Charging Lipo under load

Question

I want to use a 2s Lipo for a autonomous car built with a Beaglebone and Motor Bridge Cape from Seeedstudio. The Motor Cape has an built in voltage regulator which steps down 7,2V to 5V system voltage. This allows supplying motors an Beaglebone from same source.

While charging a 2s LiPo charger is supplied with 12V. Is it possible to charge the LiPo under load? Or do I have to supply the Beaglebone from 12V source while charging?

This would mean that there has to be a switch between battery source and 12V source which selects the source automatically. That is not a complicated task, but supplying the system by battery all the time would be easier.

For example the swithing between LiPo and 12V source could be realized like this:

^{simulate this circuit – Schematic created using CircuitLab}

Answer 1

Adding a load to the battery while charging means that the load is actually added to the charger. Since the charger must provide enough current to both charge the battery and supply the device there may be issues if the load is disconnected while the battery is being charged.

Microchip's AN1149 describes a method for converting a battery and charger into an offline supply that switches to wall power when the battery is being charged. Since the charger only ever has the battery as a load, the above problem is avoided.