Milwaukee Battery Featured Image

Milwaukee M12 and M18 Batteries

Milwaukee battery on a tool

We get a lot of questions from Milwaukee customers about battery compatibility with their M12 and M18 cordless tools, so we’ve decided to clear some things up for you. Below, you can find answers to frequently asked questions about batteries for Milwaukee cordless tools to help you determine what batteries are compatible with what tools. Spoiler alert: you can use any M12 battery with any M12 tool and any M18 battery with any M18 tool. But we’ll still break it down for you…

Milwaukee M12 vs. M18 Batteries

The M12 and M18 batteries have several key differences, the most significant of which are their voltages and power. Other key distinctions between the two batteries are their tool compatibility, size, and weight.

M12 batteries are better for a person using tools but don’t require higher voltage like the M18. M12 batteries are designed to be compatible with M12 tools only. Besides tool compatibility, their other difference is that the 12V batteries are smaller and sleeker.

M18 batteries are better for extended uses, and their larger design makes them better for heavier jobs where power is needed. Like the M12, M18 batteries are 18V batteries designed only for M18 tools. 

Shop Milwaukee M12 batteries

Shop Milwaukee M18 batteries

Milwaukee M12 Batteries

m12 batteries

Milwaukee’s M12 Compact and M12 Fuel cordless tools use M12 REDLITHIUM batteries and chargers specifically designed for the M12 tool line. These lithium-ion batteries have excellent run time, are lightweight, work well in different weather conditions, are great for light duties, and have the REDLINK intelligence system installed. They are suitable for use for short and minimal home construction repairs.

The M12 batteries come in two different variations: the compact and the high-capacity. Both are great for various jobs; the difference is the amount of power they offer. The compact battery pack is 65% lighter and 50% smaller than other compact NiCd batteries and offers either 1.5, 2.0, or 3.0 amp-hours of run time. Then there are the high-capacity 3.0, 4.0, and 6.0 amp-hour batteries, allowing for more work for an extended period. 

So, depending on what you’re working on and how much space you have in your tool bag or tool belt, you can switch between the batteries to get the best result for your work.

  • REDLITHIUM = 1.5 amp-hour
  • REDLITHIUM 2.0 = 2 amp-hours
  • RELITHIUM 3.0 = 3 amp-hours
  • High Capacity REDLITHIUM = 3 amp-hour
  • REDLITHIUM 4.0 Extended Capacity = 4 amp-hours
  • RELITHIUM 6.0 Extended Capacity = 6 amp-hours

M12 Battery Compatibility

Even with the several different M12 tools, the great thing is that you can use any M12 battery with any M12 tool. However, M18 batteries are not compatible with M12 tools.

Milwaukee M18 Batteries

A m18 battery

Milwaukee’s M18, M18 FUEL, and M18 High Output cordless tools use M18 REDLITHIUM batteries and chargers specifically designed for the M18 tool line. These lithium-ion batteries have amazingly efficient runtime and power. Since they have a higher voltage, they are heavier/bulkier and more powerful than the M12 batteries. They can handle the toughest to the coldest of worksites.

These batteries come in various sizes and three different variations: regular, XC, and high output. They were built with the same durability, and REDLINK intelligence was installed.

First, the regular compact M18 batteries offer either 1.5 or 2.0 amp-hours of runtime. These batteries are great for jobs that need portability and power but don’t need much time to finish. They are best for light household projects like drilling holes into your wall or the starting DIYer.

an m18 battery

The next type is the XC extended-capacity batteries. The XC is better for slightly heavy jobs requiring sustained power output for extended periods, such as running a workshop. These batteries come in 3.0, 4.0, 5.0, or 6.0 amp-hour sizes, allowing you to adjust your tool to any work demands.

The final type is the High-Output batteries. These batteries are specifically designed for heavy-duty and time-intensive work, making them ideal for tools such as a table saw, miter saw, or any other outdoor power equipment. The High-Output batteries are offered at either 9.0 or 12.0 amp-hours, pushing cordless tools harder and longer than any other battery.

  • REDLITHIUM CP = 1.5 amp-hour
  • REDLITHIUM CP 2.0 = 2 amp-hours
  • REDLITHIUM CP 3.0 = 3 amp-hours
  • REDLITHIUM XC = 3 amp-hour
  • REDLITHIUM XC 4.0 = 4 amp-hours
  • REDLITHIUM XC 5.0 = 5 amp-hours
  • REDLITHIUM XC 6.0 = 6 amp-hours
  • REDLITHIUM XC 8.0 = 8.0 amp-hours
  • REDLITHIUM HIGH OUTPUT 9.0 = 9 amp-hours
  • REDLITHIUM HIGH OUTPUT 12.0 = 12 amp-hours

M18 Battery Compatibility

Moreover, the M18 cordless tool line is compatible with any M18 batteries. On the other hand, they are now compatible with M12 options.

M12 & M18 Battery Chargers

Milwaukee offers many types of M12 and M18 chargers, including wall chargers, car chargers, multi-battery charger packs, and combo chargers that simultaneously charge both battery types.

m12 and m18 battery chargers

Milwaukee M12 & M18 Battery FAQ’s

1. Are M12 & M18 batteries interchangeable? 

No. Milwaukee M12 batteries are only compatible with M12 tools, as M18 batteries are only compatible with M18 tools.

2. Can you use M18 batteries with M18 FUEL tools? 

Yes. M18 batteries can be used with any type of M18 tool.

3. Are M18 batteries interchangeable with M18 tools? 

Yes. M18 batteries can be used with any type of M18 tool.

4. Are all Milwaukee 18-volt batteries the same? 

No. Milwaukee has had several versions of the 18-volt batteries. The most recent were the 18V Ni-Cd batteries, V18 Li-Ion batteries, and the current M18 Li-Ion batteries.

5. Can you use M12 batteries with M12 FUEL tools? 

Yes. M12 batteries can be used with any type of M12 tool.

6. Are M12 batteries interchangeable with M12 tools? 

Yes. M12 batteries can be used with any type of M12 tool.

If you have any additional questions, please contact our team for additional support on our Acme Tools Contact Us page.


    • Acme Tools

      March 12, 2018 at 8:11 am

      Hello, Thank you for your comment. The M12 and M18 series batteries cannot be interchanged. M12 is how Milwaukee designates their 12 volt tools and M18 is for their 18 volt tools.

      Thank you,
      Acme Tools

    • William Holmquist

      November 19, 2022 at 7:09 pm

      Will I damage my M18 sds brushless rotaryhammer if I use a high output hd 12.0 battery?
      I did it for about 5 seconds and it appeared to work fine.
      Is it like plugging a 110 into a 220?

      • Acme Tools

        November 21, 2022 at 10:05 am

        Hi William. You will not damage the M18 rotary hammer by using an M18 12.0 HO battery. It might feel like a 110V item being run on 220V, but in this case, the tool and battery are both 18V. We have always tried to explain batteries as a fuel tank. As long as you run the right kind of fuel (M18 18 Volt DC), you can select different grades of fuel. The higher the amp hour, the battery is; it acts like a higher octane fuel. You get all the benefits of running premium on your tools. The downfall, like the cost of premium fuel, is the weight of the battery. Does it make sense to run the larger batteries on smaller tools? That trade-off is up to you.

        Thank you, Acme Tools.

  • Martin

    August 25, 2018 at 10:39 pm

    My Milwaukee cordless drill came with M18 Compact REDLITHIUM Batteries. Are these batteries compatible with the MILWAUKEE 2630-20 M18 LI-ION 18V 6-1/2 circular saw (photos only show XC batteries).

    • Acme Tools

      August 27, 2018 at 8:07 am

      Hello, Thank you for your question. The 2630-20 M18 Circular Saw will work on the M18 Compact Batteries. If you are looking for more run time or increased performance we suggest looking into higher Amp Hour (Ah) batteries in the future.

      Thank you,
      Acme Tools

      • martin

        August 29, 2018 at 7:16 pm

        thanks for the answer and I was about to purchase this saw on Amazon but read this post “The Milwaukee saw you are considering requires the Milwaukee 48-11-1828 M18 XC RED LITHIUM 18-Volt battery. NO OTHER battery will work in it including the Milwaukee 48-11-1815 battery; Since it doesn’t have enough amperage Milwaukee has designed the saw to block the smaller battery. BTW the 2630-20 saw is a great saw. I’ve been using mine for several years professionally”. John Nebelsiek on August 29, 2013

        Please can you confirm this Amazon post is incorrect, and that I can run the saw with my 1815 compact batteries.

        • Acme Tools

          August 30, 2018 at 10:01 am

          The Amazon reviewer is incorrect. I personally have installed a 48-11-1815 battery on a 2630-20 circular saw that was on display at our retail location and started the saw. Video is available upon request.

          Thank you,
          Acme Tools

          • Chris

            November 30, 2018 at 8:56 pm

            There is a subtlety here that may be causing some confusion. Back in mid-2010 at Home Depot the Milwaukee representative sold me on a Saturday promotional special consisting of a drill, an impact driver, two batteries and a charger. A great set of tools that have performed very well. The batteries were labeled “M18 LITHIUM-ION”. CAT. NO. 48-11-1815. Only the letter M in “M18” is colored red. The word “RED” is not part of the name on the battery.
            According to Milwaukee’s website the “M18 REDLITHIUM-ION” battery line was introduced at about this time. Both the letter M in “M18” and the word RED in “REDLITHIUM-ION” are colored red. This likely explains the super deal that I got – they were clearing out an earlier battery line.
            As an electrical engineer I can assure you that the old M18 LITHIUM-ION 48-11-1815 will not fit in the new M18 2630-20 cordless circular saw that I just brought home from, you guessed it, Home Depot. There are two ridges on the battery, one of which that lines up with a ridge on the receiver on the saw. I would assume that this is intended to prevent the earlier model battery from fitting onto the saw that is designed to be powered by the newer RED version of the battery. So, a new 48-11-1815 will likely fit but an older version will not.
            Anyway, it’s off to HD tomorrow, yes Saturday, to see if one of the new RED batteries will fit in my old charger or if I have to buy both items.

    • Acme Tools

      June 17, 2019 at 7:54 am

      Hi Rick, Thank you for your question. Milwaukee does not make an adapter to be able to run 18V batteries on their 12V tools.

      Thank you,
      Acme Tools

    • Acme Tools

      September 23, 2019 at 8:50 am

      Hello, Thank you for your question. We do apologize but we do not have information on the UK model and are unable to offer a suggestion.

      Thank you,
      Acme Tools

    • Acme Tools

      November 4, 2020 at 8:05 am

      Hi Robert, Thank you for your question. Yes, you can use an M18 XC6.0 battery. In fact, you can use any Milwaukee M18 battery for your Milwaukee M18 Drill and Impact.

      Thank you,
      Acme Tools

  • Don Freeman

    November 19, 2022 at 3:21 am

    I am considering purchase of the M12 or M18 drill/driver set. If the tools are not used very often, which will hold their charge longest while just sitting on the shelf?


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.