• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

negative for 24V/48V and stepping down to 12V

deeperblue

New Member
Joined
Jan 6, 2024
Messages
13
Location
Washington
If I convert my motorhome to 24V (or 48V) battery bank, there are still many loads need to be powered by 12V. (light, jacks, slides, generator starting current, etc). So I need either a 24V (or 48V) to 12V step down converter, or set up an 12V battery to provide the 12V power. My question is:
Should both the 24V/48V and the 12V all connect their negative post to chassis? Or only one of them should be connected to chassis?

Thank you very much!
 
It depends on the step down converter.
Some of these have a shunt resistor on the negative side, to measure the current flowing through.
This current measurement is important for the internal control loops (if the converter has some sort of current limiting or over current protection). If you connect both negatives to chassis, and your loads are also chasis-grounded, you are in effect bypassing the negative side of the converter, which bypasses the mentioned current measurement.

I actually blew up some fuses on a step-down converter, because I thought input and output negatives could be connected through a common negative.

However I think Victron (Orion) has a non-isolated DC-DC converter (the one with only three terminals) which uses a common ground, so that could work for you.
 
See my build for how I'm doing step down from 48 volt to 12 volt. Mine is isolated.


As far as chassis connection goes, it depends on if you use an isolated or non-isolated component. See this discussion on the Victron forum:

 

diy solar

diy solar
Back
Top