I have a fixed PV array that contains 18 Talesun 235W panels. My array is split with 9 panels on the SE facing roof and 9 panels on the SW facing roof. I have 2 Classic 150's - one serving each array. I am running 3 panel strings into Midnite controller boxes. My system was installed on 1/2013 and has operated normally until last July(7/14) when I changed my voltage settings. My SG's were hovering around 1200 because my voltages and times were too low and too short to adequately charge my 48V (8) R/S S530 6V battery bank. Anyways i upped the voltage and the absorb times and then after about 4 hours of charging normally - my Classic that handles the SE facing panels started going to "Batt over V" then to "Resting/Float". I was able to get my SG's up to 1265 by June 2015 even with the one classic pooping out after 4 hours. I have since discovered a bad cell in one of my batteries and deterioration in storage capacity. Needing all of the power I can get right now - I decided to try and get the SE Classic working properly again. Recently 7/28/15 I updated the firmware on both classics. The SE classic had an RFR code of 22 (Average Battery Voltage is too high above set point (RestartTimerms = 2 sec)) I responded to this by backing down my voltages to the recommended levels for the battery temperature. Hopeful that this would correct the problem i waited until today to see if there was any improvement. It seems like there was no improvement as the SE controller was on FLOAT for 4.5 hours while the SW classic was on Bulk MPPT sitting at 53.5 when i got home from work around 3:30pm. I checked the RFR code and this time it was #5 ( Too low power and Vbatt below set point for 90 seconds). I am not sure where to go from here. I have a replacement battery on the way and would like to get the most out of my Classics during the day so we can keep up with laundry and such. Any suggestions?
Hi Rejuvination ..,
OK, believe that you have just Updated the FirmWare on both Classics, in preparation to use FollowMe (FM). This is good, and FollowMe should eliminate the issue of one CC in one state, and the other Resting due to too high battery V, etc.
It is imperative that you use the Battery Temperature Sensors of ALL charge sources. This will automatically adjust the charge voltage for the temperature that the batteries actually are at any one time.
You may not yet be running FM, perhaps because you need phone cables, or perhaps not. But FM should help you get the maximum use of the PV modules that you have.
The WhizBangJr could be a nice addition to your system, if you do not already have one, as it could allow you to end Absorption based upon the charge current actually going into the battery.
If your battery discharge pattern is quite regular, with similar Depth Of Discharge (DOD) each day, then using the Shunt End Amps ability of the Classic with the WBjr may not be a large benefit to you.
Vic
Hi rjv,
What Vic says and...
Have you checked the wiring of the array that says input v below batt v?
Those pvs have 29.5 mph so three in series should be good for 48v battery charging.
Unless there is severe shading or the wiring has gone faulty so that the sets of 3 series strings are producing much lower voltage. Check for blown fuses, corroded connections, broken wires or even loose connections and broken connections. Also look into junction boxes and combines for problems and of course the main cables from pvs to the classic. Are the connections into the classic nice and tight?
Any heat or evidence of excess heat anywhere in the PV cabling? Right through to classic.
Use a voltmeter and test voltage from each string, this may need temporary isolation from combiner but it will soon point out a dud panel or wiring problem.
I assume the classic input voltage is showing its lower or pretty close to battery voltage?
As a last resort to see if it's just poor PV output due to poor panel illumination you could try some re wiring of the 9 pvs into two strings of 4 (ignoring the 9th panel) and see if the classic starts and stays in bulkmppt.
Also follow-me will sync the charge state of the classics but it may just force the one in bulkmppt into float which is not what you want.
Dgd
To Vic,
You are correct - I recently updated both CC's to Rev. 1933 in preparation for FM. My thinking was to solve the RFR issue before implementing FM as to avoid the scenario Dgd outlined above with the RFR pulling both CC's into resting/float/ b over v.... I guess i could try implementing FM and see what happens.
I had a question on FM - is it necessary to share the ground fault is both CC's are already grounded?
also you mentioned
"It is imperative that you use the Battery Temperature Sensors of ALL charge sources. This will automatically adjust the charge voltage for the temperature that the batteries actually are at any one time." Is this a setting on the Classic? Sorry if this is a dumb question :D
Thank you,
Jeff
Quote from: Rejuvenation Farm on July 30, 2015, 10:11:58 PM
... also you mentioned
"It is imperative that you use the Battery Temperature Sensors of ALL charge sources. This will automatically adjust the charge voltage for the temperature that the batteries actually are at any one time." Is this a setting on the Classic? Sorry if this is a dumb question :D
Thank you,
Jeff
Hi Jeff,
There is a Battery Temperature Sensor (BTS), that ships with Classic Charge Controllers (or, at least it used to).
The BTS should be placed midway down the side of one of the batteries in the center of the battery pack. When you use FollowMe, one BTS is shared.
In the Charge> Limits menu, there is a setting for the Temperature Coefficient for the Classic to use based on the temp reading from the BTS. For your Flooded Surrette batteries, this coefficient should be set to --5mV. Also, in the Limits menu, there are settings for the range of Temperature Compensation of the charge voltage. Personally, would set the low limit fairly low, and the high limit above the temperature-compensated maximum EQ voltage. These exact settings will depend upon the range of temperatures that your battery bank might experience.
Also, make sure, that the battery reference temperature is set to 25C ... think that this is in the Limits menu ... will have to check.
Until you get FollowMe going, each Classic will need its own BTS.
More later, good luck, Vic
Vic:
I do have 2 BTS - one for each CC. They are improperly mounted to the tops of the lead (pos) battery and the end (neg) battery. Is there any reason not to just move them to the 2 center most batteries? Can i still use them both in FM or should I just go to one? If one is the way to go - does it matter which CC it is plugged in to?
I adjusted my charge limits as you suggested to a bit higher than max absorb and slightly below the recommended float. I had no luck however locating the battery reference temp.
Going to see how the RFR goes today then make the connections for FM and give that a go over the weekend when i can keep an eye on it.
Thanks,
Jeff
Ok - just got home from work and the left (SE) classic is in Float with an RFR of #5, while the right (SW) classic is in absorb with 2 hours remaining. I am ready to try Follow Me but am concerned that when the CC on the left goes to Float it is going to pull the CC on the right out of absorb and into Float prematurely and make my situation less desireable. I really wish i could nail down the RFR issue with the left (SE) CC.
The suggestion from dgd to test all my connections and voltages is an option, but not one I am super excited about being it is mid 90's, sun blasting and my roof is metal. Being this issue starterd after i changed my settings to up absorb time and voltage to get my batteries back on track - I tend to think the issue is related to settings and not so much connections. But who knows. As far as shading - that is not a problem here. Bad panel - not sure, never had any reason to suspect that to be the case, but I guess it is possible.
One thing worth mentioning is that I did not do a factory reset after upgrading the firmware.
Hi Jeff,
A quick comment;
You do know, when you do the Reset to Factory Default settings, that you will need to change any/all settings back to what you had before, or to what you now want.
The Defaults use a low Absorb voltage, do not know about the default on absorb time.
ALSO, the Limits menu has very a narrow range for temperature compensation of the Absorb, and probably EQ voltage as well ... With Flooded batteries, you wiii want to widen these Limits.
You really MUST install and connect the BTSes -- one for each Classic, and for any other charger that you have. As you know, the BTS is blue, and has a fairly long blue cable that plugs into the Classic.
More later. Vic
Jeff,
From your last posting it appears you system is working as expected.
For the SE Classic to be in Float that must mean it has went through bulkmppt then absorb stages and the battery is fully charged. The RFR at 5 means nothing as it is the most common RFR and was probably set late yesterday or early this morning when the sun just appeared. It only applies when the CLassic is RESTING and yours is in float.
As the sun moves away from the SE array this state will probably change to Floatmppt then resting.
Now the sun is on the SW array and it is now in bulkmppt so, assuming enough sunight, it will go through to Absorb then Float.
All this is normal and probably the expectde behaviour of your setup.
Problems I see, and this is only IMHO are:
Unless there is some significant load on the battery during the midday period between the the SE and SW classics doing battery charging then the SW one seems wasted and at worst will be over charging the battery bank by going through another Absorb cycle. You mentioned a 2 hour absorb time so I assume you are using the fixed time downcounting absorb timer.
The SW Classic should be using the Ending Amps to terminate Absorb cycle to prevent overcharging, if you do not have a WBjr installed then this should be a priority to obtain and install.
If the battery bank is too small for the load requirements so that its lost significant Amphours in the hours between each Classic coming into Absorb cycle then this means you are doing two cycles of the bank each day. Since battery life is usually measured in number of cycles then your bank is heading for a short lifetime.
I cannot see any good reason for such a split charging system with two arrays at 90degrees (SE and SW). If thats the orientation of your roof space then mounting the pvs on such a roof is NOT IMHO a great idea. Put them somewhere else or get some legs /brackets to lift each array closer to S orientation.
If you still want to flatten out the charge curve then have, say, 4 strings at S, one at SE and one at SW.
Also, athough 2 classics is allowing for possible array size expansion the two 1.9kw arrays would easily work in one Classic when charging a 48volt battery bank
Others here may have different thoughts on this and perhaps more useful or better suggestions.
Implementing Follow me on two almost completely separate charging systems will probably not offer any advantages, I suspect the state of the SE Classic will be forced on the SW Classic.
But it will be interesting to hear what happens when you try it
dgd
Gentlemen,
Thank you so much for your concern and feedback. Being a novice at all of this, it really makes me feel good to hear from those with much greater experience than I. I would like to clarify a few points as to help get to the crux of the issue.
BTS - I have them hooked up and the appear to be working fine, I need to reposition the sensors to midway down the side of the center most batteries and not leave them adhered to the tops of the first and last battery in my string. I will knock that out today.
Fixed Array - Moving and re-racking the panels just is not feasible financially right now. The thinking behind the design of having 2 arrays was to maximize sun exposure time across the array on the panels and to hedge against cloudy mornings/afternoons which could shut down daily production is all panels were set in the same direction when the clouds rolled in. A tracking array would be ideal, but financially it is next to impossible. Either one of my arrays is capable of fully charging my bank - so except for the cloudiest of days - I am getting through the absorb phase.
Battery Bank Size - We have very lite evening loads - usually 6-9 Amps, occasionally less. When charged and working properly - I can get through to the next morning fairly easily with a few amps to spare. Would I like more capacity? Sure. Can I afford more capacity? not right now. We make due with the capacity we have and have stripped out all un-necessary electrical loads. No A/C, no dryer, no dishwasher, no microwave - you get the picture.
Absorb - My absorb time is set for 4 hours. The SE array pops into float around noon everyday - whether it gets through the absorb or not. The MNGT message migrates between Resting and Float. I am actually ok with it not contributing if the SW is doing the job, where it gets frustrating is when a cloud rolls through or we do a load of laundry - the SE stays dormant when it should be contributing vital amps to the system.
UPDATE: I have just set up FM and it appears to have fixed the issue. SW is producing and holding Absorb and SE is kicking in when loads increase - just like I wanted it to do. Fingers crossed that this continues throughout the day. I will be monitoring all weekend to make sure everything is cool.
Thanks again for all of your input during this challenging time - I really feel great having improved the situation. I could not have done it without you guys.
OK, Jeff, Thanks for the update.
Good Luck, and please keep us posted on how you are doing.
Thanks! Vic