FLA Charge current Setting ?

[Corndog]

New Battery Bank 48v 16x6v Rolls S6 L16-HC, the spec sheet states Recommended Charge Current   50 A
Maximum Charge Current   85 A. Using the Classic 150, is this a setting I should be adjusting / setting in the classic ?


Charge | Discharge
Charge Voltage Range   2.45-2.5 V/cell @ 25°C (77°F)
Float Voltage Range   2.25 V/cell @ 25°C (77°F)
Recommended Charge Current   50 A
Maximum Charge Current   85 A
Self-Discharge Rate   5%-10% per month at 25°C (77°F)

[ClassicCrazy]

If you have more available power and want to set the 85 amp limit - you want to set it a different way than just using the amp limit setting in the mngp or the current limit in the Local app. Because if you set it that way it would also limit the loads to that current even if there is more available power from the PV.
But there is another way to limit the current only for the battery charging but still letting the controller supply all available power to the loads if needed.
That process is explained here
https://www.midniteftp.com/support/kb/faq.php?id=37
Also I think you were also asking about how to set  ending amps - there is info on that in the knowledge base
https://www.midniteftp.com/support/kb/faq.php?cid=1
Larry

[Corndog]

Thank you , how did I miss this knowledge base  ? Thank you again,

[Corndog]

Thank you, I have the whizbang Jr now just need to instal. In the ,mean time this is what I have for settings. Do these look correct? Brand new Bank (16 Rolls S6 L16-HC FLA) installed limited loads for two days full charge both days with 3 hours of float each day. SG checked post 1 hour float start 1.26 and 1.265

Battery Configuration:
Two strings of eight 6-volt batteries at 445 AH each
= 2 x 445 AH at 48 Volts = 890 AH at 48 Volts

Midnite Classic 150 charge controller with a 48V bank of 16 Rolls S6 L16-HC flooded batteries based on the official Rolls Battery manual for frequent cycling at 25°C:

| Parameter                | Recommended Setting        | Notes                                        |
|---------------------------|----------------------------|----------------------------------------------|
| System Voltage            | 48 V                      | Matches battery bank configuration          |
| Bulk/Absorption Voltage  | 58.8 V                    | Full charge voltage for absorption stage    |
| Float Voltage            | 54.0 V                    | Maintains full charge without overcharging  |
| Equalization Voltage      | 61.2 – 63.6 V              | Periodic corrective charging                  |
| Minimum Voltage (Vmin)    | ~52.5 V                    | Prevents controller cutoff during normal load? |
| Rebulk Voltage            | ~54.0 V                    | Typically set near float voltage              |
| Charge Current Limit      | 50 A                      | Based on ~0.1C charge rate for battery bank  |
| Input Amps Limit          | Up to 96 A or array max    | Limited by solar array and Classic 150 specs |
| Absorption Time          | 4 hours                    | Time for absorption charging phase            |
| Temperature Compensation  | -5 mV per cell per °C      | Equals approx. -0.24 V per °C for entire bank |End Amps  - 8.9 amps

Thank you in advance. Previous bank and settings were all done via the installer so a huge learning curve here.

[Vic]

Not a lot of  time, right  now,  ...

But,  for off-grid use, four hours of Absorb,   is probably a bit too long.

And,  you will probably NOT need to Rebulk this battery  --  IMO,  this function seems to primarily be for systems that are short on battery capacity,  this can be a way of entering night,  with the max available bat capacity.

In general,  we want to minimize the  number of full charge cycles,  for systems that are cycled, daily,  or almost daily.

I do not know  the function that "Minimum voltage" performs...

 EDIT>
Please review the SGs that you noted, above.
 
Generally Surrette batteries ship with 1.265 SG electrolyte.  There is usually a Temperature Compensation factor that needs to be used to determine the actual SG.  This factor is usually small,  and the Hydrometer that you are using,  may do this compensation ...

What Hydrometer/Refractometer are you using to measure SGs?

   ...   more later, Vic

[Corndog]

Sorry Vic , the SG was a typo - 1.65 is what it should have read. I have two types, floating bulb type and a specific gravity refractometer which I calibrate each time with distilled water.

[Vic]

Hi Corndog,

OK,  but, the SG for your model battery,  should be 1.265, nominal,  when fully-charged.

You might try using the other meter.  I assume that the 1.65 reading,  probably came from the Refractometer.

Did you do the Commissioning procedure for your new battery,  as described in the Surrette battery manual?

What is the battery voltage reading for the entire battery,  when there has been no charging for hours,  like early in the morning?

Later,  thanks,  Vic

[Corndog]

Thank you Vic, sorry typo twice now. SG was 1.265 we did commission as per the manual. No sun here for two days now, Classic reads 48.5 this morning and the bank with Multimeter is 48.4

[Vic]

Hi Corndog,

Thanks for the updated info,  it looks like your batteries were fully-charged,  or very close to it, when you took those SG readings.

You mentioned a steep-ish learning curve, relative to your system.  YES,  it can feel that way,  but FLA batts tend to be very forgiving,  and,  one of the best things that one can do to get good performance from a system,  is to pay careful attention to it.

Many folks with new Surrettes FLAs have never even seen the Battery Manual,  done the proper Commissioning charge,  etc.

You appear to be off to a great start for that new battery.  Thanks, Vic