2Ah vs 4Ah vs 5Ah Batteries: What Changes in Real DIY
How battery size affects runtime, weight, balance, and which tools actually need bigger packs.
Published: 2026-02-18
Battery choice is the fastest way to make a cordless tool feel “amazing” or “annoying”.
The simple model
- Ah = runtime, but also weight
- Big batteries help high-draw tools (grinders, circular saws)
- Small batteries help comfort (drilling overhead, tight spaces)
What each size is best for
2Ah (light + balance)
Best for:
- drill/driver for furniture
- impact driver for short bursts
- overhead work
Tradeoff: you’ll swap batteries more often.
4Ah (the default “do everything”)
Best for:
- most DIY drilling
- impact driving
- oscillating tool
- jigsaw
If you only buy one size first, this is usually it.
5Ah+ (power tools that drink energy)
Best for:
- angle grinder
- circular saw
- long sanding sessions
Tradeoff: heavier, can make compact tools nose-heavy.
Battery strategy that saves money
Don’t buy three huge batteries. A smarter setup:
- one small (2Ah) for comfort tasks
- one medium (4Ah) as your daily driver
- one large (5Ah+) for saws/grinders