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I’ll present you how one can simply construct a DIY LiPo Battery Discharger utilizing halogen gentle 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.
There are different strategies of discharging LiPo batteries, discover out extra right here: https://oscarliang.com/dispose-lipo-battery-safely/.
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: https://oscarliang.com/lipo-battery-guide/
If you’re discharging for disposal, depart the battery plugged in till the sunshine goes out, indicating that discharging has stopped. Be aware that halogen gentle bulbs have a cutoff voltage of round 1 to 2V, which means they gained’t utterly discharge the battery. Affirm the ultimate voltage utilizing a multimeter set to voltage mode: https://oscarliang.com/multimeter-fpv/#How-to-Measure-DC-Voltage.
If there’s slightly cost left, I merely join it to an influence resistor to carry the voltage to zero, which shouldn’t take lengthy. Lastly, end it off by fastidiously shorting the optimistic and unfavorable leads within the battery in a fire-safe place earlier than disposing.
This technique can utterly discharge a completely charged 4S 1500mAh LiPo battery in lower than an hour.
LiPo Discharger Circuit Diagram
I take advantage of 6 gentle bulbs on this discharger, together with an on-off toggle change.
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 increased than 24V, however it needs to be high-quality for brief durations, particularly since you’re usually 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 whole present draw will likely be round 5A, theoretically draining a 3S 2000mAh battery in simply 24 minutes. Nonetheless, because the voltage of the battery drops, the present draw decreases, and the discharge will take longer than 24 minutes.
I’ve stored the design so simple as potential, all of the components can be found on Amazon or AliExpress. The entire price needs to 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 needs to 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 (could be inserted into XT60 feminine connector):
On-off toggle change x 1 (optionally available):
Constructing the LiPo Discharger
PCB Screw Terminals
You possibly can solder the sunshine bulbs on to the PCB, however I desire 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). Additionally they doubtlessly will let you join various kinds of electrical masses, reminiscent of excessive energy resistors, making it a extra versatile gadget.
Make sure you add loads of solder to deal with the excessive present.
12V/24V Discharging Mode Swap
The sunshine bulbs are rated for 12V, so for discharging a 4S battery or increased, you must put these bulbs in sequence, successfully doubling the voltage ranking to 24V.
That is why I’m utilizing a 3.5mm bullet connector, appearing because the “mode change”. 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 complete).
On-Off Swap and Discharge Cables
The on-off change is optionally available, as you’ll be able to flip off the discharger by merely unplugging the battery (or the bullet connector). Nonetheless, a toggle change could be extra handy and safer, permitting for fast shutdown throughout an emergency.
I take advantage of further lengthy electrical wires to maintain the battery as removed from the sunshine bulbs as potential throughout discharging in case of a fireplace.
Future Upgrades
These bulbs can get very heat! I’m contemplating including a fan on prime to assist 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 stop brief circuits.
Testing
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 rapidly stabilized at 1.6A. If I reconnect the bulb rapidly, the surge doesn’t appear to happen once more, which is an attention-grabbing remark, 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 practically 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 a listing of construct parts
- Jan 2024 – Up to date directions and product hyperlinks
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