Mag Instrument (Maglite) · Flashlights
Maglite ML300L 4D battery
4 × 1.5V alkaline cell
Short answer: four D alkaline cells. Replace all four together with positive toward the head. Shorter Maglite D LED models may take two or three D cells — count the cells in the barrel.
How to replace it
| Compartment | Tail cap / barrel |
|---|---|
| How to open | Unscrew the tail cap; remove all four D cells; install four fresh D alkaline cells with positive (+) toward the head; reinstall and tighten. |
| Orientation | Positive (+) end toward the lamp/head |
| Access | Tool-free |
| Notes | Replace all four together. Shorter Maglite D barrels may be 2-cell or 3-cell — count cells before buying. |
Important
- 4× D — not 2× D or 3× D classic Maglite LED.
- Not C-cell Maglite.
Sources
Need a D?
Mag Instrument (Maglite) ML300L 4D LED Flashlight uses 4 × D.
Helpful for this device
Optional tools for opening, testing or charging — separate from the battery answer.
- Ansmann Energy Check LCD
Quick household cell check (good / low / replace)
- ZTS Mini-MBT Multi-Battery Tester
More informative state-of-charge style checks across common formats
- Digital multimeter
Measure open-circuit voltage and general electronics checks
New battery but still not working?
A fresh 4 × D should restore Mag Instrument (Maglite) ML300L 4D LED Flashlight if the battery was the problem. Work through the checks below before replacing the device.
- Check orientation
Confirm the cell is seated correctly: Positive (+) end toward the lamp/head
- Check the battery type
This device needs 4 × D (alkaline). Same size does not always mean the same battery.
3 more checks
- Check known model-specific issues
4× D — not 2× D or 3× D classic Maglite LED. Not C-cell Maglite.
- Confirm the battery itself
If you have a battery tester or multimeter, check the cell. A low open-circuit voltage often means replace; for rechargeable AA/AAA, a capacity test is more informative than voltage alone.
- Still not responding?
If a correct, fresh battery installed properly does not restore the device, the fault may be elsewhere — the device may need service or replacement.