Common negative bus bar different voltages?

[mcarthur]

One of the YT channels showed a DC solution wherein the 48V and 12V negatives all went to the same negative bus bar (positive bus bars were separate). Now I’m far from an electrical savvy person, but it confused the heck out of me - do they connect the negative bus bar to both the neg end of the 12v battery AND the neg end of the 48v battery? Can you do that?! Does that work? Any issues?

 

[GoneFarrell]

That's how my 48v start and 12v house banks are connected, 31 years!

 

[twistedtree]

Yes, its just fine to do that.

 

[rwidman]

Negative is zero volts in all systems so that's fine.

 

[MYTraveler]

It is fine as long as the cable from the bus is capable of conducting all of current without significant resistance. If that cable is "high" resistance at max amperage (or in the worst case, if that cable becomes disconnected) the voltage potential between batteries (or other power source) and that bus bar will not be zero, and the electricity (especially that coming from the 48v devices connected to the bus) will seek an alternate path to ground, through the 12v devices, potentially damaging their circuits in the process.

 

[mcarthur]

Thank you all. I'm definitely learning!

So the single negative bus bar has "inputs" from various DC appliances no matter their voltage (12v,48v,144v,etc). It has multiple "output" connections to the negative terminal of all source batteries, no matter their voltage (assuming all are DC!)? All that is ok, making sure the wiring size and bus bar can handle the combined amperage and has low resistance?

 

[socalrider]

Yeah - your negative bus is kind of like the sewer line for your house. Everthing ends up there, whether it's sinks, toilets, showers, whatever. Just gotta make sure nothing backs up so use big pipes!

 

[FlyWright]

If it's appropriately sized, no problem! As already mentioned, it's all about the size of the hose.

 

[mcarthur]

Woohoo - simplifies my wiring I'm sure. Thanks everyone!