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Why Is My Milwaukee Charger Blinking Red and Green?

A toolbox is undeniably one of the most necessary accessories to have at our houses in case when we need to fix something or make modifications to our homes.

Milwaukee power tools are one of the popularly used electric tools across the US. Therefore, it is important to know its functionalities which you can learn from the abstract below.

Why is My Milwaukee Charger Blinking Red and Green?

A Milwaukee Charger Blinking red and green could be due to either of two reasons: Your battery was not placed into the charger port properly or your battery pack is damaged or faulty. For the second case, you need to replace the battery, unplug the charger to reset it and then plug it back on.

Milwaukee chargers are used to recharge batteries for wireless Milwaukee power tools. 

The Milwaukee chargers have two LEDs in them: Red and Green, which are used as status indicators for the charger as well as to signal out error codes in the form of blinking to help troubleshoot any issues.

The charger checks the batteries by communicating directly with the battery to monitor their temperature, voltage and state to charge while charging.

They show the result of their diagnosis by using the LEDs, whether if everything is going good or if there’s an issue.

There are commonly two patterns of blinking lights: One being only the red light that lights up if the battery is overheated, while the other is the blinking red and green light.

Both of these are indicators that the charger is facing an issue and the batteries aren’t charging. The Blinking red and green light can be caused by two common causes:

Improper battery placement:

One of the reasons you might come across the blinking red and green lights while trying to charge the batteries if they weren’t lodged into the charging ports properly.

The fix for this issue is straightforward, you need to remove the battery from the charging slot and replace it back.

If the error was due to the battery placement, the blinking red and green light would go away and the battery would start charging normally.

Defective Battery:

If the reason behind the blinking red and green lights was not improper battery placement, then the issue could be that your battery is defective.

But before coming to this conclusion, you need to remove and replace the battery into the slot a couple of times just to make sure that the issue is not about battery placement.

If the blinking red and green light still persists, then you should first clean the battery terminals with alcohol and then try again. If nothing works, then you need to replace the battery because they’re faulty.

Why is my Milwaukee m12 charger blinking red and green?

Milwaukee m12 chargers are used to charge the batteries of Milwaukee power tools and they have a green and red light in them that correspond to their charging status.

The blinking pattern of those two lights can also help in identifying and troubleshooting any issues that are preventing the charger from charging the batteries.

In most cases, you will not face any blinking red or green lights if your charger is charging the batteries correctly – the blinking pattern only comes up when there is an issue in the battery or the charger that is preventing the batteries from charging.

Primarily two types of blinking patterns are noticed – red blinking pattern is observed when the battery temperature is too high for charging.

The red and green blinking pattern is observed in either of two cases: If the battery is not properly seated into the charging slot, or if the battery is faulty or damaged.

Why is my Milwaukee charger flashing red and green without the battery in it?

The Milwaukee charger is manufactured and programmed in such a way that its lights would activate only if the batteries are placed in their respective slots.

The charger should not have its red or green lights flash without the batteries even if they are connected to a power source.

The flashing red and green light on the Milwaukee charger means either the battery is in the charging slot but has not been properly placed thus the charger cannot charge the batteries well.

The second scenario being the placed batteries are defective or damaged.

However, both of these cases require a battery in the charger to trigger the flashing red and green lights. But if you get these error flashes even if there are no batteries in the charger, then your charger is defective or damaged.

The sensors responsible for detecting battery placement in the charger could be giving false positive feedback which could be causing this error.

What does it mean when a Milwaukee charger blinks red and green?

There are a few conditions that might trigger a Milwaukee charger to blink red and green. The possible reasons are detailed below:

Battery not placed properl:

If you placed your batteries in place but the Milwaukee charger is blinking red and green lights, then it is possible that the batteries have not been placed correctly or have not been lodged properly in the slots.

That is one of the common causes for the blinking red and green light if both the charger and battery are in good condition – removing and replacing the battery back properly will solve this issue.

Battery is defective:

If you are sure that you placed the battery properly in the charger and the charger is in perfect condition as well, then there could be another reason that is triggering the blinking red and green lights.

If the sensor in the charger faces difficulty in detecting the voltage, temperature and other status of the battery then this blinking pattern gets triggered.

Therefore, the battery must be damaged or defective which is causing the charger to obtain the data from the battery properly.

Charger is defective:

If you checked for the previous two cases however the blinking red and green light still persists, that means the problem lies not in the battery or placement but in the charger itself.

Whether the entire charger is defective or the sensors in the slots are defective has to be investigated.

How do you reset a Milwaukee battery?

In case of some defective batteries, you can reset their memory to make them hold charge again. The process to reset a Milwaukee battery is laid below:

Attach jump cables to a 12V power source:

In order to reset the memory of your batteries to allow them to hold charge again, you need to connect them to a stronger power source such as a 12V car battery.

In order to do so, you need to connect jump cables to the positive and negative terminals of the 12V source.

Connect the cables to the battery terminals:

Once the jump cables are connected to the 12V terminals, connect the red cable to the positive terminal of the Milwaukee battery and the black cable to the negative terminal.

Hold the cable in this manner for 5 seconds to allow the power surge from the 12V source to reset the Milwaukee battery.

Clean the sulfate deposits:

The power surge from the 12V source would cause the Milwaukee terminals to have sulfates flow out from the battery’s insides and accumulate.

Keeping them there would cause the battery to become defective and unusable, therefore you need to clean the sulfate deposits off the terminals before you can recharge them.

How do you jumpstart a Milwaukee battery?

To jumpstart a Milwaukee battery to get them up and running, you need to get a good and fully charged battery temporarily.

Next, connect the positive and negative terminals of the good battery to the corresponding terminals of the bad battery using a 14-gauge copper wire.

Hold the wire in place for 3 minutes to allow a power surge to take place from the good battery to the bad one.

Afterwards, the bad battery would be ready to be charged by your charger but keep in mind that this battery was bad and thus will not have the same capacity as a good battery.

If you are using the battery for short-term use, then there is no need to get a good battery. However, if you plan to use them long-term the performance of the batteries will not be satisfactory and it is better to get new ones.

Final Thoughts

A Milwaukee Charger blinking red and green lights might be caused by two things: battery not correctly inserted into the charger port, or battery pack is broken or defective. In the second situation, you must remove the battery, disconnect the charger to reset it, and then plug it back in.