Here ar the three status screens I can't make sense out of it. Can somebody help me interpret what am I looking at?
Pics were taken at noon with full sun exposure no shadows. The system was installed 10 days ago and last weekend was my second visit and check up.
Shouldn't I be seeing numbers like close to 700 Watts, 15 amps, 90 Volts or something close to that? Any comment would be highly appreciated.
SIGP2101
sigp..
Looks normal to me.....when in absorb the batteries will need less current to maintain the absorb set point. This is due to the bulk stage of charge putting in the most of the current bringing the batteries to the absorb set point, they can absorb less amps now so your Classic is doing what it is supposed to.
If your batteries were still low in voltage at this point you would see more power like 700 watts....but they are getting charged at a lesser rate because they need less now to charge now. Not to worry! Power and current will fall much further when you hit the float set point.
td
Quote from: tecnodave on June 28, 2016, 06:02:57 AM
sigp..
Looks normal to me.....when in absorb the batteries will need less current to maintain the absorb set point. This is due to the bulk stage of charge putting in the most of the current bringing the batteries to the absorb set point, they can absorb less amps now so your Classic is doing what it is supposed to.
If your batteries were still low in voltage at this point you would see more power like 700 watts....but they are getting charged at a lesser rate because they need less now to charge now. Not to worry! Power and current will fall much further when you hit the float set point.
td
Thanks for your input it is encouraging to know that CC is working the way it suppose to. So Bulk happened prior to this like earlier in the morning and numbers would have been different then and made more sense to me if I was there in time to record that. Right?
QuoteLooks normal to me
Huh? I nearly fell off my chair...
I was thinking it was a 48V system and this seemed way too low, then I noticed sigp's at 36V. But now I'm wondering if this a tad high? Trojan lead acid are normally between 2.35-2.45/cell IIRC. Maybe I'm overlooking temperature correction?
~ks
Quote from: kitestrings on June 28, 2016, 11:13:51 AM
QuoteLooks normal to me
Huh? I nearly fell off my chair...
I was thinking it was a 48V system and this seemed way too low, then I noticed sigp's at 36V. But now I'm wondering if this a tad high? Trojan lead acid are normally between 2.35-2.45/cell IIRC. Maybe I'm overlooking temperature correction?
~ks
Here is what Trojan has to say about it.
System Voltage 36 Volt
Bulk Charge (2.47 VPC) 44.5
Absorption Charge (2.35 â€" 2.45 VPC) 42.3 â€" 44.1
Finish Charge (2.70 VPC) 48.6
Equalize Charge (2.70 VPC) 48.6
Float Charge (if desired 2.25 VPC) 40.5
So where I am according to all this? Temperature compensation is not set yet it is left on default Classic settings. I didn't have time to do it yet properly.
Trojan recommends correction of 0.028 VPC for every 5.55C below and same for above 25C. Is this close to default Classic's settings or not I do not know.
Quote from: sigp2101 on June 27, 2016, 11:18:07 PM
Here ar the three status screens I can't make sense out of it. Can somebody help me interpret what am I looking at?
Pics were taken at noon with full sun exposure no shadows. The system was installed 10 days ago and last weekend was my second visit and check up.
Shouldn't I be seeing numbers like close to 700 Watts, 15 amps, 90 Volts or something close to that? Any comment would be highly appreciated.
SIGP2101
In addition to what David said,
The first Status screen shows the total kWh delivered by the Classic to battery charging, plus power for any loads for the solar day.
The second Status screen, is essentially the same as the first, except the totals delivered by the Classic is shown in Amp hours.
The third Status screen shows the last Voc that was measured by the Classic in its last Sweep to find the Maximum Power Point, I believe ... cannot see the images while Posting.
AND, you will seldom see full rated power output from any PVs, unless the outside temps are cold, and perhaps there is some wind, as well. PVs are rated at Standard Test Conditions (STC). This is where a Flash Tube is used to briefly illuminate the PV module, with the Cell temperature at 25C. In full sun, the PV cell temps rise. This temperature rise reduces the cell output voltage. The common derating factor is commonly to multiply the STC power value by 0.77, or for your 3 X 235 watt PVs, this would be about 180 watts X 3, or about 540 watts typical. On HOT days, this power amount might be reduced a bit further.
Looking at the rated NOCT for your PVs, is also a fairly good guidline for what you might expect for power output +/-- a bit.
You probably know most of this. FWIW, Vic
Will add one more thing ...
At 2.3 A output, in Absorb from the Classic, it would seem that your batteries should be fully-charged, or very close to it, depending upon the Temp Compensation value, and weather it has been set, or Defaults to the correct -- 5 mV/Cell/C for your batteries.
Forget, do you have, and use a Hydrometer to measure the SG of each cell of the battery? This is a very important tool. Number each battery and cell with a felt tip marker.
Make a battery Log Book, and record SGs, date when and water volume added to the battery bank, EQ date, voltage and duration, plus any changes to charge parameters and modifications to the system, etc. Looking at trends in SG changes verses changes to charge parameters, and DOD of battery, etc can be helpful. FWIW, Vic
Ok all
Here is my master battery set point schedule.....please note that there are 3 sets of set points...
Start with mean.......the average of all systems.....if specific gravity is too low after 2-3 weeks use , then use max set points.....if specific gravity is too high use min set points. The exact set points will depend on battery condition , age, temp, etc. Some experimentation will result in the exact point in which your batteries will have the manufacturers specific gravity......1.265.... after resting for several hours after a full charge......let the surface charge leak off and acid to stabilize.
<master set point chart>
Battery notes
Charge Stage
Volts per Cell (VPC) 12V 24V 48V
Min â€" Mean â€" Max Min â€" Mean â€" Max Min â€" Mean â€" Max Min â€" Mean â€" Max
Absorption / Bulk
2.40 2.45 2.50 14.4 â€" 14.7 â€" 15.0 28.8 â€" 29.4 - 30 57.6 â€" 58.8 - 60
Equalization
2.58 - 2.63 - 2.67 15.0 â€" 15.8 - 16.0 30.8 â€" 31.6 â€" 32.0 61.6 â€" 63.2 â€"64.0
Float
2.20 2.21 2.23 13.2 â€" 13.3 - 13.4 26.4 â€" 26.6 â€" 26.8 52.8 â€" 53.2 - 53.5
<end set point chart>
I have two sets in service right now.....I'm using the minimum set points and have s.g. 1.265 on all cells. One set new. Interstate L-16's Floor sweeper batts, and 1 set recovered form failed system bought as scrap and recovered Rolls-Surette S-530 400 a.h. L-16's
I haven't done any 32-36 volt systems in many years now but the volts per cell values are in the first column.
Please note these values are for large format deep cycle batteries such as GC-2 , GC-8, L-16 and other dedicated deep cycle batteries
This does not include any motorhome/marine "sorta deep cycle" batteries that have a CCA "cold cranking amps" rating....those are not true deep cycles and should not be used in off grid applications.
I have downloaded every reputable battery manufacturers data sheets and have gleaned this data from that and my apprenticeship at Alaksa Husky Battery Company where we made very special batteries that start your car at 70 degrees below zero F. Really heavy plates and 1.320 normal specific gravity......these would not live long here as they don't like heat.....conversely tropics batteries are formulated with much weaker acid and thinner plates to stand the heat but will freeze at 30 below.
David
Great INFO GENTS !
V & D
VT
Agreed. A solid strategy there Dave.
Sigp's batteries are T105s. They are predominantly a golf cart battery. They are not L16s, but for a low-cost, smaller system I've found them to hold up pretty well - better than the "marine sorta's" that you described and commonly found at the local auto parts store. The spec's are comparable, perhaps a touch lower. See:
http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf (http://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf)
~ks
Kitestrings,
Yes I know the t-105's. These are the same type of construction as the GC-2 /L-16 type of construction. Use lots of them in smaller systems. The CG-2/ GC-8 is the smallest format I use for deep cycle use.....my preferred battery manufacturer in order of preference with reason in ( )
Interstate (warranty,delivery,service) Trojan (warranty,service) Rolls-Surette ( quality) Penn-Deka (quality)
Interstate and Trojan are both local to me, Rolls-Surette and Penn-Deka are east coast outfits and delivery is problematic on the left coast.
Size of battery is dependent on system needs. One bank of L-16's is way better than two banks of GC-2's. If I did bigger systems I would look at 4KS25's or the 36" tall 2 volt Trojans rather than use multiple strings of batteries. For my use bang for the buck is the Interstate floor sweeper L-16's but due to weight factors the standby system in my work truck uses GC-8's.....it's more of a battery flywheel system with engine driven 24 volt alternator and inverter
David
Thanks to all who contribute to this thread.
Since this is newly installed system I worked on over the winter, and fact that I do not have much experience my main concern now that it has been finally put together is overcooking or undercharging batteries. That is why I posted those pics for someone's else analysis.
I will be going to the site this weekend and I can take more pis of various screens if someone wants to provide more comments.
This forum is great.