4ah vs 5ah 20v Battery: Which One Should You Buy?
A 5Ah pack runs longer than a 4Ah pack on the same 20V tools, so pick capacity by runtime and check the charge gauge, warranty and pack count first.
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A drill that quits halfway through a brake job and a saw that stalls mid-cut share the same cause more often than not: the battery ran out of charge before the job was done. That is the whole question behind 4ah vs 5ah 20v battery: a 5Ah pack holds more charge than a 4Ah pack on the same 20V platform, so it runs a tool longer between charges, while the voltage, and the tools it fits, stay the same. Pick the 5Ah pack when runtime matters most, and the 4Ah pack for short jobs.
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Below: what the amp-hour number means, the 4 batteries in this guide ranked, and how to choose between 4Ah and 5Ah for the jobs in your garage.
4ah vs 5ah 20v battery: what the amp-hour number means
Amp-hours measure how much charge a battery holds. A 5Ah pack holds more charge than a 4Ah pack, so it runs a tool longer before the charger calls it back. Voltage is a separate number: the DEWALT packs here are 20V MAX packs and the CRAFTSMAN pack is a V20 pack, so within a system the tools a pack fits do not change with the amp-hour number. Think of it like a fuel tank: a bigger tank does not make the car faster, it takes it farther between fill-ups. That is why the choice is about runtime, not power.
The DEWALT XR POWERPACK 4Ah pack below carries a maker claim of 50% more power, which is a claim about that pack’s cells, not about the 4Ah number itself. The maker also claims a longer life than traditional cylindrical batteries for that pack. Read the claim as the maker’s words, and weigh it against the capacity, the pack count and the warranty term the listing states.
The 4 batteries in this guide, ranked
Every pack below is a 20V pack from the listings in this guide, ranked from the strongest listing to the weakest on what each listing states: capacity, pack count, charge indicator, warranty term and stated safety features.
| Battery | Capacity | Pack | Charge indicator | Warranty term |
|---|---|---|---|---|
| DEWALT DCB205-2 | 5Ah | 2-pack | 3 LED fuel gauge | 3 year limited warranty |
| DEWALT DCB2104-2 | 4Ah | 2-pack | LED indicator | Not stated |
| Bslite 5.0Ah with DCB112 charger | 5.0Ah | Battery plus charger | 4-level LED, 25-50-75-100% | 365-day warranty |
| CRAFTSMAN CMCB204-2 | 4Ah | 2-pack | 3 LED | Not stated |
DEWALT DCB205-2: 5Ah 2-pack
The DEWALT DCB205-2 tops this ranking on the strength of its listing: a 5Ah capacity in a 2-pack, a 3 LED fuel gauge that shows the state of charge, and a 3 year limited warranty, the longest warranty term stated in this guide. The listing states one battery weighs 1.4 lbs, and the spec table lists an item weight of 2.8 pounds for the pack. It fits the 20V MAX system, so it works with 20V MAX tools and chargers. The listing states a size of 20V MAX and dimensions of 9.25 inches x 7.0 inches x 3.63 inches.
DEWALT DCB2104-2: 4Ah XR POWERPACK 2-pack
The DEWALT DCB2104-2 is a 4Ah pack from the XR POWERPACK line, sold as a 2-pack. The maker claims 50% more power and a longer life than traditional cylindrical batteries, and lists an overmolded base built for impact resistance plus an LED indicator for the state of charge. The listing states an item weight of 2.75 pounds and dimensions of 5.978 inches x 6.467 inches x 3.771 inches. One wrinkle: the title calls it a 2-pack while the spec table lists NumberOfItems as 1, so confirm the pack count before ordering. No warranty term is stated in the listing.
Bslite 5.0Ah battery with DCB112 charger
The Bslite kit pairs a 5.0Ah replacement battery with a DCB112 charger, so it is the only pick here that adds a charger to the box. The listing states a 5000mAh capacity, a 4-level LED display at 25-50-75-100%, and a maker claim of 30% longer runtime than standard batteries. The maker lists an 8-layer protection system with overcharge and over-discharge cutoff, short-circuit and overload protection, and temperature control, plus UL2056, CE, RoHS and UN38.3 compliance, an IP54 code, a temperature range of -4°F to 140°F, and cell balancing, with the maker stating 1500+ charges. The charger shows a red light while charging, a solid light when charging is done, and a green light if a fault is detected. The listing states a 365-day warranty with lifetime tech support, and dimensions of 11.0 inches x 4.0 inches x 5.5 inches.
CRAFTSMAN CMCB204-2: 4Ah V20 2-pack
The CRAFTSMAN CMCB204-2 is a 4Ah V20 pack sold as a 2-pack, with a 3 LED state of charge indicator and a maker-stated 60 Min Charge Time. The listing states premium grade high energy cells, no memory effect and virtually no self-discharge. The title calls it a 2-pack while the spec table lists NumberOfItems as 1, so confirm the pack count before ordering. The warranty field reads “Visit Craftsman.com” with no term stated, so no warranty term is stated here. It fits the V20 system, not the 20V MAX system, so it pairs with V20 tools.
How to choose between 4Ah and 5Ah
Start with the tools you already own. A 20V MAX tool takes a 20V MAX pack, and a V20 tool takes a V20 pack; the amp-hour number does not change which tools a pack fits. Then weigh runtime against the job: a 5Ah pack runs longer between charges, while a 4Ah pack is the pick for short jobs. If the garage holds a mix of drills, saws and grinders, the 5Ah packs cover the hard-working tools and the 4Ah packs cover the light-duty ones.
Check the charge indicator before the job, not during it. A 3 LED gauge or a 4-level display at 25-50-75-100% shows the state of charge at a glance, so a pack that reads low goes on the charger before the work starts. Keep a charged spare on the bench: a 2-pack means the spare is already there.
Charging, storage and care
Charge on the charger the maker lists for the pack: the DEWALT packs use 20V MAX chargers, the CRAFTSMAN pack uses a V20 charger, and the Bslite kit ships with its own DCB112 charger. The CRAFTSMAN listing states a 60 Min Charge Time, and the Bslite charger signals charging with a red light, a full charge with a solid light, and a fault with a green light. The Bslite maker lists a temperature range of -4°F to 140°F for its pack, so keep the pack inside the range the maker states. When a pack will sit unused, check the gauge before the next job; the listings here state no memory effect for the CRAFTSMAN cells and the Bslite cells, so a partial charge does not cut the pack’s life.
Lead-acid batteries can release hydrogen while charging, so charge in a ventilated space away from sparks and flames, connect positive first and negative last, set the charger to the battery type (flooded, AGM, gel, lithium), and wear eye protection. Read our Safety Disclaimer.
FAQ: garage tools
Will a 5Ah battery fit the same 20V MAX tools as a 4Ah battery?
Yes, on the 20V MAX platform. The DEWALT 5Ah and 4Ah packs are 20V MAX packs, and the DEWALT listings state compatibility with 20V MAX tools and chargers. The amp-hour number changes how long a pack runs, not which tools it fits. The CRAFTSMAN V20 pack is the exception here: it fits V20 tools, not 20V MAX tools.
Does a 5Ah battery give a tool more power than a 4Ah battery?
No. Both packs are 20V packs, so the voltage stays the same and the amp-hour number measures capacity, not power. A 5Ah pack runs a tool longer between charges than a 4Ah pack. The DEWALT XR POWERPACK 4Ah pack carries a separate maker claim of 50% more power, which is a claim about that pack’s cells, not about the 4Ah number.
How long does the CRAFTSMAN V20 4Ah battery take to charge?
The listing states a 60 Min Charge Time. That is the maker’s stated charge time for the CMCB204-2 pack.
Can I use a Bslite 5.0Ah replacement battery with DEWALT 20V MAX tools?
The listing states compatibility with DCB200 and DCB204, and with 20V MAX tools such as the DCD796 drill, the DCS367 saw and the DCG413 grinder. The kit also ships with a DCB112 charger. The maker lists UL2056, CE, RoHS and UN38.3 compliance and a 365-day warranty.
What warranty comes with these 4Ah and 5Ah batteries?
The DEWALT DCB205-2 lists a 3 year limited warranty, and the Bslite kit lists a 365-day warranty. The DEWALT DCB2104-2 listing states no warranty term, and the CRAFTSMAN listing reads “Visit Craftsman.com” with no term stated.
Related: 3Ah vs 6Ah 20V battery, our cordless tool sets for mechanics and the cordless tools hub. Also see our battery charger maintainer picks.
