Total newbie and confused

[Isaac-1]

As long as the wire is the proper size I don't see where it matters much, though you will want to include a solar disconnect for when are doing maintenance

 

[HOOOPTEEE]

I can see the logic. It makes some sense. It's just not a shortcut I'd take unless the wire run was too far to the batteryIt's not so much the run as it is eliminating the step of having to drill a hole through the floor and run a separate line to the batteries. Just wondering if this would bypass that step.

Let's get a few things straight. It would help to know if you have a "Progressive Dynamics PD4645V charger and stock inverter" as you said, or if you have a Converter/Charger. Perhaps you misspoke about the "inverter."

How much solar do you plan to install? I ask because the current coming out of your solar charge controller generally is not all that large. So, using heavy gauge "welding wire in conduit" is overkill unless you're installing 800w or more of panels. Typically, on a Class C you'd see something like 400w and that produces less than 30-amps max coming out of your charge controller.

What charge controller are you planning to use, and are you wiring in Parallel, Series or a combination of both?

I haven't seen the YouTube you mention, but I'd have to guess that that guy just used the battery connection at the charger simply for wiring convenience - not actually using the charger for anything. It's very unusual and your plan to wire directly to the battery bank is the right way to go - just reconsider the very heavy wiring from controller to the batteries. For 30-amp you'll be fine with 10ga wire unless it's a long run and then consider 8ga.

Character flaw on my part. I tend to overthink and overbuild things. I already bought the 8awg solar wire and the 4awg welding wire so I might as well use them.

I would install buss bars. Then crimp on ring connectors on the 3-pairs of wire; one pair from solar, one pair from converter/charger output and a third pair from the battery bank. Then give each wire their own post on each buss bar.


In essence you will not be adding any extra amperage. When plugged into shore power your converter/charger will take on charging your batteries. When not connected to shore power your solar charge controller will take on charging your batteries. The solar charge controller reads your battery voltage and applies charging based on that voltage. When your converter/charger is charging your batteries at 13.7v (or more) your solar charge controller is smart enough to read that voltage as battery voltage and stop nearly all charging.

People mistakenly think if they are plugged into shore power and charging a battery with 30 amps from a converter/charger and also are parked in the sun that their solar charge controller is adding another 30 amps for a total of 60 amps. But in my experience, my 300w of solar only applies it's charging amps when no other charger is present. This includes while driving and getting a charge from the alternator.

that's exactly what I thought about the 30a plus 30a. Thanks for clarifying.

 

[PJ Stough]

I would install buss bars. Then crimp on ring connectors on the 3-pairs of wire; one pair from solar, one pair from converter/charger output and a third pair from the battery bank. Then give each wire their own post on each buss bar.


In essence you will not be adding any extra amperage. When plugged into shore power your converter/charger will take on charging your batteries. When not connected to shore power your solar charge controller will take on charging your batteries. The solar charge controller reads your battery voltage and applies charging based on that voltage. When your converter/charger is charging your batteries at 13.7v (or more) your solar charge controller is smart enough to read that voltage as battery voltage and stop nearly all charging.

People mistakenly think if they are plugged into shore power and charging a battery with 30 amps from a converter/charger and also are parked in the sun that their solar charge controller is adding another 30 amps for a total of 60 amps. But in my experience, my 300w of solar only applies it's charging amps when no other charger is present. This includes while driving and getting a charge from the alternator.

In most cases, I believe this to be true, but in cases of batteries that could accept more than the max output of your charger/converter or charger/inverter, then I believe you would see output from your solar array going into the batteries as well. I am particularly thinking of lithium iron phosphate batteries that have a very high acceptance rate.

 

[creativepart]

I am particularly thinking of lithium iron phosphate batteries that have a very high acceptance rate.

If the LFP batteries are being charged they show the charge voltage being applie on any voltmeter. They don't show the actual battery voltage, just the charge voltage. The solar charge controller is wired directly to the batteries. It monitors battery voltage directly. Hence, when the battery voltage is displaying the charge voltage THAT is the voltage the solar charge controller sees and acts upon.

It can't see past that to know the true state of charge of the battery - only it's voltage. Solar charge controllers have multi-level smart chargers and they apply a charge based upon the battery's voltage.

The solar charge controller doesn't stop all charging in this case, it just reduces it to a bare minimum. I'm speaking of a MPPT controller. A PWM controller basically ignores all voltage from the solar panels that is greater than battery voltage and switches charging on and off based on the voltage it reads. The lower the battery voltage the longer a PWM switches charging on. The higher the battery voltage the more the charger switches off. When the battery is "fully charged" the PWM charger is mostly in the off state.

The same is true of a fully charged battery, regardless of whether or not the RV is plugged into shore power. If the battery is 12.7v the solar charge controller will work to keep up with any discharge as necessary but when the battery is fully charged the controller (any smart charger) is programmed to reduce charging to prevent over charging.

 

[John From Detroit]

I would connect the charge controller direct to the batteries.. You might not need to drill a hole if you can follow some plumbing (I do not suggest the Fridge LP line but the ice maker line is ok) if the hole is big enough.

WHY: there is some voltage differential between the converter terminals and the battery terminals. It's not much.. but it may cause the solar controler to say "Full up" and then you are paying for power instead of getting it free from God Power and Light.

 

[Alontheway]

I dont understand all the discussion...
You want to run the solar panel voltage straight into the RV charger? No!

Run the wires from the solar panels to a solar charge controller (MPPT I suggest but PWM will work) then to your battery. That's it.

The MPPT charge controller is very very good, likely better than your onboard charger. It will be cheap at $50 or so n up to $100 or more, and will give you a redundant charger in case the other goes out.

It does not matter to us how you route the wires, through the fridge, under the oven, over the bed - run them however is the shortest, and you should be able to keep them inside which is safer than exposed to the road, but conduit would work too.
The inverter is on the other side of the battery as are all DC powered appliances and will not come into discussion when adding a solar charger.

Welding wire is over-kill. 12g or thicker will work for most runs. Solar is not giving a lot of amps. It's strength is small power all day.