left & 6 sets of Commercial Grade Blue. Need some lights for Burning Man and I like that shipping is only $7 for all 8 sets of lights... The color is perfect. The Whites are 40-50% brighter but the blues are gorgeous and still bright. Will use kill a watt and report back the power usage.

(Pics uploaded to amazon)

Plugged it into a Kill-A-Watt
On a standard 120 house line
Power draw is 0.03 - 0.04 Amps or 2-3 Watts per string
8 strings power draw is .32 Amps or 38 Watt
60 HZ and .93 PF and a VA of 3

I plugged it into the HaborFreight Chicago Electric 600W amp crank. $79 on sale
http://www.harborfreight.com/5-in-1-por ... 96157.html
I was sadly disappointed… I had pictures of all the energy use etc.. but camera got stolen and I lost all the data. Yet, I know it only lasted 4 HOURS!!! before it started squealing! Damn internal inverter fan ran on the Powerpack the whole time… I’m sure that cost me 4x the power of the lights. So that just won’t work… I was trying to figure out what I wanted to do…

Anyone have input on the Duracell model? Does it’s fan run all the time too?

I already purchased the invertor $70

http://www.costco.com/Browse/Product.as ... Desc1&Sp=C

I was planning on the $300 panels and using them more each year… but my car got busted into $200 window and lost $150 camera (with the kill-a-watt photos and $300 worth of cloths etc.) so I’m trying to reign in the project. Anyway
I 'm leaning away from $300 panels now, not sure I would need all that to run just a light strings anyway… the $100 5 watt toppers? (also possible I run a pump [solar?] for the evap pool.. with a back-up regular pump… Anyone else do a Solar Pump on their Evap Pool build?)

[If anyone can help with my power needs calculation it would be great the only thing I need to run is the lights the power draw is the 0.03 - 0.04 Amps or 2-3 Watts per string with a total of 8 strings power draw is .32 Amps or 38 Watt for 8-12 hours a night… with 10% inverter penalty wouldn’t that be 418 a night worse case (probably 4 strings are turned off at night… for probable 300 watt burn a night or can I even measure in watts? Amps 11.35 amp hours a night? Not sure I got any of that right]

$300 solar panels 60 watts
http://www.costco.com/Browse/Product.as ... opnav=&s=1
$100 2x 5watt trickle chargers
http://www.costco.com/Browse/Product.as ... opnav=&s=1

Costco Deep Cycle Marine batteries planning on 2?
Can I use the 27 DC or is that oft current from 24 DC? Will my converter just adjust it?
27DC Fitment code 16: DeepCycle 750CA/115Ah = $68$
or just the
24DC Fitment code 15: DeepCycle 685CA/95Ah = $62

Tell me where I’m steering wrong please…
See ya on the playa,
War & Love
Griffen Agrippa
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Postby kickstart » Wed Aug 11, 2010 1:41 am

just a quick note on the costco batteries (or any other deep cycle battery of a similar type). the "27DC" and the "24DC" are both referring to the size code of the battery.

for the price difference, if you choose to go this route, get the bigger battery if you have space for them.
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Re: In enquiry LED strings… Powerpacks, Solar Panel, Inver

Postby kman » Wed Aug 11, 2010 3:44 am

griffen wrote:In enquiry into the power usage of LED strings… Powerpacks, HaborFreight, Kill-a-Watt, Solar Panel, Inverter

I ordered 8 Sets of LED all look and run perfect. ( I also have some Solar backups)

http://www.amazon.com/Commercial-Grade- ... B003T0LZRU
http://www.amazon.com/Commercial-White- ... B003T0IF1Y

2 Strings of Cool White top left & 6 sets of Commercial Grade Blue. Need some lights for Burning Man and I like that shipping is only $7 for all 8 sets of lights... The color is perfect. The Whites are 40-50% brighter but the blues are gorgeous and still bright. Will use kill a watt and report back the power usage.

(Pics uploaded to amazon)

Plugged it into a Kill-A-Watt
On a standard 120 house line
Power draw is 0.03 - 0.04 Amps or 2-3 Watts per string
8 strings power draw is .32 Amps or 38 Watt
60 HZ and .93 PF and a VA of 3

I plugged it into the HaborFreight Chicago Electric 600W amp crank. $79 on sale
http://www.harborfreight.com/5-in-1-por ... 96157.html
I was sadly disappointed… I had pictures of all the energy use etc.. but camera got stolen and I lost all the data. Yet, I know it only lasted 4 HOURS!!! before it started squealing! Damn internal inverter fan ran on the Powerpack the whole time… I’m sure that cost me 4x the power of the lights. So that just won’t work… I was trying to figure out what I wanted to do…

Anyone have input on the Duracell model? Does it’s fan run all the time too?

I already purchased the invertor $70

http://www.costco.com/Browse/Product.as ... Desc1&Sp=C

I was planning on the $300 panels and using them more each year… but my car got busted into $200 window and lost $150 camera (with the kill-a-watt photos and $300 worth of cloths etc.) so I’m trying to reign in the project. Anyway
I 'm leaning away from $300 panels now, not sure I would need all that to run just a light strings anyway… the $100 5 watt toppers? (also possible I run a pump [solar?] for the evap pool.. with a back-up regular pump… Anyone else do a Solar Pump on their Evap Pool build?)

[If anyone can help with my power needs calculation it would be great the only thing I need to run is the lights the power draw is the 0.03 - 0.04 Amps or 2-3 Watts per string with a total of 8 strings power draw is .32 Amps or 38 Watt for 8-12 hours a night… with 10% inverter penalty wouldn’t that be 418 a night worse case (probably 4 strings are turned off at night… for probable 300 watt burn a night or can I even measure in watts? Amps 11.35 amp hours a night? Not sure I got any of that right]

$300 solar panels 60 watts
http://www.costco.com/Browse/Product.as ... opnav=&s=1
$100 2x 5watt trickle chargers
http://www.costco.com/Browse/Product.as ... opnav=&s=1

Costco Deep Cycle Marine batteries planning on 2?
Can I use the 27 DC or is that oft current from 24 DC? Will my converter just adjust it?
27DC Fitment code 16: DeepCycle 750CA/115Ah = $68$
or just the
24DC Fitment code 15: DeepCycle 685CA/95Ah = $62

Tell me where I’m steering wrong please…


Ok, first some basic information.

In general, with deep cycle marine batteries, the lead-acid technology used means that you don't actually get the full rating out of them. The batteries literally start eating themselves as you start dipping below 50% discharge.

So if you take 120 amp-hour batteries, you really only get 60 amp-hours of use out of them before you need to get some juice flowing back into them.

The Harbor Freight power station you linked only has an 18 amp-hour battery in it.

Do you see why this is a problem?

Second, inverters. Inverters are incredibly inefficient. You actually waste at least 10% of your power in the conversion from DC to AC. Further, inverters only hit this "peak" efficiency (I use that term loosely) when they're running close to their maximum output. In other words, big inverters that are oversized for your actual needs draw a LOT more power than they need to, just because they (theoretically) have to be ready to supply more power than is being asked at any time, up to their rated capacity. So that 600w inverter is horribly mismatched to a tiny 18 amp hour battery.

If you're only running a few strings of lights, 38w actual power draw, you want to match that size as closely as possible. In other words, the most efficient setup you could get would have an inverter that's rated just 10% over your actual needs. If you need 38w, 38+10%= 41.8. So a great inverter for your needs would actually be rated at 45w, let's say.

Run your same strings off a 45w inverter plugged into the same Harbor Freight power pack and you should see a significant jump in output. Just keep the built-in monster inverter off and use a 45w inverter plugged into the cigarette lighter jack instead.

Clearly, however, you'd be much better off going with a big deep cycle battery. 120 amp-hours (or more) is a heck of a lot more runtime than the puny 18 amp hour battery in the HF power pack. I'm using the Costco 115 amp-hour battery, and it's a nice battery. A bit big and heavy as hell compared to the little portable "power packs", but there are no free lunches when it comes to power.

Figure out the amperage draw of a 45w inverter pushing all 8 strings of lights, and you can see how long you'll be able to run it using half of the 115 amp hours of capacity before you need to recharge your battery.

As for charging, you have a number of options, ranging from solar cells, to hooking up to a friend's generator, to simply turning your car on with jumper cables attached to your battery and letting the alternator charge it up while your engine idles. (No escaping some math no matter which way you choose, but at least it's not overly complex math)

PS: Your calculations seem headed in the right direction, although I haven't double-checked them individually (did you do the math to convert your draw to 12v?). All you need to know is:

Watts = Volts * Amps
Volts = Watts / Amps
Amps = Watts / Volts
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Postby Zhust » Wed Aug 11, 2010 6:23 am

In case you're curious, I wrote an Instructable on analyzing the power differences between rewiring a string for 12V and using an inverter. In the end, you really can't match the 11-14V car output (or even the 11.5 to 12.9V battery output) close enough to really gain any efficiency savings by rewiring the strings versus just using an inverter.
May your deeds return to you tenfold,
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Postby Token » Wed Aug 11, 2010 6:32 am

Stop! Don't Panic there Zaphod!

Get your towel and drape it over your shoulders!

The led lights you got are expandable and you can connect several strings together ti the same plug, correct? This what the Amazon page sayz.

Look at the led string.

There should be a two prong NEMA plug on one end that goes in the wall.

A cable runs from the plug to a rectifier; this could be a small box or even embedded in the cable.

The cable should go to a locking twist connector where you can unscrew the led part from the plug part.

Then come the led lights and at the end of that cable should be another twist lock connector which is used to link multiple string together from the same line socket.

You can easily measure the voltage on the end of the led string by using a multimeter.

Be very careful not to electrocute yourself.

The individual led lights probably run on 3V DC, maybe less.

You can also measure the voltage out of the cable that has the rectifier as well to be sure.

Most led lights that plug into a wall socket can be quickly converted to direct battery operation.
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Postby Token » Wed Aug 11, 2010 7:02 am

@JCR - Good Geek! I like it.

The only benefit seems to be fewer moving parts via the inverter being eliminated.
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Postby kman » Wed Aug 11, 2010 10:34 am

jaycerochester wrote:In case you're curious, I wrote an Instructable on analyzing the power differences between rewiring a string for 12V and using an inverter. In the end, you really can't match the 11-14V car output (or even the 11.5 to 12.9V battery output) close enough to really gain any efficiency savings by rewiring the strings versus just using an inverter.

Well done!

That's a LOT of work, though. I agree that when you start breaking down AC-designed lights, and re-wiring them, it's probably not worth bothering to convert them to DC power. Too many resistors and such (not to mention lots of soldering) are needed.

Better to start off with LEDs that were designed with 12v power sources in mind in the first place.

OR to use a properly-sized inverter. Again, the issue for the OP was not really using the inverter, the issue was using too large of an inverter for the project at hand. That wastes a lot more juice than simply using the right size inverter in the first place.

I know Harbor Freight is not alone in this (I own a Black & Decker and Duracell power stations that are very similar), but the idea of [permanently] marrying a large inverter to a small battery is downright silly, unless it's really only for use for a few minutes at a time. For small projects, better efficiency is obtained by using a small inverter. The good news is, the small cheap inverters are... cheap. :)
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Postby uski » Wed Aug 18, 2010 6:51 pm

You can use LED strings such as these:
http://www.dealextreme.com/details.dx/s ... r.78212949
(actually bought 5 of them)

I've found they run quite well at 3.4V, and don't use as much current as they do at 4.5V (nominal voltage).

Plan for 300mA @ 3.4V per LED string, this is 1.02W

Use a step-down switching regulator to generate that 3.4V from your battery voltage, such as this one:
http://cgi.ebay.com/MC34063-Based-Switc ... 0257679193

For simple step-down regulators based on MC34063 such as the one above, connect no more than 2 LED strings per regulator. Adjust the potentiometer so that the output voltage is 3.4V. You can lower that voltage for a lower consumption but you'll get much less fancy colors.

Assuming the efficiency of the regulator is 80%, this means you use 1.3W per LED string, or 2.6W for both.

Let's assume you want 10 of these strings, this is 13W.

13W at 12V is a lil more than 1A.

To run such a setup for 8 hours from battery power, you would need 8.6Ah from a 12V battery (or 103Wh). As it has been pointed out, it's best to have a bigger battery so that it lasts long. Plan to use a 20Ah battery.

For an 8 hour charge, with a charge controller that is 80% efficient, you need to pump out 128Wh from your solar panels within 8 hours, or 16W continous during those 8 hours.

So you would need a ~30W panel to be safe, because assuming you use a dumb solar charge controller (not MPPT tracking), you can safely say that you're using your panels at 50% of their maximum possible power.

==> RECAP :
30W solar panel
20Ah 12V battery
Solar charge controller
10 LED strings like the ones I mentionned
5 1A step-down switching regulators

Optional but recommended: automatic night switch so that the LED strings are not lit during daytime (or you'll need a bigger solar panel that can both light them up AND charge the battery).

[edit ->] Optional but highly recommended: low voltage cutoff circuit (integrated in many solar charge controllers) to prevent your battery from being discharged too much if it wasn't charged a lot during the day

Method to adapt this to other LED strings :
The calculations done here are universal. The only important things are the power consumption of your LED strings, and the voltage they require. Once you know this it's just a matter of selecting the good components.
I think you could run 3 strings per step-down regulator, but I wouldn't risk it. Better have some margin.

|edit ->] I've been very conservative in most of the estimated above and using the values I provided should lead to a system that WILL work. You SHOULD be able to reduce a few values (battery capacity and solar panel power), it should still work... but it may not :)

==> Whatever you do TEST your system before you go to BRC <==

Hope this helps!
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Postby teardropper » Thu Aug 19, 2010 10:02 am

I'm using solar to run some lights, sound and general camp uses. I've got a 64 watt UniSolar panel and use 2- 225 amp/hour 6v golf cart batteries. These are pretty heavy, at maybe 65# each, in a battery box, it's a heavy move. I've done almost no calculations since I don't know exactly what is being used. I do know that golf cart batteries will go pretty deep and still give a lot of cycles. If you need the power and can afford the weight these are a pretty good option, at $75 each at Costco.
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