Shared ownership does not mean shared batteries since rails and pinouts are intentionally different. To avoid another charger buy tools that use the same battery platform you already have, otherwise plan on a second charger or unload the extra packs.
Also check the app for accidental no-go lines or merged rooms and make sure the vacuum starts fully charged - some models limit exploration when battery is low. Inspect the side wheels drive rollers and encoder areas for hair or threads wrapped around them, since cleaning those is a cheap fix that often stops drifting and missed edges.
