Testing the New Milwaukee 4.0Ahr Battery Pack

February 13, 2013 | by Ethan (email) |

Every year tool manufacturers fight for even the tiniest advantage, and that often translates into millimeters off the tool size or ounces off the total weight. These upgrades, while beneficial, are not earth-shattering. However, advancements in battery technology are moving at a rapid pace, and I’m very excited about the new, higher amp-hour (Ahr) batteries that are starting to come out. If you keep up with OPC on Facebook, you know Milwaukee recently sent us their new 4.0 Ahr extended capacity and 2.0 Ahr compact batteries, and I put the 4.0 Ahr battery to the test in the OPC workshop.


Why Do Amp-hours Matter?

Stuart from ToolGuyd recently wrote a great article about what does Ahr mean and how is that an important metric for cordless tools. The take-home message is that Ahr is a measure of the total charge capacity of a battery pack, and that affects power and/or runtime (depending on configuration). As you might expect, higher Ahr ratings are better, and I’d encourage you to check out the article for a full explanation.


The Test

The new Milwaukee batteries claim up to 2X more runtime, 20% more power and 2X more recharges than standard lithium-ion batteries. I’m not equipped to test power or recharging capabilities, but it was easy to set up a runtime test. I rigged up my Milwaukee cordless 4-1/2″ grinder without an accessory, and pitted the M18 XC high capacity REDLITHIUM battery (3.0 Ahr) against the new M18 XC 4.0 extended capacity REDLITHIUM battery (4.0 Ahr) to see how long each battery lasted.

Fresh off the charger and at a no-load speed of 9,000 RPM:

  • 3.0Ahr battery lasted 31 minutes and 37 seconds
  • 4.0Ahr battery lasted 49 minutes and 0 seconds – a whopping 55% increased runtime!


Looking to Upgrade?

At the time of this article, Milwaukee is jumping out in front of the competition. While most manufacturers have announced 4.0 Ahr batteries, Milwaukee is actually distributing here in the USA. You can find the new batteries at your local Home Depot and various online retailers for about $129.00.

Also, now through March 31, 2013 participating Milwaukee distributors have a promotion going. When you trade in a 14.4V or greater professional grade cordless tool with 2 or more batteries, receive $100 off instantly when you purchase a qualifying M18™ XC Kit. The new M18™ FUEL products with the 2.0/4.0 batteries are included in this promotion.

17 Responses
  1. Brady says:

    It seems Milwaukee is walking out ahead of the old standard, DeWalt, in cordless drills/batteries. My only knock is the same as it was ten years ago. Why charge $129 for a single battery when you can buy a new drill with two batteries and a charger for $199?????? What a rip off. When your battery dies, you may as well buy a new set with higher volt batteries, newer drill tech (higher torque, longer run time, better clutch, etc.), and brand new, faster charger!! This may always be the case, which is a shame because of the waste.

    • Ethan says:

      I think you’re absolutely right Brady, and probably not the only one who just buys a new tool. The downside to rapid battery innovation is that the price never has a chance to drop.

    • trebor says:

      This is (personally, anyway) why I feel Ridgid cordless products are a good investment. Lifetime replacement on batteries!

  2. Icarus says:

    How does one responsibly recycle their old batteries?

    • Some tool/battery manufacturers have a 1-800 number on the bottom of the batteries to recycle them. Some others have discount programs on new tools when old ones (and/or batteries) are turned in. I presume they recycle them. Otherwise there is the Call2Recycle website where you put in your zip code and it shows you on a map the places that take old batteries.

      • Ethan says:

        Took the words right out of my mouth. I checked with Milwaukee before publishing and they don’t have a “buy-back” program going on right now. That tool trade in is the only promo that would help upgrade batteries.

  3. Eek565 says:

    Man, my drill feels old now. I”m still rocking a 12 volt nicad Dewalt. I’ll have to tell Santa to start saving.

  4. Reuben says:

    This is cool. I’m glad technology is improving. However, it also seems a bit unnecessary for a casual DIY’er like myself. This battery arms race is probably quite beneficial for contractors and heavy users, though.

  5. poiboybf says:

    Do you think that when DeWalt comes out with the 4.0 Ahr battery, it will be interchangeable with their current lineup of 20V drills? I am considering a new drill/impact driver combo (Model # DCK280C2) from DeWalt, and it would be nice to know if, when the 4.0s come out, I’d be able to swap them out for the supplied batteries and use the 1.5s as backup batteries. Anyone have any intel? I’d also welcome feedback on that product if people have had good or bad experiences. Reviews on and Amazon are good, but wanted to check with all of you.

    • The 4.0 Dewalts came out in the UK first. They are the same form factor as the 20V max so they should work well with the tool. In the UK (and other places) the batteries and tools are marked as 18V XR but it’s the same as the 20V Max line in the US.

      • poiboybf says:

        Thanks Jeff! I guess I’ll just have to hop a plane over to the UK (for batteries, of course. I’d then come straight home.) Good to know!

  6. bigredmachine says:

    Looks like its made to do most any job I would ever need it for, hate all the fast dying batteries

  7. HANDYMAN51 says:

    Probably a good choice for the guy who forgets to recharge the spare.

  8. marinemerchant says:

    Regarding the promotion… is it offered to consumers? I only found it offered through Graybar so far, and I don’t think I can swing by their local shop without having a customer account with them.

    • Ethan says:

      Hi MarineMerchant,

      According to Milwaukee: All industrial construction accounts were invited to take part in the promotion, and Fastenal is one of the big names participating.

  9. Batteries sure have come a long way since those old nicads that had a mind of their own..LOL.Looking forward to getting some of these batteries.. It’s murphy’s law that my old batteries are always flat when I need them..

Leave a Reply