Sun Joe AJ798E Cordless Scarifier & Dethatcher
Our AJ798E cordless dethatcher removes years of compacted thatch and moss buildup without dragging extension cords across your yard. Powered by a 40-volt lithium-ion battery, it runs whisper-quiet for up to 40 minutes per charge—long enough to restore 2,500 square feet of tired lawn. Fifteen spring-steel tines spin at 3,400 RPM to lift dead grass and matted debris so air, water, and nutrients finally reach the roots.
We engineered the AJ798E for homeowners who want thick, green grass without the noise and fumes of a gas engine. The adjustable deck drops to three working depths—thatching, scarifying light, or scarifying deep—so you can match the tool to your soil condition. At just 24 pounds with the battery installed, it's light enough to maneuver around flower beds and tree rings. The collapsible handle folds flat for garage storage, and the 13-inch working width covers suburban lawns in one Saturday morning.
Quick specs for the AJ798E
Battery runtime & charging
The 40-volt 5-amp-hour battery delivers forty minutes of continuous scarifying on a full charge—enough to treat a quarter acre of suburban lawn. Runtime drops slightly in dense St. Augustine or Bermuda thatch, where the tines work harder. We include a rapid charger that refills the battery in ninety minutes, so you can finish larger properties in one afternoon with a midday break.
The battery slides onto a rail mount at the rear of the deck and locks with an audible click. A four-LED fuel gauge on the battery casing shows remaining charge in 25 percent increments. When the last LED blinks red, you have roughly five minutes of run time left. The same 40-volt battery fits our entire iON cordless lawn tool lineup, so one charger powers your mower, trimmer, and blower.
Tine design & scarifying depth
Fifteen spring-steel tines mount on a cylindrical drum that spins perpendicular to the direction of travel. Each tine flexes over rocks and sprinkler heads, then snaps back to vertical—that resilience prevents bent tips even when you hit a hidden root. The tines space one inch apart across the thirteen-inch width, so each pass leaves narrow furrows where seed and fertilizer drop straight to soil.
Depth adjustment
A single lever on the right side of the deck selects three working positions. Position one sets the tines 0.2 inches below the grass surface for light dethatching—ideal for spring cleanup when thatch measures less than half an inch. Position two drops the tines to 0.4 inches for moderate scarifying, cutting through compacted runner grass. Position three reaches 0.6 inches deep for overseeding prep or breaking up heavy clay. The drum automatically lifts when you release the bail handle, so the machine stops scarifying the instant you let go.
Collection bag & debris volume
The rear-mounted 10.6-gallon fabric bag catches thatch as the tines fling it backward. A rigid plastic frame holds the bag open, and a top-mounted carry handle lets you lift the full bag without spilling. On typical cool-season lawns, the bag fills after twelve to fifteen minutes of scarifying—plan to empty it four or five times during a full-property pass.
When the bag reaches capacity, airflow restriction causes the motor to bog slightly—that’s your signal to empty and continue. We recommend composting the collected thatch or spreading it as mulch under shrubs. The bag unclips from two spring hooks in three seconds, and the fabric wipes clean with a hose. You can run the AJ798E without the bag attached if you prefer to rake debris manually or mulch it back into the lawn with a mower.
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Common questions about the AJ798E cordless dethatcher
The AJ798E offers three fixed depth settings: 0.2 inches for light dethatching, 0.4 inches for moderate scarifying, and 0.6 inches for deep soil preparation. The deepest setting works well for breaking up compacted clay or creating furrows for overseeding. A single lever on the right side of the deck adjusts all three positions.
We recommend dethatching when grass is dry or only slightly damp. Wet thatch clumps around the tines and clogs the collection bag, reducing airflow and bogging the motor. If morning dew is present, wait until mid-morning when the sun has dried the lawn surface. Scarifying damp soil works fine—just avoid saturated or muddy conditions that cause the wheels to sink.
Most cool-season lawns benefit from annual dethatching in early spring or early fall. Warm-season grasses like Bermuda and Zoysia accumulate thatch faster and may need scarifying twice per year. If your thatch layer measures less than half an inch, you can skip a season. Use the lightest depth setting for routine maintenance and reserve the deep setting for renovation projects.
The spring-steel tines flex when they hit solid objects, so they typically bounce over sprinkler heads without breaking the plastic caps. We still recommend flagging sprinkler locations before your first pass. Shallow wiring less than two inches deep may catch on the tines at the deepest setting—check your irrigation wire depth or use a shallower scarifying position in those zones.
Yes. The 40-volt 5-amp-hour battery and charger included with the AJ798E are compatible with our entire iON cordless series—lawn mowers, string trimmers, hedge trimmers, leaf blowers, and pole saws. One battery and charger can power your whole outdoor tool collection. Runtime varies by tool, but the 5Ah capacity delivers longer cuts than our standard 4Ah packs.
We include a plastic tine-cleaning comb that slides between the drum and the deck to scrape off packed grass. After each use, flip the AJ798E onto its side with the battery removed, then run the comb along each tine from the center outward. Wipe the drum with a damp cloth and let it air-dry before storing. Check the tines monthly for bent tips—they should all point straight down when the drum is stationary.
Yes. The bag unclips in seconds if you prefer to leave thatch on the lawn and mulch it back in with a mower. Some users rake the debris manually after scarifying. Running bagless increases runtime slightly because the motor works less to push air through the collection system. Reattach the bag for spring cleanup when you want thatch off the property entirely.