Isolated or non isolated DC DC converter

[Cuprani]

Can anyone please explain why I need an isolated DC DC converter?

I've had a non isolated 72V-12V DC DC converter on my old ebike setup (20S Li-ion with Leili 5000 watt squarewave controller) and it worked perfectly. (not the controller, but the dc dc converter).

I'm currently building a new setup with a 72V 20S li-ion battery and a Kelly 7230S sinewave foc controller.

I recently discovered my old DC DC controller has died and I need a new one for my setup.
I know the basics of electronics but that's about it. I know an isolated DC DC converter has got it's own ground wire. Using the same ground for both the Engine/Battery and 12V system could give ground loops?

How could this ground loops interfere with the engine management? How will this affect my ride?
Short: Do I really need an isolated converter?

The non isolated are a lot cheaper and better available in waterproof and smaller housing.

 

[billvon]

Can anyone please explain why I need an isolated DC DC converter?

You probably don't. As long as you follow good grounding practices and understand your ground return paths you are probably fine.

 

[Cuprani]

Ok thanks, that makes it a lot easier to find a good converter.

 

[john61ct]

I know isolated is needed with multiple units, when outputs get connected in series to boost voltage, or at mid-point taps, say 2x 36V converters (or PSUs) to charge a 72V bank without having to break/reassemble the two halves.