I tried to figure out how the Victron Battery protect device is constructed. When you watch this video on YT you see that the guy is splitting the heat sink in half to be able to access the inner parts.

The device input port goes directly to MOSFET Drain via to220 tabs attached to aluminum block and the Source (output) goes via PCB to the output port.

Now my question is, how is the input isolated from the blue heat sink? I dont see any isolation as the inner aluminum block seems to be directly attached to the large blue heat sink, this would be catastrophic if this is bolted to negative frame of a vehicle.

There must be an isolation but where is it ?

 

Isolation of a transistor from a heat sink, at low voltages, can be almost invisible if it is done carefully and with the right materials. In addition to that, the blue anodized surface (aluminum oxide) of the heat sink is an excellent insulator, as it is a form of ceramic material. That, coupled with a thin film of silicone oil, will conduct heat quite well and electrical current very poorly. In addition, there is transparent insulation material available from many distributors. AND not all heat sink grease is white.

Besides that, consider that a large portion of youtube video material is faked.

 

Isolation of a transistor from a heat sink, at low voltages, can be almost invisible if it is done carefully and with the right materials. In addition to that, the blue anodized surface (aluminum oxide) of the heat sink is an excellent insulator, as it is a form of ceramic material. That, coupled with a thin film of silicone oil, will conduct heat quite well and electrical current very poorly. In addition, there is transparent insulation material available from many distributors. AND not all heat sink grease is white.

Besides that, consider that a large portion of youtube video material is faked.

MOSFETs are not isolated from the inner aluminium block, thats the design, input goes directly to it through PCB and connects all TO220 tabs. The inner Aluminium block MUST be isolated from the blue heat sink and I figured it out from the vid how it's done.

 

Like I stated, the insulation can be very difficult to see in some installations.