Charging issues... low SG

[Rngr275]

 There was no initial SG measurements taken when the system came on line. Initial Voltage set points for the 2 Classic 200's seemed a little off so adjustments were made to what Trojan recommends. (16 L16RE's 370AH each, 740AH battery bank). Current settings of the charge controller are 62V EQ, 59.2 ABS, 52.8 Float. RAised the times from .5hrs minimum to 2 hours and raised the 2hr maximum to 4 hours. My first SG measurements a month ago were in the 1.250 range even though the FNDC said the bank was at~99%, the voltage readings on both the FNDC and Classic were at ~50.9V (which is what it should be) but the SG is low @ 1.250 (Trojan 100% SG is 1.277). This a brand new temp compensated Hydrometer purchased from this sight. I am a Chemical Technician so I feel I am using the correct protocol to do the measurements. Trojan has told me it takes a number of cycles to get batteries to its full potential. Here is what has been don in the last month and my measurements/observations.

3wks or so ago batteries were in float when I got home so I did my first EQ, unfortunately I could only do it for ~2hrs. SG went from 1.250 range up to the 1.261 range when I had to quit.

Had some good sunny days and bad ones after a couple good sunny days, battery voltage (FNDC, and Classic) was ~50.8, I measured the SG and again the SG was in the 1.250-1.255 range.

Installer suggested letting the batteries get a little lower (never been below 49.9 volts/90%SOC on FNDC). Hurricane Sandy comes and I let batteries go down to ~ 49.4 V and FNDC reads 83%. Measured SG and it was at ~1.230 or ~75%.

Using my generator I brought the batteries up and went trough a good long absorb (end amps was ~14), FNDC said ~95 %. The next day was sunny so when I got home the controller was in float I measured may test cells and the SG was @ 1.250. Did a 3 hr EQ using the generator watching the SG and it came up to the 1.263-1.266 range and for the first time the FNDC said that all charge parameters were met. SG was still low though. That was a week or so ago.

Haven't had to much sun over the last few days so I fire the generator up this morning for a good 3hrs to give the batteries a good boost knowing the sun would be out all day. Came home battery voltage is at 50.9, FNDC says 100% SOC, Measure my test cells ( 1 cell in 6 different batteries) and the SG is @ 1.241!
I am freaking out as I can't figure out why.
I went to the data logger in the controllers and here is what they did:
Controller 1 (upper array) @
7:20am genny off for 1.5hrs REsting V-Bat@51.7v, Vin@136, Amps Out@0
SAme thing for next hour except a slight rise in Amp out
8:50am BLK MPPT, VBat@53.4, Vin@130, Amps Out@10.6
amps out and VBat slowly increase until ABS is reached
9:30am ABS Vbat@59.1, Vin@138, Amps Out@15.6
9:50am ABS Vbat@59.1, Vin@ 137, Amps Out@13.8
10:10am Float, VBAt 52.7, Vin@146, Amps Out 1.0

Controller 2
Was the same up until controller 1 went to Absorb. Once that happened controller 2 went to Rest, then Float for most of the day.
Looks like I got about a 20 minute absorb.

If every thing is based on voltage and amperage...i.e. voltage to reach for the absorbtion stage to start, taperd amperage during absorbtion. Float voltage, as well as SOC being based on the battery bank voltage, Then how can the battery bank be reading 50.9V ~100% (48V bank) but the SG of the bank is ~1.24 on average(~80%)?

Should both Classic 200's be mirroring each other during the day.... both in Bulk MPPT, Absorb, and Float at the same time.... Do they look at the battery bank independently and do their own charging according to the feed bak from the battery bank? Not sure how they work together... I don't beleive they are master/slave.

Also, with all the charging and a couple EQ's ( only 2-3hrs ea) I have not needed to add 1 drop of water. Water level is still at the perfect level!

Does any of this make sense? Seems like everything is based on voltage and amperage. Can my battery bank really be at 50.9 volts and have a specific gravity of 1.240?? Suggestions. How do I measure the voltage with my voltmeter. Is there a way to check the hydrometer against a "Standard". Something is amiss and I want to get it figured out.

I apologize for the length of this post.
McD

[SolarMusher]

Your batteries are sulfated. You will just need to give them a longer EQ at 62/63V (disconnect your DC loads) with your gen/charger (forget solar) at slow charge (35/40ADC) for 4hr to 8hr or more. Let the gen run and check a pilot cell every hour until it reach 1.280SG. Manage battery temp under 40/50°C. Stop Your EQ and allow the batteries to cool for a while. Your Classic settings are good, Trojan REB needs 58.8V Absorb and 52.8V Float, 62V EQ. You'd better use EA to control the end of Absorb. To find this EA, set Max time to forever on your Classic and watch absorb until current stops decrease (generally between 1 to 2%), add 1A, this will be your EA setting (add loads amps to this setting if you need). You can then set your Min time to 30mn and Max time to 3hr to begin with a good EA value.
Good luck,
Erik

[Rngr275]

Thanks for the advice. Batteries have only been in service since Spetember 5th of 2012. Do you still think sulfated is the problem?

[SolarMusher]

Thanks for the advice. Batteries have only been in service since Spetember 5th of 2012. Do you still think sulfated is the problem?

Off course, truth is in your SG only. If your batteries are recent, you will bring them back to full SG easily (1.280 for L16REB).
Your FNDC need to be calibrate with a full charge (SG1.280) to show you real charge value.
Erik

[Rngr275]

Trojan told me the same thing... SG low at intalation and I am only charging back up to the low SG since my system thinks that that is 100% when it is truely @ 80%.

EQ it is.

Thanks

[SolarMusher]

You're welcome.
Erik

[Vic]

Hi Rngr..

First, what is the exact model number of of the L16 battery you are using?

Are you absolutely certain that the correct target SG for these exact batteries is 1.277-1.280?  I would guess that the target SG would be closer to 1.265.  You have been speaking with Trojan,  and they do know,   but,  I'd felt that the RE batts had lower SG,  and the HC  the higher SG.

Also,  I have just learned the real way that the Classic uses EA.   You do need to set your Min and Max times in the Charge menu to very long times in order to have the EA setting always donimate.  You may want to set these times to 6 or so hours.

IMHO,  you can just IGNORE the FNDC and its readings for now ... it is just confusing "info",  until your batteries get cycled 30 - 50 cycles.  And these cycles should really be to 70% SOC or a bit lower.  This affects the CAPACITY,  and therefore the desired calibration settings of the FNDC.

Also,  voltage readings of batteries are very,  very poor indicators of SOC.  SG readings are the gold standard.

Please make certain that you rinse your Hydrometer several times after each SG measuring session.  Use Distilled Water.  This rinsing is essential to preserve the accuracy of the Hydrometer.

More later,  thanks,  Vic

[SolarMusher]

Hi Vic,
Trojan L16REB 6V 370A/58.8V absorb or L16RE 6V 370A/59.2V spec are 1.280SG.
A+,
Erik

[Vic]

Hi Erik,

Well,  did a bit of  searching around,  and the L16-RE that shows up is the 2V version,  all else is RE-A  and RE-B.

See NO reference to SG,  other than the cryptic,  "All Premium batteries manufactured before March,  2012 used 1.260 SG ... "  or similar.  So,  PERHAPS,  the A and B suffixes denote the/a SG  change

I dunno why these companies feel the need for 1.277/80 SG,   and rating Capacity at 80 F ...  these are mostly specmanship games to make their batts look (slightly) better than the competition.

I'd prefer to see RE batts use 1.250 SG electrolyte ...  Anyway,  thanks for the info.

Rngr ..,   Believe the Classic FW that will allow Master/Slave relationship twix multiple Classics is almost ready for release.  Might even be out at this moment.

Until you load this FW,  each Classic is autonomous.  The pair in use here have worked very well together  (each with its own "identical" PV array),  until Absorb is reached.  And,  then,  early in Absorb,  mostly they seem to work well.   When one goes to Float,  the behavior of the other is a bit unpredictable.   The M/S FW should help this sharing alot.

I DO wish that there was going to be a way for M/S to get EA for the two CCs to be summed,  such that EA would work with a pair or more CCs,  but read that this it not going to happen.  Do not tell anyone,  but have secretly bussed together the two PV arrays,  switched the second CC to OFF,  and EA seems to work OK this way (for me)  using a single Classic.

Rngr,  do not recall your location,  and this time of year can be a bit challenging  when trying to cycle batt banks down to 70% or lower SOC if you are in Northern climes,  but if you can do this,  and actually recharge very close to the speced SG for your exact batteries,  it could be beneficial.

A positive note;  think that it great that you are actually paying ATTENTION to your battery bank,  taking and looking at data,  and actually measuring SGs.   So many times,  we read on a Forum like this about,  "Why do the lights go out at 9:45 PM "  Am certain that you will soon get on top of the issues there,  and have a long-term relationship with your batteries and Power Hardware.  Vic

[SolarMusher]

Vic,

Also,  I have just learned the real way that the Classic uses EA. You do need to set your Min and Max times in the Charge menu to very long times in order to have the EA setting always donimate.

In fact, it was the same for me and I'm sure for a lot of people. One thinks that he has understood Min and Max time, but in fact it's a little bit more hard. I read it several times before to be sure I understand what that really means 
I must be a little dummy...
Did you update your FW with Varimax? If you have understood it, please feel to share with me 
I will update only when I'll understand it.

(16 L16RE's 370AH each, 740AH battery bank).

The batteries rngr is talking about are 370AH, so it could only be 6VL16. I have spec sheets for both L16RE and L16REB and SG is 1.280 for both of them.
A+
Erik

[Vic]

Hi Erik,

I do not believe that either of us are dummies.  Personally,  I just need a very concise explanation,  AND,  since the MX-60 was designed by (mostly) the same team that did the venerable MX-60,  had felt that the Classic's operation using EA would behave in the same manner -  this does not appear to be true.  Not a big deal,  if I really do understand -- but one often does not know what one does not know.

I am still with 6/29 FW,  as the site with the Classics is mostly unattended,  and do not want to load new FW,  and then turn my back on the CCs,  assuming that I understand how it actually works.

Yes on the L-16s being 6V,  no disagreement there,  just was trying to say that the ONLY REs that I see currently listed are the 1000+ AH 2V batts in the L-16 case.

And the subtle differences between the RE-A and RE-B escape me.

OK,  Thanks Erik,   and give the dogs a treat for me.  Vic

[boB]

Hi Erik,

I do not believe that either of us are dummies.  Personally,  I just need a very concise explanation,  AND,  since the MX-60 was designed by (mostly) the same team that did the venerable MX-60,  had felt that the Classic's operation using EA would behave in the same manner -  this does not appear to be true.  Not a big deal,  if I really do understand -- but one often does not know what one does not know.

I am still with 6/29 FW,  as the site with the Classics is mostly unattended,  and do not want to load new FW,  and then turn my back on the CCs,  assuming that I understand how it actually works.

Yes on the L-16s being 6V,  no disagreement there,  just was trying to say that the ONLY REs that I see currently listed are the 1000+ AH 2V batts in the L-16 case.

And the subtle differences between the RE-A and RE-B escape me.

OK,  Thanks Erik,   and give the dogs a treat for me.  Vic

Vic, maybe it would be helpful if I displayed the Ending Amps timer ?  That way you could watch it count down towards
zero when the battery current is below EA setting  AND  the battery voltage is at (or above) the absorb set point.

This might be good to place in the EA setup screen as a VIEW menu because there is also the Re-Bulk adjustment
and it also has a timer similar to the EA timer.

boB

[SolarMusher]

Hi Vic,

I am still with 6/29 FW,  as the site with the Classics is mostly unattended,  and do not want to load new FW,  and then turn my back on the CCs,  assuming that I understand how it actually works.

Don't give up, I start a new thread to ask boB a little more details on how varimax works and if I understand it I will "try" to help  (clearly).

OK,  Thanks Erik,   and give the dogs a treat for me.  Vic

50 howlings from the dogs!
Erik

[Vic]

Vic, maybe it would be helpful if I displayed the Ending Amps timer ?  That way you could watch it count down towards
zero when the battery current is below EA setting  AND  the battery voltage is at (or above) the absorb set point.

This might be good to place in the EA setup screen as a VIEW menu because there is also the Re-Bulk adjustment
and it also has a timer similar to the EA timer.

boB
[/quote]

Hi boB,

boB,  your recent explanation of the EA function of the Classic helped a lot ...

In the post quoted above,  the Timer value display you were proposing  is the countdown of number of seconds that remain until the Absorb stage is terminated due to EA having been met   If this is what you were proposing,  then  this would be helpful,  at least when one is becoming familiar with the EA function,  and how it is working.

And Erik,  saw your post RE Vari-Max,   but have not tried it yet.

Good looking dogs,   have fun in the snow.  Here in CA,  it is 53 F with a little drizzle,  but no real sun so far today.

Thanks,  Vic

[Rngr275]

The batteries are the L16RE-B's with an AH rating of 370 my bank is 740AH. I talked to Trojan's Tech.Support and the target SG is 1.2777 for these batteries. They believe that since the batteries were not at a full charge when the system went online that the batteries are still in need of an EQ to bring up the SG. They ship the batteries @~80% SOC which about the SG readings I currently have. They told me to do a good EQ qnd do it this way:
EQ @ 62v
Check SG every hour
Stop EQ when the SG does not rise for 3 consecutive readings. Which I went over with the Tech guy 2-3 times. This means that over the course of 3hrs of EQ the voltage should not rise.

Vic I live in the Finger Lakes region of New York. Between Corning and Rochester.

We are very conservative with our energy usage and have never gotten the batteries down to the 70% SOC. Should I just run wild using lots of electric or turn off the PV breakers sometime to let the batteries get a deeper discharge? My installer suggested the same thing. Deeper discharge  then a good long charge up to 100%.

Trojan said to do an EQ first to get the batteries to the correct SG, then some deeper discharges.

Doing an EQ today

Starting SG ~1.250, 2hours in SG @ 1.260.
I will keep this updated.