The checker uses exact model identities and manufacturer evidence. It keeps battery-to-tool and charger-to-battery questions separate.
Four verdicts
| Verdict | Use |
|---|---|
| Compatible | A manufacturer source supports the exact model pair without an unresolved use condition. |
| Conditional | A documented condition or required physical-label check remains. |
| Incompatible | A manufacturer exclusion or separate system rule applies. |
| Unknown | Exact-model evidence is absent, ambiguous or incomplete. |
Order of checks
- Match the exact model and product type.
- Apply a specific model rule before a general platform rule.
- Apply official exclusions before broad system descriptions.
- Check charger AC input separately from pack fit.
- Check whether the tool requires one or two packs.
- Return unknown if the supporting facts do not reach the exact question.
Three-part result
The tool combines the battery-to-tool and charger-to-battery results conservatively. An incompatible part makes the whole set incompatible; an unknown part leaves the whole set unknown; a remaining condition makes it conditional. It does not silently reverse FLEXVOLT direction or turn an M12/M18 charger into tool cross-compatibility.
Evidence boundary
A model can exist in the catalog without a positive rule for every pair. This avoids inventing a verdict from a common voltage or connector. Each published non-unknown pair has a manufacturer source link and review date.