Cordless Reciprocating Saws - Part 4

Conduct endurance tests of 18-volt cordless reciprocating saws to determine work that can be anticipated at fire/rescue incidents.Subject:  Cordless Reciprocating Saws, Part 4Topic:  Endurance Testing of 18-Volt Cordless Reciprocating SawsObjective...

The Milwaukee recip saw was able to cut 27 to 35 cuts with the battery cutting from four minutes, 52 seconds to a maximum of six minutes, five seconds. Under the conditions of this aggressive cutting test, the Milwaukee batteries lasted 37% as long as during their initial no-load test.

Since the DeWALT saw ran nearly twice as long as the Milwaukee in the initial no-load test, I anticipated twice the performance cutting wood. That theory, however, did not hold true. The DeWalt saw with the original XR2 battery was able to complete from 16 to a maximum of 27 cuts through the 2x4 lumber, operating for an average of five minutes, 40 seconds. This work output matched that of the Milwaukee saw. The DeWalt batteries powered the saw under load for approximately 25% of their no-load run time.

The A-Pillar Metal-Cutting Test

To simulate a typical vehicle rescue scenario, I developed an A-pillar test. In this evaluation, one firefighter used the same reciprocating saw to cut through the same front A-pillar of a car. As cuts were made, times were recorded at the completion of each cut. Each test stopped when the saw’s cutting action stopped.

The Milwaukee reciprocating saw made 10 to 12 cuts through a typical A-pillar. The battery lasted from six minutes, 37 seconds to seven minutes, 43 seconds of operating time.

For the DeWalt A-pillar test, I used both an original XR2 battery and the upgraded XR+. With the XR2, the DeWalt saw typically operated for seven minutes and cut approximately 12 slices off an A-pillar. Fitted with the new-generation XR+ battery, in excess of 20 A-pillar cuts were completed with the saw running from eight minutes, 20 seconds to almost 121?2 minutes.

The Power Hawk 12-Volt Battery Test

Curtiss-Wright manufactures the Power Hawk line of extrication equipment. Its system operates all its components off 12-volt DC electrical current. In a cooperative venture with Milwaukee, the Power Hawk product line now includes a kit to power a Milwaukee 18-volt reciprocating saw off the system’s 12-volt power pack. This 12-volt battery is huge compared to the small 18-volt batteries used on the cordless saw and gives the saw a remarkable run time.

The adapter fits only the Milwaukee cordless reciprocating saw and retails for approximately $416. This includes the power cable and the 12-volt adapter that fits on the saw handle.

I conducted tests to measure the work-output difference between a Milwaukee recip saw with the Power Hawk 12 battery pack and one connected to only a single 18-volt battery. One firefighter with the Milwaukee saw and the Power Hawk battery pack cut through the B-pillar of an automobile seven to 10 times, simulating the average work capability of a single 18-volt battery. B-pillar cuts require more effort than A-pillar cuts because of the thicker materials that comprise the pillar. In addition in this test, one of the cuts not only went through the B-pillar, but also sliced through a Grade 8 backing plate of the seatbelt assembly. Milwaukee Torch blades were used.

Seven B-pillar cuts required five minutes, 20 seconds to complete. Upon completion, the Power Hawk battery pack indicated that 76% of its energy remained after all cuts were completed. At that rate, it is estimated that use of Power Hawk’s 12-volt power unit lets the reciprocating saw operator cut for at least 22 minutes, four or more times the work possible with a single 18-volt battery.

The Nomad Battery Pack Test

To answer objections of short run times for individual 18-volt batteries, the Fiskars Energy Systems Co. of Wausau, WI, introduced the Nomad 7000 Energy System. The Nomad unit lets the user connect three DeWalt 18-volt batteries in a parallel circuit and store them in a portable backpack-style carry pouch. All three batteries are fitted with end caps inside the pouch, connecting them into one electrical circuit.

Extending from the pack is a thick coiled cord with an end piece that resembles a DeWalt battery. This attachment is the power conversion unit microprocessor, which converts the energy from the three batteries to sufficient voltage to power the reciprocating saw. Another feature of the new Nomad unit is that it comes with a built-in trickle charger. Connecting the Nomad to a 110-volt power source will let all three DeWalt batteries charge while inside the Nomad pouch. Because it is a trickle charger, however, it takes 12 to 14 hours for all batteries to fully recharge.