How To Calculate Battery Size For LED Lights?

To determine the size of the battery bank for LED lights keep this in mind.

  1. No. of LED lights/Total watts
  2. No of hours you would like to run the lights
  3. Battery Type

In short, Multiply the total number of LED lights (Watts) by the number of hours you would like to run and then divide it by 12 (for a 12v battery). Further, multiply this number by 2 for a lead-acid type battery

Still confused? Keep reading I'll explain to you with the help of examples

Video - Explaining Battery amp-hour, watt-hour, and C rating

Watch this video to understand the basics of battery capacity

What Size Battery Do I Need For LED Lights?

To run a 10W LED light or bulb for 24 hours you'll need a 12v 20Ah lithium-ion battery or 40Ah lead-acid type battery

The size of the battery bank will depend on the number of total LED lights and their input wattage (which you can check on the box)

LED lights come in different sizes and wattage requirements, the larger the size is the more wattage it will require to run.

Now let's convert the watts into amps (because the capacity of a battery is measured in amp-hours)

Amp = Watts/volts

Watts will be the number of total input LED light watts, For LED lights a 12V battery is recommended.

100W/12V = 8.3

So a 100W LED bulb will require 8.3 amps per hour.

And now let's say you need to run this 100W bulb for 6 hours

8.3*6 = 50Ah

In total a 100W LED bulb will require 50 amp-hours of current in 6 hours

Battery Depth of Discharge (DoD) limit

Every battery type has a different discharge limit. A lead-acid, AGM, and Gel battery has a discharge limit of 50% (Usually)

But on the other hand lithium-ion (lifepo4) battery types can be fully discharged which makes them expensive

So if you already have a lead-acid, AGM, or Gel battery then multiply the total amps required by the LED bulb by 2

50Ah*2(50% DOD limit) = 100Ah 

You'll need a 12V 100Ah lead-acid or AGM battery to run a 100 watt LED light or bulb for 5 hours continuously

How Long Will a 12v Battery Last With LED Lights - Calculator

Battery Capacity
Battery Volts
Select Battery Type
Load Connected with inverter?
Total Load (watts)

For Example, 12V 18Ah lead-acid battery will last 10 hours while running 10 watts of LED lights without an inverter (but connect the LED lights through a charge controller or DC-DC regulator)

Related Post: How Long To Charge 12v Battery With Solar panel

Can You Run LED Lights Off a Battery?

You can run LED lights or LED strips off a 12v or car battery with the help of charge controller or DC-DC converter

The charge controller or DC-DC regulator will keep the voltage constant (12V) which LED lights or strips are rated for.

How Many LED Lights On a 12V Battery?

How many LED lights you can run a 12v battery at a time will depend on the size of your charge controller. For instant, with a 10A charge controller, you can run 120 watts of total LED lights

10 * 12 = 120 watts 

you can run a total of 120 watts of LED light with a 10A PWM charge controller.

With the help of the above formula, calculate the charge controller's size according to your need.

Final Thoughts

To calculate the size of the battery bank to run LED lights, Divide the total wattage used by the LED lights by 12 (for a 12v battery) then multiply the value by the number of hours you would like to run the lights.

I hope this short guide was helpful to you. still, have any queries? Contact us

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Chris Tsitouris is a renewable energy professional with 10+ years of experience as Director of Engineering at Solar Spectrum, previously working as Project Manager at SunPower and Energy Analyst at the National Renewable Energy Laboratory. As a thought leader, Chris has authored numerous articles and research papers.

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