Community Forums

Jbelshoff · 04-11-2022, 04:55 AM

Me and my wife have been told since I started wanting to use solar as a alternative source and been told you can't use a converter and need to shut it off when I'm using solar through my solar control box and inverter. So when I switch to solar I have to shut off converter. After reading this thread I'm confused why I've been told this. I would love to be able to just run my panels through control box directly to converter and battery.

twinboat · 04-11-2022, 05:20 AM

Your solar has a controller. That controller connects to your batteries to charge them.

Your converter/charger does what it's name implies, converts 120 volts to 12 volts and charges batteries .

When on 120 volt shore, or generator power, both your solar and the converter/charger can charge your batteries because they are both voltage controlled to not overcharge them. Nothing needs to be turned off.

You mentioned inverter. If your powering it from the batteries in the RV and connecting an inverter to your shore power line then you need to turn off the converter/charger.

You can't use the inverter and batteries to power a converter/ charger to charge the same batteries. It's a self discharging loop. Science hasn't figured out how to do that.

wrvond · 04-11-2022, 05:24 AM

The converter takes the 120 volt AC and converts it to 12 volts DC to charge your battery. The solar controller takes the 12 volts DC from your solar panel(s) and applies it to your battery.

My MPPT solar controller works in conjunction with all other charging sources, Since it senses the battery needs it will avoid overcharging and damaging the battery.

It's possible your controller does not work this way, but you should check on that.

Edit: apparently I'm a slow typist - Twinboat beat me to it!
Edit: edit: and said it better!

computerguy · 04-11-2022, 10:58 AM

Quote:

Originally Posted by Jbelshoff

Me and my wife have been told since I started wanting to use solar as a alternative source and been told you can't use a converter and need to shut it off when I'm using solar through my solar control box and inverter. So when I switch to solar I have to shut off converter. After reading this thread I'm confused why I've been told this. I would love to be able to just run my panels through control box directly to converter and battery.

One NEEDS to be careful where they "heard" this from. What sort of experience does this person have? Did they give you reasons as to why? Generalizations are really really bad especially from someone not knowledgeable.
Is it possible that the combination of a shore powered converter AND a solar controller being "bad" for your batteries? In the strictest sense, yes. But you would need a LARGE converter, a LARGE solar array with LARGE solar controller and a small battery bank for it to be bad. There is something known as C (Coulomb) rates one should not exceed when charging/discharging batteries. To exceed those rates one would need to know the battery bank specifications, the controller specs AND the solar controller/array specs.
I doubt you are going to exceed your battery bank C rates with your setup. That said, not knowing all those details, one cannot say with any level of accuracy if it is ok.

computerguy · 04-11-2022, 11:06 AM

Quote:

Originally Posted by twinboat

...You can't use the inverter and batteries to power a converter/ charger to charge the same batteries. It's a self discharging loop. Science hasn't figured out how to do that.

I would change this up a little bit.
You shouldn't use the inverter and batteries to power a converter/ charger to charge the same batteries.

I've seen some folks try this and wonder why their batteries are run down pretty quickly

tnrvers · 04-11-2022, 12:46 PM

Jbelshoff

Things have already been explained very well, so let me tell you what we do. We have a DP, hence we have an invertor/convertor as a single unit. When we are on solar and battery power and want 110 voltage for microwave, TV, etc, we turn the invertor on for the time we want or need the 110 volts and then turn it off (it does consume battery 12volt power just turned on, even if you aren't using 110 volts). Since there is no 110 power coming into the invertor/convertor, the convertor part of the unit isn't in play. The convertor part only works and charges the batteries when 110 volts come from shore power or generator.

We only have 300 watts of solar and have never worried about over charging the batteries as the panels are hooked to a controller that adjusts the charge rate depending on battery status. The solar is totally independent from either the invertor or convertor as it is hooked directly to the batteries, so it does care a whit about what those units are doing. However, the solar controller will allow more of the solar charge to the batteries when those units are in use.

If you have two separate units, a convertor and an invertor, then as stated, be sure to turn your convertor off when you use the invertor for 110 volt power. This would be true even if you didn't have a solar array.

Hope my two cents helped you in some little way.

Tom and Barb
2000 Fleetwood Bounder 39Z

ArtJoyce · 04-11-2022, 01:37 PM

Bottom line is if you are not connected to shore power and charging your batteries with solar. If you have an inverter which is powered from the batteries and if the AC to DC converter is on. The converter will work at charging the battery.

If you look at an inverter and converter there is energy loss from watt in to watts out of each of them. So your system will be drawing watts from the battery and with energy loss inverting it to AC, then with energy loss you will convert it to DC and charge the battery.

Net result will be discharging the battery from the energy loss of the converter and inverter.

vsheetz · 04-11-2022, 02:17 PM

Multiple chargers connected simultaneously is ok. Commonly done.

Properly configured, the charging amps can be additive

I've inverter/charger, solar charger, and converter/chargers.

Jbelshoff · 04-11-2022, 10:52 PM

You all are awesome and have started to get this all to make since. I thought I was on track and running efficiently with our 760 watts of panels and 200 watts control and renogy battery. And 2000 watt inverter. That then things just haven't been adding up because for the simple fact me and my wife are currently living off grid on our 100 acres and are motivated to use Mother nature and the good lords creation and use the energy from the sun. Gas prices ect are ...... lol. But anyways when we started this we have been told by many people running of grid to run batteries through inverter as shore power or generator. But my confused part is now that everything is all set up our controller will read 14.1 v, and as soon as I hook shoreline into inverter and shut down converter our volts drop fast to 12.5 and just down hill from there. You all have helped explain so much I am grateful. I guess my question now is what is my best way to run our system efficiently? Our inverter draws from batteries and converter is plugged into an outlet and then running to batteries.

Persistent · 04-12-2022, 08:20 AM

Lots of good advice above. It seems confusing. For better advice post make and model of RV built in charger, inverter, and solar controller.

In general, I agree with TwinBoat's post above. The issue is probably confusion among the terms "inverter", "converter", "charger".

Sometimes people have a combined inverter/converter/charger/transfer switch. They may call the whole thing an inverter. It is more than that.

A combined system like this manages itself. No worries.

Other people have separate components. It then depending on how the components are installed. They may need to turn the charger "off" when they turn the inverter "on".

This is not an optimum system, but if that is what you have then you do need to turn the charger "off" when the inverter is "on".

None of this should affect your solar controller. It can be "on" no matter if on shore power, generator power, or inverter power.

I wish you good luck and happy trails ahead!

Persistent · 04-12-2022, 08:48 AM

Quote:

Originally Posted by Jbelshoff

... controller will read 14.1 v, and as soon as I hook shoreline into inverter and shut down converter our volts drop fast to 12.5 and just down hill from there. You all have helped explain so much I am grateful. I guess my question now is what is my best way to run our system efficiently? Our inverter draws from batteries and converter is plugged into an outlet and then running to batteries.

12.5 volts is probably the state of charge (SoC) of the batteries.

14.1 volts is the "bulk" charge voltage of the converter/charger. It will vary depending on the SoC of the battery, the charger programming, and the capacity of the charger. It could vary from SoC to 14.4.

The solar controller will have a charge voltage depending on its programing and the amount of power it gets from the solar panel. It will vary from SoC to 14.4 depending.

Voltage should slowly raise when sun is high in the sky, clear weather, and solar controller is "on".

If power draw of appliances exceeds what solar can provide, then voltage will drop. Turn the inverter or other 12 volt appliances "off" and see if voltage slowly rises.

All of these work together just fine. The highest voltage will simply provide the most charging power.

Provide make and model of inverter, make and model of converter/charger, make and model of solar controller. Also provide a careful description of how all this is wired together.

So, maybe converter is a converter/charger. It plugs into a 120 volt outlet. The outlet is powered from shore connection.

It has a 12 volt output that is connected to the battery. Is it connected to anything else?

Inverter input is connected to battery. Inverter 120 volt output goes where? Does it go to the same 120 volt outlet that powers the converter?

If so, converter/charger must be "off" when inverter is "on". Battery will supply 12 volts. You do not need the converter and the charger will not charge the battery from the inverter power. So needs to be "off".