What volts, amp-hours and newton-metres mean
On a battery and a drill label you almost always see three letters: V, Ah and Nm. In the shop they are often folded into one sentence — “bigger means more powerful”. That is wrong. Each measures its own thing, and if you confuse them you buy the wrong battery or expect from the machine what it never promised.
Examples from Scheppach batteries and cordless drills. For choosing the machine itself: how to choose a cordless drill.
V — voltage and platform
Volts (V) are battery voltage. SBP2.0 and SBP4.0 are both 20 V. BC-CD50SC-X kit also runs on 20 V. The same V means one manufacturer voltage class — not that any other 20 V pack will fit.
SBP2.0 suits Scheppach 20 V tools, but GEN2 does not work with GEN1. Worx WA3639 is also 20 V / 2.0 Ah, yet another brand’s system. Two “20 V” labels are not interchangeable — like “petrol” is not the same as any key for any car.
In practice: before you buy, check the platform (Scheppach GEN2 / GEN1) and tool compatibility, not voltage alone.
Ah — how long, not how “strong”
Amp-hour (Ah) is capacity. SBP2.0 is 2.0 Ah; SBP4.0 is 4.0 Ah. Higher Ah usually means longer work between charges, not higher torque.
If you screw a shelf for 15 minutes, 2.0 Ah is often enough. If you work all day with frequent starts, 4.0 Ah is comfort. But 4.0 Ah does not turn a 50 Nm machine into a 150 Nm machine — torque still sits on the tool’s Nm line.
Nm — torque on the machine
Newton-metre (Nm) belongs to the drill, not the battery. It shows how “hard” the machine can turn within the limits the maker states.
- C-DTB74/1-X — up to 45 Nm (20 V 2.0 Ah in the kit).
- BC-CD50SC-X — up to 50 Nm.
- BC-DD60-X kit — up to 60 Nm, 2.0 Ah in the kit.
- BC-CD70SC-X — up to 70 Nm.
- BC-CD150-X — up to 150 Nm.
50 Nm with 2.0 Ah and 50 Nm with 4.0 Ah is the same torque — what changes is how long you can work. So “bigger battery” ≠ “stronger drill”.
Charger A ≠ battery Ah
The charger is rated in amperes (A); the battery in amp-hours (Ah). They are not the same unit.
SBC4.5A — 4.5 A (about 35 min for 2 Ah, 60 min for 4 Ah). Many kits include a 2.4 A charger — the fastest times from the 4.5 A model do not apply to that. See also chargers.
A faster charger saves waiting. It does not raise the tool’s Nm.
How to read it in 20 seconds in the shop
- V + platform — does the battery fit this machine?
- Nm — does torque suit your screw and material?
- Ah — how long do you want to work between charges?
- A on the charger — how fast do you recharge?
Frequently asked questions
Is 4.0 Ah “stronger” than 2.0 Ah?
Usually longer runtime. Torque is still on the tool’s Nm line.
Are all 20 V tools in the shop one system?
No. Scheppach 20 V plus GEN1/GEN2 warning. Worx 20 V is a different product line.
Can I “upgrade” the machine with a bigger battery?
You improve runtime (if the platform fits). Torque — no.
In short
V = platform, Ah = how long, Nm = how hard the machine turns, A on the charger = how fast it charges. Before you buy, compare those lines on the specific model — not on the feeling that “the number looks bigger”.
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