Need help with all the settings on my Classic 150

[ClassicCrazy]

I don't trust voltages to show SOC for AGM's Vic - at least smaller ones. I have seen them have good voltage but take a big dive as soon as load is on them. The more accurate way to test them would be for how many battery manufacters publish cell voltages for certain loads.
Just reading the cell voltage at rest won't do it in my experience.

Larry

[Lisa234]

Vic thanks very much for going to the trouble of getting that info.  Unless I'm missing something it seems to me everything's perfectly fine with my batteries. In the morning while still at rest (and after being in rest for 8 hours) they're each at 12.90v. Which would be 95% full, yes?  On the "skip the charge day" they all bulk up to float 'set point' pretty quickly after the sun comes up. My float set point is 27.3v.  Soc reading wavers from 100% to 99% all day.  (I have my Frige and three computers on it most the day)  So, 27.3v per string is really not 100% if I'm correctly recalling what i've read about the AGM batteries so it sort of seems right to me that SoC wavers from 100 to 99%.

Larry, thanks for your input, really appreciate it.  I just asked my BF how one tests batteries with a load and he said we'd need a load tester and said we'll get one eventually but (in his opinion) these are new batteries and we're not putting much load on them so they really don't need testing now. Not to take away from your point but just saying perhaps I don't need to test with load for awhile. ??

Anyway, I get the feeling people who have had these systems awhile have learned to be very cautious (and perhaps mistrusting) about their batteries. I was on the Outback board first before I came here and a few people told me there that I would almost CERTAINLY ruin my first battery bank. Yikes - I read that and felt determined not to be one of those. Do you guys find that a lot of these batteries are sold in substandard condition?  Or is this more about batteries not being properly cared for -- because batteries require so much attention ?

[justinbowser]

Lisa,

Newb here as well.  Most of the solar forums tell folks they will ruin their first bank so get cheap batteries so the learning experience is not so expensive.  I would counter with, "If you have a good balanced system you are not going to ruin your first bank."  When we first put in our solar system (Rev 1) I started the banks life off with it being probably slightly undercharged for the first couple of months.  As I read more and started learning more I re-wired things to better take advantage of the 'economy" 40 A MPPT controller.  After about 4 months I had stuff pretty much dialed in and everything was fine in battery land.  I ran this 300 AH bank (6 12V 100 AH AGM wired series parallel) for around two years and it was still going strong.

Last summer we installed solar system (Rev 2) which I wanted to take care of future needs and be able to run AC when it got hot.  I wound up with 9 310W Mission Solar panels and a Classic 200SL feeding the original battery bank.  This spring I upgraded to a considerably larger LiFePO4 battery bank and moved the AGM bank out to the shop/barn to run lights, etc., and the batteries are still fine.  This is at our cabin which is 100% off-grid.

If I haven't put you to sleep yet I'll close with saying that if you feed your batteries what they need and take care of them you won't ruin them whether you are a newb or not!

[ClassicCrazy]

Vic thanks very much for going to the trouble of getting that info.  Unless I'm missing something it seems to me everything's perfectly fine with my batteries. In the morning while still at rest (and after being in rest for 8 hours) they're each at 12.90v. Which would be 95% full, yes?  On the "skip the charge day" they all bulk up to float 'set point' pretty quickly after the sun comes up. My float set point is 27.3v.  Soc reading wavers from 100% to 99% all day.  (I have my Frige and three computers on it most the day)  So, 27.3v per string is really not 100% if I'm correctly recalling what i've read about the AGM batteries so it sort of seems right to me that SoC wavers from 100 to 99%.

Larry, thanks for your input, really appreciate it.  I just asked my BF how one tests batteries with a load and he said we'd need a load tester and said we'll get one eventually but (in his opinion) these are new batteries and we're not putting much load on them so they really don't need testing now. Not to take away from your point but just saying perhaps I don't need to test with load for awhile. ??

Anyway, I get the feeling people who have had these systems awhile have learned to be very cautious (and perhaps mistrusting) about their batteries. I was on the Outback board first before I came here and a few people told me there that I would almost CERTAINLY ruin my first battery bank. Yikes - I read that and felt determined not to be one of those. Do you guys find that a lot of these batteries are sold in substandard condition?  Or is this more about batteries not being properly cared for -- because batteries require so much attention ?

You don't need an additional load tester. Just turn on all the loads you have and plug in some more . See how much current you are drawing and what the voltage drops to.  Ideally you would have some large fixed resistance loads to test with - like space heaters which are 1200 watts and made to dissipate the heat they generate. Kind of depends how much you can plug into your inverter.

Larry

[Vic]

I don't trust voltages to show SOC for AGM's Vic - at least smaller ones. I have seen them have good voltage but take a big dive as soon as load is on them. The more accurate way to test them would be for how many battery manufacters publish cell voltages for certain loads.
Just reading the cell voltage at rest won't do it in my experience.
Larry

Hi Larry,

Thanks for chiming-in.

Given that Lisa's AGMs  appear to be young,   seems that they are probably not suffering from the most common causes of batteries having good resting terminal voltages,   but little capacity  --  heavy sulfation,   or  heavy plate erosion.

Seems that some smallish SLA batteries are incorrectly called AGM,   when they are probably really Gel.   Some Gels can be permanently damaged by excessive charge current (which can form gas bubbles,  isolating the plates from the gelled electrolyte).  This may not be the situation
you noted.

To me,  running a long Absorb stage every 10 - 14 days,  should ensure that the batteries are getting a full charge,   at least at those times,   and  this will help get/keep the two strings in better balance,  without this long Absorb.

We do not do a real Load Test on the Flooded banks here,   but  do discharge the banks to 80 percent SOC,  or a bit lower,   and measure the terminal voltage of each battery,   as a check for infirmity.   The most common load at the 20-hour Rate,  by using portable 1500 W 120 VAC electric heaters,   as you alluded to.

Am still not certain just how well EA ending Absorb really it for most AGMs.   Some manufacturers use a vanishingly small EA value,  or  a rate-of-change in this current,   rather than an absolute percentage of C.

And,  Lisa,   would guess that 12.90 V  rested,   is nominally about 95% SOC.  Having parallel strings could mean,  that batteries may need a longer rest,   as any imbalance in actual SOC of batteries in each string,   actually means that the higher SOC string  will be discharged,  while it is charging the other string during the first part of the "rest"  (IMO).   This could add a bit more uncertainty in the resting voltage,  and required rest time.

As noted before,  SOC readings  are really approximations,   and need not be taken too seriously.   IMO,  they are not absolutes,  just estimates.   And,  when Skipping days of charge,   the longer since a full-charge (and the Reset to 100% SOC),   the greater chance for accumulating errors in the actual battery SOC,  vs the SOC that is calculated by the Classic,   using the WbJr.

I am no expert on batteries,   especially Sealed batteries.   All just IMO,   FWIW,   Thanks,   Vic

[Lisa234]

Justin, Larry, Vic -- thanks very much for all your input. It's really a huge advantage to get input from people who've had experience with these systems.

I feel pretty confident at this point that my bank is not on its way to ruination any time soon.  But I will test them with an extra heavy load and see how that goes.

[Lisa234]

So, around mid-day today I plugged the vacuum cleaner into the inverter and had it on for 5 minutes.  This was on top of the usual load, so as to make sure to draw from the batteries. After turning on the vacuum the overall voltage dropped by 1 volt pretty fast but then seemed to slow up. I tested each battery while the vacuum was still on -- all the batteries remained perfectly uniform. Batteries never went below 12.46v.

[Vic]

Hi Lisa,

Assume that the Classic was in Float,  when you ran this test  …

You could switch the Classic Mode=OFF,   so all of the loads would be supplied by the batteries.   The WB Status page will tell you how much current is being drawn from the batteries.

The relatively quick drop in battery voltage is probably mostly from,  what is called Surface Charge.    Lead Acid batteries are affected by this.   Your batteries were probably being Floated (assumed),   at about 13.7 V per 12 V battery.   So   it takes some time to remove this surface charge.   The removal of this takes a bit of time,   and the time depends on the amount of the current being removed from the batteries.  Resting a battery (for hours  --  no charge,  no load)  allows the surface charge to dissipate,   and so on.

Later,    Vic

[Lisa234]

Oh, that's good to know.  Yeah, the batteries popped right back up to float level (27.3) as soon as the vacuum was turned off so it was obviously not a true discharge.  However!!  I just a few minutes ago remembered that I had put the batteries on the vacuum cleaner for five minutes or so back when we first hooked up the batteries to the inverter - this was a few months ago and we were just seeing if the inverter was working.  PVs weren't hooked up yet. So I've already kind of done this test. The batteries had been in rest for a week, and all of them discharged the same, and as I remember, all of them discharged very little.

Anyway, when I get around to testing them (more stringently) I'll remember to do it after they've rested overnight & before they bulk to float with Classic off. Today wasn't a waste of time though - I got my kitchen vacuumed.

Thanks for the answer Vic!