questions on the settings for a classic 200

[exiledoracle]

Greetings, I am a novice at solar but learning.

I have recently changed my batteries from FLA to VRLA (Renogy AGM 12v 200Ah)
I have 8 batteries set up into two 48v banks (400Ah)
The spec from Renogy say that the 'cycle use voltage' is between 14.4v - 14.8v.
Is this the absorb voltage? Should i set the absorb to 58.4v? Seems kind of high
The default on the classic is 57.2v. this is what I have it set to now, and it works
But, I was wanting to maximize the efficiency, and it seems slow to charge
Also, should the absorb be set the same as the EQ? The Renogy EQ spec is 56.8v

I already have the float setting good at 54.8v (13.6v - 13.8v Renogy spec)

I appreciate any help!

Derek

[ClassicCrazy]

Greetings, I am a novice at solar but learning.

I have recently changed my batteries from FLA to VRLA (Renogy AGM 12v 200Ah)
I have 8 batteries set up into two 48v banks (400Ah)
The spec from Renogy say that the 'cycle use voltage' is between 14.4v - 14.8v.
Is this the absorb voltage? Should i set the absorb to 58.4v? Seems kind of high
The default on the classic is 57.2v. this is what I have it set to now, and it works
But, I was wanting to maximize the efficiency, and it seems slow to charge
Also, should the absorb be set the same as the EQ? The Renogy EQ spec is 56.8v

I already have the float setting good at 54.8v (13.6v - 13.8v Renogy spec)

I appreciate any help!

Derek

Yes that would be the absorb voltage 14.4 to 14.8  ( x 4) = 57.6v 
Start with the low end of range for new batteries and adjust for age or other conditions as needed.
You don't normally equalize AGM batteries so I always disable that - but set it for the Absorb setpoints just in case it ever gets turned on by accident.
You did not mention the absorb time you have set , or if you are using a  Whizbang which would let you use Ending amps to terminate absorb.
Most AGM batteries are very similar so look up some other brands and compare their settings to yours - most manufacturers show graphs of the voltage /current/ SOC relationship.
Regarding the slow to charge - in absorb cycle the voltage will hold steady and the current will decrease to hold the absorb setpoint. 
When it gets to the absorb time it goes to float ( or to ending amps if you have that set ).
Also don't forget to set up the temperature compensation setting ( usually -3mv or -5 mv ) which will change the absorb and float setpoints as the battery gets warmer or colder.
Larry

[boB]

In addition to these settings there is a MIN and MAX  battery temperature compensation adjustment.

If these batteries say not to exceed some particular voltage, no matter how cold they are, then you would set that voltage for the maximum temp comp'd voltage.

Same for minimum voltage.

These settings would normally be slightly higher and slightly lower than your set Absorb voltage.   They may not need changing but would not hurt to check it out.

boB

[exiledoracle]

Awesome! Thank you Larry and Bob. I appreciate your expertise. I have adjusted the absorb to the low end at 57.6v

I have the absorb time set at 2hr. It's what it was already set to with the old batteries. Could I increase it to 3 or 4? Or is 2 good?

I have the EQ off already too. The batteries were perfectly balanced when I installed them and I figure I would check and balance manually as necessary.

The temp comp setting is already set to -5mv as well. The specs call for -24mv. Should i readjust it to that? The range only goes to -10mv

I don't have settings for min/max temp adjustments on the specs available. I will look at other brands to see if I can find similar batteries with more settings

I have attached a pic of the spec sheet

Thanks again for your help!

Derek

[ClassicCrazy]

You set temp compensation to -3 mv and the Classic will multiply that out for how many cells you have ( it knows according to battery voltage).
Interesting that they show two different temp compensation values for absorb and for float - one is -3 mv and the other -4 mv . Take your pick I guess.
Most other agm batteries usually say -3 mv I think.
Your absorb time sounds okay. You will have to watch it and see how that relates to the SOC of the battery being full.
Do you have a Whizbang and external shunt on your system ? That really is the best way to really know what is going on with the system.
And you can also then set up ending amps if you have Whizbang and then the absorb time will be better managed according to what the battery needs.
When in ending amps the Absorb terminates to float either when ending amps is reached or when absorb time is reached - which ever comes first.
Larry

[exiledoracle]

I have a midnight shunt but not a whiz bang. I just researched it and I am going to get one! Much more sensitive control for charging. I appreciate all your guys help!

[ClassicCrazy]

You will be happy to have the Whizbang on your system.