Solar vs Dock power wiring for charging system

[Worldwalker88]

I know this is in the forums somewhere, but I couldn't find the info as it applies to our boat, or possibly my misunderstanding of 12V charging.
We're moving to an unpowered dock, installing 100W solar panel with a 20A two battery controller. One house, the other is starting/reserve. All well and good there.
But my question is, if we are visiting another port and charge up using dock power, should battery charger be wired to the other post than the one the solar controller is charging to?
Maybe this is a silly question, but since the controller reads battery state ect... would having the dock powered charger on the same battery post do anything to the controller? Or does it just read a steady current and act accordingly? i.e. allows nothing and there is no "back current" to harm either controller or solar panel?
Thanks for any info, including specifying where this would already be covered in the forums.
WW

 

[jen-and-fred]

I have my solar charger going to a circuit breaker before it gets to the batteries. Manually I disconnect the solar when I plug into shore power. I have had them charging in parallel without incident. I have also had the solar and engine charging in parallel without incident, but I try to avoid that as much as possible. I believe that the different chargers could confuse each other but more likely, one would be stronger than the other, it would do it's thing, and the other would see that the voltage is high and it would assume the battery is charged and do nothing, This probably differs by charger, type, and brand.

 

[Worldwalker88]

Well... I feel stupid...
I was so immersed in wiring this out on paper, it didn't even occur to me to do separate controllable circuits..
Thanks!

 

[Gunni]

This is a great question! I also ponder the question as I power up my genset for testing while plugged to shore power. I can't use both at the same time (my AC panel has an either/or Generator/Shore selector. But I always wonder what happens to all those electrons racing about with 6.0kW of amperage pushing them and colliding with those Baltimore Gas & Electric electrons? I want to add a solar power source, but the whole thing confounds me. You can see why I need a competent electrical pro

 

[Worldwalker88]

I spent lunch today redrawing so one is separate from the other.
It will cost me a couple of switches, a few fuses and about 10 feet of wire... and I'll sleep better!
;-)

 

[Tom J]

I don't have any way to disconnect the solar panel, and sometimes, when we are motoring, the alternator shuts down when the batteries are fully charged. The only down side to this is that the tachometer goes to zero rpm's.

 

[Maine Sail]

Maybe this is a silly question, but since the controller reads battery state ect... would having the dock powered charger on the same battery post do anything to the controller?

Multiple charge sources feeding one battery bank is done every day and causes no harm. I have numerous cruising boats out there with wind, solar, inverter/chargers & alternators and they often are all working at the same time, in bulk. I even have a couple customers with hydro generators and one with a fuel cell added into the mix.

These devices are all voltage regulated. If the system is above the voltage limit the device will simply shut off until the voltage falls back into range. If the system voltage is below the regulation limit, or at it, the controller or charger just supplies the current necessary.

 

[Don Lucas]

My solar controller senses when something else is charging the batteries and just shuts down.

 

[Maine Sail]

My solar controller senses when something else is charging the batteries and just shuts down.

It can certainly do that if the other source has a voltage that is higher than the solar set point AND the solar current is not needed to maintain the higher voltage of the other source....

For a proper set up of multiple charge sources best practice is for the largest current source to have the highest programmed voltage.

 

[Worldwalker88]

So, if I have this correct:
I would set the charger on the 30amp dock line @ 15.0V (I'm making numbers up here just to see if I have the concept right), solar panel controller @ 14.5, and if I added a wind generator down the line, set it at 14.0 and the the battery doesn't care where the poew comes from, as long as it is in a set range. Correct?
So it is prioritized, to " best available" (for lack of a better term) power at any given moment.
Therefore, the lower voltage setting just takes that system out as long as a stronger one is present.
Do I have that right?

 

[kloudie1]

Yes.. Ya got it !
and.. when the battery voltage is below all set points, it will (as it is able) take current from all sources.

 

[Worldwalker88]

And... just to make it clear to me...
All this is wired in parallel. True?

 

[Bill Roosa]

yes parallel,
you own the concept but.....
the devil is in the details. 15, 14.5 and 14.0..... would work the way you intend but would boil the water out of the batteries when you motor. Yes made up numbers but if you are shooting for fully charged batteries with the motor that sets the high point and setting it lower for the other (even 0.1 volt lower) charge controlers can have some unplesant battery life and SOC consequences. Remember that 13.2 to 12.1 is the normal resting voltage for a wet cell (100-50% SOC) so you are playing with just over 1.0 volts to set the chargers.
All I can say is good luck and I'd be thinking the following:
motoring is sock it to the batteries or top them off time and go full max allowable voltage
genset charging: same same as the motor is probably not on when the ganeset is
solar: trickle charge and you are looking to either bring the batts up to full charge over a long period of time or replacing what you used last night
wind: can charge more than solar so it is more like a genset but it also can just sit there so assume it will not be avalable and set it lowest.
Really depends on how you use your boat and the environment you live in.

Good luck

 

[Worldwalker88]

Well...
It's all in.
Redid the cable management, for both 12v and 110v, fabricated a frame from 306 SS tube and redid the fuses and circuit breakers throughout.
I'll post pic when I get from the phone to a computer and can manipulate the pics better.
WW

 

[Worldwalker88]

Fabricated off set tee poles out of 306 ss, used the KISS principle to attach the aluminum legs (hose clamps), fabricated the cross clamps from mild steel plate (burnished and painted), and it all seems to work and solid in the wind. She's at the (unpowered) dock now and we're happy with it!
Thanks for all the help!