MPPT controller size and AC-DC battery charger needs?

[Photobug]

I currenlty own two solar controllers. A Smartsolar 100/20 and a much larger one that lives in my RV. The Victron is in my custom battery pack to charge my Lifepo4 battery. I bought it overkill it only controls one portable panel and might be used to control up to 200watts of portable panels. In my RV, the previous owner added a huge battery bank connected to 300 watts of solar panels using a very large solar controller. The battery pack, MPPT controller and battery charger take up a huge amount of space in my largest storage area. I would like to shrink down this footprint.

How do I determine what sized Victron charger would control the 300 watts on my RV?



I also want to consider replacing the battery charger. Except in winter I do not need it at all in summer only in winter for the few months the solar panels are covered up, but will likely pull the batteries and store in the garage to keep charged once a month.

Currently I have an older NOCO that I carry from vehicle to boat to charge my batteries. I am considering either a newer NOCO or a Victron charger to use as needed. I have been very happy with the NOCO but the newer one is smaller, lighter and puts out more amps at 7.2 amps vs 10 amps. The Victron brings 15 amps to the game.

My current charger.

The two chargers I am considering upgrading to.

 

[Buddha.]

The 100/30 I had is good for 440 watts, you could probably go with a smaller one if you weren’t adding more solar.
You want to replace that converter/charger with a battery charger?
The converter is more than a battery charger. It supplies the 12v fuse panel in your camper as well.

 

[john61ct]

The 100/20 is fine for 300W of panels.

20A max **output**

times your CV profile setpoint

Even 400W would not do any damage

and panels IRL hardly ever touch their W or A ratings, brief peaks in very unusual conditions only.

 

[Photobug]

The 100/30 I had is good for 440 watts, you could probably go with a smaller one if you weren’t adding more solar.
You want to replace that converter/charger with a battery charger?
The converter is more than a battery charger. It supplies the 12v fuse panel in your camper as well.

The system I am trying to figure out here is not the RV house battery system. It is a 3rd battery system besides the starter battery and coach battery system. The coach battery has DC-DC charger, generator and a converter/charger system. I have gone 4 days using this coach battery without any issues. At one point over the winter it got low and I needed to recover the batteries so I am concerned about the health of the house battery.

What I have pictured is completely separate from the RV's built in power system. The previous owner added solar and instead of adding to the "coach" battery system. He added 300 watts of solar panels, a solar controller, and a separate battery charger for this system which has 4-6v golfcart batteries. This system connects to a 1000w inverter the previous owner used to power the 32 inch tv. The tv, charger and this entire 3rd battery system has gone unused since I have owned this RV.

I want to shrink this 3rd battery system down to the bare minimum.

1. Remove the huge AC-DC charger which I have never used, but carry a spare AC-DC charger in case it is needed.
2. Remove 2 of the 6v batteries and put the remaining 2 in a proper box, they sit in a huge Rubbermaid container now.
3. Put a smaller solar controller in the compartment.
4. Tie the solar and this 3rd battery into the "coach" battery system.

 

[Photobug]

The 100/20 is fine for 300W of panels.

20A max **output**

times your CV profile setpoint

Even 400W would not do any damage

and panels IRL hardly ever touch their W or A ratings, brief peaks in very unusual conditions only.

I have only analyzed my 100w folding panel and from my Victron controller I see 50-60 watts at and 4-5 amps at peak hours.

 

[john61ct]

Yes. Was there a question there?

On this specific question, the scientific method is unnecessary, it's just basic knowledge + a little math.

 

[Buddha.]

Yeah you definitely don’t need 2 converter chargers.
If you’re not using that third bank have you thought of getting rid of it and connecting the solar power to the house bank?
If the third bank batteries are better than your house batteries move 2 of those 6v batteries to the house bank location, if they fit.

 

[Photobug]

Just dont set them on a concrete floor.

I don't think that applies anymore.

The Concrete Truth About Batteries Stored on Concrete

Have you heard the one about batteries discharging when stored on concrete? Apparently, some people have taken to storing 12V batteries—the kind used in electric wheel chairs and emergency lighting systems—on wooden shelves to maximize their life expectancy. Is there a spark of truth to this or...

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BatteryStuff Articles | Myth Busted. The Truth About Storing Batteries on Concrete Floor

Learn about this old wives tale and if you should (or can) store your batteries on concrete floors from the battery experts at BatteryStuff.com.

www.batterystuff.com

 

[Photobug]

Yeah you definitely don’t need 2 converter chargers.
If you’re not using that third bank have you thought of getting rid of it and connecting the solar power to the house bank?
If the third bank batteries are better than your house batteries move 2 of those 6v batteries to the house bank location, if they fit.

Kind of the plan. Take out the better batteries and put them in the coach battery location. I have 3 other vehicles that also need batteries, I will shift the best ones around provided they fit. I am tempted to keep a second coach battery in this location but with a generator, I guess no need for an extra battery.

 

[john61ct]

Just dont set them on a concrete floor.

Yes, old wives tale, not been true for over a century