S/V Ninaa Ootakii - system startup (2x classic 150's @ 24v)

[Stone]

Good evening.
First post, please be gentle

System:
8 TrinaSolar Ss265p-72
Maximum power 265w
Open circuit voltage 44.2v
Voltage at pmax 35.33v
Short circuit current: 8.2a
Current at pmax 7.5a
Max system voltage 1000v
Fuse 15a

Deployed in 2 banks, wired series parallel.
(panel 1 and 2 in series, 3 and 4 in series, those in parallel to controller a, 5-6, 7-8 on controller b)

Batteries: (4) 6v, in series
(Interstate 903hc-s, 430ah@20 hours each)

Questions:
1) Can someone confirm that I can start up the classic 150 charge controllers at a battery voltage of 12-72 volts?
(can't find it in the manual, I would assume yes, but you know what they say about assumptions, lol)

2) System was designed to be 12v dc, and the choice to run 2 controllers was based on output current (I think) per tech support.

I changed to 24v on the advice of my battery guy when he told me what a 3,000 watt 12v inverter wants for current draw.

Do I actually need the second controller with the change to 24v?
(I'm considering an expansion, and if these will all work on one controller, I can use different panels for the other... barring that, how many of these can I run on one controller with the battery voltage change, and does anyone have a source for more?)

I'm in the pacific northwest, on the water, so it doesn't get crazy hot here.

Thanks for reading, sorry for the long winded explanation, and I deeply appreciate any advice you can give a newbie

Thanks,
-Stone (s/v Ninaa Ootakii)

[ClassicCrazy]

The thing to do is enter your PV in the Midnite string calculator and see what it says .
http://www.midnitesolar.com/sizingTool/
You can change the amount in series to find out different options.
It sounds like you are okay on your 72 volts with two PV in series.
The string calculator will tell you how many PV you can put in series without going over the Classic 150 voltage  limit also  based on outdoor low temperature.
It is better to be closer to the battery voltage than a lot  higher since you get better charging efficiency and the Classic doesn't heat up so much.
It was a good idea to have the four batteries in series at 24v since it is easier to keep them balanced than if you did two series and two parallel for 12v.
And much smaller wire size needed to the inverter that way too.

Larry

[Stone]

Okay, this looks promising, and I feel kinda stupid.

I don't have numbers for
VOC Temperature Coefficient
Or
VMP Temperature Coefficient
So went with the defaults.

Number Of Modules In Series: 2
Number Of Parallel Strings: 4
Total Modules: 8

Rated PV Array Power: 2120W
Anticipated Array Power @ 98F: 2008W
Rated PV Array Current: 30A
Battery Charging Current @ 28.8V: 73.6A
VMP (Maximum Power Point Voltage): 70.66V
VOC (Open Circuit Voltage): 88.4V
VMP @ 28 F°: 79.4V
VOC @ 28 F°: 96.4V

Classic 150
Max Operating Voltage: 150

Max Non operating VOC  (HyperVOC) @ 24V Nominal Battery Voltage: 174   
Maximum Number Of Modules In Series: 3   
Max Number Of Modules In Series (Using HyperVOC): 3   
Max Allowable Output Current Per Classic Based On This Current Configuration: 94A
Max Allowable Wattage Per Classic Based On This Current Configuration: 2700W
Present PV Array Wattage Of This Configuration: 2120W

Design Check:

Max VOC: OK
Temperature The Classic Will
Enter HyperVOC -302.8 (lol)

Array Power (Wattage): OK
Classics Required   : 0.8

At 12v that "classics required" turns into 1.6

Other options @ 28.8v:
2 parallel groups of 3 panels in series, (6 panels total):
55.2A, .7 classic 150's.

3 parallel groups of 3 in series, (9 panels total):
82.8A, 1 classic 150.

If I can find a 9th panel, that last one might be worth doing, although I'm going to be running them sealed, so that might be pushing it, and mounting it might be annoying (is it worth the extra 9.2a max?)

So it appears that I can do this reasonably off one controller.

Does this pass a sanity check from where you're sitting?

I do have 3 25W panels and a different 12v battery bank I can use the other controller on...
-Stone (s/v Ninaa Ootakii)

[ClassicCrazy]

I would go with the first one with 8 pv .
Your Classic will be running a lot cooler with the lower input voltage closer to the 24v battery voltage.
Yes you can use your extra Classic for more power to your system with other PV  - room for expansion which is always nice. You either run it independent or hook it up to the other Classic in Follow Me mode.
There is good info here
https://www.youtube.com/user/MidNiteSolar/videos
and here ( especially on using Local App)
https://www.youtube.com/user/ryanmidnitesolar/videos
and here
http://www.midniteftp.com/support/kb/index.php
and if you have an android get Grahams Classic Monitoring App from the Playstore
as well as other monitoring options depending on your level of geek skills  in Open Source area of the Forums

Larry

[Stone]

So I finished up at 11:30 pm, triple checked everything, and powered the system up. So far so good.

I went with 4 series parallel strings on one controller.

Now I wait for the sun to come up, lol.

-Stone (s/v Ninaa Ootakii)

[ClassicCrazy]

So I finished up at 11:30 pm, triple checked everything, and powered the system up. So far so good.

I went with 4 series parallel strings on one controller.

Now I wait for the sun to come up, lol.

-Stone (s/v Ninaa Ootakii)

Great - let us know how it goes or if you have more questions.
if they are new batteries you probably want to break them in by cycling them down deeper than normal a few times to at least
50% I think.  If you want your batteries to last very long time only take 20% out of them ( less deep you cycle them the more cycles you get ).
Also Vic ( the guy on here who knows flooded lead acid batteries very well )  would advise to number all the cells , get a decent specific gravity tester , and then log the readings in a book so you can track any changes from new over time. That way you can spot any cells that may need more equalizing than normal.
And Vic would also advise to rinse your hydrometer with distilled water often and well at the end of testing . Of course only use distilled water in your batteries.

Larry

[Stone]

So the best charge rate I've seen so far is 10.2 amps, but it's been cold and overcast.

... did a half throttle test of my inverter and battery bank today... Held up a 1500 watt space heater for 2 hours (78.8 amp draw per the whizz bang jr).

... tomorrow we'll see how fast it recovers.

[Stone]

Day 2 of test recovery.

I dug into the configuration, and made some changes.

1st: WBJ: changed AH from 400 to 435
(per the top of my batteries).

2nd: WBJ Changed efficiency to 85%, down from 94%
(WBJ manual says 80-85% for lead acid)

3rd: WBJ: "percentage of capacity change per degree C of battery temperature" from 0% to 1%.

4th: enabled "WBJ assisted charging".

... currently charging 28v, 14.5a.
... currently sitting at 333 ah out of 435.

I feel like I'm treading in dangerous waters here, and I need some advice.

Questions:
Batteries are 4 Interstate 903hc-s 435ah in series. (L-16-H, but I can't find them on interstate's site, and I've spent 2 days searching for specs, and Interstate themselves can't seem to answer the questions?)

Does someone have an "optimum settings" document somewhere for these, or a walkthrough? (barring that, did I do something dumb yet?)

If my panels are not capable of reasonably keeping up with the loads, is there an easy way to hook a large 24volt battery charger to this, so when I'm running my generator (power tools, etc) it will top up the bank at the same time? (If so, how/anything special?)

If I need to go with a big backup charger, any recommendations?

Also, is all-in-one-thread the best way to do this for this forum?

Thanks!
-Stone (s/v Ninaa Ootakii)

[ClassicCrazy]

The best bet for charging is to have an inverter with charger feature in it.
You can get higher current independent 24v chargers but they will cost a few bucks .
Most all lead acid batteries are similar in their specs - though the construction may be a bit different . So I would just use the specs from a company like East Penn Deka .
look under Monoblock / Flooded to compare to batteries you have in link below
https://www.eastpennmanufacturing.com/wp-content/uploads/Renewable-Energy-Charging-Parameters-1913.pdf
You can find other detailed lead acid battery maintenance info if you dig around on the East Penn Deka site  ( like for the floor scrubber batteries) A lot of battery manufacturers put different labels on the same batteries so floor scrubber L-16 same as solar L-16 .
I am surprised you had 0 instead of 1% for that capacity change - I thought the Classic come default at 1%  ?
I don't understand what you are referring to about Whiz Bang assisted charging ?  The only place Whiz Bang comes into play in charging is to be able to use it for ending amps to go from Absorb to Float.

Larry

[Stone]

"Whizbang jr assisted charging" is what the section header is on page 5 of the WBJ manual, lol. But yeah, the end amps and which shunt (internal or external) to use.

Thanks for the info, lemme see if I can figure this out.

[ClassicCrazy]

You have two ways of stopping the Absorb and going to Float.
One is just to set up time Absorb Time.
The other is to figure out the point where the batteries are full - it is at that point that the amps going into the batteries starts to level off.
You kind of have to watch your charging for awhile - it really helps to see it on a graph and you can do that if you set up Mymidnite and then graph System Amps , SOC , battery voltage.
When you see the amps going into the battery - and the SOC going up towards 100% you confirm that by taking specific gravity . ( you can also tweak your battery efficiency setting that way to match what you observe )  That way you can set up the Ending Amps where the batteries are full. You would set the Absorb timer a bit longer than needed . So whichever comes first - ending amps or absorb timer will stop Absorb and it will go to Float. Using ending amps is more accurate to what the battery really needs than just using absorb timer.
There is a section on how to determine ending amps in the Knowledge Base that I linked earlier.

Larry

[boB]

Assisted charging eh ?   OK....  and the manual says the mid 80% range ?  I wonder if maybe we need to revise this ?

So, the efficiency figure for the WB Jr. settings are for Amp-Hour efficiency and not energy efficiency.

Amp-Hour efficiency is typically in the 90% range and not lower unless the batteries are really old maybe.

This is why the default is at 94%.  That is what others do as well like the Bogart, a world-wide acclaimed battery meter.

Thanks for this info, Stone.

[ClassicCrazy]

"Whizbang jr assisted charging" is what the section header is on page 5 of the WBJ manual, lol. But yeah, the end amps and which shunt (internal or external) to use.

Thanks for the info, lemme see if I can figure this out.

Look in knowledge base for ending amps topic
http://www.midniteftp.com/support/kb/index.php
See attached photo
Larry

[ClassicCrazy]

Assisted charging eh ?   OK....  and the manual says the mid 80% range ?  I wonder if maybe we need to revise this ?

So, the efficiency figure for the WB Jr. settings are for Amp-Hour efficiency and not energy efficiency.

Amp-Hour efficiency is typically in the 90% range and not lower unless the batteries are really old maybe.

This is why the default is at 94%.  That is what others do as well like the Bogart, a world-wide acclaimed battery meter.

Thanks for this info, Stone.

Bob ,
Maybe they are talking about the ability to limit charging amps

Frequently Asked Questions
All Categories » CLASSIC CHARGE CONTROLLER - Features and Programming
CLASSIC - WBJR - How do I limit Battery Current based on the Whizbang jr. ?
The purpose of this document is to explain how to set up a current limit on the Classic based off
the WBjr current. This will only control the specific Classic that has the WBjr connected to it so
if the desire is to limit more than one Classic each Classic shall have its own WBjr and need
these adjustments made.

The Classic MUST have firmware version 2096 or newer.

[Vic]

Assisted charging eh ?   OK....  and the manual says the mid 80% range ?  I wonder if maybe we need to revise this ?

So, the efficiency figure for the WB Jr. settings are for Amp-Hour efficiency and not energy efficiency.

Amp-Hour efficiency is typically in the 90% range and not lower unless the batteries are really old maybe.

This is why the default is at 94%.  That is what others do as well like the Bogart, a world-wide acclaimed battery meter.
Thanks for this info, Stone.

There has been this difference in opinion,   ongoing for a number of years here,  regarding the AH Efficiency of Flooded Lead Acid (Lead-Antimony)   batteries.

Folks like me are seeing an average AH Efficiency in the mid-seventy percent range for these FLA batteries,   and others note that this value should be in the mid-ninety percent range.

A number of battery manufacturers seem to state that this value is about 80-85%,   and this is probably for complete discharge/charge cycles  --   where discharges are to 0% SOC,   from 100% SOC.   This would represent the highest AH Efficiency.

Have cited the following Sandia Labs article,  in the past,  regarding AH Charge efficiencies:

https://xtronics.com/uploads/batpapsteve.pdf

As a side note,   would agree that AH Efficiencies of AGM batteries are probably in the 90+ percent range,   as  there is little,  to no gassing involved in charging AGMs.   And the primary reason for lower AH Efficiencies for Lead-Antinomy FLAs,   IS from Gassing.

But,   guess that this is just my interpretation of what some FLA battery manufacturers say,   the net of what was studied in the above article,   and what we see from our FLA battery banks in use here.

Not my hill to die on,   but  just an alternate set of views.

73,  FWIW,   and so on,   Vic   .   .