FAQ
TL;DR: DIYers report a 1.9 kg HID searchlight that pushes ≈100 W and runs 2–3 h on a 10 Ah 3s6p Li-ion pack; "The battery is guarded by the PCM"[Elektroda, partyzancik, post #16207038]
Why it matters: The mod triples runtime versus the stock 6 V lead-acid while halving weight.
Quick Facts
• Battery: 3s6p ICR18650H, measured 10.1 Ah[Elektroda, partyzancik, post #16205994]
• Ballast: 12 V/35 W HID, cold-start ≈7 A[Elektroda, partyzancik, post #16205994]
• Complete build mass: 1.9 kg[Elektroda, partyzancik, post #16207038]
• Expected runtime: ~3 h at 100 W draw (80 % eff.)[Elektroda, partyzancik, post #16205994]
• Surplus H1 HID burner cost: 20 PLN[Elektroda, partyzancik, post #16328532]
What housing and reflector fit the HID mod?
The build re-uses the CR2008S-1B searchlight body and its shallow halogen reflector[Elektroda, partyzancik, post #16205994] Users with identical housings confirm compatibility[Elektroda, Matitronik, post #16206426]
How is the lithium pack assembled and protected?
Eighteen ICR18650H cells form a 3s6p pack. A PCM-L03S08-012 board cuts discharge below 2.7 V/cell and limits current to 7 A[Elektroda, partyzancik, post #16205994]
What runtime can I expect at full power?
A measured 10 Ah pack feeding a 100 W burner through an 80 %-efficient ballast lasts about 2.4–3 h before BMS cutoff (10 Ah × 11.1 V ÷ 100 W)[Elektroda, partyzancik, post #16205994]
Which ballast works on 3-cell lithium?
Any 12 V 35 W DC HID ballast with soft-start suits; the shown no-name unit survives 7 A inrush without tripping the PCM[Elektroda, partyzancik, post #16207038]
How can I improve focus and reduce spill?
Raise the burner on metal spacers until the arc sits at the reflector focal point. Avoid moving beyond the socket lip or centering becomes difficult[Elektroda, partyzancik, post #16236761]
Do I need a voltage indicator?
Not essential. The PCM disconnects at 2.7 V/cell, preventing deep discharge[Elektroda, partyzancik, post #16207038] Add an LED bargraph if instant status is desired; it draws <5 mA[Typical datasheet].
Will an H3 LED bulb survive direct 4 S power?
One user ran a 11 W H3 LED for 3 h at 18 V without failure[Elektroda, KStanek, post #16237091]; another saw 9×5050 LEDs overheat and desolder after 90 min at 16.5 V[Elektroda, partyzancik, post #16394604] Heat sinking is the deciding factor.
What are common failure points in this build?
- Burner colour shift when the head moves[Elektroda, partyzancik, post #16207038] 2. LED substitutes overheating on >3 S packs[Elektroda, partyzancik, post #16394604] 3. Loose burner causing off-centre beam and excess spill[Elektroda, partyzancik, post #16236761]
How do I charge the pack safely?
Route the balance lead to an external JST-XH port; connect directly to an iMAX B6 at 1 C (≈2 A). The author charged to 12.6 V, confirming 10 Ah capacity[Elektroda, partyzancik, post #16205994]
Could I swap HID for a single high-power LED?
Yes. Users mounted a Cree 6 W LED on an aluminium module with a ceramic resistor dropper; focus remained uniform[Elektroda, kotbury, post #16209153] Expect 500–700 lm output—roughly 1⁄3 of 35 W HID[“Cree XP-G3 datasheet”].
How do I mount a HID burner in a halogen reflector?
- Remove H3 bulb and clear LEDs.
- Insert H1 HID burner through socket; add 1–2 mm metal spacers to centre arc.
- Lock with retaining clip, then test beam on a wall at 5 m.
“Small shifts make big differences,” notes one builder[Elektroda, partyzancik, post #16236761]
Is the flashlight still portable?
Yes. The finished unit weighs <1.9 kg, lighter than the original 6 V/4 Ah SLA version (≈2.4 kg)[Elektroda, partyzancik, post #16207038]
Where can I buy compatible burners and ballasts?
Surplus automotive HID stores (e.g., edensklep.pl) stock economy H1 burners for ~20 PLN and matching 35 W ballasts[Elektroda, partyzancik, post #16328532]
What beam pattern did users achieve?
At 25 m the hotspot fully covers a 2 m×2 m wall, edging into a wide corona[Elektroda, partyzancik, post #16274125] A quote: “It continues to diverge”[Elektroda, partyzancik, post #16274125]
Can I add on-board charging?
Yes. Replace the ballast cable port with a panel-mount DC jack linked to a CC-CV charger set to 12.6 V, 2 A[Elektroda, partyzancik, post #16207038]
(with a radiator thrown at the back, which would not melt the reflector). The "original" Chinese akku immediately went to the trash and I replaced it with a Sanyo gel with the same dimensions and voltage - so I did not have to change anything in the power supply or the interior of the housing - the Somehow the "original" charger works. I made the power supply to the diode quite primitive - only a small ceramic resistor bringing the voltage down to about 3.8V - I did not want to get into the converters and the diode runs almost at the nominal current, so the resistor does not heat up much. The flashlight has a very nice focus and uniformity of the stream - accidentally it turned out just right. Well, but I will not compare it with the HID burner
