Recomendation for settings

[carmelo]

Hi everyone.

I have the following setup and need your guidance for bulk, absorb, EA, and float.

2 strings of 4 panels in parallel for a total of 8 panels with the following specs:

Solarworld
Pmax 240
Voc 37.2
Vmpp 30.2
Isc 8.44
Impp 7.96

1 Classic 150 @ 24v

10 Ritar RA12-105F AGM Sealed batteries (attached are the only specs that I could find) combined on 5 parallels for a total of 525a @ 24v. Yes! I know that I shouldnt be using so many parallels, but my inverter was already an AIMS 6000 24v. Iam planning on eventually changing the inverter to 48v and fix all the parallels.

My problem with the batteries is that I dont know how to interpret the specs. So Iam blind in terms of which parameters should I use on the Classic.

Any help?

[carmelo]

I forgot to mention that I also have a wbjr correctly attached to the classic.

[KyleM]

We can all guess what the settings will work for your batteries, but the only people that will know is the manufacturer.


http://www.ritarpower.com/contact.asp

Kyle

[ClassicCrazy]

I agree check with manufacturer
But for starters my best guess  from what I see on their graphs and formulas

Bulk - no setting - it should accept up to 126 amps
Absorb 28.8 v
Float  27.3
Absorb time 4 hours if using ending amps and whizbang
Ending Amps  10.5 amps ( I am not totally sure about this maybe someone else can weigh in )
-3 mv for temperature compensation setting

Let us know what you find out from manufacturer

Larry

[carmelo]

We can all guess what the settings will work for your batteries, but the only people that will know is the manufacturer.


http://www.ritarpower.com/contact.asp

Kyle

I just sent an email to the manufacturer. Will post their response as soon as I get it.

[Vic]

Hello carmelo,

As you probably know,   your batteries appear to be designed primarily for Float service.   The data sheet does make reference to Cyclic use.   But,   generally,   sealed batteries that have  Float service as a primary design use,   will have will not endure daily-cyclic use.

We do not know about the purpose of your system (have not looked at all of your posts).    If your system is for off-grid daily cycling,  these batteries may not have a long life (depends upon Depth of Discharge,  battery temperature,  etc).

In addition to your reference to five strings of batteries,  there is one other thing;

Your Classic 150 will have an STC string Vmp of about 121 volts,  with those strings of four SW PVs.   Depending upon the lowest temperature at the site for this system,  you could easily find the Classic in Hyper VOC,   or perhaps,   worse than that.

Have you used the Classic String Sizing Tool,   for your array configuration,   and the lowest possible temperature for your site (?):
http://midnitesolar.com/sizingTool/displaySizing.php

Strings of two SW 240s should be fine for a 24 V AGM Battery,    but would not work well on a 48 V system (when you upgrade).

FWIW,    Vic

[carmelo]

I agree check with manufacturer
But for starters my best guess  from what I see on their graphs and formulas

Bulk - no setting - it should accept up to 126 amps
Absorb 28.8 v
Float  27.3
Absorb time 4 hours if using ending amps and whizbang
Ending Amps  10.5 amps ( I am not totally sure about this maybe someone else can weigh in )
-3 mv for temperature compensation setting

Let us know what you find out from manufacturer

Larry

I had something similar to those parameters:

Absorb 29.2
Float 27.4
Absorb 2 hours but using wbjr ending amps
End Amps 10.5

What I noticed with this settings is that even after a week of floating with no loads, when going offgrid and adding loads, the SOC was going down fast. From 100% at 5:14pm to 93% at 9:18pm with an average load of 16A.

5:14pm
SOC 100%
BattVolts 26v

9:18pm
SOC 93%
BattVolts 25.3v

After some reading, I decided to change the Ending Amps to 5.25 and it took 3 hours to get there from 41.4A at 10:18am to 4.8A at 1:00pm that it changed to Float.
Previously at 10.5 ending amps, it was taking 1 hour to reach it.

[carmelo]

Hello carmelo,

As you probably know,   your batteries appear to be designed primarily for Float service.   The data sheet does make reference to Cyclic use.   But,   generally,   sealed batteries that have  Float service as a primary design use,   will have will not endure daily-cyclic use.

We do not know about the purpose of your system (have not looked at all of your posts).    If your system is for off-grid daily cycling,  these batteries may not have a long life (depends upon Depth of Discharge,  battery temperature,  etc).

In addition to your reference to five strings of batteries,  there is one other thing;

Your Classic 150 will have an STC string Vmp of about 121 volts,  with those strings of four SW PVs.   Depending upon the lowest temperature at the site for this system,  you could easily find the Classic in Hyper VOC,   or perhaps,   worse than that.

Have you used the Classic String Sizing Tool,   for your array configuration,   and the lowest possible temperature for your site (?):
http://midnitesolar.com/sizingTool/displaySizing.php

Strings of two SW 240s should be fine for a 24 V AGM Battery,    but would not work well on a 48 V system (when you upgrade).

FWIW,    Vic

Thanks Vic.

I completely understand your point on the type of batteries. They are indeed design for UPS Systems (big server data rooms), but the main purpose of my system is for emergency backup and hopefully not for daily use. I live in Puerto Rico and after the hurricanes, the power still goes down almost twice a week...

As for the PV arrays, the lowest temp here is 70*F and they are old PVs.  Attached are the sizing for 24v and 48v. Where can I see my average or max Vmp?

[Vic]

Hi carmelo.

Thanks for the info on your location,   and the purpose of your system.   We all feel for you,   who are sticking it out in PR.   Wish you luck!

I ran the MN Classic Sizer,   for your existing SW240s - two strings of four PVs on a 24 V system,   and a different string configuration for a 48 V system,  with THREE strings of THREE SW240s (guess that you probably do NOT have that ninth PV at this time),   Strings of three of these 60-cell PVs is ideal on a 48 V system,   and should also be fine on a 24 V system.   These are attached below.

On a 24 V system,  strings of two 60-cell PVs is ideal (but strings of three would be OK, too).

The Classic Sizer notes,    that your system  could/would spend cold temperatures in HyperVOC.   This is where the Classic will stop producing power,   to protect itself  --  waiting for the input voltage to decrease below 150 Volts from the strings of four PVs.

Your batteries should be OK on a Grid Backup system.   Most of those larger AIMS inverters have a high Tare (Idle) power consumption with no loads,   but that is what you have,   and   it should be OK.

More later,   Good Luck,   Vic

[carmelo]

Thanks Vic.

Will definitely try to move from 24v to 48v and add that additional PV.

[ClassicCrazy]

I had something similar to those parameters:

Absorb 29.2
Float 27.4
Absorb 2 hours but using wbjr ending amps
End Amps 10.5

What I noticed with this settings is that even after a week of floating with no loads, when going offgrid and adding loads, the SOC was going down fast. From 100% at 5:14pm to 93% at 9:18pm with an average load of 16A.

5:14pm
SOC 100%
BattVolts 26v

9:18pm
SOC 93%
BattVolts 25.3v

After some reading, I decided to change the Ending Amps to 5.25 and it took 3 hours to get there from 41.4A at 10:18am to 4.8A at 1:00pm that it changed to Float.
Previously at 10.5 ending amps, it was taking 1 hour to reach it.

With something of a 16 amp load for 3 hours it does not sound unreasonable for the SOC to go down that much . It is taking power out of the batteries .
When the batteries are charging back up you should be able to see as the SOC climbs up to 100% then it should have also charged back in all the amp hours that were taken out the night before. Plus a bit extra for the efficiency factor. So if when you are charging , the SOC gets to 100% and you are not at your ending amps of 10.5 amp then perhaps you have to do some tweaking . You don't want to overcharge AGM or Gel type batteries because they can vent which isn't good for them.

Larry

[carmelo]

I had something similar to those parameters:

Absorb 29.2
Float 27.4
Absorb 2 hours but using wbjr ending amps
End Amps 10.5

What I noticed with this settings is that even after a week of floating with no loads, when going offgrid and adding loads, the SOC was going down fast. From 100% at 5:14pm to 93% at 9:18pm with an average load of 16A.

5:14pm
SOC 100%
BattVolts 26v

9:18pm
SOC 93%
BattVolts 25.3v

After some reading, I decided to change the Ending Amps to 5.25 and it took 3 hours to get there from 41.4A at 10:18am to 4.8A at 1:00pm that it changed to Float.
Previously at 10.5 ending amps, it was taking 1 hour to reach it.

With something of a 16 amp load for 3 hours it does not sound unreasonable for the SOC to go down that much . It is taking power out of the batteries .
When the batteries are charging back up you should be able to see as the SOC climbs up to 100% then it should have also charged back in all the amp hours that were taken out the night before. Plus a bit extra for the efficiency factor. So if when you are charging , the SOC gets to 100% and you are not at your ending amps of 10.5 amp then perhaps you have to do some tweaking . You don't want to overcharge AGM or Gel type batteries because they can vent which isn't good for them.

Larry

Thanks for the clarification Larry.

I suspect that more tweaking needs to be done because of the following example:

Bulk charge starts at 6:52am with 94% SOC and BattVolts 26.6v


Bulk charge continues at 7:59am reaching 100% SOC and BattVolts 27.6v


Absorb charge starts at 8:21am keeping 100% SOC and BattVolts 28.9v


Absorb charge ends at 9:55am keeping 100% SOC and BattVolts 29.0v


Shouldn't the CC transition from Bulk to float exactly when it reaches the Absorb voltage AND 100% SOC ? In my case, SOC is reaching 100% and staying on Bulk before reaching the Absorb voltage.

[FNG]

SOC % doesn't cause a transition to float, You may be hitting 100% SOC prematurely based on efficiency settings etc. The Classic transitions to float on 1 of 2 things and only number 1 by default:

1- Absorb timer is expired, This timer will count towards the set time programmed by you any time the classic is in absorb and when it reaches that time it drops into float
2- End Amps, By default this is disabled, You can set this up so that when the current into the battery falls below your setpoint the classic transitions to float. This one can be handy but does really require q WBjr and some time watching things to get it right. How I prefer to do this is, Set the absorb time abnormally long and let the local app graph the WBjr current through the day. As you see the graph flatline on the lower amperage side then you know the battery has reached a state that it can no longer accept any charge. This flat line current is the true End Amps but you would want to set it slightly higher. Say the current drops and settles at 3 amps for an hour I would set it for around 4 amps.

[ClassicCrazy]

When batteries are new they need a few cycles to work properly - did you ever drain them way down and then charge them back up ? Or maybe you have had them for awhile.

FNG above made all the correct points about how it works.

What do you have the efficiency set for ?

Larry

[carmelo]

The batteries are approximately 5 months old and they have seen maybe 30 discharges of no more than 50%.

I have the efficiency set at 98%