Does M12 Gen 1 Stubby lose power with use?

[BikeRider]

I've had the Gen 1 M12 3/8" Stubby impact for 3-4 years now, use it all the time. But lately it feels like it's lost a bit of power, and I'm wondering if it's my imagination or if others have experienced this. I use it with the 5Ah high capacity battery, fully charged, at level 3, and also the older 6Ah battery. It still removes most fasteners, just seems to take a bit more time now, and doesn't get tougher ones such as suspension bolts as consistently as it used to. I use the same impact sockets as I always have, Tekton shallow and Pittsburgh deep, and always fasten fasteners to torque using a decent torque wrench. I'm going to be near a local Milwaukee service center later today so I'll take it in for them to look at, just wondering what folks here have experienced.

 

[signcrafter]

I wondered the same thing when I was using my m18 high torque on a pinion nut to crush the crush sleeve. I posted on here about it and what others said was that the gun doesn't loose power but the batteries will. I ended up getting another m18 tool with new battery and gun seemed to be back to normal power.

 

[Odd-job]

9 times out of 10 its the batteries which seem to be the weak link of modern brushless cordless tools. Degradation is a real thing fortunately or unfortunately on lithium ion. I do wonder how much battery cycling vs over discharging/charging vs heat/cold vs letting the battery sit there fully charged contributes to degradation. With my use pattern of letting m12 batteries sit on tools at a full charge in the hot garage am thinking I am probably accelerating the degradation curve.

 

[dnschmidt]

I agree. It's typically the battery. Having about 75 Milwaukee batteries between M12 and M18 for me to make this test is a no-brainer. The best M12 battery is the 5.0. I've had the most failures with the 3.0 M12 compact and the 6.0XC M12 and for the M18 the 8.0, 9.0 and 12.0 have been a problem which hopefully has been fixed with the FORGE series but these haven't been out long enough to make a legitimate call.

 

[spyerx]

Is it still under warranty? If so, send it in. With brushless it's either the hammer / impact mechanism or the battery. Battery is easy to try. The hammer mechanism can wear out with use, its spring actuated and there is literally hammering going on with the mechanism to drive the torque. This video has a good explanation of it and what can wear.

If not under warranty you could always try to disassemble and clean and grease the hammer/drive gears.

 

[BikeRider]

Is it still under warranty? If so, send it in. With brushless it's either the hammer / impact mechanism or the battery. Battery is easy to try. The hammer mechanism can wear out with use, its spring actuated and there is literally hammering going on with the mechanism to drive the torque. This video has a good explanation of it and what can wear.

If not under warranty you could always try to disassemble and clean and grease the hammer/drive gears.

I was renewing my driver's license today and the nearest Milwaukee service office was literally next door, so I took it there, explained the situation, and they said they'll have a look and decide what to do. It's still under warranty so I'm good either way. Pushing my luck, I asked if it's possible to upgrade to the Gen 2 or if they're ever swapped for a Gen 1 if a replacement is warranted, and they said maybe but probably not. Worst outcome, they find nothing wrong and I get the same unit back. Best outcome, I get an upgrade for free. Unlikely, but can't hurt to ask.

 

[tak1313]

As other's have stated, the higher likelihood is the battery, assuming the battery has gone through a number of charge/recharge cycles.

The impact mechanism is pretty straight forward, a motor spins a weight in a circle. The weight is "loaded" by a spring that makes the weight go back and forth between pounding the anvil mechanism and pulling away. Cycle starts all over again multiple times per second.

There IS a potential, however, if the unit itself is old, for the grease to dissipate or even "dry out" somewhat causing more friction that works against that spinning so the inertia of the impacts are reduced. Another thing that could happen over time is the anvil or hammer becomes worn over time. As the hammer becomes worn, the inertial force gets reduced simply because the hammer weighs less, but such differences are usually pretty small that I don't think it would be noticeable unless it's really old with a LOT of use. The grease thing would more likely be the reason if it's mechanical.

That being said, the Gen1 Stubby being brushless, other than potential issues with the bearings getting old/worn, there's not much to go wrong with the motor mechanism. One could make the argument about the potential of the magnets in a brushless motor getting weak, but I PERSONALLY think that's stretching.

 

[BikeRider]

Quick followup. They ended up replacing the guts, circuit board, motor & mechanism, so it's essentially a new wrench in an old body. I tested it at home, unloaded. It seemed to work fine, although at a certain point when I was switching between modes to test them all out, it stopped working and the battery level LEDs started flashing in alternative sequence when I pulled the trigger, in auto shutoff mode and switched to forward. But I waited a few seconds and it worked fine after that. Should I be worried? I used a 5Ah battery at full charge.

Incidentally, when I went to pick it up I brought my several year old Gen 1 rotary tool for them too look at, that had been sounding kind of rough lately. It was still under warranty so they didn't even bother to test it, just put it in the recycle bin and gave me a new one. No charge for either. And the new one is warrantied till 2030. The wrench still retains the original warranty, till 2026.