Why would a car stall and lose power after a new battery had been fitted?

A car might stall and lose power after a new battery is fitted due to several reasons, such as poor electrical connections or loose terminals that prevent proper power flow. Additionally, if the alternator is not functioning correctly, the battery may not be charging adequately while the engine is running. It's also possible that the battery replacement process inadvertently disturbed other components, leading to issues like fuel delivery or ignition problems. Lastly, if the new battery is not compatible with the vehicle's electrical system, it could cause malfunctions.