Packs are shared across the 18 V range, so capacity is usually the decision rather than fit. The newer tabless cells are the ones worth knowing about: current leaves the cell by many paths instead of one, so internal resistance and heat both drop. In practice that means noticeably longer runtime and shorter charging on hard-working machines — the gain is largest where the tool draws heavily and smallest where it doesn't. They replace the previous HighPower packs at the same price. Capacity choice follows the work. Compact 4.0 Ah packs keep a drill balanced overhead; 8.0 Ah packs sustain what a saw or extractor pulls. Smaller 10.8 and 12 V packs serve the compact machines. Chargers differ in speed and in how many packs they take — one, two, or a Systainer-mounted multi-charger for a van — and energy sets pair packs and charger in a single part number, which is the simplest way in from nothing.
Compare products and choose the right one for your work.