Can You Use M18 Milwaukee Power Tool Batteries With M18 Fuel Tools? (And Should You?)

Most hardware brands that offer a few different battery systems have do's and don'ts about which ones are allowed or able to intermingle. We're talking about high-performance, potentially expensive equipment here, so you definitely want to ensure you're using the best possible power sources, ones that won't negatively affect your tools' longevity. As far as powerful tools are concerned, for the Milwaukee hardware brand, some of its highest-spec tools are those included in the M18 Fuel series, such as the multi-purpose Power Head or the Super-Hawg right-angle drill.

Milwaukee M18 and M18 Fuel tools have several tangible differences that warrant the latter's higher price tag, such as brushless motors and thermal protection circuits. There are definitely some Milwaukee tools that are better to buy brushless, but most of these features are related to the tools' actual operation. As far as power needs go, M18 Fuel tools possess the exact same battery connection rails as the regular M18 tools. This means that it's perfectly safe to use the same M18 battery pack with an M18 Fuel tool that you would use with an M18 tool, though you might not get the best possible performance out of it.

Despite the addition of "Fuel" in their names, M18 Fuel tools are still technically part of Milwaukee's broader M18 ecosystem. You can see this if you check the battery connection ports on an M18 and M18 Fuel tool; they're exactly the same, which means any M18 battery pack can slide right onto the rails and power the tool. In fact, there aren't actually any dedicated M18 Fuel battery packs, as the whole system uses those same connection ports. This also means you don't need a dedicated charger for Milwaukee M18 Fuel batteries.

M18 battery packs, collectively known as Redlithium, all utilize the same connection rails and deliver power in more or less the same way. Using the simplest, cheapest Redlithium battery pack on your M18 Fuel tool will not harm or endanger its functions in any way; it's perfectly safe. It is worth noting, however, that M18 Fuel tools are a bit more power hungry, due to their more elaborate features. As such, while the cheapest Redlithium battery won't hurt your tool, you also might not get the best possible performance and runtime out of it.

Several M18 Fuel tools come bundled with batteries from the second-highest tiers of Redlithium packs to better accommodate their needs. The M18 Fuel Super-Hawg, for example, comes with a pair of Redlithium High Output Extended Capacity batteries, which boast both greater overall energy storage and more power output to better match the tool's capabilities. You could also personally spring for the highest-tier Redlithium battery, a Redlithium Forge, which delivers the highest possible power, storage, and recharge speed.