Battery storage with solar

[4x4ord]

I was reading in Trojan’s literature that to properly store lead acid batteries It is best to monitor voltage or specific gravity and recharge batteries when they drop to 70% charge (12.37 volts). I could very easily switch my solar panels off and monitor the battery voltage with the intent to switch the panels back on at 12.37 volts to recharge the bank. Is this better than leaving the panels on 100% of the time? My charge controller will boost charge at 14.4 volts in the morning until the batteries are fully charged then switch to float charge (13.8 volts) for the remainder of the day. By morning the voltage drops to between 12.9 and 13 volts so the charge controller starts out charging at 14.4 volts again.

[wopachop]

Lwiddis wrote:
“I was taught how the constant solar charge is not enough amps.“

What? In good light my panels putout 16+ amps. It’s the batteries that determine how much they will accept...bulk, absorption, float and equalization. Did you mean volts? Note batteries are full, 1.9 amps is mostly parasitic, 17+ volts.

Oh weird not sure how i missed this. Why is it showing 17v, is that panel voltage? I only know the very basics of solar so far. Even if my setup was able to do 16 amps i still would not consider that adequate for my main charger. But it would be great while out camping.

I still think there are times you are better off unhooking the batteries. Let them self discharge. If its a day you are exercising the generator first toss a bunch of lights on. Drain the batteries to a certain level. Then blast them with the charger that came with the trailer when the genny is running. Only because its most likely a much higher amp charge than your average solar setup.

If you are on shore power then you would have more freedom to decide when to use the trailer charger.

To me its a mistake to have a trailer on shore power, battery switch disconnected, but solar hooked up. I had batteries die quickly doing that. I used to think they got fried, overcharged. Everyday sitting there at float voltage in the hot sun. Then i was taught the reason my 2 year old batteries died was from being undercharged. My solar setup could never hit them with a nice strong charge. Which is needed to keep the plates nice and clean. Is how i understand it. Same reason to do a 16v charge is to bubble those suckers.

Still curious what people would consider to be a minimum charge rate in terms of a % of C20.

[FLY_4_FUN]

Here's my take. Being from Alberta your panels will see snow starting soon...and it will be on your roof quite often. Unless your prepared to keep them free of the white stuff you cant rely on solar to keep batteries from going dead. This assumes you are leaving parasitic loads connected. If you keep the rv "live" and panels are obstructed then they will drain/freeze/toast! Because of that I remove batts to garage/maintainer and pull the fuse on solar system.

[4x4ord]

time2roll wrote:
Is your controller adjustable? I would go 14.8v with a short absorption like 5 minutes during storage. Then float at 13.2-13.4v

Otherwise I would let it run daily as programmed.

I can change some settings on the controller, although I'm not certain as to what degree I can change things. I think it is programmed to vary the voltage output based on battery voltage and temperature so at warmer temperatures 13.2 is likely the voltage it will float charge at.

[4x4ord]

^^^^ The solar panels could be switched off and the battery isolation switch is shut off so that no power is going to the RV. I have a Xantrex inverter charger in the RV that could be used. It would hold the batteries at 13.9 volts day and night at our present temperatures.

[StirCrazy]

if your leaving the batteries on the RV and hooked to solar you are not storing them as they will still be in service. I have not pluged in my fith wheel in the winter for 6 years now unless we have some one visiting and staying in it. just have to change out the batteries next summer after 13 years.

Steve

[wopachop]

What % of C20 would start to be too low?

[theoldwizard1]

wopachop wrote:
I was taught how the constant solar charge is not enough amps. The flooded batteries like that big beefy charge. Also the solar controller might not reach high enough voltage. I always forget. Don't we want 14.7 or 14.8? Your controller might allow you to choose a flooded option.

Modern MPPT solar controllers will provide plenty of amps and volts to charge flooded batteries, if the solar array is sized appropriately for the battery bank.

An occasional top off with a AC powered multi-step charger is still a good idea.

[time2roll]

Is your controller adjustable? I would go 14.8v with a short absorption like 5 minutes during storage. Then float at 13.2-13.4v

Otherwise I would let it run daily as programmed.

[Lwiddis]

“I was taught how the constant solar charge is not enough amps.“

What? In good light my panels putout 16+ amps. It’s the batteries that determine how much they will accept...bulk, absorption, float and equalization. Did you mean volts? Note batteries are full, 1.9 amps is mostly parasitic, 17+ volts.

[wopachop]

I was taught how the constant solar charge is not enough amps. The flooded batteries like that big beefy charge. Also the solar controller might not reach high enough voltage. I always forget. Dont we want 14.7 or 14.8? Your controller might allow you to choose a flooded option.

How is the charger on the trailer? You could always cycle the batteries if/when you cycle your generator. Use the trailer charger to pump into the batteries assuming the solar isnt very strong.

I go one step further and store my batteries in the garage. Charge them with my stand alone charger that is fancy and allows for exact voltage and amps. I go months without checking them. They are a year old and only have 20 or 30 cycles on them. Need to get out camping more!!

[Lwiddis]

If your solar controller is a quality unit, let the controller maintain the batteries.

[corvettekent]

Continue doing want you are doing now. I have been doing the same as you for the last seven years expect my batteries get down to 85% charged in the morning before the sun comes out.