Ryobi P108 Replacement Battery Guide

The Ryobi P108 is a 4.0Ah high-capacity battery for the Ryobi ONE+ 18V platform. Here’s everything you need to know about finding a replacement.

P108 Specifications

Voltage: 18V
Capacity: 4.0Ah (72Wh)
Chemistry: Lithium-ion
Platform: Ryobi ONE+
Fuel gauge: Yes — onboard LED indicator
Weight: Not stated in our sources (US part number)

What Tools Does the P108 Fit?

The P108 is compatible with all Ryobi ONE+ 18V tools — over 200 tools, Ryobi UK says, spanning drills, saws, blowers, lighting, and more. Any Ryobi tool with the ONE+ battery slot will accept the P108. This includes both the standard ONE+ range and the newer ONE+ HP tools, which benefit from the higher capacity.

Replacement Options

Direct replacement (same spec): Check current listings for the P108. If you want the exact same battery, you can buy it individually or in twin packs.

Upgrade options: If your P108 has worn out, consider stepping up to a higher-capacity Ryobi ONE+ battery for longer runtime:

• RB1860X (6.0Ah) — 0.7 kg
• RB1880T (8.0Ah HIGH ENERGY) — 1.3 kg
• RB1840T (4.0Ah HIGH ENERGY) — 0.72 kg; Ryobi says HIGH ENERGY packs give more runtime and power than its previous lithium packs

All of these are fully backward compatible with every ONE+ tool you already own.

Where to Buy

Search for Ryobi P108 on Amazon

Browse all Ryobi ONE+ 4.0Ah batteries on Amazon

Tips for Getting the Most from Your Replacement

If your P108 died earlier than expected, a few simple habits can extend the life of your new battery. Let it cool down after heavy use before charging, store it indoors at partial charge if you won’t be using it for a while, and always use a genuine Ryobi charger. For our full guide, see How Long Do Power Tool Batteries Last?

Related Guides

• Every Ryobi ONE+ 18V Tool and Which Batteries Fit
• Can You Use Ryobi Batteries in Other Brand Tools?
• How Long Do Power Tool Batteries Last?
• Can I Use a Higher Ah Battery in My Drill?

Video Guide

Frequently Asked Questions

Key Specifications

Signs Your P108 Battery Needs Replacing

Lithium-ion batteries degrade naturally over time. Here are the key signs that your Ryobi P108 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 Ryobi charger flashes red or shows error lights rather than charging normally, it has detected a fault in the battery. Most Ryobi 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 Ryobi P108, you have two main options: genuine Ryobi batteries or third-party compatible alternatives. Both will physically fit and power your ONE+ tools, but there are meaningful differences worth considering.

Choose genuine Ryobi batteries if you want a pack Ryobi makes and supports under its guarantee; Ryobi says every ONE+ battery fits every ONE+ tool.

Third-party batteries can suit users who want more packs at a lower cost; quality varies, so check the seller and warranty.

How to Get the Most from Your Replacement Battery

Follow these care tips to maximise the lifespan and performance of your new Ryobi P108 replacement battery:

1. First use: charge a new pack fully before use.
2. Storage: Ryobi UK advises a cool, dry place, ideally between 5 °C and 20 °C, not leaving packs fully charged or completely depleted for long periods, and checking the charge every few months.
3. Avoid temperature extremes: never leave batteries in a hot vehicle or in direct sunlight.
4. After charging: remove the pack once charged unless your charger manual says it can stay connected.
5. Use a Ryobi ONE+ charger: Ryobi UK says its ONE+ chargers (such as the RC18120A, RC18150 and RC18180) are compatible with all ONE+ 18V lithium-ion batteries; the RC18150 is not for NiCd packs.