Quick answer
On the Makita DC18RC and DC18RD, red means charging, green means charging is complete, and a flashing red light means the battery is too hot or too cold. Green and red flashing alternately means charging is not possible: Makita's manual gives two causes, dust on the terminals of the charger or battery, or a worn-out or damaged battery. Yellow lights are cooling and conditioning states, not faults, and the battery can still charge.
Try our charger light-code decoder for these patterns. Everything below comes from Makita's manuals for the DC18RA/DC18RC and the DC18RD.
LED code decoder
DC18RC (also covers the DC18RA)
| LED state | What it means (Makita's manual) | Action |
|---|---|---|
| Green flashing, no battery | Ready to charge | Insert a battery |
| Red charging light lit | Charging | Wait |
| Red goes out and green stays lit | Charging is complete | Remove the battery and unplug the charger |
| Red flashing | The battery is too hot (just used, or left in direct sunlight) or too cold; charging may not start | Wait. A hot pack starts once the fan has cooled it |
| Green and red flashing alternately | Charging is not possible: terminals clogged with dust, or the battery is worn out or damaged | Check the terminals for dust; if they are clean the pack may be worn out or damaged |
| Yellow flashing | Cooling warning: trouble with the cooling fan, or incomplete cool-down (for example dusty vents). The battery can still be charged, but takes longer | Check the fan sound and the vents; service if it flashes frequently |
| Yellow lit | Conditioning charge, which extends battery life; takes longer than usual | Nothing needed |
Source: Makita DC18RA / DC18RC instruction manual, pages 2 and 3.
DC18RD (two-port charger)
The DC18RD manual says it can charge two batteries at the same time. It shows the same states as above, plus two temperature levels:
- One charging light flashing red: battery temperature about 50°C to 70°C.
- Two charging lights flashing red: battery temperature more than about 70°C.
In both cases let the battery cool; charging begins when it reaches a chargeable temperature. The manual does not say charging runs at a slower rate.
Source: Makita DC18RD instruction manual, pages 3 and 4.
Chargers we don't list
We don't have a manual for the DC18RF or DC18WA, so we don't list their light codes. The file we had labeled DC18RF turned out to be the DC18RA/DC18RC manual. Check your charger's own manual.
Charging temperature
Makita's DC18RC manual says not to charge a battery when the room temperature is below 10°C (50°F) or above 40°C (104°F). It also says that when the battery temperature is under 0°C (32°F), charging may not start. The 50°F figure is a room-temperature limit, not a battery-temperature one. The DC18RD manual gives the same 10°C to 40°C room range, and says charging may not start at cold temperatures.
If a cold pack flashes red, let it reach room temperature and retry.
Green and red flashing alternately
The manual lists the two causes and gives no other steps. In practice:
- Check the metal terminals on the charger and on the battery for dust, and clear any you find.
- Try a second known-good pack on the same charger. If the second pack charges, the original pack is the likely problem.
- Try the suspect pack on a different Makita charger that lists it.
Which packs each charger takes
The DC18RC manual lists a range of Makita packs, and says some, including the BL1830B, BL1840 and BL1860B, can be charged with the DC18RC only and not the DC18RA. The DC18RD manual lists packs including the BL1815, BL1820, BL1830, BL1840 and BL1850, and does not list the BL1860B. Check the manual for your charger before assuming a pack fits.
Makita 18V LXT vs 40V XGT
Makita's service FAQ says batteries are compatible within each platform; for example, LXT batteries are compatible only with LXT products. XGT is a separate platform with its own chargers (the DC40RA and DC40RB). Makita's ADP10 adapter lets an XGT charger charge LXT batteries; it is a charger adapter, not a way to run an LXT battery in an XGT tool. 36V (18V X2) LXT tools use two 18V LXT batteries. See our LXT vs XGT guide and the battery compatibility checker.
If it still isn't working
Read Makita's current warranty page; it lists three years for lithium-ion tools, batteries and chargers. If a pack is swollen, cracked or leaking, stop using it.
View Makita 18V LXT 5.0Ah Battery (BL1850B) on Amazon (paid link)
FAQ
What does the red and green alternating light mean on my Makita charger?
Makita's manual says charging is not possible: the terminals on the charger or battery are clogged with dust, or the battery is worn out or damaged. Check the terminals first, then try a second pack.
What does a flashing red light mean on my Makita charger?
The battery is too hot or too cold. Charging may not start until it reaches a chargeable temperature. A hot pack starts after the charger's fan cools it.
What does the yellow light mean?
Flashing yellow is a cooling warning (fan trouble or incomplete cool-down) and the battery can still charge, but more slowly. A lit yellow light is a conditioning charge.
What is the lowest temperature a Makita charger will charge in?
The DC18RC manual says not to charge below a room temperature of 10°C (50°F), and that charging may not start when the battery is under 0°C (32°F).
Can a Makita LXT battery charge on a DeWalt or Milwaukee charger?
Makita says its batteries are compatible within their own platform, and its manuals say to charge only Makita batteries on its chargers.