Saturday, 29 October 2016

DIY Cordless Flood Light

DIY Cordless Flood Light - Intro

It is important to realise that you can buy a cordless flood light on ebay or similar for £20, and making the below described flood light will cost probably £40 or £60.

BUT . . . . if you make it you can repair it. All of the bits are stand alone parts that can be purchased if they go wrong. This is particularly true of the battery, sealed lead acid batteries that are normally used have a short life span, and in a few months you floodlight may stop working, at which point you can replace the battery easily in your DIY model.

Sturdy, Dependable and Very Repairable

DIY Cordless Flood Light - Bits

List of bits required with description of each needed for constructing DIY cordless flood light.


A lithium battery LIfePo4 being the best bet as it is light and will last for maybe 500 - 1000  charge cycles. But one of these with built in BMS at 12v will cost £70 (EV Power) and so it rather expensive.

I had a sealed lead acid battery left over from a project and so I used this, it is 22ah capacity which will give the large flood light 3 hours run time (9 ah used), as you should not discharge a lead acid battery past 50% regularly.

Basic Wiring

Really choose the battery first based on how long you want to run you flood light between charges.

For example if you wanted your flood light to last the whole working day of 10 hrs, you would need to use a less powerful light say 10w, which would equate to 1A of current, a 22ah lead acid battery run down to 50% would provide 12 hours of light.


Many will already have a 12v charger that is used for your car battery, and in most cases this will be OK to use.

If not head to ebay and but a suitable charger a small inexpensive charger will deliver 1.0 - 1.5 amps of charge. So will charge a large battery over night.

Crocodile clips can be clipped directly on terminals, or you can fashion a plug and socket as described below, so as to avoid opening your case every time you charge.


For my plug and socket I purchase a " male and female kettle lead" I then chopped this in half, and used the end to connect the charger to the battery, drilling a hole in case to pass the wire through.


An ammo box is ideal. An ex. military one is cheap enough around £10 on ebay. They are very tough and will last a life time. Make sure it is big enough for your battery.


A toggle switch of around 3A rating will be OK, but for size and robustness you may prefer to opt for a 10A variant.


Rather unglamorous, but something to pack around you battery to stop it shaking around inside the casing is important. Some stiff foam would be ideal or at a pinch bubble wrap or similar packed around the the battery.

DIY Cordless Flood Light - Tools

  • Drill
  • Drill Bits
  • Soldering Iron & Solder or Wire Crimps

DIY Cordless Flood Light - How its Done

Drill all the whole required to pass the wires to the battery via the switch, solder it all together. And that's pretty much it. It is very basic electronics just check your polarity before you connect anything up. 

The charge lead is live all the time so use a male end of the kettle lead to prevent exposed connectors. 

The toggle switch can break the negative of positive to the light. 

Place toggle switch so it does not foul battery when closing lid. 

Leave charge lead long to it hangs down, this prevent water running in to hole.