12-V DC Flow?

rjg23 · #1 (**permalink**) 12-24-2010

Looking for clarification/understanding regarding the flow of electricity through a DC circuit. I have the house battery connected to a bus bar and all systems connected to this, via switch panels, fuse boxes, etc. I understand the flow with this setup. However, if I then add the alternator and solar to this bus bar, that's where I lose it. This seems, to me, to go against the "flow". What am I missing regarding the flow of energy, through the circuit?

Bob

Just realized this is in the wrong forum. Meant to be in "Electrical Systems"

mitiempo · #2 (**permalink**) 12-24-2010

The alternator output (B+) should go to battery + but you haven't posted enough information about your charging arrangement to give a definite answer.

peikenberry · #3 (**permalink**) 12-25-2010

Basic Electricity New Boatbuilders Home Page - Basic Electricity DC Page 1

The alternator generates AC which is rectified to DC and transformed to 12V (actually anywhere from 12 to 14 depending on how it is regulated) The positive output goes to the positive lug on the battery and the negative goes to the negative on the battery. When the alternator is turning over it is pumping electrons into the battery thereby charging it. If you are running equipment some of those electrons, plus some from the battery plates provide the current to run the equipment. But overall the alternator supplies enough to charge the battery while it is being used.

That's about as simple as I can make it.

asdf38 · #4 (**permalink**) 12-26-2010

The alternator current is going to flow from the alternator, to the bus bar and then from there it's going to split - some will go to your loads and some will go into the battery to charge it.

When the alternator shuts off, the current flowing between the battery and the bus bar will reverse and the battery will takeover supplying current to the loads.

A good way to imagine it is with water. Imagine you have a water tank (battery) in your house supplying a bunch of faucets. The water tank is positioned at a height of 12' (think 12V). A pipe runs to a central distribution point (the bus bar) and then to a bunch of faucets (loads). Every once and a while a 14' tall water tank truck (alternator) drives up and plugs into the central distribution point - this will flood the central distribution point so it's higher than your water tank so water will flow into the tank to charge it. At the same time water will continue to flow to any faucets that are on.

peikenberry · #5 (**permalink**) 12-26-2010

Very good analogy.

rjg23 · #6 (**permalink**) 12-26-2010

Thanks for the explanation/analogy. That makes sense.

mitiempo · #7 (**permalink**) 12-26-2010

As I posted more information is really required. The op states "the house battery is connected to a bus bar and all systems connected to this..."

This does seem to leave out a start battery which would not get any charge in this scenario.

What has been posted is correct but that doesn't necessarily solve all the op's problems.