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Construct a DIY LiPo Battery Discharger utilizing Halogen Gentle Bulbs

I’ll present you learn how to simply construct a DIY LiPo Battery Discharger utilizing halogen mild bulbs. This discharger is able to dealing with 2S, 3S, 4S, 5S, and 6S LiPo batteries. A halogen bulb discharger is an efficient technique for discharging LiPo batteries, both for storage or disposal.

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There are different strategies of discharging LiPo batteries, discover out extra right here:

The best way to Use

Merely plug your battery into the sunshine bulb discharger and place it in a fire-safe space.

If you’re discharging for storage, monitor the battery voltage carefully. When the voltage drops to round 3.85V per cell, unplug the battery. The cells is probably not balanced and will require additional balancing utilizing a LiPo charger in storage mode.

Additional Studying: how ought to LiPo batteries be dealt with correctly:

If you’re discharging for disposal, go away the battery plugged in till the sunshine goes out, indicating that discharging has stopped. Observe that halogen mild bulbs have a cutoff voltage of round 1 to 2V, that means they gained’t fully discharge the battery. Verify the ultimate voltage utilizing a multimeter set to voltage mode:

If there’s slightly cost left, I merely join it to an influence resistor to convey the voltage to zero, which shouldn’t take lengthy. Lastly, end it off by rigorously shorting the optimistic and damaging leads within the battery in a fire-safe place earlier than disposing.

This technique can fully discharge a completely charged 4S 1500mAh LiPo battery in lower than an hour.

LiPo Discharger Circuit Diagram

I exploit 6 mild bulbs on this discharger, together with an on-off toggle swap.

There are alternatives for 12V/24V discharging modes:

  • 12V for 2S/3S LiPo
  • 24V for 4S and 6S

The utmost voltage of a 6S LiPo is 25.2V, which is larger than 24V, but it surely must be fantastic for brief intervals, particularly since you might be typically discharging half-empty batteries.

The halogen bulbs I’m utilizing are rated at 20W, so at 12V, every will draw 1.67A of present. With 3 bulbs in parallel, the overall present draw will likely be round 5A, theoretically draining a 3S 2000mAh battery in simply 24 minutes. Nevertheless, because the voltage of the battery drops, the present draw decreases, and the discharge will take longer than 24 minutes.


I’ve saved the design so simple as attainable, all of the elements can be found on Amazon or AliExpress. The overall value must be lower than $10.

12V 20W Halogen Bulbs x 6:

3-pin PCB screw terminals x 4:

Prototyping board x 1:

Two lengthy electrical wires appropriate for the discharging present (my max discharging present is 10A, so 20AWG must be sufficient. Try this Wire AWG Chart for the acceptable wire gauge):

Male & feminine XT60 connectors x 1:

Male 3.5mm bullet connector x 1 (will be inserted into XT60 feminine connector):

On-off toggle swap x 1 (elective):



Constructing the LiPo Discharger

PCB Screw Terminals

You’ll be able to solder the sunshine bulbs on to the PCB, however I favor utilizing screw PCB terminals for simpler bulb substitute when wanted (though I didn’t have to exchange a single bulb within the 6 years I’d been utilizing this discharger). In addition they probably mean you can join various kinds of electrical hundreds, reminiscent of excessive energy resistors, making it a extra versatile system.


Make sure you add loads of solder to deal with the excessive present.


12V/24V Discharging Mode Change

The sunshine bulbs are rated for 12V, so for discharging a 4S battery or larger, it is advisable put these bulbs in sequence, successfully doubling the voltage score to 24V.

This is the reason I’m utilizing a 3.5mm bullet connector, appearing because the “mode swap”. You should utilize it to attach both simply the primary array of bulbs for discharging 2S-3S LiPo (3 bulbs related in sequence) , or to 2 arrays of bulbs related in parallel for discharging 6S LiPo (3 bulbs per array, 6 bulbs in whole).


On-Off Change and Discharge Cables

The on-off swap is elective, as you may flip off the discharger by merely unplugging the battery (or the bullet connector). Nevertheless, a toggle swap will be extra handy and safer, permitting for fast shutdown throughout an emergency.

I exploit further lengthy electrical wires to maintain the battery as removed from the sunshine bulbs as attainable throughout discharging in case of a fireplace.



Future Upgrades

These bulbs can get very heat! I’m contemplating including a fan on high to help in warmth dissipation. A small fan usually requires 5V, which might require a step-down voltage regulator that will get energy from the battery being discharged.

I additionally plan to use liquid electrical tape over all soldered joints and connections to forestall quick circuits.


I examined the unit with only one bulb related.

Upon turning on the sunshine bulbs, I noticed an preliminary present surge of two.6A, which shortly stabilized at 1.6A. If I reconnect the bulb shortly, the surge doesn’t appear to happen once more, which is an fascinating statement, let me know within the feedback in you recognize why.

These bulbs are rated at 20W. With a battery at 11.9V, the precise energy draw is 19W, which is barely decrease than anticipated however okay.

Within the 24V discharging mode (utilizing two arrays of bulbs in parallel), the facility consumption drops by almost half as anticipated. Due to this fact, when you’ve partially discharged your 4S or 6S battery under 12V, it’s advisable to modify to the 12V discharge mode for extra environment friendly discharging.


Edit Historical past

  • Oct 2015 – Article Created
  • Jan 2018 – Up to date article with an inventory of construct parts
  • Jan 2024 – Up to date directions and product hyperlinks

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