question for the solar gurus

[dalej]

Trailer is stored and not being used at present.

The solar system is active and keeping the batteries charged up. Every morning it goes into 14.4 volts absorb and later 13.7 float.

The batteries are deep cycle AGM.

Do you think this might be causing any problems or decreasing the life of the batteries?

[BFL13]

AFAIK, an inverter-charger must be connected to a battery to operate at all, and "disabled" refers to the charger part only. So there would be a draw from the inverter on standby.

Some of those inverter-chargers have higher standby draws than a straight inverter--like 1.5 amps instead of 0.5 amps or whatever. The monitor would be in addition to that AFAIK.

I don't have one so I am going on what I have seen reported here.

[bpounds]

dalej wrote:
...only parasitic load I am aware of is the monitors for the Xantrex and the Morningstar MPPT-60 controller...

Entertainment System
Television
Propane Detector
Anything with a wireless remote control
Thermostat (depends on style)

There are usually more than you realize. But yes the draw should be minimal.

[time2roll]

You have an excellent controller with very flexible programming. This is the same as mine. All these parameters can be selected to the minute and to the hundredth of a volt all fully temperature compensated.

Now get back into the manual.

[dalej]

Wow, thanks for all the great replies.

A little more information I should have shared. The solar is dedicated to a Xantrex Freedom SW 3012 inverter/charger and the only parasitic load I am aware of is the monitors for the Xantrex and the Morningstar MPPT-60 controller. The inverter is disabled at present The controller is set on a factory setting for AGM. It goes into Absorb for a minimum of 180 minutes each morning.

There are seperate house batteries that are charged when the inverter is on that would have a parasitic load

As JimK-NY wrote

" Charging should stop whenever the charging amps drops to less than 0.5% of the AH rating. For example charging should be discontinued for a 100 AH battery when the charge amps drops below 0.5 amps. Many solar chargers are not capable of making this determination. Most will automatically hold the 14.3 charging voltage for a couple of hours even if the battery is fully charged and the amps drops towards zero."

This is what I read could happen and wanted to try and learn how to avoid.

As ya'll can tell I tend to overthink things but I really want to learn all I can about the system.

[markchengr]

In my opinion the first reply you got was the best.

[bpounds]

My controller is user programmable too. But I figure you can drive yourself to drink worrying about fine tuning a controller, in an effort to prolong the life of batteries, which are a consumable item anyway. And at the end when you replace those batteries, you won't be able to prove whether your effort did anything positive, but at least you'll be good and drunk.

I use the canned program for AGM, which looked almost identical to the flooded settings, except that it disabled the boiling cycle.

[2oldman]

BFL13 wrote:
Some fancier controllers will have an adjustable time to stay at Vabs before dropping to float.

I set my Outback Flexmax 60 to almost 0 for Lithium.

[time2roll]

BFL13 wrote:
Some fancier controllers will have an adjustable time to stay at Vabs before dropping to float.

My controller has three settings all programmable. Start the day at full charge voltage can have a very short ABS time. Mine is set at 5 minutes. While in use ABS is extended to 2 hours automatically based on start voltage. If battery is overly discharged it stays in ABS all day.

[2oldman]

I don't see a problem. AGMs hold a charge for a long time and could be disconnected with no worries also.

[BFL13]

RLS7201 wrote:
You're charge controller is doing exactly as it should.
It will charge at 14.4 until it sees the current flow drop to a minimum amount and then work it's way to float.

Richard

Depends on the controller's charging profile. The standard profile for EP Solar ones is to raise the battery voltage to 14.x (where x has three choices for Wet, AGM, Gel) and then hold it there for a fixed two- hour time and then drop to Float.

Others with one settable voltage will go that setting and stay there all day till night allows the battery voltage to go back down.

Some go to 14.x and then drop to 13.x right away. Some of those have adjustable settings for the two voltages, so you could lower the first one to float and it will "drop" to the same voltage, or if you want time at the higher voltage you can set the float voltage up to near the absorption voltage.

Some fancier controllers will have an adjustable time to stay at Vabs before dropping to float.

[RLS7201]

You're charge controller is doing exactly as it should.
It will charge at 14.4 until it sees the current flow drop to a minimum amount and then work it's way to float.

Richard

[time2roll]

How long does the controller hold 14.4 before dropping to float?
What are the charging specs?
Have you turned off any automatic equalization?
I assume no temperature compensation?

Yes could be a bit on the high side for TX summer. Probably fine in winter. AGM actually has a very slow self discharge. You could fully disconnect the batteries after a week and just let them sit 4 to 6 months. Always disconnect the solar panels from the controller first if disconnecting the controller from the battery.

Possibly you could upgrade the controller to have fully adjustable settings. Not sure this would be worth it.

[JimK-NY]

If the battery is fully charged and stays that way, blasting the battery at 14 plus volts could shorten the battery life. Charging should stop whenever the charging amps drops to less than 0.5% of the AH rating. For example charging should be discontinued for a 100 AH battery when the charge amps drops below 0.5 amps. Many solar chargers are not capable of making this determination. Most will automatically hold the 14.3 charging voltage for a couple of hours even if the battery is fully charged and the amps drops towards zero.

There is a reason float voltages are set at about 13.3 v.

[BFL13]

According to this it should be ok.

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

Choice is Float while connected or Storage while disconnected (wires off--the disconnect switch still leaves some things on drawing down the battery).

If you store, but leave the wires on, then the OP's solar float method is the way to go.