Original Makita BL1840 Battery (OEM Option)
Genuine Makita 18V LXT 4.0Ah battery.
Buy Original Makita BL1840 Battery
Compatible Replacement Batteries for Makita BL1840
| Battery | Capacity | Fits Makita 18V LXT | Charger Compatible | Buy Link |
|---|---|---|---|---|
| Makita BL1840 (OEM) | 4.0Ah | Yes | Yes | Check Price on Amazon |
| Compatible Makita Battery | 5.0Ah | Yes | Yes | Check Price on Amazon |
| High-Capacity Compatible | 6.0Ah | Yes | Yes | Check Price on Amazon |
Genuine batteries, chargers and kits for this platform
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Before you buy: check that the size, fitting/bore and maximum-rated speed marked on the accessory match what your tool’s manual specifies. We have not physically tested these products; listings are compiled from published specifications. These are affiliate links.
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Which batteries fit which tools — cross-brand, adapters & Ah, decoded.
Compatible Chargers
Ready to Replace Your Makita BL1840 Battery?
- Buy Original Makita BL1840 Battery
- See Compatible Makita 18V Batteries
Related Guides
- Every Makita 18V LXT Battery Compared
- Every Makita 18V LXT Tool and Which Batteries Fit
- Makita 18V LXT Charger Compatibility Guide
- Makita 18V LXT vs 40V XGT
- How Long Do Power Tool Batteries Last?
Frequently Asked Questions
What is the difference between the BL1840 and BL1840B?
Makita UK describes the BL1840B as a 4.0Ah battery with a charge level indicator. Makita’s charger manuals list the BL1840 and BL1840B together.
Can I charge a replacement BL1840 on my existing Makita charger?
Makita’s DC18RC, DC18RD and DC18SD manuals list the BL1840/BL1840B, and Makita says a rapid charger charges the BL1840B in about 36 minutes. Makita’s charger manual says it is for Makita battery cartridges only, so charging a third-party pack is at your own risk.
Are cheap BL1840 replacements worth buying?
Budget replacements can be good value for light-duty use but may not match OEM capacity or longevity. Look for batteries from established aftermarket brands with positive reviews, proper safety certifications, and at least a 12-month warranty. Avoid no-name batteries with suspiciously low prices.
How many charge cycles does a BL1840 replacement typically last?
Makita does not publish a cycle life for the BL1840B, and we hold no reliable figures for third-party packs. Keep packs cool and dry and recharge them before use after long storage.
Video Guide
Key Specifications
| Specification | Details |
|---|---|
| Nominal Voltage | 18V |
| Capacity | 4.0 Ah |
| Watt-Hours | 72 Wh |
| Chemistry | Lithium-Ion |
| Weight | 0.64 kg (BL1840B, Makita UK) |
| Battery Indicator LED | Yes |
| Compatible Platform | Makita 18V LXT Series |
Signs Your BL1840 Battery Needs Replacing
Lithium-ion batteries degrade naturally over time. Here are the key signs that your Makita BL1840 battery needs replacing:
- Rapid discharge: The battery drains noticeably faster than when it was new, even after a full charge. If a battery that once lasted an hour now dies in 20 minutes, capacity has degraded significantly.
- Charges but dies quickly under load: The battery appears to charge fully but shuts off within minutes when powering demanding tools. This indicates internal cell failure where the battery can no longer deliver sufficient current.
- Excessive heat during use or charging: While some warmth is normal, a battery that becomes uncomfortably hot during operation or on the charger has damaged cells. Excessive heat is both a symptom and a cause of further degradation.
- Physical swelling or damage: Any visible bulging, cracking, or deformation of the battery casing means the cells inside have failed. Stop using a swollen battery immediately and dispose of it safely at a recycling point.
- Charger error indicators: If your Makita charger flashes error lights or refuses to charge the battery entirely, it has detected a fault. Most modern chargers include diagnostic features that identify damaged batteries.
- Age: lithium-ion packs lose capacity with age and use. If an older pack’s runtime has clearly dropped, replacement is worthwhile.
OEM vs Third-Party Replacement Batteries
When replacing your Makita BL1840, you have two main options: genuine Makita batteries or third-party compatible alternatives. Both will physically fit and power your tools, but there are meaningful differences worth considering.
| Factor | Genuine Makita | Third-Party Compatible |
|---|---|---|
| Typical Price | £40-80 | £20-45 |
| Cell Quality | Makita genuine pack | Varies by manufacturer |
| Warranty | Makita UK: 2 years for Li-ion batteries bought from 1 April 2025; batteries are not eligible for the 3-year registration extension | Varies by seller |
| Safety Certifications | Built and certified to Makita’s own standards, with UKCA/CE marking | Varies by seller. Markings such as UKCA or CE are the manufacturer’s own declaration, not independent proof of testing — check who the responsible manufacturer or importer is before buying |
| Expected Lifespan | Not published by Makita | Not published |
| Performance Consistency | Made for Makita 18V LXT tools | Compatible, slight variation possible |
Choose genuine Makita batteries if you use your tools professionally and depend on them for income: you get a pack Makita makes and supports, with a known warranty route.
Third-party batteries can suit homeowners and occasional users who want a lower cost; quality varies, so check the seller and warranty. You can often buy two third-party packs for the price of one genuine unit.
How to Get the Most from Your Replacement Battery
Follow these care tips to maximise the lifespan and performance of your new Makita BL1840 replacement battery:
- First use: charge a new pack fully before use.
- Storage: keep packs in a cool, dry place out of direct sunlight, and recharge before use after long storage.
- Charging temperature: Makita’s DC18RC manual says not to charge when the room temperature is below 10 °C or above 40 °C. Never leave batteries in a hot vehicle or in direct sunlight.
- After charging: Makita’s DC18RC manual says to remove the battery cartridge from the charger after charging.
- Use a Makita LXT charger that lists the pack: Makita’s DC18RC, DC18RD and DC18SD manuals list LXT packs including the BL1830B, BL1840B and BL1850B; the DC18RC manual says not to use it for other manufacturers’ batteries.
How we compile this guide
We cross-reference compatibility details against manufacturer specifications where available, official tool manuals, and the physical standards that govern fitment (bore sizes, arbor diameters, voltage platforms, connector types). We prioritise primary sources over retailer listings, flag anything we can’t confirm, and re-verify the data on a regular cycle. Where we give a buying recommendation, we tell you the reasoning — not just the link. More on our method →
