Sorry Framer, cannot agree. I wanted to upload an electrical diagram, more detailed than the one posted before, but have problems doing so. But there are available on the net.
Do not confuse a battery failure with a bus failure.
In your example, when the battery fails, plus the charger, the hot bat bus is fed via TR3. Then there is an auxiliary batt charger on the airplanes where there is a dual battery installed, also feeding the hot batt bus.
Yes, in case the hot battery and the switched batt bus would fail, you have another can of worms.