I've been looking at battery chargers and I've noticed there are some that offer a connection path to the battery that is separate from the system load. Others have a path that's shared. What's the tradeoff? With a separate path it seems like the charger chip can charge the battery separately while supplying the system load with the charging source (ie. a USB plug). Whereas with the shared path it seems like the battery is always supplying the system load -- is that bad for battery health? How does a HW designer decide which is better?
Here are some examples so it's clear.
Here's a reference design that makes it clearer:
Here's a reference design showing the shared path: