Milwaukee M12 Battery and Charger Review




Milwaukee M12 Battery and Charger

The Milwaukee M12 line uses a Lithium-ion batteries and a 30 minute charger, leaving the user with little to no down time.  The Milwaukee batteries are extremely light, weighing only .6 lbs.  The charger comes with a 5 year warranty and the batteries have a two year warranty. There is a nice visible display on the charger that gives the user status on the power in the batteries.

The Review

When testing all of the different tools that came in Milwaukee’s M12 kit, we had no problem whatsoever getting through all of our reviews on one battery charge per project. The Milwaukee charger worked and performed well, adhering to the 30 minute time frame for a full charge. The batteries are light and very compact, making the tools very easy to use on all projects attempted.

Final Thought

Milwaukee does a superior job on power generation technology when it comes to keeping their tools running!  We like the light batteries , but love the 30 minute charge time.


  1. How do I tell if My M-12 Millwaukee Charger is working when Both lights are flashing when inserting new Batteries ? Have gone through two Chargers . Batteries work in M-12 drill-driver and run drill but charger has both lights flashing . How do I tell if the Batteries are bad or the Charger ?

    • Are they first generation batteries? Do you have access to another charger? Sounds like bad batteries, especially if they are GEN 1

  2. just received second Charger and both red and green lights flash on the second Milwaukee M-12 Charger . batteries are new one has a full charge and the other lights up only one light and does not run the drill .read on Amazon site under feedback one person is on the 5th charger . But the info on any web site does not give information on how to test the charger or the Batteries to see which is not good ?

  3. How can you tell one battery has almost a full charge and runs the drill but when insetring into the charger the red and green nlights both flash . So what is the difference between first gen battery ?

    • All my first Gen batteries died and did the same thing yours are doing. Some would hold a charge for a bit some wouldn’t. First Gen batteries just say Milwaukee on them no m12 and no Redlithium.

  4. Hi
    The batteries that I have are M12 and have Millwaukee on the bottom protective cover . took the top cap off and checked for a fuse link etc and found none . Batteries are Samsung about the the size of a AA battery with a small circut board on top and connections have lots of solder But saw nothing out of place . Batteries are made in Korea and then shipped to China for other work . Took a multi Meter and checked the posts on the Charger and get 12 volts .The M12 batteries have red Lithium on them .Can’t tell if they are 1st or second generation batteries .Bottom label gives Pat. voltage and parts number only .Have discharged one completly and then inserted in Charger and still have red and green lights Flashing and made sure battery is seated .

  5. Hi
    Millwaukee contacted me today and said ship all to them and they will replace all with working charger and batteries but shipped a battery back to supplier . And can check charger with Multi metter and last one checked out at 12 volts but have 3 other prongs in front and have no idea what they do. When I pulled the power cord the lights will still flash with battery installed in charger. Have had Ryobi 18 volt and have never had a problem with the Charger or batteries and have used 8 batteries in 12 years .

  6. Seller sent email back about M12 Red lithium batteries and said the Red Lithium are 3rd generation Batteries and have a low fail rate . The 3 prongs on the front of the battery case are for each battery .One prong per battery and prongs may not be making contact in the charger when seated and then have red and green lights flashing . Each prong is a over load circut . And Milwaukee sent me a address to ship to a repair center and they will Fedex back the charger and batteries etc . Seller says not to discharge battery completly . So at this point do not know if I have a bad battery or a Charger and on the second New Charger .

  7. So it appears red lithium batteries have a fail rate . So comoparing Ni-Cad Batteries I have had in the past 12 years against the new Lithium batteries .Have not had one defective Ni-Cad battery Normally wore them out . And same with Ni-Cad chargers zero fail rate . Can’t say this for the Red lithium batteries or Chargeres

  8. Both of mine are shot after about two years. They were barely used for light home projects. Sent them to Milwaukee and they told me to pound sand but would replace them for 40.00 each. Nice. I won’t be buying anymore M12 tools. My plan is to bite the bullet and purchase another M12 battery and hope for the best. My tool is like new with very little use and I’m hoping to get at least a small amount of my moneys worth out of it. Ed


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