Milwaukee REDLITHIUM 2.0 CP and 4.0 XC Are Truly an Upgrade


Milwaukee has certainly been making a splash lately with their introduction of the new FUEL line of brushless tools and the extended capacity batteries that are being released to accompany them. While everyone is anxiously awaiting the M12 FUEL lineup launch (very soon!) I thought that it could be a good idea to check out the M18 4.0XC and 2.0CP REDLITHIUM batteries and see exactly what their improved capacity and intelligence actually gets them in terms of increased run time.

M18 battery review

The tool I used for the job was an M18 Hackzall with a standard 5 TPI “Ax” Sawzall blade on it, and I set out to see how many times each battery could cut through a 2×6 that I had laying in my pile of scrap lumber (it had a section routed out of it and a crack in it as well as being pretty dry). All the cuts were on the same piece of lumber, but a crack in the board made some of the pieces fracture into smaller chunks during the cut. The reason I used a Hackzall instead of a drill or impact was because I was worried that I would be drilling holes or putting in screws all weekend before I could deplete these three batteries, while the Hackzall would only make for a solid afternoon of work.

review of new milwaukee m18 batteries

First I went to work with the 2.0 Ah REDLITHIUM CP Battery 48-11-1820 and tried to see how many cuts I could make across my piece of wood before the battery died. I ended up with 16 (and a half) cuts over what was probably about 10 minutes of Hackzall use.


Next, I got out the old, tried and true M18 REDLITHIUM XC 3.0 Ah 48-11-1828 battery to see how it stacked up against the 2.0Ah CP. The battery only weighs about a half pound more than the CP battery, but it is about an inch bigger, which could make a difference when trying to fit your tool into a tight space (something the Hackzall is designed for). The extra half pound and Amp-hour made for an extended runtime. I was able to make 23 cuts on one charge in about 15 minutes of use. To eliminate the factor that blade wear might have had on the test results, I was sure to change the blade after I made 16 cuts.


Finally, I got out a fully charged M18 REDLITHIUM XC 4.0 48-11-1840. This battery is the highest capacity 18V Lithium Ion Battery Milwaukee offers at the moment at 4.0 Ah and has the advanced REDLINK technology that is present in the current generation of batteries. Despite its increased capacity, it weighs exactly as much as the 3.0 Ah battery and is right about the same size. This battery made a whopping 42 cuts in my 2×6 (again with a blade change at 16 cuts) in about 22 minutes of use. I have to say after using all of these batteries right in a row it seemed like this battery lasted FOREVER. It made all of the cuts that the other two batteries made combined and ordered 3 more for dessert when it was done. I was beginning to worry that I would run out of 2×6 before the battery ran out of power by the end.

review of new M18 Redlithium milwaukee batteries

After all that largely pointless cutting, I had nothing left to do but sit back and wait for my batteries to recharge so they would be ready when I actually needed to do something with them. The batteries charged at a pretty predictable rate of 15 minutes for every Ah of capacity – 30 minutes for the 2.0, 45 for the 3.0 and an hour for the 4.0.

milwaukee tools halo 4

Waiting made easy.

I guess at the end of the day, if you are going to be constantly using a Hackzall with your M18 batteries you had better have a few backups if you don’t want to experience downtime. However, if you are going to be drilling or using an impactor you can get a pretty good run out of any of these batteries, but it should be noted that there is more to the new batteries than the increased amp hour. I didn’t have any handy for testing but it would not serve as a surprise at all if the new CP batteries competed side by side with the larger 18V Lithium Ion batteries of the past.

UPDATE: Milwaukee is currently running a contest that will give away over $5000 in new REDLITHIUM batteries. They are looking for people to submit pictures of a job that would be easier if they had an upgrade. Click here for the actual contest site and details.



You can get all sorts of M18 and Milwaukee Tools at Ohio Power Tool, and if you have any questions about them you can call a pro at (800) 242-4424.



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  1. Paul Hardy says:

    I bought this battery as an accessory to a twin-pack of Milwaukee tools. It works on both tools, it charges on the supplied charger. It has more capacity. I like it.

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