L16 rolls 445 ah x 3 strings 24v

offgridcabin2015

So i put my 3 strings of batts into service today. 

what should be the absorb time in hrs? 

i found rolls tech video on utube say  .42*ah (for me 445x3 is 1335) / current coming into batts from array. (i have 2000watts) so 30amps in + time in hrs.   so that's 18.69 hrs. That will never happen. seriously

so today i did bump the absorb to  3.5 hrs. These are BRAND NEW batteries. they never seen any load yet. 

My goal is to be very proactive and manage them the BEST i can. Room temp is never above .25 degree C. More like 16-20 C.

I will be adding 2000 more watts before summer is out.

Thankyou.

Vic

Hi ogc..,

The amount of Absorb time needed, is determined, by the DOD, in the previous discharge cycle.

That Surrette formula, has always seemed bogus.  Perhaps that "ah" could be, the AH, removed from the battery, in its previous discharge.

QUESTIONS:
Is this battery bank, three strings of four 6 V L16 batteries, for 24 V, system voltage??
Are these batteries new?
Are they Flooded batts?
Have you followed the Commissioning A New Battery Bank (or similar), in the Surrette Battery Manual?  Here:
  https://www.solar-electric.com/lib/wind-sun/surrette-manual.pdf
If these batts are Flooded, do you have, and use a good quality Hydrometer (of Refractometer?

Thanks for answers to the above questions.  Answers to the above questions, and others,  will help those willing to try to help target answers to the system that you actually have.  AND consume less time of all those involved, in the process, etc   ...   Later, Vic

Photowhit

offgridcabin2015 said:

I will be adding 2000 more watts before summer is out.

That will be a good start, I think Rolls suggest the ability to charge at 10% of the battery bank capacity. So a 445x3= 1335 ah, so a 1000 watts of array has roughly a max charging of around 1000 x 75%(NOCT value)= 750/28 volts charging voltage = @27 amps charging, 4000 watts should be fine for a weekend cabin, but might be a little light for everyday use.

I would ask Rolls for their absorb times. I recall them wanting a bit longer in general.

FWIW - I charge my 24 volt 665ah battery bank with 4000 watt array. It's a forklift battery I used 3 hrs for the first 7 years of it's life then went to 4+

offgridcabin2015

Answers :  
Is this battery bank, three strings of four 6 V L16 batteries, yes  3 strings  for 24 V, system voltage?? 24v 
Are these batteries new?brand spanking new. no loads have evver been placed on em yet
Are they Flooded batts? yes. lead acid.

yes i own Refractometer? and i do use it and can read it and factor in temp 

Vic

Hi ogc..,

THANKS for the answers.

Please DO read the Surrette Battery Manual.  There is a detailed Commissioning procedure for new batteries,  please use this, for the best future for this bank.

Start a Battery Notebook, to record SG readings, Distilled Water consumption, EQ dates, time, voltage, and SG observations, during/after EQs,  Absorb  voltage/duration, float voltage,  etc.  This will help you see trends, and should help you determine the best parameters to change, etc.  Label each battery string, with a number/letter, and each battery position with a letter/number, to allow you to keep track of each cell and string.

OK, Good Luck.  It IS great that you are beginning the relationship with this new battery bank, by paying attention to all of them.

Vic

Ralph Day

Don't pooh pooh the Surrette numbers.  I got 8 S550's 3 years ago and the charge/absorb time is accurate.  A 20% discharge takes me 5.5-6 hours to fully charge with my system...2.1kw pv .  If i need it done sooner I augment with generator or utility early on.

offgridcabin2015

Thanks for chiming in Ralph. i'm in the same size array currently. The great news is i'll be adding another 2000watts before summer is out . so i'll be able to cut time in half at least in theory and in summer mths. As we all know it takes no how , time + Cash  .
Thanks for all who have chimed in.

MichaelK

I don't see any mention of what charge controller you are using?  With a battery bank of 1335Ah, you want at least 134A of charging, though Rolls would rather you charge at 1/8C or 167A.  Assuming you de-rate your panels to 85% you are likely to see a max amperage of (2000W/25Vbulk) X 85% = 68A.  A Midnight200 or Outback80 should be able to handle 2000W.  Will you be paralleling a second controller for the second 2000W of panels?

Assuming you go with two parallel controllers, they'll need to be exactly the same model and share the same firmware, if they are going to be expected to communicate with each other.

offgridcabin2015

hi my friend. 

Im having zero issues at charing my bank with only one flexmax 80 / 2000watts of solar currently installed. i only use my batts during day time. Night time use is a joke. / 2 dc  12v fans and one led strip light  12vdc. 
The battery are overkill which means they will last my lifetime i'm sure.   Even my old interstate batts are still going strong.  7 years now. 

I will be adding a second charge controller. again flexmax 80 for another  2000watts before fall.

I have another 2000 watts more solar too giving me  6000 watts in total but i n eed to buy another charge controller. not there yet. 

One baby step at a time. 

Thanks for chiming in. 

#i appreciate you ALL. 

JRHill

offgridcabin2015 said: The battery are overkill which means they will last my lifetime i'm sure.  

Don't be TOO sure on this. I may be stirring up a hornet's nest but I'm good at that.

It is probably true that a very lightly used bank should/will last longer than an abused one. By lightly used I mean lightly charged and lightly discharged and kept mostly near full. By abused I mean not charged to the correct voltage or with too short an absorb or being drawn below 50% repeatedly or not being fully recharged when drawn down or not maintaining connections and water levels low or to high of temps, etc, etc. My point is that I believe lead batteries NEED to be used hard - both on charge and discharge. I don't necessarily mean fully using their capacity in up and down cycles but loads that make 'em bubble and giggle, burb and fart on both charge AND discharge. This I believe keeps them happiest. It doesn't matter if they are girl or guy batteries, they all burp and fart. The technology, as well as burps and farts, has been around for longer than any of us have been alive but little has changed except for some high tech designs and material improvements.

I'm not sure why you built a three string bank. It must be for planned future use that is greater than now. If so, good choice as you don't want to add new batteries later. I've got notes, stickys and lots of time in gathering SGs and data over 15 years and the bottom line is I don't use batteries hard and never will. Lead batteries, Trojan L16REa's first then L16REBFLAs next, in my case, did not have the long term life I expected.

One thing is for sure: our systems, usage and practices vary greatly and what works for one doesn't necessarily work for another. I had to come back to this thread after letting it go but it bothered me that I didn't say anything. So take my opinion as you wish.