Bosch PS31-2A 12V Lithium-Ion 3/8″ Drill Driver Review

Bosch PS31-2A drill

Last year we put our hands on the Bosch PS41-2A 12V Impact Driver, which turned out to be a tool that packed a lot of punch in a small footprint. About a year later we’re getting to lay hold of some more miniature powerhouses, the first of which is the PS31-2A 3/8″ Cordless Drill/Driver. We’ve been big on the importance and sheer convenience these new 12V tools provide and it was great to be able to take Bosch’s newest product to the bench and on the job site to see what it could do. Given the experience we’ve had with some of Bosch’s other tools and the steep competition in this market, the bar was set high – real high.

The Case for a 12V Tool

For a bit of background, our fascination in these new “low calorie” 12V products stems from a realization that not every job requires a heavy, full-sized tool. That, coupled with better battery technology and new form factors (made possible by the introduction of lithium-ion), and you’ve got potential for a whole new type of cordless tool. This is what has prompted many manufacturers to go off on wild developmental sprees and bring to market all manner of cordless tools, from 12V hammers and oscillating multi-tools to advanced products like Bosch’s PS40-2A miniature impact driver.

Bosch PS31-2A drill driver

While a full-size driver will offer you more power and higher torque, the attraction to a 12V tool is that you can just about hold it over your head all day long. They way comparatively little compared to their 18V brethren and you can just about put them in your pocket – and certainly in your tool belt. Even professional tool users are starting to take a long hard look at keeping one or two of these 12V products around the job site or in the truck for quick jobs and smaller-scale projects. We find them an easy sell, though their high price will keep them out of at least some homeowners’ hands since many don’t buy more than a single type of driver solution.

The real trick, of course, is whether or not a 12V tool can take the place of your 18V model for most consumer applications. We’d have to say that it probably could, but for those who run into projects requiring higher torque, you may want to opt for both.

Bosch PS31-2A Build Quality

Our test tool arrived in a well-protected retail box with a zippered storage case inside. We’ve complained in the past about these cases, which seem to accompany the latest 12V tools from both Bosch and Craftsman and seem to defy logic. Suffice it to say that the zippered case is just large enough to store your tool, batteries and the included charger within. Everything is secured under flexible straps and there is a hook & loop strap for the PS31-2A Drill/Driver. The case is just large enough to keep everything inside and won’t accommodate placing the tool inside while it is loaded with any sort of bit.

Bosch PS31-2A kit

Bosch has made the exterior housing of the PS31-2A out of its now signature blue and black flexible Durashield ABS and nylon blend that is designed to take jobsite abuse without cracking. Rubber overmold covers the front and back of the grip as well as the back of the motor housing which is where users will typically apply force when needed. There is also an extra-thick rubber overmold that surrounds the front of the motor housing just behind the clutch. This was clearly intended so that the tool doesn’t get damaged when set on its side and helps create a perfect 3-point landing for the tool when it is rested against a flat surface (the other two points being the back of the motor housing and the base of the handle).

Overall we’d have to say that this is a very attractive tool and one that was designed with protection in mind. It should last and certainly withstand any general wear and tear short of throwing it into a cement mixer or dropping it off of a 5 story apartment building…

Motor and Grip

The new PS31-2A 12V Max Drill/Driver is powered by a high-performance frameless motor that shrinks the head length even further from their first-generation tool. The motor still has all-metal gears housed inside an aluminum housing. If you look at both tools, what seems to take place is that Bosch has pulled back the clutch even further so that it sits atop the integrated LED work light rather than in front of it. The handle angle also looks to have adapted to the new design and the tool indeed feels perfectly balanced in the hand, not tipping forward or back during use.

Bits seemed to go in and out well and we liked the easy-grip offered by the chuck. It could get slippery if your hands were sweaty or wet. This wasn’t a problem with gloved hands, but something to note since the texture of the chuck is smooth. Few real external ridges provide friction during bit changes. Unlike Bosch’s PS40-2A, which has a ring of LEDs around the bit, the PS31-2A only has a single LED. Positioned above the trigger, it leaves a big dark spot just over the target area. The variable speed trigger provided ample control and delivered positive feedback. Bosch also shaved off a little weight on this tool compared to its predecessor. It measured just 2.13 pounds according to our internal scale.

PS31-2A vs. PS30-2A Drill/Driver

When Bosch came out with the PS31-2A it was clear they aim to perfect the 12V sub-compact tool market. But how well does the PS31-2A stack up, in terms of its improvements, to the older PS30-2A? Here’s a quick rundown on the two tools:

Torque265 in.-lbs.220 in.-lbs.
 Weight2.1 lbs.2.4 lbs.
 Clutch20 + 120 + 1
 LED Light2nd Gen + batt indicator1st Gen

Bosch PS31-2A Testing and Use

For our bench tests, we set up a piece of pressure-treated 4×4 and drove a series of 3″ coarse thread drywall screws flush into it. We got 20 screws in at high speed until there was a noticeable, and nearly instant, power drop. The next four screws would only go in about halfway. Switching to low speed we were able to drive home those four and ten more with the LED battery indicator showing two out of three lights. When it dropped to just one light we still were able to sink another 15 screws until we ran out… of screws that is!

We took the 12V Max Lithium-ion 3/8″ driver and removed every single screw from our test piece of 4×4 lumber. Then we sank another 6 screws back in before the battery gave out. Grand total? 51 screws in, and 45 screws out – all on a single charge. You’ll like get different results depending on the material used, length of the screw, etc – but that’s a very respectable amount of work. We also felt that the Bosch Drill/Driver didn’t seem to be very finicky about knots or whether the PT wood was soft or hard – it just drove screws. This tool can do some heavy-duty work.

Bosch PS31-2A driving

Quiet But Powerful

The sound level output by the Bosch PS31-2A is pretty reasonable, reaching only 83 dB SPL at our customary 36-inch distance. The noise is mostly a higher-pitched whine, representing the high-speed motor and it actually drops a dB or 2 when you set the drill to high speed. The measured speed on the Bosch PS31-2A was 380 rpm in low speed (1) and 1275 rpm in high speed (2). That’s within a margin of error of 3/10ths of a percent. Bosch has consistently been accurate and truthful about its numbers and it’s great to see them maintain this trend on their newest line of tools.

Bosch PS31-2A fastening

For a more practical real-world test, we installed a new deadbolt into our shed. We used the 12V max tool to drill out the required holes with a hole saw. During the hole saw drilling the tool definitely didn’t speed through the job with the finesse of a larger tool. Bosch makes 18V lithium-ion tools for this purpose. For heavier-duty work like this, we’d recommend a heavier-duty solution.

Still, the 12V drill/driver got it done without shutting down or going into overload protection. That says something good about its ability to handle excessive torque conditions. For the final lock assembly, we used the 12V Drill/Driver to perform the “daintier” tasks of screwing in the deadbolt and lock plate. It was good to know that a reasonable amount of heavy-duty work could be expected from this tool. It did equally well on smaller jobs where a full-size tool is simply overkill and cumbersome.


The Bosch PS31-2A 12V Lithium-Ion Drill/Driver is an impressive tool that packs a lot of punch into a small package. If you want a compact rechargeable tool that will do wonders for both drilling and driving, Bosch’s solution is one of the best on the market. Those who appreciate a good warranty will love their three-year ProVantage Tool Protection Plan. It offers a no-questions-asked replacement policy for the first year that you own the tool. In the second and third years, they will replace any parts worn under normal use free of charge.

For the first two years, you own the tool they even replace the batteries within 48 hours! We gave this tool a very high-performance rating of 9/10. It puts out impressive power in an equally impressive compact size. The excellent features and the reasonable price had us placing our Value rating at 8/10. Even though it’s not cheap, it seems worth every penny.

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