M12 Vs. M18 Batteries

The difference between M12 batteries and M18 batteries is their voltage and power.

Milwaukee makes some of the most robust tools on the market. As more contractors rely on their cordless tools for hours of endless construction, the need for more power has become a priority.

The new M18 batteries offer that the added power that professional contractors need.

However, the M18 models come at a higher price. Is it worth the money?

When you are shopping for replacement batteries, you need to know which ones are compatible with your M12 or M18 cordless tool.

Many of our readers bought the bare tool, and now want to buy the right battery. However, there are a lot of options! If you are holding a screwdriver in one hand in your phone in the other, use our links below to get the right one.

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M12 Batteries Vs. M18 Batteries

To make it simple, these batteries are not interchangeable. They have different voltages and power, and if you did manage to interchange them, it could ruin the tool. Thankfully Milwaukee keeps you from making that mistake.

You need an M12 battery to go with an M12 tool—this the 12-volt tool line.

The M18 batteries are designed to go with Milwaukee M18 tools. With an 18volt power supply, they offer extended power for long days on the job site.

Click Here to See M18 Batteries

Click Here to See M12 Batteries

Milwaukee M12 Batteries

The beauty of the M12 tool line is that they are more lightweight. The Milwaukee M12 compact line is an absolute pleasure to use, and they offer a lot of power for their small size. For the contractor who loves compact tools, the M12 Fuel cordless tools offer more power and hardened cases. 

All of the M12 REDLITHIUM lines uses lithium-ion batteries for long run times with extended battery life over thousand of recharging events. 

With the M12, you can choose between either the compact size or the high capacity size. This gives you the ability to customize your kit for your preferred style of working — and is something that most other tools don’t offer. 

The compact battery has three lithium-ion cells, where the XC battery offers six lithium-ion cells for longer run time. You can tell the XC versions apart by their wider base. This wider base also comes in handy as the tool can rest on them.

For most of your screw-guns and other high-speed cordless tools, you will want to choose the M12 Redlithium 6.0 Extended Capacity batteries. 

You can use any M12 battery with any Milwaukee M12 tool. This allows you to connect the massive, high capacity batteries to any of their tools. This lets you give new life to the older tools that you find. 

Milwaukee M18 Batteries

The Milwaukee M18 batteries power Milwaukee’s M18 and M18 Fuel tools. 

The Milwaukee M18 high-demand batteries are extremely powerful and are compatible with all M18 power tools. 

As with the M12 (which has six different batteries), the M18 comes in 7 different sizes. 

They come in three variants:

  • Regular
  • XC
  • High Demand

The M18 CP’s are their compact version that only has 1.5 or 2.0 amp-hour lithium-ion cells. These are great for running their Milwaukee flashlight or for a homeowner doing small tasks. 

Most of our readers who choose the M18 line will want the XC extended capacity batteries that come in 3.0, 4.0, 5.0, or 6.0 amp-hour battery.

It is important to recognize that there is a massive difference between the different XC batteries. If you find some on sale, you want to make sure that they have the correct amp-hour rating that you are looking for. 

Above the XC categorization, the M18 also offers a high demand battery. This provides a 12 amp hour power supply, making it perfect for those power-hungry tools like the Milwaukee Fuel Impact Wrench or for contractors who need to put in 12 hours a day on the job with their impact drivers.

Just to reiterate: any M18 battery will go with any M18 tool. Any M12 battery will go with any M12 tool.

Milwaukee Redlink Technology

The Milwaukee Fuel tools offer Redlink power management technology. This is additional circuitry that is built into these tools to help them manage the power. This helps them increase the battery life, while also helping the tools to work better during cold weather. If you are using their Fuel drill/driver, you’ll appreciate how long this lets you attach fasteners without recharging.

Milwaukee Battery Chargers

If their variety in batteries isn’t enough, Milwaukee also makes a variety of chargers. In addition to their basic wall charger, they also have 4-pack and 6-pack sequential chargers that let you get more batteries recharged at once.

My favorite is their M12 & M18 charger. If you have both tools (most of us do!), this one charger lets you charge either battery size. Since M18 batteries take longer to charge, having a multi-bay charger like this one is a good investment.

If you are using M18 High Demand batteries, you will want to invest in their new supercharger that can charge those batteries in one hour.

Many of these can also be bought as a combo kit with both battery and charger.

Frequently Asked Questions On Milwaukee Batteries

Are M12 and M18 batteries interchangeable?

The batteries are not interchangeable. You have to match M12 batteries to M12 tools and M18 batteries to M18 tools.

Is There A Milwaukee M12 to M18 Adapter?

There is no M12 to the M18 adapter and no M18 to the M12 adapter. One of the nice features of the Dewalt 20v system is that their larger battery is backward compatible with their lower-voltage tools. That is not the case with Milwaukee. You have to buy the correct battery pack for your tool type. “Use the right tool for the right job,” as my grandfather would say.

Milwaukee seems to have the same philosophy.

Milwaukee 12v vs. 18v

For a long time, 12-volt tools have been the gold standard. Eventually, however, contractors want more options. Some of the tools — like an air compressor, circular saw, hammer drill, impact wrench or cordless miter saw — simply require a higher voltage to match the performance of corded tools.

You are welcome to continue using the 12-volt tools and enjoying their features, such as being lighter weight and having a faster recharge time. Eventually, most contractors begin upgrading their tools to ones that accept the larger battery.

An M12 impact wrench should be enough to run a hole saw or auger — more than enough power for the average homeowner.

Are Milwaukee M12 Tools Good?

The M12 series are excellent and have built thousands of homes across America. As battery technology develops, Milwaukee developed the new M18 line to help them stay competitive in a world that constantly needs to move more quickly.

Heck, the M12 fuel circular saw delivers 3,600 RPMs of power and is lighter than the M18. The M12 fuel impact wrench is one of the best on the market while still being lightweight. There are a lot of arguments to be made for staying with the 12-volt tools instead of upgrading. Our DIY homeowners will likely be happiest with these smaller tools.

Is Milwaukee M12 Brushless?

Both the M18 and the M12 series us4e brushless motors. Brushless motors tend to have less drag and longer battery life. Both tool series also use the Redlink technology to maximize battery usage.

How Long To Charge Milwaukee M12 Battery?

It only takes about 30 minutes to charge the compact batteries and 60 minutes to charge the extended capacity batteries. One of the advantages of Milwaukee tools is that they tend to have some of the fastest charge times in the industry.

How Long To Charge a Milwaukee M18 Battery?

Milwaukee’s larges battery, the 12.0 amp-hour M18 high demand battery, can take up to 241 minutes to charge on a standard charger. For this reason, many users are switching to the new Super Charger, which can charge the batteries in 60 minutes.

Is The Milwaukee M18 or Dewalt 20-Volt MAX XR better?

It’s hard to play favorites, here. By the numbers, the M18 high demand offers a 12.0 amp-hour rating. This is one of the highest amperage ratings among any cordless power tool. The Dewalt XR only has a maximum of 6 amp-hours.

However, both tools are used heavily by contractors. In fact, many contractors choose the smaller M18 XC extended capacity batteries, which have a similar rating to the Dewalt model.

Milwaukee SuperCharger vs. Rapid Charger

The new Milwaukee supercharger is extremely fast and has contractors all over the country falling in love with it. The M18 High Demand battery — the largest they make — only needs 60 minutes to reach a full charge on it.

By comparison, the Rapid charger would require 130 minutes to deliver the same charge.

Most of our readers are only use the 6.0 amp hour batteries. Those can be charges in as little as 35 minutes with either the Super Charger or the Rapid Charger.

So the advantage of owning the Super Charger is reserved for those with the larger, M18 XC, and HD batteries. Folks using the batteries with 5.0 amp-hours or lower, won’t see much of a benefit from the new charger.

Milwaukee Battery Only Charges To Three Bars

You have to push the pack in very firmly. They go in more firmly than most of the competing brands, and it requires you to make sure you hear a good “click.” Just dropping the battery, it won’t work.

If that doesn’t fix it, it is possible that your batteries may degrade over time, or that you get a bad charger. If you are having the same problem with multiple batteries, it is very likely that you are dealing with a charger problem — unless all of your batteries experienced the same event, such as being dropped or left sub-zero temperatures.

If the problem continues, reach out to Milwaukee for warranty help. A lot of times, you can exchange it at your local Home Depot if you are having problems.


One of the downsides with Milwaukee is that they have too many battery options. I mean, there are six different versions of the M12 battery! How crazy is that?

The upside is that this lets you customize the battery configuration to your needs. Is weight important? They have the battery. Need more battery life? There is one for that, too!

Unfortunately, this makes it extremely confusing.

For most readers, either the M12 or the M18 is going to be a good choice, and staying around the 6.0 amp-hour life will save you money in the form of expensive chargers while matching the performance you are used to from competing brands.

With Milwaukee, you can go further than any other brand, and that’s people who love them.

About Zachary Drumm

Hey! My name is Zachary Drumm! This site allows me to try these tools out, piddle around in the garage, and create fresh content for you. When it comes to tools, home improvement, and being a “shade tree mechanic,” you’ve come to the right spot.