Understanding load output as a tool for saving batteries

[CleverTomato]

I think I am in the right spot. Hours of google. Factory videos and manuals. DIY channels on youtube. (Thanks to everyone that takes the time to teach...you are all amazing!!!!)

Inheritied a house: 12V DC lights, ceiling fans, refrigerator. AC wall outlets for other things. 4 ET 310W (2 extra not connected) Renogy 60A MPPT Charge controller. 4 6V deep cycle batteries. 2 in series paralelled with 2 in series. So 12V with 26amps (i think). 2000W Bestek inverter AC and DC.

Set up... Panels --> controller --> load output to 12V. Panels --> controller --> batteries --> inverter

VERY simply stated...i understand that my Renogy Charge controller does this: Sends sun energy directly to my DC gadgets through load output in the daylight. Charges my batteries. Batteries go to inverter for AC. At night batteries power all.

Understaning it may not be a real thing... What I want: I want solar to power my DC during the day and charge my batteries. At night I want batteries to do all.

But I don't want to have to change it all manually. At present I am not able to find 'how' or an example of...or get this. I set my load output (Light + 10)...all works going into the dark...in the morning it just shuts off...so 12V all goes off. Then have to manually turn load on to get back to panel--> controller--> DC.

Thoughts...Advise... And thank you in advace to all!.... and at the end of the day... What...Me Worry?

 

[TacomaJoe]

The simple thing would be to move your 12V loads from the load output of the Renogy and connect the loads directly to the battery. During the day, any solar production above the 12V load will charge the battery. As solar production drops, the battery will pick up the 12V load.

 

[CleverTomato]

Thank you... The original set up is: solar --> controller-->batteries--> inverter and then the 12V from the inverter to the 12V fuse panel.

the percent charge for the battery drops very rapidly when there is no solar energy coming in... from 100 to approximately 60 then slowly continues to go down. We have tested the batteries with dvom and all show 6ish. independently. if we disconnect from the AC it goes down slower still but on average from 60 to 30ish and that is only powering12V LED lights, and 12v fridge.

 

[TacomaJoe]

I think that the weak link is battery capacity. A 12V fridge will use a fair amount of battery. The percent of charge reading may not be accuate. I would get a voltage reading when the battery is charged and use a chart to get state of charge. A shunt will give an accuate level reading and also show how much the load is.

 

[CleverTomato]

We will put in the shunt and see what we get. We have checked batteries with DVOM, Hydrometer and 'bench' tested with a multipurpose charger/jump/test/restore all say good. We did some more methodical data collection over the weekend. Mix of clouds and sun and switching loads from DC to AC and generator vs. solar power. As near as we can tell...our Starlink modem/wireless router is the primary draw for any load.

The entire place (800sqft) is off grid. As mentioned....All lighting, ceiling fans and fridge for the house is 12V. With DC loadoutput from the controller and With inverter off (no 110/120Vload) we will see an ~8-10% decrease/increase when the fridge cycles. We can run ceiling fan and lights with very little impact and total drain overnight is between 10-15%.

It makes perfect sense that using AC will be a big drain... but tv/sound bar... computer on the charger etc does significantly less than the modem/router. We are not sure why there are no 12V outlets. To use any of the wall outlets inverter must be on.

Our next line of thought is to use the two panels that are installed but not connected to isolate the fridge with it's own battery and charge controller..and fuses...the previouse owner must have been afraid of them. There are 5 more panels available and hundreds of feet of wire... we are not entirly sure what the previous owner was thinking but it seems like it was a mix of ability and convience....perhaps with the thought of 'when I have more time/knowledge' We have been checking insolation maps pricing new components and hoping for good sunshine...

Thank you for all the thoughts and info. I will pop in access more in the near future.

E&M

PS...for anyone that might be curious... attached is the set up. This is how we inherited it with one exception. The Blue is the orginal path of the DC. It went from inverter to fuse panal only. Current is the green from Load output to panel. Custom for sure! Cheers All!!

 

[mikefitz]

the percent charge for the battery drops very rapidly when there is no solar energy coming in

I guess this percent charge is given by the Renogy charge controller. This is totally inaccurate based on battery volts. Since the battery volts will drop when there is no charging taking place, the Renogy system assumes, Incorrectly, that the battery state of charge has reduced.

I want solar to power my DC during the day and charge my batteries. At night I want batteries to do all.

The Renogy load outputs can be configured to be always on, or active at night, see the manual for settings.
The advantage of powering DC loads via the load output, ( except the inverter that must connect to the batteries) , is that you can program a 'protection level' so the battery cannot be over-discharged.