Victron Orion 48/24 + PWM regulator for charging 12V batteries

I have a 51.2v battery and I want to charge a 12v battery. I’ve noticed that Orion batteries are used to charge the battery, but I couldn’t find a smart model that is recommended for charging. So I thought about using an Orion 48/24 to simulate a solar panel and have the PWM regulator charge the 12v battery.

Orion Smart Isolated 48/12-30

In my location I can’t find that Orion, I only found the one that isn’t smart.