BOTTOM LINE

There are still a lot of saws in the 18-volt category that are too weak and slow to cut all framing materials reliably, but the standouts can hold their own against bigger and heavier 36-volt models. They may even bump corded saws out of the hands of builders on occasions when a day's worth of gas would be burned to power saws with a generator.

The Milwaukee saw is clearly the best of the bunch, with winning times in both power tests that eclipsed even the champion 36-volt saw, and with excellent runtime. The DeWalt DCS391 ranks second, placing just behind the winner in both power tests, and with very good runtime.

The DeWalt DCS390, the Bosch, and the Hilti occupy the next tier down and stand out in different ways. The DeWalt placed third in the power tests, and the Hilti and the Bosch led in runtime.

Makita's saw rated just above both the Hilti and the Bosch in power, but its lower runtime bumps it down a notch. Still, its ample power, compact size, and great features make it a solid trim saw.

The Kobalt and Hitachi saws are relatively weak, though they posted good runtimes. The Ridgid — despite many nice features — is held back by its tendency to stall, while the Porter-Cable tool is simply outclassed by the competition.

Michael Springer is the former executive editor of TOOLS OF THE TRADE.

Thanks to Irwin for supplying the saw blades used in this test.

BATTERY VOLTAGE EXPLAINED

The full-size battery packs that come with most cordless circular saws contain ten 3.6-volt lithium-ion cells. The cells are wired in series (connected end-to-end, as in a flashlight) in strings of five, and then wired to each other in parallel. Battery voltages are additive when cells are wired in series, so each group of five produces 18 volts (5 x 3.6 volts = 18 volts). When cells or groups of cells are wired in parallel, the amp-hour (Ah) ratings are additive but the voltages are not, so connecting two 18-volt strings of 1.5-Ah cells in parallel produces an 18-volt 3.0-Ah battery pack. — David Frane

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Like other full-size 18-volt packs, the Makita LXT battery has 10 cells.

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DeWalt calls its new slide-mount system the 20V Max to distinguish it from the earlier 18-volt XRP tool system (which had tower-style batteries). In fact, though, the new system is also 18 volts, with 5-cell compact and 10-cell full-size batteries.

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Hilti's tools in the 18-volt size range are actually 21.6 volts; instead of five cells per string there are six (6 x 3.6 volts = 21.6 volts). The company's compact batteries have 6 cells and its full-size batteries have 12.

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BOSCH CCS180K

BOSCH CCS180K Specs

Battery: 18 volts, 2.6 Ah (tested with 3.0-Ah battery)
Rpm: 3,900
Max cut at 90° and 45°: 2 1/16 inches, 1 11/16 inches
Weight (by TOTT): 8.28 pounds (w/3.0-Ah battery)
Kit includes: tool, one 2.6-Ah battery, charger
Web price: $290 (kit); $100 (bare tool)
Country of origin: China
Pro: Battery stores securely in tool in safety position with no electrical connection; excellent runtime; average power in testing
Con: Less-comfortable button-type trigger-lock release; included (2.6-Ah) battery has no fuel gauge; with 3.0-Ah battery, gauge is not visible when pack is on the tool

  • Excellent guard action
  • Very good cut-line markers
  • Good bevel setting with raised marks every 5°
  • Good blade visibility
  • Fair motor-to-base stability
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DEWALT DCS390L

DEWALT DCS390L Specs

Battery: 18 volts, 2.0 Ah (also accepts 2.2-Ah nicad)
Rpm: 3,700
Max cut at 90° and 45°: 2 3/16 inches, 1 11/16 inches
Weight (by TOTT): 8.34 pounds (8.96 w/nicad)
Kit includes: tool, battery, charger, large plastic case
Web price: $245 (kit); $120 (bare tool)
Country of origin: Mexico
Pro: Flexible-fuel tool takes tower-type li-ion or nicad batteries; shares base and guard-assembly design with highly rated DCS391; very good power in testing
Con: Uncomfortable trigger design with sharp-edged finger recess; heavy when used with nicad battery; no battery fuel gauge

  • Good guard action
  • Very good cut-line markers
  • Very good bevel setting with engraved marks every 1°
  • Very good blade visibility
  • Very good motor-to-base stability
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DEWALT DCS391L1

DEWALT DCS391L1 Specs

Battery: 18 volts (20 volts max), 3.0 Ah
Rpm: 3,700
Max cut at 90° and 45°: 2 3/16 inches, 1 11/16 inches
Weight (by TOTT): 8.33 pounds
Kit includes: tool, one battery, charger, large plastic case
Web price: $230 (kit); $100 (bare tool)
Country of origin: Mexico
Pro: Includes battery fuel gauge; shares base and guard-assembly design with highly rated DCS390; excellent power in testing; better-than-average runtime
Con: Tool name — 20V Max — is confusing, since this is in fact an 18-volt tool

  • Good guard action
  • Very good cut-line markers
  • Very good bevel setting with engraved marks every 1°
  • Very good blade visibility
  • Very good motor-to-base stability
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HILTI SCW 18-A CPC

HILTI SCW 18-A CPC Specs

Battery: 21.6 volts, 3.3 Ah (also available with 2.6-Ah batteries)
Rpm: 4,000
Max cut at 90° and 45°: 2¼ inches, 1 11/16 inches
Weight (by TOTT): 8.60 pounds
Kit includes: tool, two batteries, charger, large fabric duffel
Web price: $460 (kit); $200 (bare tool)
Country of origin: China
Pro: High-quality features include battery fuel gauge, precise bevel quadrant, metal locking levers, and large stable base; battery stores securely in tool in safety position with no electrical connection; comes with two batteries; best runtime of any saw tested
Con: Stalled often in power testing

  • Very good blade guard action
  • Excellent cut-line markers
  • Excellent bevel setting with engraved marks every 1°
  • Very good blade visibility
  • Very good motor-to-base stability
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HITACHI C18DSLP4

HITACHI C18DSLP4 Specs

Battery: 18 volts, 3.0 Ah
Rpm: 3,400
Max cut at 90° and 45°: 2¼ inches, 1 5/8 inches
Weight (by TOTT): 7.68 pounds
Sold as bare tool; includes loose blade wrench and small rip fence
Web price: $135 (bare tool only)
Country of origin: China
Pro: Fuel gauge built into tool body; incandescent headlight; only tool with body and base attached in line with the handles for extra stability
Con: Only tool whose blade wrench doesn't store on the tool; angled edge along left side of base difficult to guide along a square or straightedge; stalled often in power testing

  • Good guard action
  • Very good motor-to-base
  • Poor bevel setting with engraved marks every 5°
  • Very good blade visibility
  • Excellent cut-line markers stability
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KOBALT K18LC-16A

KOBALT K18LC-16A Specs

Battery: 18 volts, 3.0 Ah
Rpm: 4,500
Max cut at 90° and 45°: 2 3/16 inches, 1 11/16 inches
Weight (by TOTT): 7.60 pounds
Sold in four-tool li-ion combo kit (KCLC2000A) with one full-size and one compact (1.5-Ah) battery
Web price: $270 (combo kit)
Country of origin: China
Pro: Includes battery fuel gauge
Con: Less-comfortable button-type trigger-lock release; stalled often in power testing; limited number of tools on this battery platform

  • Fair guard action
  • Poor cut-line markers
  • Fair bevel setting with raised marks every 5°
  • Good blade visibility
  • Fair motor-to-base stability
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MAKITA BSS610

MAKITA BSS610 Specs

Battery: 18 volts, 3.0 Ah
Rpm: 3,700
Max cut at 90° and 45°: 2¼ inches, 1 5/8 inches

Weight (by TOTT): 7.56 pounds
Kit includes: tool, two batteries, charger, large plastic case, small rip fence
Web price: $340 (kit); $150 (bare tool)
Country of origin: China
Pro: LED headlight; adjustable 45° bevel stop; comes with two batteries; good power in testing — slowed but never stalled
Con: No battery fuel gauge; less-than-average runtime

  • Excellent guard action
  • Fair cut-line markers
  • Good bevel setting with raised marks every 5° and stop at 45°
  • Good blade visibility
  • Good motor-to-base stability
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MILWAUKEE 2630-22

MILWAUKEE 2630-22 Specs

Battery: 18 volts, 3.0 Ah
Rpm: 3,500
Max cut at 90° and 45°: 2 1/8 inches, 1 5/8 inches
Weight (by TOTT): 9.06 pounds
Kit includes: tool, two batteries, charger, fabric duffel, large rip fence
Web price: $370 (kit); $125 (bare tool)
Country of origin: China
Pro: High-quality features include battery fuel gauge, precise bevel quadrant, and extra-large stable base; comes with two batteries; excellent runtime; excellent power in testing — cut faster than every other cordless model
Con: Heaviest 18-volt saw tested (though 1.7 pounds lighter than the average 7¼-inch corded model)

  • Good guard action
  • Excellent cut-line markers
  • Excellent bevel setting with engraved marks every 1°
  • Good blade visibility
  • Good motor-to-base stability
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PORTER-CABLE PC18CSL

PORTER-CABLE PC18CSL Specs

Battery: 18 volts; 2.6 Ah
Rpm: 3,700
Max cut at 90° and 45°: 2 1/8 inches, 1¾ inches
Weight (by TOTT): 7.69 pounds
Sold as bare tool; includes batteries for laser guide
Web price: $50 (bare tool only)
Country of origin: China
Pro: Blade-right model operates like a standard sidewinder saw; inexpensive
Con: Less-comfortable button-type trigger-lock release; bulky laser line pointer module makes it difficult to reach guard-lifting lever; no battery fuel gauge; stalled often in power testing; only tool that could not complete all time trials of the power test; near bottom in runtime

  • Good guard action
  • Poor cut-line markers
  • Poor bevel setting with engraved marks every 5°
  • Poor blade visibility
  • Poor motor-to-base stability
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RIDGID R8651B

RIDGID R8651B Specs

Battery: Fits brand's 18-volt slide pack batteries — tested with 3.0 Ah
Rpm: 5,000
Max cut at 90° and 45°: 2 1/8 inches, 1¾ inches
Weight (by TOTT): 7.82 pounds
Sold as bare tool
Web price: $100 (bare tool only)
Country of origin: China
Pro: Blade-right model operates like a standard sidewinder saw; high-quality features include battery fuel gauge, precise bevel quadrant, LED headlight with secondary grip switch
Con: Stalled almost constantly in power testing; only tool that could not complete first circuit of runtime test; less-than-average runtime

  • Good guard action
  • Poor cut-line markers
  • Very good bevel setting with painted marks every 1° and stops at 15°, 22.5°, 30°, and 45°
  • Excellent blade visibility
  • Very good motor-to-base stability