LED Rope Lights Run Out of Power in Only a Few Hours

[lagunabluevette]

This is my first solar panel installation. It's a pretty simple setup to power LED rope lights to illuminate the length of my dock.

Configuration:

• Renogy 100w starter kit
• Wanderer Series 30A PWM
• Krieger KR1100 power inverter
• Harbor Freight 12v 35AH battery
• A simple outdoor light dawn-to-dusk light sensor
• 160 ft of LED rope lights (120v)

All is working as can be seen in this photo, but the lights go from being bright, to dimming and eventually going out in about 3.5 hours time. I would think the capacity of my setup is more than up to the task.

I do have the Krieger KR1100 powered on. Is it consuming the power to render my batter too drained to power the lights for long? Thank you in advance for any advice.

 

[Hedges]

What is power consumption of the rope light?

You have 400 Wh of battery, and the lights stayed on 3.5 hours.

 

[lagunabluevette]

What is power consumption of the rope light?

You have 400 Wh of battery, and the lights stayed on 3.5 hours.

I'm new to this and I suck at math. So here is what I can provide based on stuff I'm reading. I have 160 ft of rope lights, 120v and 1 watt per foot. So 160 watts x 10 hours is 1600 watt hours.

 

[Bud Martin]

That is lots of Watts.
You only have 100W so at the best with 5 hours of Sun, you'll be lucky to get 500Wh.
"Harbor Freight 12v 35AH battery" Lead Acid, so usable is about 35Ah/2 = 17.5Ah @50% SOC = 210Wh
Did you check the current draw on the DC Inverter input when it is on w ith and without LED string connected? You do have a way to measure DC current, correct?
The inverter will draw current when it is on and without having load connected.

 

[Hedges]

So if you'd like 10 hours of operation, you want 1600 usable Wh.
Your math looks OK so far.

The battery is 12V (or so) and 35 Ah. 12V x 36Ah = 432 Wh

160W x 3.5 hours = 560 Wh. So it probably used a bit less than 1 W/foot

Your inverter has some low voltage shutdown. It is probably too low to be good for the battery. fully discharging the battery might reduce its lifespan to 100 nights. It is commonly suggested to only drain a lead-acid battery 50%.

You want 10 hours, but only got 3.5, so using 3 batteries would make it through a 10 hour night initially. As the batteries wear out they will go empty sooner.
Having 6 batteries might give decent use for a couple years.
You could get a single 200 Ah 12V battery which would be better. For instance:

Sun Xtender PVX-2120L Solar Battery Apex Battery

This is the 12v 212ah 4D Deep Cycle Sun Xtender PVX-2120L Solar Battery .This <b>maintenance free</b> and <b>sealed</b> lead acid battery, fixes the acid electrolyte in a gel or in an absorptive fiberglass mat. The advantage of this design is that the ba

www.apexbattery.com

At 50% depth of discharge, this battery should be good for 1000 cycles or around 3 years.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

You also need to fully recharge it. Figure you will consume 432 x 3 = 1300 Wh/day. Lead-acid batteries are about 70% efficient. 1300/0.7 is about 2000Wh. Sunlight varies with location and season, 5 effective hours during the sunnier months. 2000Wh /5 hours = 400W.
So you'll need about 400W or so of PV panels.

You could use 400W of "12V" panels with a PWM controller (the 30A you've got might be just enough, or might be overstressed)
Better is an MPPT charge controller which will extract more of the panels' power, and can work with higher voltage input.

If $600 for batteries every 3 years doesn't sound good, lithium batteries should be good for 10 years (if treated right) and 80% depth of discharge is reasonable.

 

[Popuptoaster]

I'd get rid of the rope lights and buy a reel of wire and some individual LED lights to string along the dock, easier to lower consumption than increase capacity.

 

[Supervstech]

Instead of having the full length of lights, perhaps you can have a few evenly spaced individual LED bulbs strung on the dock.
You have 160’ of dock to illuminate. Maybe a set of Christmas tree strings with led bulbs would last longer?
Also, many LED lights operate at 12VDC, so the inverter wouldn’t be needed. Go from 160W, down to 25 and you should make it through the 10 hours...

 

[lagunabluevette]

So if you'd like 10 hours of operation, you want 1600 usable Wh.
Your math looks OK so far.

The battery is 12V (or so) and 35 Ah. 12V x 36Ah = 432 Wh

160W x 3.5 hours = 560 Wh. So it probably used a bit less than 1 W/foot

Your inverter has some low voltage shutdown. It is probably too low to be good for the battery. fully discharging the battery might reduce its lifespan to 100 nights. It is commonly suggested to only drain a lead-acid battery 50%.

You want 10 hours, but only got 3.5, so using 3 batteries would make it through a 10 hour night initially. As the batteries wear out they will go empty sooner.
Having 6 batteries might give decent use for a couple years.
You could get a single 200 Ah 12V battery which would be better. For instance:

Sun Xtender PVX-2120L Solar Battery Apex Battery

This is the 12v 212ah 4D Deep Cycle Sun Xtender PVX-2120L Solar Battery .This <b>maintenance free</b> and <b>sealed</b> lead acid battery, fixes the acid electrolyte in a gel or in an absorptive fiberglass mat. The advantage of this design is that the ba

www.apexbattery.com

At 50% depth of discharge, this battery should be good for 1000 cycles or around 3 years.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

You also need to fully recharge it. Figure you will consume 432 x 3 = 1300 Wh/day. Lead-acid batteries are about 70% efficient. 1300/0.7 is about 2000Wh. Sunlight varies with location and season, 5 effective hours during the sunnier months. 2000Wh /5 hours = 400W.
So you'll need about 400W or so of PV panels.

You could use 400W of "12V" panels with a PWM controller (the 30A you've got might be just enough, or might be overstressed)
Better is an MPPT charge controller which will extract more of the panels' power, and can work with higher voltage input.

If $600 for batteries every 3 years doesn't sound good, lithium batteries should be good for 10 years (if treated right) and 80% depth of discharge is reasonable.

Wow! Lots of helpful information here. Thank you for taking the time to provide such a thorough explanation.

 

[lagunabluevette]

Instead of having the full length of lights, perhaps you can have a few evenly spaced individual LED bulbs strung on the dock.
You have 160’ of dock to illuminate. Maybe a set of Christmas tree strings with led bulbs would last longer?
Also, many LED lights operate at 12VDC, so the inverter wouldn’t be needed. Go from 160W, down to 25 and you should make it through the 10 hours...

Ugh! Math! So your suggestion is what I'm going to need to do. I'm just trying to wrap my head around how many lights and doing the numbers to not end up back to where I am. On the surface, seeing that you can buy rope lights that come with their little solar panels you stick in the yard, gave me the thought that for sure a 100w solar panel could power these with ease. I guess you just have to do the math.

 

[Mike Jordan]

120v lights is where you went wrong. Those lights do not run on 120v. They are stepped down, probably to 12v. Only for you to have to step UP your 12v batt to 120v, through the inverter. Lots is lost in all of that translation

Start with 12v LED lights and loose the inverter. They will be significantly lower draw. Then pay attending to the watts

 

[nwillitts]

just bypass the the power block and wire directly into the lights.

 

[lagunabluevette]

120v lights is where you went wrong. Those lights do not run on 120v. They are stepped down, probably to 12v. Only for you to have to step UP your 12v batt to 120v, through the inverter. Lots is lost in all of that translation

Start with 12v LED lights and loose the inverter. They will be significantly lower draw. Then pay attending to the watts

Do you know how I attached lights that have a standard plug directly to the battery and still go through a light sensor so they only draw power at night?

 

[Rider]

Do you know how I attached lights that have a standard plug directly to the battery and still go through a light sensor so they only draw power at night?

I'm sure there are 12V light sensors, you'd need to do a little research.
Alternatively, replace the PWM controller with a controller that has load connections that can be controlled by an internal timer or presence/lack of light on the solar panels. Look at the specs of the EPever 20 and 30 amp controllers, just for an example of what you might look for.

 

[Hedges]

just bypass the the power block and wire directly into the lights.

I wondered for a moment if the power supply was a current source rather than a voltage source. But then I remembered mine allows multiple ropes connected in series with a single supply.

Ideally you would put PWM into the lights; they will consume less power than at 100% on, and be more efficient than at reduced voltage. But that is a project by itself.

Check what voltage comes out of power supply and into lights and proceed from there. But that will only save a percentage, perhaps 1/3 between inverter and power supply.

What you want is a 12V DC rope light of lower wattage, could be larger spacing between LED.

I bought a couple 50' rope lights from HD, which I daisy chained. They worked pretty well, but one connection eventually got smashed.
I found a similar but longer set on eBay direct from China at lower price. Rope seemed the same but supply was different.
It works, but the plastic rope yellowed with UV the first year anywhere it had direct sun. The one from HD had very little discoloration.

Rope lights can use a significant amount of power even though they are LED. They do run warm. Mine is one of the things I turn off if I am going to be on batteries overnight. It could drain 7% of my 20 kWh bank, 10% of useable capacity. Anything that's always on really adds up.

 

[lagunabluevette]

This is my first solar panel installation. It's a pretty simple setup to power LED rope lights to illuminate the length of my dock.

Configuration:

• Renogy 100w starter kit
• Wanderer Series 30A PWM
• Krieger KR1100 power inverter
• Harbor Freight 12v 35AH battery
• A simple outdoor light dawn-to-dusk light sensor
• 160 ft of LED rope lights (120v)

All is working as can be seen in this photo, but the lights go from being bright, to dimming and eventually going out in about 3.5 hours time. I would think the capacity of my setup is more than up to the task.

I do have the Krieger KR1100 powered on. Is it consuming the power to render my batter too drained to power the lights for long? Thank you in advance for any advice.

View attachment 38768
View attachment 38769

I've given up on this project and returning the whole setup. Maybe someday all of this calculating of volts, watts, and amps and power draw will become simplified for the average person to figure out. I appreciate the attempts to help. For $40 I was able to buy an individual solar light for every piling.

 

[WSix]

I recently saw a vid where the folks measured the watts used on those lights and it was crazy!

 

[Supervstech]

I have gone into a kitchen remodel and found rope lights used under counter etc, and the melted plastic from the led’s or the step down circuits is massive...
They are fine for quick lighting... but NOT suitable for sustained illumination.