How Long to Charge a Cordless Reciprocating Saw (18V, 5Ah)?
Charging a Cordless Reciprocating Saw (18V, 5Ah) from empty to full takes about 2 h 49 min with its standard 45W charger. The battery holds roughly 90 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 (18V, 5Ah)
Estimated charge time
2 h 49 min
Includes the slower li-ion taper phase above 80%.
Charge time by charger wattage
| Charger | Power | Full charge (0-100%) |
|---|---|---|
| Standard charger | 45W | 2 h 49 min |
| Fast charger | 90W | 1 h 25 min |
| Super fast charger | 135W | 56 min |
Battery capacity: 90 Wh · Chemistry: li-ion
When tackling heavy-duty pruning tasks like sectioning gnarled tree limbs or grinding through compacted garden waste, the 18V lithium-ion battery delivers sustained cutting power without the tether of a power cord. The cordless design liberates you from extension-cable clutter, allowing seamless movement through dense shrubs and overhead branches. After extended cutting sessions—particularly when working through hardwood or fibrous materials—the battery will naturally warm as it powers the saw's rapid reciprocating motion. This is normal behavior with li-ion chemistry; allowing brief cooling intervals between jobs preserves the battery's internal structure and ensures consistent performance over many seasons of garden work.
Smart charging habits with your 18V lithium-ion pack begin the moment you finish cutting. Rather than leaving the battery depleted or perpetually topped off on the charger for weeks, aim to store it at a moderate charge state between active projects—this middle-ground approach significantly extends its lifespan and maintains its ability to handle tough cutting work season after season. Keep your batteries in a cool, dry environment away from temperature extremes, as heat accelerates chemical degradation in li-ion cells. When you notice the saw beginning to cut more slowly or the blade losing power mid-cut, that's your signal to return the battery to the charger; responding promptly to these subtle performance cues prevents deep discharge cycles that can compromise the chemistry over time.
With the fastest charger listed here (Super fast charger, 135W) it takes about 56 min. With the slowest (Standard charger, 45W) it takes about 2 h 49 min. Reciprocating saws are perfect for pruning thick branches and cutting through dense garden waste materials.
Frequently asked questions
- How long does it take to charge a Cordless Reciprocating Saw (18V, 5Ah)?
- From 0% to 100% with the standard 45W charger, it takes about 2 h 49 min. Using a faster charger shortens that; using a weaker one extends it, see the table above for exact numbers.
- Why does my 18V reciprocating saw's battery feel warm after cutting through thick branches?
- Lithium-ion batteries generate heat during high-demand work like sustained reciprocating motion through dense wood or fibrous garden waste. This warmth is a natural byproduct of the internal chemical reactions powering the blade. As long as the battery isn't extremely hot to the touch, this is normal operation. Allowing the battery to cool naturally between jobs is the best practice—avoid immediately recharging a warm battery, as this can stress the li-ion cells. If the battery feels excessively hot or you notice a burning smell, stop use immediately and let it cool in a safe location away from flammable materials.
- How should I store my 18V cordless reciprocating saw and its battery during winter or long periods of non-use?
- Store your saw and battery in a cool, dry place—ideally indoors where temperature and humidity remain stable. Before storing for weeks or months, charge your battery to approximately mid-capacity rather than leaving it fully drained or fully charged; this neutral state minimizes stress on the lithium-ion chemistry and helps it hold capacity for next season. Keep the battery away from direct sunlight, heating sources, and damp areas. If your saw will sit unused for more than a few months, periodically check the battery and recharge it to mid-level if it has self-discharged significantly. This preventative care ensures your cordless saw is ready to tackle spring pruning and summer garden projects without the disappointment of a battery that has lost its strength.
- How is this charge time calculated?
- We divide the energy needed (90 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.