Start by matching the battery platform to the charger, then reseat the battery and check the indicator in the manual for your exact charger model. A pack can temporarily refuse to charge because it is too hot or cold; persistent faults, visible damage, or an unresponsive pack should be referred to Milwaukee service. Do not open the battery or charger.
1. Confirm that the charger matches the battery
Check the label on the battery and the catalog number on the charger before troubleshooting. Milwaukee makes multiple battery systems, and compatibility should not be assumed across every Milwaukee charger and pack.
Milwaukee says M18 batteries work with M18 tools and chargers, and that authentic M18 batteries must be charged on Milwaukee M18 chargers. Its official M18 FAQ states: “Authentic M18™ batteries must be charged on Milwaukee M18™ chargers. Users should not use third party batteries or chargers.” For another battery platform, use a charger specified for that system and verify compatibility in the relevant product documentation.
2. Reseat the battery and inspect for visible problems
- Remove the battery from the charger, then slide it back into the bay until it is fully seated.
- Look for obvious damage or debris on the battery, charger, and accessible contacts. Do not use equipment that appears damaged, and do not probe or dismantle it.
- Check the charger’s indicator again. If there is no light, use the reset or retry procedure in the manual for that exact charger model.
The cited 48-59-1806 charger manual instructs users to remove and reinsert the battery when its indicator does not come on. It also specifies unplugging that charger for at least two minutes before retrying. That sequence is not a universal rule for all Milwaukee chargers: follow the manual matching the catalog number on yours.
#1 Best Overall
- Product will either come in original packaging that is in less than perfect shape and has been opened to inspect contents or will come in non-retail packaging (brown/white box or white/clear bag). Charges pack up to 40% faster, reducing downtime and maximizing productivity.
- The charger accepts all M18 and M12 batteries, providing an upgrade for both systems.
- The charger indicates when the battery reaches an 80% charge.
- Single unit simplicity for quick charge of all M12 and M18 battery packs.
- Sequential charging: automatically charges the second inserted pack once the first pack is fully charged.
3. Interpret the light using your charger’s manual
There is no safe universal translation for a flashing Milwaukee charger light. Indicator patterns and recovery steps vary by charger model, so find the catalog number on the charger and consult its operator manual rather than applying a pattern from another model.
If the charger shows no indicator
For the cited six-pack charger, the manual says to reseat the battery and, if needed, unplug the charger for at least two minutes before retrying. If the indicator still does not appear, the manual directs users to contact a Milwaukee service facility.
Rank #2
- DUAL CHARGING: This charger can tackle both 18 and 12 volt Milwaukee batteries, holding one of each in the unit at the same time.
- SEQUENTIAL CHARGING: Do not worry about managing charge cycles. This will take care of your batteries one at a time, devoting full charging power to each one.
- BATTERY COMMUNICATION: The charger has a chip that communicates with its batteries, keeping track of how much they have charged. It saves you power by reducing the amount of charge produced as the battery reaches full charge.
- FAST ACTING: Compact batteries can be fully charged in as little as 30 minutes, while extended life batteries can be charged in as little as a single hour.
- INDICATOR LIGHTS let you know whether a battery is charging, fully charged, and whether it needs maintenance or not.
If red and green lights flash
On that same charger, the manual first advises checking that the battery is fully seated and reinserting it. If the flashing continues, the pack may be extremely hot, cold, or wet. Allow it to cool, warm, or dry before trying again. If the condition persists, contact Milwaukee service. These instructions apply to the cited charger, not automatically to every model.
If the red light flashes rapidly
The 48-59-1806 manual identifies fast red flashing as a pack that is too hot or too cold to charge. That indication is model-specific. Let the battery return naturally to a suitable temperature, then retry according to its own manual; do not apply external heat or cooling.
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Rank #3
- Replacement for 12V battery charger 48-59-2401, 48-59-1812, 48-59-1201, 48-59-1807, 48-59-1204, 48-59-1810, 48-59-1808 and 18V battery charger 48-59-1804 48-59-1802 48-59-1806
- Compatible with all MIL 12V lithium-ion batteries 48-11-2401, 48-11-2440, 48-11-2460, 48-59-2420, 48-11-2430, 48-11-2411 and all 18V lithium-ion batteries 48-11-1862, 48-11-1880, 48-11-1850, 48-11-1852, 48-11-1812
- Supports 100-240V AC input, 10.8V-18V 3.0A DC Output. Can charge 12V and 18V batteries in less than an hour for jobsite efficiency.
- Indicator lights that show the status as batteries are charged and maintained. The built-in high-end protection board provides overcharge, overcurrent and high voltage protection for your mobile devices, ensuring the stability of the charging current.
- This Charger comply with FCC RoHS and CE security testing standards. Contact us: any question please click the "Ask a question" on our storefront or in "YOUR ORDER" options click the "contact seller".
If the red light is steady
For the 48-59-1806, continuous red indicates normal charging when the pack is within the charger’s acceptable temperature range. Check that charger’s manual for the meaning of its own lights.
4. Allow for temperature and normal charging time
A pack outside the charger’s acceptable temperature range may not charge until conditions return to normal. Let it cool or warm naturally in a suitable place, then retry. Charging time also depends on the battery pack, charger, and surrounding environment, so a pause or longer charge is not by itself proof of failure.
Rank #4
- M18 six pack sequential charger
- The product is easy to use and easy to handle
- The product is highly durable
Milwaukee Tool reports these Super Charger examples from room-temperature testing; the company says actual results may vary:
| Battery | Reported charge time |
|---|---|
| M18 REDLITHIUM FORGE XC6.0 | 25 minutes to full; 15 minutes to 80% |
| M18 REDLITHIUM HIGH OUTPUT HD12.0 | 60 minutes to full |
| M18 REDLITHIUM HIGH OUTPUT XC8.0 | 45 minutes to full |
| M18 REDLITHIUM XC5.0 | 60 minutes to full |
These are manufacturer test examples, not a guaranteed charging time for every setup. The cited 48-59-1806 manual separately says a fully discharged pack at a normal internal temperature takes 30 to 90 minutes, depending on the pack; that statement is specific to that charger manual, identified as 58-14-1810D2 (2014), and should not be conflated with the Super Charger examples.
Best Value
- This charger can tackle both 18 and 12 volt Milwaukee batteries, holding one of each in the unit at the same time.
- Compact batteries can be fully charged in as little as 30 minutes, while extended life batteries can be charged in as little as a single hour.
- The charger has a chip that communicates with its batteries, keeping track of how much they have charged. It saves you power by reducing the amount of charge produced as the battery reaches full charge.
- Indicator lights let you know whether a battery is charging, fully charged, and whether it needs maintenance or not
- In easy-to-open bulk packaging to pass the savings on to you.
5. Determine whether the battery or charger needs service
If you have access to another compatible Milwaukee charger or battery, a careful cross-check can help isolate the problem: see whether the suspect battery behaves the same on a known-compatible charger, or whether a known-working compatible battery behaves normally on the suspect charger. Only use equipment confirmed compatible with the relevant platform, and stop if anything is damaged or behaves abnormally. This is a troubleshooting comparison, not proof that a particular part is defective.
If a pack or charger is damaged, remains unresponsive after the model-specific checks, or continues to show a fault, contact Milwaukee service. The cited operator manual says not to disassemble the pack or charger and directs repairs to a Milwaukee service facility. Do not buy a replacement battery solely because one charging attempt failed.
6. Check the warranty before replacing the pack
Battery warranty terms vary by pack description and generation; there is no single period to apply to every Milwaukee battery. Check the current warranty terms for the exact pack or ask Milwaukee service to assess eligibility. The cited manual lists different warranty periods for different battery groups, says registration is not necessary for the stated battery warranty, and notes that manufacturing date may be used when proof of purchase is unavailable. Confirm the terms that apply to your battery before paying for a replacement.
Charger compatibility if replacement is needed
Replace a charger only if checks point to a charger fault and the replacement matches the battery platform. Milwaukee’s product page for the 48-59-1808 M18/M12 Rapid Charger says it accepts Milwaukee M18 and M12 batteries. The 48-59-1811 Super Charger page says that model is no longer available and has been replaced by 48-59-1815, so the 48-59-1811 is not a current purchase recommendation.
Quick Recap
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