Why does my lights blink on and off?

Woodhook13

New Member
Joined
May 13, 2022
Messages
2
I have a 100 watt solar panel that is only connected to 6 led landscape lights. They are all 5 watts. That’s the only load. I have 1 lead battery (lawn mower) that’s being charged by the panel. Every night the lights come on great, but after a couple of hours they will only stay on for a second then go off for 3 or 4 seconds, then back on for a second. I’ve tried three solar controllers and the results are the same. I’ve read where the voltage may be traveling back to the solar panel and if it is, I don’t know what to do.
 

Bud Martin

Photon Sorcerer
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Aug 27, 2020
Messages
2,997
Hard to do long distant troubleshooting without details and pictures.
How about giving us details of what you have and how they are hooked up?
Pictures?
Make and model of the SCC?
Panel spec?
What Voltage and current being shown on the SCC during charging and discharging?
Do you have multimeter to take measurement?
 

Rednecktek

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Sep 8, 2021
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On a boat usually.
First thing first, measure the battery voltage right before you turn the lights on and again once they start blinking.

Most small batteries are just that, small and at 30w of draw that's almost 3 amps per hour. IF your battery is a deep cycle and not just a bog standard lawnmower battery then that's about half the capacity in the first hour. If it's just a normal battery they're designed to release a whole lotta power all at once then get recharged and can't really maintain a load for very long.

By the sounds of it the battery is discharging to the cut off voltage setting of the PWM (I'm guessing the lights are on the LOAD port of the SCC?) and the batteries cut off. Then they recover right above the cut-off and come on, which drops them right below the cut-off and rinse, repeat. To calculate a battery you'll need to do some math.

Napkin math says 30w @ 12v - efficiency = 3A/hr. $Running hours * 3amps / hr = capacity required. Lead Acids are good for 50% DoD, so 3A/hr * $RunningHours * 2 = Battery Capacity in Ah rating, or simplified is $RunningHours * 6 = Ah.

Example: You want the lights to stay on all night long which in winter is 14 hours. The lights require 30 watts and your battery is a WallyWorld Deep Cycle because it was cheap. 30w * 14hr = 420Watt-Hours to keep the lights on all night. Since your system runs at 12v that's 420Wh / 12v = 35Ah. Since you're using led acid because it's cheap and available, you only get 50% out of the rating on the sticker in Ah, so 35Ah *2 = 70Ah, You'd need a 70Ah battery to get through 1 night and have to fully charge it the next day. If you wanted the lights on and the weather was krappy you'd need ANOTHER 70Ah of battery to make it 2 nights, or 140Ah total. Stupid math!

I tell people Watts are like Grams. It takes a LOT to do a little and nobody is gonna get ripped and totally swol on 5000 gram (or 11lb for us American types) weights. :)

Tl;Dr: I think your battery is too small and can't handle the load for long.
 
Last edited:

mikefitz

Photon Sorcerer
Joined
May 28, 2020
Messages
1,160
I don’t know what to do.
You need a new battery, a 100 Ah battery would be suitable. The existing battery is too small, or faulty or just too old.

The solar controller you have may/will have programmable load outputs. This will allow the controller to switch on/off the lights at certain times and disconnect the lights if the battery gets too low.
It's probably the low battery feature that's turning the lights off and on. ( the battery recovers slightly).

Mike
 
Last edited:

Woodhook13

New Member
Joined
May 13, 2022
Messages
2
Thanks guys, you’ve given me a lot of information. It’s great to have sources to go to when your unsure about problems! I’ll do some math and upgrade my battery! Thanks again!
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
Messages
5,780
Location
Rural NE Ontario Canada
Give us the Specs, Name/Brand/Model of your Inverter/Charger.
From your description, you have ECO Mode / PowerSave Mode ON. This will allow the Inverter to go into Powersave mode once a minimum Amp Draw is reached (many can set this to different values pending on the quality/brand of the inverter).

PowerSave / EcoModes operate in such a way that the inverter essentially powers down and every few seconds it sends a Voltage Pulse to determine if there is a "demand draw" and if there is, it powers up the inverter to supply the required power. If the "Draw Demand" is below the preset Watts/Amps threshold, the inverter will remain in "SAVE" mode and keep pulsing.

Different Inverter Systems do handle this in different ways.
 

timselectric

If I can do it, you can do it.
Joined
Feb 5, 2022
Messages
3,134
Give us the Specs, Name/Brand/Model of your Inverter/Charger.
From your description, you have ECO Mode / PowerSave Mode ON. This will allow the Inverter to go into Powersave mode once a minimum Amp Draw is reached (many can set this to different values pending on the quality/brand of the inverter).

PowerSave / EcoModes operate in such a way that the inverter essentially powers down and every few seconds it sends a Voltage Pulse to determine if there is a "demand draw" and if there is, it powers up the inverter to supply the required power. If the "Draw Demand" is below the preset Watts/Amps threshold, the inverter will remain in "SAVE" mode and keep pulsing.

Different Inverter Systems do handle this in different ways.
There's no inverter in this system.
100w solar, charging battery during the day.
Landscape lighting using the power at night.
Everything is 12v DC.
The battery is just too small to last all night.
 
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