Flex 24V Stack Lithium 4-Battery Charger: Four Batteries at Once, Finally

Introduction

Most cordless tool users know the routine: two charger ports, a queue of batteries, and a lot of waiting. The Flex 24V Stack Lithium 4-Battery Charger throws that routine out. It charges up to four Stack Lithium batteries at the exact same time, all four ports active simultaneously rather than two at a time with the rest queued behind.

This is not a small iteration. Flex claims 1,120W of total output and 50% faster charging than a standard charger. Pair that with Stack Pack system compatibility and smart battery locking, and you get a charger that feels like a genuine piece of job site infrastructure rather than an afterthought accessory.

Who This Charger Is For

If you run a lot of Flex tools on a busy site, this charger removes the biggest friction point in the ecosystem: downtime between charges. Tradespeople with four or more batteries in rotation, crews sharing a charging station, or anyone tired of babysitting a two-port charger will feel the difference immediately.

Flex’s Stack Lithium batteries use a rectangular pouch cell design instead of cylindrical cells, which the company says enables very high power output, fast charging, and long run times. This four-port charger is built to exploit exactly that.

Main Strengths

The headline feature is obvious: four batteries charging at the same time, each with its own dedicated indicator light so you can see the status of every battery at a glance. There is also an 80% charge indication, handy when you want a quick top-up rather than a full charge.

Charging speed is the other big win. A 6Ah battery reportedly charges in roughly 30 to 35 minutes, and the whole unit is claimed to be 50% faster than a standard charger. Despite the 1,120W output, the charger ran without tripping breakers or dimming lights in use. The unit itself weighs a reasonable 8.5 lb without batteries.

The hardware details are thoughtful too. A collapsible handle makes it easy to carry or remove the charger from a stack, and the power cord wraps around rubberized corner feet with a retention clip so it will not fall loose during transport.

Stack Pack Integration

This is where the charger gets genuinely clever. It clips onto the sides of Flex’s Stack Pack storage boxes and can be oriented facing forward or sideways. Once mounted, you can drop batteries in and the locking mechanism holds them securely, even when you lift the box lid with the charger and batteries still attached.

That means your charging station can live on top of your tool storage. Load up your top case with bits, head out to the job site, pop the lid with the charger and batteries riding on top, lift the assembly off by the handle, and start working. At the end of the day, everything snaps back together and heads home as one unit.

Things to Consider Before Buying

The port count is the differentiator, but it is only useful if you actually own four or more Flex Stack Lithium batteries. With fewer batteries, a smaller charger makes more sense.

Also note the 8.5 lb weight is without batteries; loaded up with four, it gets noticeably heavier. And while 1,120W did not cause breaker issues in testing, on older circuits with lots of other equipment running you should still be mindful of total load.

One thing worth knowing: Flex extended a lifetime warranty on its tools in 2023. Buy any Flex tool now and register it, and it is covered for life. That level of backing makes committing to the platform easier.

Buying Advice

If you are already in the Flex 24V ecosystem with a battery collection, this charger is one of the most practical upgrades you can make. Four simultaneous ports, fast charging, and Stack Pack integration solve real, daily problems.

If you are new to Flex, the lifetime warranty (on tools bought and registered since 2023) is a strong reason to consider the platform, and this charger is a sensible anchor for a multi-battery setup.

Conclusion

The Flex 24V Stack Lithium 4-Battery Charger is a rare thing: a charger that feels designed rather than commoditized. Four batteries at once, 1,120W, 50% faster charging, an 80% charge indicator, and clever Stack Pack integration add up to a genuinely useful piece of kit. For anyone running Flex tools seriously, it is an easy recommendation.