How Long to Charge a Cordless Reciprocating Saw (20V, 5Ah)?
Charging a Cordless Reciprocating Saw (20V, 5Ah) from empty to full takes about 2 h 21 min with its standard 60W charger. The battery holds roughly 100 Wh, and this page estimates the time for every common charger wattage, using the Lithium-ion (Li-ion / Li-Po) chemistry it actually uses.
Charge time calculator for Cordless Reciprocating Saw (20V, 5Ah)
Estimated charge time
2 h 21 min
Includes the slower li-ion taper phase above 80%.
Charge time by charger wattage
| Charger | Power | Full charge (0-100%) |
|---|---|---|
| Standard charger | 20W | 7 h 4 min |
| Fast charger | 60W | 2 h 21 min |
| Rapid charger | 90W | 1 h 34 min |
Battery capacity: 100 Wh · Chemistry: li-ion
The Cordless Reciprocating Saw's li-ion battery pack is built to endure the rigorous demands of demolition work, where prolonged cutting through tough materials pushes both tool and power source to their limits. Unlike lighter-duty cordless tools, this demolition-focused pack benefits from being cycled under full load—cutting through metal studs, thick wood, and composite materials—as part of its intended operational envelope. To maximize the lifespan of your li-ion pack, develop a habit of returning it to the charger immediately after finishing a job rather than letting it sit depleted for days. Storing your pack in a cool, dry location away from extreme temperature swings will preserve its chemical integrity; li-ion chemistry is sensitive to heat, so keep it out of direct sunlight and away from heated work vehicles or job-site heaters.
Real-world demolition crews routinely rotate between multiple batteries to maintain continuous workflow—one battery charging while another powers the saw. This rotation pattern naturally suits li-ion chemistry, which performs best with regular, moderate recharging cycles rather than deep discharges followed by marathon charging sessions. Pay attention to the battery's physical condition; if it becomes unusually warm during charging, shows visible cracks, or develops a swollen profile, discontinue use and replace it safely. The 20V designation reflects the nominal voltage architecture of this pack, and respecting proper charger matching ensures your li-ion cells receive the correct charging profile. Over time, you may notice a gradual reduction in runtime between charges—this is the expected behavior of li-ion chemistry and does not indicate a defective pack, merely one that has completed part of its service life.
With the fastest charger listed here (Rapid charger, 90W) it takes about 1 h 34 min. With the slowest (Standard charger, 20W) it takes about 7 h 4 min. The demolition-duty pack used on cordless reciprocating saws.
Frequently asked questions
- How long does it take to charge a Cordless Reciprocating Saw (20V, 5Ah)?
- From 0% to 100% with the standard 60W charger, it takes about 2 h 21 min. Using a faster charger shortens that; using a weaker one extends it, see the table above for exact numbers.
- Why does my reciprocating saw's runtime seem shorter after the battery has been in service for several months, even though it charges fully?
- Li-ion batteries naturally experience a gradual decrease in capacity over their lifespan due to the electrochemical nature of the chemistry itself. This decline is normal and expected, especially in demolition-duty applications where the saw operates under sustained high current draw. You'll typically notice the effect first during heavy cutting tasks before it becomes apparent in lighter work. When runtime degrades noticeably, it's time to rotate in a fresh pack and retire the aged one.
- Should I leave my 20V battery connected to the charger overnight, or is there a risk of overcharging with li-ion chemistry?
- Modern li-ion chargers are designed with safeguards that stop active charging once the pack reaches full capacity, preventing overcharging damage. However, best practice for extending battery longevity is to disconnect it once charging is complete rather than leaving it trickle-charged indefinitely. On job sites where you're rotating between multiple packs throughout the day, this naturally happens as you grab whichever battery is ready. If you know a pack won't be used for extended periods (weeks or longer), store it at room temperature and avoid keeping it perpetually on the charger.
- How is this charge time calculated?
- We divide the energy needed (100 Wh times the percentage you're charging) by the charger's effective power, which is the charger's wattage times the battery chemistry's real-world charging efficiency (85% for Lithium-ion (Li-ion / Li-Po)). The same formula powers both this page and our API.
ChargeTimeCalculatorestimates are based on typical charger efficiency and battery chemistry, not a live connection to your device. Always follow your manufacturer's charging guidance.