4.0Ah capacity: finish the car and patio on one charge
4.0Ah of fade-free 21V power: wash the car and patio on one charge, with Makita-style fit and triple protection.
4.0Ah covers the whole job
The 4.0Ah (4000mAh) lithium-ion cell holds enough charge for a full vehicle wash plus patio and furniture, so you are not walking back to the outlet halfway through. Actual runtime varies with the washer or tool you run.
Steady power, no slow finish
Output stays consistent as the pack drains instead of fading in the last stretch, so spray pressure holds from the first panel to the final rinse.
Makita-style slide fit
A standard sliding socket seats firmly in compatible cordless washers and yard tools, letting you run it as your main pack or a drop-in backup. Fits Makita-style sliding-socket tools only.
Overcharge, overheat, short-circuit protection
Built-in safeguards stop charging at full, manage heat under load, and cut off short circuits, protecting both the battery and your tool. The charging adapter is included, so you can top up and get back outside.
Keep your weekend cleaning moving with a spare 4.0Ah battery
Keep a charged 21V 4.0Ah pack ready so weekend car, patio, furniture, and garage jobs continue without downtime.
Vehicle washing
With a 4.0Ah pack in your cordless washer, you can move from rinse to soap to final spray without stopping to recharge. Keep a second battery charged and swap it in when needed.
Patio tile rinsing
Rinse patio tiles and walkways in one session. The 4.0Ah capacity supports continued cleaning so a low battery does not cut the job short.
Outdoor furniture cleaning
Clean outdoor furniture before guests arrive. A charged 21V pack keeps the washer running through chairs, tables, and cushions, while the included charging adapter gets the next battery ready.
Garage and yard tools
Use the same Makita-style sliding interface for compatible garage and yard tools. Keep this 4.0Ah battery as a backup so projects continue when your primary pack runs down.
4.0Ah kit vs. generic replacement batteries
| This 4.0Ah kit ($29.99) | Generic replacement battery | |
|---|---|---|
| Stated capacity |
4.0Ah (4000mAh) printed on the pack, matched to the cells inside
|
Label often claims more than the cells can hold
|
| Charger adapter |
Charging adapter included in the box
|
Sold separately, or not offered at all
|
| Protection circuit |
Built-in overcharge, overheat, and short-circuit safeguards
|
Frequently shipped with no protection board
|
| Tool interface |
Makita-style sliding socket that locks in securely
|
Loose or inconsistent fit that can cut out mid-job
|
| Runtime through the charge |
Fade-free power for washing vehicles, patios, and furniture
|
Noticeable power drop as the pack drains
|
| Total cost to get running |
$29.99 covers battery and charging adapter in one order
|
Low sticker price, then add a charger on top
|
21V 4.0Ah lithium battery with charger: specs at a glance
Voltage, capacity, cell type, interface, and box contents — plus one spec the manufacturer doesn't publish.
- Voltage
- 21V (Max)
- Capacity
- 4.0Ah (4000mAh)
- Battery type
- Lithium-Ion (Li-ion)
- Interface
- Makita-style sliding socket
- What's in the box
- 1 x 21V 4.0Ah battery, 1 x power charging adapter
- Charge time
- Not published by the manufacturer; depends on the adapter and outlet
- Runtime per charge
- Varies with the washer or tool it powers
- Safety protection
- Overcharge, overheat, and short-circuit safeguards built in
What's in the Box: Complete Power Kit
21V 4.0Ah Lithium-Ion Battery ×1
4.0Ah capacity for extended runtime
Charging Adapter ×1
No separate charger to buy
Battery + Charging Adapter Bundle
$29.99 total — both included
Questions before you buy: fit, charging, runtime, returns
Will this battery fit my tool?
It uses a Makita-style sliding socket, so it fits tools that accept that sliding interface — including the cordless high-pressure washer it was built for, plus compatible yard and workshop tools. It will not fit tools with plug-in blade terminals or other brands' slide systems, such as DeWalt, Milwaukee, or Ryobi. Check your tool's battery port before ordering: if the pack slides in from the front onto two rails, this battery is designed for that.
How long does it take to charge with the included adapter?
Charging time depends on the power source you plug the adapter into and the battery's remaining charge, so we don't publish a single fixed number. The box includes a dedicated charging adapter made for this 4.0Ah pack, so you can top up between jobs instead of waiting on a generic charger. As with any Li-ion pack, a partial charge takes less time than a full one.
Is this an original Makita battery?
No. This is a third-party 21V 4.0Ah lithium-ion pack with a Makita-compatible sliding interface. It is not manufactured or branded by Makita, and it is sold as a replacement or backup battery for compatible tools — not as an OEM part.
How long will one charge actually last?
Runtime varies with the tool and the job. A high-pressure washer under continuous load draws more current than a light-duty task, so expect longer run time on light jobs and shorter run time under constant heavy use. Ambient temperature, battery age, and how often you trigger the tool also affect results. The 4.0Ah capacity is sized for extended outdoor cleaning sessions rather than quick touch-ups.
What safety features protect the battery?
Built-in protection guards against overcharging, overheating, and short circuits. Those safeguards are there to protect both the pack and your tool, and they help extend the battery's overall service life.
What about shipping and returns?
Your order ships with tracking, and shipping cost and delivery estimates are shown at checkout before you pay. Returns are handled under the store's posted return policy, which is also linked at checkout. If the battery arrives damaged or does not fit your tool, contact us before use and we will help you resolve it.
The $29.99 battery and charging adapter kit that keeps your car wash and yard cleaning powered
$29.99 gets you the 21V 4.0Ah lithium battery plus its charging adapter, with a straightforward return guarantee.
Add the $29.99 kit to cartLimited stock on this battery-and-charging-adapter bundle — order below while it's available.