Milwaukee M18 REDLITHIUM 5.0Ah Battery (48-11-1850) vs Ryobi 40V Battery and Charger Kit, 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A
Head-to-head spec comparison to help you pick the right battery for your needs.
Deciding between a genuine pack and a cheaper aftermarket one? Read our honest genuine vs aftermarket batteries guide.Read the guide →
Spec-by-Spec Comparison
| Spec | Milwaukee M18 REDLITHIUM 5.0Ah Battery (48-11-1850) | Ryobi 40V Battery and Charger Kit, 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A |
|---|---|---|
| Platform | M18 | 40V |
| Voltage | 18V | 40V MAX |
| Capacity | 5 Ah | 4 Ah |
| Type | high-output | kit |
| Genuine OEM | Yes | Yes |
| Fuel Gauge | No | No |
| Warranty | 5 years | 3 years |
| Price | $67.99 | $109.96 |
| Rating | 8.8/10 | 8.5/10 |
| Buy on Amazon | Buy on Amazon |
Pros & Cons
Milwaukee M18 REDLITHIUM 5.0Ah Battery (48-11-1850)
Pros
- Genuine Milwaukee M18 pack backed by Milwaukee's 5-year warranty
- Drops straight into any M18 tool — no adapters, no guesswork
- 5.0Ah capacity gives solid runtime for daily-use M18 tools
- REDLITHIUM cell design is Milwaukee's own in-house spec
Cons
- No onboard fuel gauge — can't check remaining charge at a glance
- Costs more than aftermarket M18-compatible packs
- Only fits the M18 platform, not M12 or other brands
Ryobi 40V Battery and Charger Kit, 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A
Pros
- Bundles a 4.0Ah 40V battery (OP4040) with a charger (OP403A) in one genuine Ryobi kit
- 4.0Ah is a mid-to-high capacity pack for the 40V outdoor-power platform
- Currently in stock on Amazon
- Genuine Ryobi OEM parts, not aftermarket
Cons
- Only one battery included — no second pack for hot-swapping on longer yard jobs
- 40V packs are heavier than ONE+ 18V packs, worth weighing if you're carrying it around
- We haven't independently timed a charge or measured runtime; 4.0Ah is Ryobi's stated rating
Our Verdicts
Milwaukee M18 REDLITHIUM 5.0Ah Battery (48-11-1850)
A genuine Milwaukee M18 pack is the safe first buy for anyone standardized on the M18 platform — real Milwaukee chemistry and the full manufacturer warranty, not a third-party guess.
Ryobi 40V Battery and Charger Kit, 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A
A genuine Ryobi 40V battery-and-charger bundle with a solid 4.0Ah pack — practical if you're buying into the 40V outdoor platform or need a spare set.
Ryobi 40V Battery and Charger Kit, 4.0 Ah Lithium-Ion Battery Set OEM OP4040 + OP403A
$109.96
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