Milwaukee 48-11-2420 M12 REDLITHIUM 2.0 Battery Kit with Charger Review

When we first unboxed the Milwaukee 48-11-2420 kit, we knew we were holding something that would change how we approach cordless tool power management. After months of putting this battery and charger combination through real-world job site conditions, we’re ready to share everything we’ve learned about this essential Milwaukee M12 system upgrade.

Price: [price_with_discount]
(as of [price_update_date] – Details)

As an Amazon Associate, I earn from qualifying purchases. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon Site(s), as applicable at the time of purchase will apply to the purchase of this product.

What Makes This Milwaukee Battery Kit Stand Out

The Milwaukee 48-11-2420 kit delivers exactly what serious tool users need: two genuine M12 REDLITHIUM 2.0Ah batteries paired with the reliable 48-59-2401 charger. During our testing period, we used these batteries across multiple M12 tools, from impact drivers to rotary tools, and the performance consistency impressed us every single time.

What really caught our attention was how Milwaukee engineered these compact powerhouses. The 2.0Ah capacity hits a sweet spot—offering substantial runtime without adding unnecessary bulk to your tools. We’ve used these batteries on overhead work for extended periods, and the weight difference compared to larger capacity batteries becomes genuinely noticeable and appreciated.

REDLITHIUM Technology: More Than Marketing Hype

Milwaukee’s REDLITHIUM branding appears on many products, but after extensive use, we can confirm it’s not just clever marketing. These batteries incorporate advanced battery management systems that we noticed immediately in cold weather performance. We tested these batteries in temperatures hovering around 35°F, and they continued delivering consistent power when other brands would have faltered.

The fade-free power delivery is another standout feature we experienced firsthand. Whether the battery showed four bars or one bar remaining, our tools maintained their torque and speed until the very end. This predictable performance means you can actually plan your work around battery life rather than guessing when power will suddenly drop off.

Superior Cell Protection We Put to the Test

Milwaukee’s individual cell monitoring isn’t something you see during normal use, but it’s working behind the scenes constantly. We intentionally subjected one battery to demanding stop-start cycles during repetitive drilling tasks. The internal electronics balanced the cell load seamlessly, and after six months, both batteries still charge to full capacity without any noticeable degradation.

The M12 Charger: Simple Yet Sophisticated

The included 48-59-2401 charger might look basic, but Milwaukee designed it with practical intelligence. We appreciated the clear LED indicator that communicates charging status at a glance—no guessing, no confusion. The charger accepts both M12 and M12 Compact batteries, which added flexibility we didn’t initially expect but quickly came to value.

Charging times consistently impressed us. From completely depleted to full charge, these 2.0Ah batteries typically finished in about 30 minutes. We timed this across multiple charge cycles and found Milwaukee’s estimates to be accurate. For professionals rotating between jobs or DIYers tackling weekend projects, this quick turnaround time is genuinely practical.

Real-World Runtime That Actually Matters

Numbers on spec sheets only tell part of the story. We wanted to know how these batteries perform during actual work. Using a Milwaukee M12 3/8″ drill/driver with a 1/2″ bit, we drilled 45 holes through doubled 2×4 lumber on a single charge. With an M12 impact driver, we drove approximately 200 screws (3-inch construction screws into framing lumber) before needing a recharge.

For lighter tasks like cutting PVC pipe with an M12 hackzall or detailed work with an M12 rotary tool, battery life extended considerably. We managed nearly two hours of intermittent use on projects involving sanding, cutting, and grinding. Having two batteries in this kit means you can keep working while one charges—a workflow we found invaluable.

Why Two Batteries Changes Everything

Milwaukee could have sold a single battery with the charger, but including two batteries transforms this from a basic kit into a complete power solution. During our testing, we developed a rotation system: one battery in the tool, one on the charger. This simple approach eliminated downtime completely.

For professionals, this kit represents a backup power system or an opportunity to run two tools simultaneously. We found ourselves frequently using an M12 impact driver and M12 work light at the same time, each powered by these batteries. The convenience factor multiplied significantly with that second battery.

Compatibility Across the Entire M12 Ecosystem

One advantage we can’t overstate: these batteries work with every tool in Milwaukee’s extensive M12 lineup. We own seven different M12 tools, and these batteries powered all of them flawlessly. Whether you’re investing in your first M12 tool or expanding an existing collection, these batteries integrate seamlessly.

Build Quality You Can Feel

Milwaukee constructs these batteries with impact-resistant housing that we’ve accidentally tested more times than we’d like to admit. Drops from waist height onto concrete left minor scuffs but caused no functional damage. The battery terminals remain clean and make solid connections even after months of repeated insertions and removals.

The fuel gauge built into each battery proved surprisingly useful. Four LED indicators show remaining charge at the press of a button. We checked this gauge religiously during our testing and found it accurate enough to trust for planning work sessions. When it showed one bar remaining, we typically had about 15-20% capacity left—enough to finish immediate tasks before swapping.

Temperature Performance That Surprised Us

Battery performance in extreme temperatures varies wildly across brands. Milwaukee’s REDLITHIUM technology includes cold weather operation down to 0°F and hot weather operation up to 140°F. We tested the cold weather claims during early spring renovation work, and these batteries continued operating when we expected reduced performance.

The onboard electronics prevent damage from temperature extremes by managing discharge rates. During particularly hot summer attic work, we noticed the batteries felt warm but never concerning. The built-in protection systems worked as advertised, preventing the overheating issues we’ve experienced with competing brands.

Customer Reviews Analysis: Milwaukee M12 REDLITHIUM 2.0Ah Battery 2-Pack with Charger Kit

Diving into hundreds of customer reviews validated many of our own findings. Professional contractors consistently praised the runtime-to-size ratio, echoing our experience that 2.0Ah capacity provides excellent balance for most M12 applications. Several HVAC technicians specifically mentioned using these batteries all day with periodic charging during lunch breaks.

Home users frequently commented on the value proposition of receiving two batteries with a charger. Many reviews mentioned this kit as their entry point into the M12 system, with users appreciating that they could start working immediately without purchasing additional batteries. This mirrors our recommendation that this kit serves as an ideal starting point or expansion package.

Some negative feedback centered on users wanting higher capacity batteries for demanding applications. We understand this perspective—if you’re running an M12 Fuel circular saw continuously, larger batteries make sense. However, for the majority of M12 tools and applications, reviewers agreed with our assessment that 2.0Ah batteries deliver optimal performance.

Long-term durability emerged as a common praise point. Multiple reviews from users who’ve owned these batteries for 2-3 years reported minimal capacity loss. This aligns with our experience during testing and speaks to Milwaukee’s battery management technology genuinely extending cell life beyond typical lithium-ion expectations.

The fast charging capability received consistent appreciation across reviews. Professional users noted being able to charge batteries during brief breaks, while hobbyists valued not waiting hours between project sessions. One reviewer calculated charging approximately 200 times over two years with both