More Surrette problems

stephendv · September 2011

Re: More Surrette problems

With those loads you have quite a large battery bank. E.g. to take you down to 50% DoD would take almost 7 days of complete darkness.

But on the other hand, your panels are sized to recharge what you've used, so in my opinion having that large of a bank is not a huge problem. Especially since you're ready to use the generator to occasionally charge in winter. A larger battery has more resistance and has more self discharge so you would need to make up for that with a bit more charging.

So, if you can sell or get a refund for half that bank, then that'll save you some money. But if not, or if you can get very little for them, then you could keep them. It would mean that the whole bank gets drawn down to a much shallower DoD which means a longer life for the whole bank. Additionally, you would be recharging and discharging at a gentler rate which means less heat, more capacity and longer life.
You've probably seen the cycle life vs. depth of discharge curve before: http://itacanet.org/eng/elec/battery/lifedep.jpg

As your installer pointed out, taking the bank down to 50% would mean a very long recharge time so a 25% DoD makes more sense.

His suggested approach seems reasonable too, except I'd be tempted to just try and charge the whole bank from the get go once the faulty cells have been replaced. If that doesn't work, then split them.

BB. · September 2011

Re: More Surrette problems

You want to keep the batteries in the 80 to 95% state of charge range for the long term.

The longer the batteries sit below ~75% state of charge, the fast/more they will sulfate and fail (i.e., letting batteries "rest"/operate for days/weeks/months below 75% state of charge, the faster they will loose capacity (sulfate or the "fluffy" lead sulfate turns into lead sulfate crystals--which will never again participate in the charge/discharge cycle again--and there is no way chemically or using a desulfator to fix the problem--note there are lots of heated discussions about desulfators if they work and some issues about their use).

So, the normal assumption is that you would get up in the morning and look at the state of charge of the battery bank and the weather. If the battery is >75% state of charge, don't use the genset.

If the battery is below 75% state of charge you might start the genset early in the morning and recharge to ~80-90% state of charge and let the solar panels finish the charging off.

If the battery is below 50% state of charge, you would probably want to start the genset right then and get the battery back above 50% state of charge (if sunny weather is forecast) and above 75% state of charge if more bad weather is in the future.

And, if the battery is approaching 20% state of charge, get the genset running, turn off unneeded loads, and/or figure out what is going wrong. Taking a deep cycle battery bank below 20% state of charge can kill weak cells/batteries.

For efficient generator operation, you really want to keep them loaded to at least ~50% of rated load, or higher (for diesels, you usually want 40-60% minimum load to keep them from wet stacking, coking up, glazing cylinder walls).

So, you want to turn off the genset and let solar take over when the battery bank is around 80-90% full and the charger/battery bank are starting to draw less power as they shift from bulk to absorb charging cycle (constant/maximum charger current to slowing tapering down charging current as battery approach full charge).

-Bill

niel · September 2011

Re: More Surrette problems

again i have to clarify that you cannot leave a battery at 80-95% soc as a battery has to be periodically brought up to 100% soc. any prolonged undercharged battery will sulfate even if it is only that particular 5% of dod for a 95% soc kept battery. deficit charging is not good for any battery be it fla or agm.

mike95490 · September 2011

Re: More Surrette problems

Generator usage is not controlled by hours, but by battery/load demand. And with large batteries, you need a lot of current to agitate/ stir the electrolyte to reduce stratification in the cells. Your panels cannot alone, produce enough power to de-stratify the cells.

Vic · September 2011

Re: More Surrette problems

It is my belief that a high charge current, 10% of capacity for example, has very little to do with mixing electrolyte. But, rather has more to do with keeping the active plate material exposed to the electrolyte.

It is, IMHO, the later part of Asorb, and EQ which causes the remixing of electrolyte. This occurs when we hear the electrolyte bubbling. This certainly does NOT occur in my Surrette banks during High-Rate charge. Vic

waynefromnscanada · September 2011

Re: More Surrette problems

Vic wrote: »

It is my belief that a high charge current, 10% of capacity for example, has very little to do with mixing electrolyte. But, rather has more to do with keeping the active plate material exposed to the electrolyte.

It is, IMHO, the later part of Asorb, and EQ which causes the remixing of electrolyte. This occurs when we hear the electrolyte bubbling. This certainly does NOT occur in my Surrette banks during High-Rate charge. Vic

Agree, but it was my interpretation of Mike's post was that without sufficient charge current, the batteries would never get to the "boiling" stage and even if they did, the bubbling would not be active enough to do the job.

Cariboocoot · September 2011

Re: More Surrette problems

It's two parts of the same thing: without the high current potential you won't get the sulphur off the plates and back into the water; without the high charge Voltage you won't get it de-stratified and all mixed up into a viable electrolyte sulphuric acid solution.

Funny how so many things about electricity are co-dependent. :roll:

Vic · September 2011

Re: More Surrette problems

Marc,

Well, it has become SO common, here, to see the reference to High-Rate charge required to mix the electrolyte, which, I believe is just not correct.

Banks that are lightly cycled and charged from solar, will almost never see high rate charging (even if C/5 rate was avaliable), unless the day starts very cloudy until about solar noon. Because, the bank is (usually) recharged at lower rates, starting early in the morning, and the bank is out of bulk well before solar noon.

The drum that I am trying to beat, is the one that says that if a battery bank is NOT cycled deeply, a high rate charge (ie C/10) is not required on a daily basis. IT should be done monthly or so, for the health of the batteries. And for a lightly cycled bank, having C/10 available from solar, the bank will not experience anything like C/10 rates (daily), unless there are stromy conditions in the AM, OR, if there are serious morning shading issues.

And so on, perhaps just too fine a nit to pick. Here, when we do our occasional high rate charge, need to shut off the solar input for a few days to discharge the bank enough to allow enough time at C/10 to do any real good.

Cariboocoot · September 2011

Re: More Surrette problems

Vic;

We're all succumbing to short-cut syndrome. The fact that shooting for that 10% peak charge current just happens to bring the whole system design in-line so that it will work reliably well under most circumstances is leading people to believe it's the be-all and end-all to system design. I just can't think of any other way to explain it without going "Tolstoy". :roll:

I'm glad you mentioned the need for regular EQ charging on lightly-cycled banks. That' another character trait of deep cycle batteries; they actually do want to be drawn down and charged up hard every now and again. Keeping them burbling along at 10% capacity in/out also isn't good for them. Normally this isn't a problem because batteries are so expensive people can't afford that much capacity and they have to run them at 25% to 50% DOD.

It's a problem trying to explain things in general terms and rules-of-thumb to get people started and then have them come under the impression that no more is required. The site-specific nature of solar says that can not be so. But people get easily overwhelmed by all the variables. It is complex and daunting and by trying to make it easier to understand technical accuracy tends to suffer.

If anyone can come up with a better way to explain it that includes the nuances but doesn't take 6,478 paragraphs ... we all want to hear it!

SolaRevolution · December 2011

Re: More Surrette problems

A little side bar for this thread:

Vic wrote: »

Marc,

Banks that are lightly cycled and charged from solar, will almost never see high rate charging (even if C/5 rate was avaliable), unless the day starts very cloudy until about solar noon. Because, the bank is (usually) recharged at lower rates, starting early in the morning, and the bank is out of bulk well before solar noon....

...And so on, perhaps just too fine a nit to pick. Here, when we do our occasional high rate charge, need to shut off the solar input for a few days to discharge the bank enough to allow enough time at C/10 to do any real good.

I've been thinking about this for some time. It seems to me there is a good arguement for a SE facing array for off-grid.

I did an off-grid Sunny Island, Sunny Boy, system with 18kw of PV for a cell tower where the site requires a SE orientation and a fairly high tilt which helps shed snow. The loads run 24 hours a day with typical phone peak hours. The array is in full, fairly perpendicular, sun by 9:AM. The batteries seem to get a great AM charge and are usually full by 1:PM. There is not much on the panels after that so the generator usually runs in the late evening- middle of the night. If the budget ever allows we will be adding about 50% more PV with a SW orientation.

I'd like to try an off-grid with a fairly large SE array and a modestly sized tracker. This would provide a high charge rate for AM recovery with afternoon float charging.

Dave Angelini · December 2011

Re: More Surrette problems

Vic wrote: »

It is my belief that a high charge current, 10% of capacity for example, has very little to do with mixing electrolyte. But, rather has more to do with keeping the active plate material exposed to the electrolyte.

It is, IMHO, the later part of Asorb, and EQ which causes the remixing of electrolyte. This occurs when we hear the electrolyte bubbling. This certainly does NOT occur in my Surrette banks during High-Rate charge. Vic

Just had to quote this again because it is so very true. I would add that the one thing that people often forget is the mechanical nature of batteries. While being so concerned with the electro-chemical science they forget the stress that happens everyday offgrid.

I believe that the mechanical conditioning of a bank that delivers a fairly constant quantity of KWH day in and day out is very important for long life. Deep discharging, high charge rates, and crazy things like arc welding are not going to get you 10 + years of service. I copied nearly all of my design techniques from
sailors and the guy's who designed their batteries and charging systems. Most of it in the 70's and 80's. Sometimes I think the power system design guy's on spy satellites copied them also!

Batteries that need to last 10+ years for a offgrid home like slow charging/discharging daily.

terrynew · January 2012

Batteries still not charging

Happy New Year, everyone. It's been 3 months since I tried to fix my low gravities problem by dropping one of the two strings of 8 batteries. Sadly (understatement) the problem is not improving. Can I ask for help, please?

First, a brief review of the situation. In Nov 2010 my system was installed, twelve 215 W panels and 16 S600 batteries with an FM80 CC and a Magnum 4400 W inverter/charger. After 9 months of gravities stuck over 1300, Surrette found one shorted battery and replaced all 16 under warranty (yay). But the new batteries slowly went from a 1255 average down to a 1240 average despite 3 monthly EQs, and one cell was 1100 after the third EQ. So Surrette replaced that one battery in Sept 2011 and their tech support recommended I go with what several of you guys recommended: dropping one of the two battery strings.

You guys helped me with lots of suggestions and we tried many things. Most importantly, we concluded (and bonus to Coot for getting this right from the start) that neither the panels nor the generator could give enuf amps to fully charge the two parallel strings of 8 batteries. Since we also found my loads were much lower than originally estimated (63 Ah/d @ 48 V, or 3.0 kWh/d), we decided to remove one string of batteries instead of buying more panels. The plan was to see if a single string of 8 batteries could be restored to gravities of 1265 now that the panel and generator currents weren't being split across two strings.

So here's what happened: I disconnected string B, so string A was online alone, and I replaced the bad battery in string A with the new one (Sept 28/11). I did EQs Oct 5 and Nov 5, at which point the EQs had only improved slightly to average 1245. Not wanting to let string B discharge too much unconnected, I then disconnected string A and put string B online (Nov 6/11). I gave string B three monthly EQs (Nov 6, Dec 3, and today), but as with string A, little improvement has occurred: the post-EQ gravities average 1240.

So my big question #1 is, why haven't things improved now that I'm sending enough current to the batteries? (FYI, I'm presently doing 3 hr absorbs (57.6 V) and 4 hr EQs (63.2 V).) Here are some related things to consider:

Question 2: 215 * 12 = 2580 Watt array. At typical 77% efficiency: 1986 Watts / 57.6 Volts = 34 Amps peak potential current. The FM80 read 42 A out at 10:30 a.m. this morning as it went into absorb charging so that verifies we have the proper current. (Incidentally the FM80's absorb voltage is set for 57.6 V but it was automatically adjusted by my new RTS -- compensation set to Wide -- to charge at 58.4 since the room was cool.) The 10% current rule on my 450 Ah string comes to 45 A, so does this mean that even with just one string I still don't have enough current? Or am I close enough that we can rule out this as the problem?

Question 3: Some of you had thought I might have loss due to thin cables between the FM80 and the batteries. A local electrician had a look and thinks it's enough. But today when asbsorbing started, the FM80's output voltage displayed as 58.2 V, and a DMM across the 8 batteries read 57.2 V, a drop of 1 V. Similarly, during the EQ, the FM80 displayed 63.1 V and the DMM across the batteries read 62.3 V. Should I worry about this loss? Or should I set the FM80's VBatt compensation?

Question 4: My Generac Guardian 10 kW generator has a 45 A circuit breaker, but the MS4448SAE inverter/charger has a 60 ADC continuous output that only requires 17.5 A AC @120 V from the generator. But Surrette's tech support recommends a 50 ADC maximum to a string of 8 S600's. So should I be changing the MA4448SAE's Max Charge Rate to 83% (50/60)? It's 90% right now. And might this be affecting my troubles?

Question 5: In the last couple of months I've been generally charging by generator whenever the voltage drops to around 47 V, usually just for 90-120 minutes to get it up to 57.6 V. When I'm at 47 V, the MS4448SAE displays an SOC of 70%. Am I right that it's probably lower than this % due to the specific gravities never reaching 1265? I know that most of you recommend a 20% DOD rather than 50%, but I'm trying to balance between battery life and propane costs.

In closing, I wish someone could reply with a "GOT IT" Deus Ex Machina moment, pointing out some setting I have wrong or a specific component that isn't functioning. I tell ya, guys, I've been pulling my hair out on this system for over a year now and it's frustrating that it can't even charge the batteries properly. If I can't get it to normal gravities, I'm considering calling this whole thing a $35,000 loss and going on-grid. There's no way I could have found the time for all these discussions, meetings, studying and measurements if I wasn't unemployed this past year. It just can't go on like this. (more whines, edited out)

Thanks in advance for your thoughts. You guys are amazing.

...Terry in eastern Ontario

mike95490 · January 2012

Re: Batteries still not charging

If the batteries were low enough, for long enough, they may have sulfated. Sometimes, a Desulfator will cure it, sometimes not. Maybe that's your only hope now. Can you shine a light into the cells, what do the plates look like ?

If your acid is locked up in sulfur crystals, you are done, if a desulfator won't bring them back, and sometimes, the PWM phase of charging, can look like a desulfating waveform.

mike95490 · January 2012

Re: More Surrette problems

Question 5: In the last couple of months I've been generally charging by generator whenever the voltage drops to around 47 V, usually just for 90-120 minutes to get it up to 57.6 V

47V = dead batteries, And that rapid of recharge smells like sulfated batteries.

Cariboocoot · January 2012

Re: More Surrette problems

In addition to what Mike said ...

I would be worried about the size of wire between the charge controller and the batteries. A 1 Volt difference is too much. This means the controller will not get an accurate reading of the actual Voltage at the batteries, which is what it bases its charging on. It thinks they're about 2% higher than they really are. Measure the distance, use the nominal Voltage and maximum current and see what kind of V-drop you get. The FM80's V-Batt adjustment is for tenths of a Volt, and you need a really good meter to set it with (measure at the controller first to be sure the meter agrees with that point).

The Magnum's max charge rate is really there to keep from overloading a generator. This is probably not a problem. The inverter-charger will adjust its output current according to what the batteries need, not according to what is available from the generator.

I share Mike's concerns that it may already be too late for these batteries. Do you see any improvement at all from EQ cycles? Or does the SG just hold steady? Regrettably sulphated batteries will read "proper" Voltage and appear to function right, albeit with diminished Amp hour capacity. This means they'll charge quickly - and discharge quickly.

I suppose I shall reiterate here that the 10% peak charge current rule-of-thumb is a guideline, not an absolute. It does not mean you will be charging your batteries at 10% of their Amp hour rating @ system Voltage. It is a means of judging if there is enough capacity to properly recharge the batteries quickly enough (within the window or opportunity of good sunlight) so that they won't suffer damage. It is based on the lowest you want your batteries to go (system Voltage) and the peak current which would be applied at that point (10%). The batteries will start to charge wherever they are at when the sun hits the panels. They may not be down to system Voltage and they may not be 50% depleted so you will not see that current @ Voltage show up. Even if you do at the start, as batteries charge and come up in Voltage the current will reduce.

This situation is complicated by running systems while charging: net charge rate is gross minus current going to loads. So if you try for 10% you may, with everything detracting from it, achieve 7%. And again that will drop as needed because the closer you get to charged the less current flows. You really do not want to apply 10% current all the way up to and through the Absorb stage (unregulated charging). That's another way to wreck batteries!

jeffkruse · January 2012

Re: More Surrette problems

Like everyone else said.

Don’t let your batteries get below 48 votls (I think that’s less than 50% SOC).

Raise your ab voltage so the batteries are at 58.8 volts. You might need to set the ab voltage on the CC to 59.8 volts to have 58.8 on the batteries.

If your ab time comes from the panels and not a generator then set it to the max time.

terrynew · January 2012

Re: More Surrette problems

Whoa, I'm not arranging the funeral yet, guys. Good suggestion, Mike, on looking at the plates -- I don't see any sulfur crystals. Here's a photo -- what do you think?
Attachment not found.

To support my hope that the batteries are still useful, the answer to Coot's question about seeing a change in gravities during the EQ is yes: I checked one cell halfway through the 4-hr EQ and then again after it ended. It went from 1230 to 1245.

And thanks for the suggestion, Coot, to check the voltages on the wires inside the FM80. Under light clouds outside, the FM80 displayed V-out = 51.8 V but my DMM on the BAT+ and BAT- cables inside it read 51.1 V. The DMM on the other end of those cables (2' to the e-panel + 4' to the battery box) read 51.0 V. So am I right that this means the cable thickness isn't an issue and I should call Outback?

I'm quite frazzled to hear I've been damaging the batteries by going down to 47 V, given that my inverter tells me that is at 70% SOC. I guess it can't be trusted if a full charge doesn't take the batteries to 1265. I'm guilty as, uh, charged.

One possible recovery method is a suggestion from Surrette's Tech Support: "I just finished 'reviving' a set of batteries for a local customer. They are 6 years old and happened to be low on capacity and SG. All I did was put the S460s on charge at 15A for 36 hours and then did 2 charge-discharge cycles. After this, the batteries were back at 80% capacity tested, which is acceptable. Is this something you think you could achieve?" May I ask what you guys think of this suggestion, and how it might be achieved? 36 hours sounds like trouble for my generator.

I'd be grateful for some optimism from you based on what I've said in this message ... anyone? In hope,
...Terry

Cariboocoot · January 2012

Re: More Surrette problems

terrynew wrote: »

And thanks for the suggestion, Coot, to check the voltages on the wires inside the FM80. Under light clouds outside, the FM80 displayed V-out = 51.8 V but my DMM on the BAT+ and BAT- cables inside it read 51.1 V. The DMM on the other end of those cables (2' to the e-panel + 4' to the battery box) read 51.0 V. So am I right that this means the cable thickness isn't an issue and I should call Outback?

No. If the FM80 shows 51.8 Volts on its screen but your DMM reads 51.1 at the FM80 that is only a difference of 0.7 Volts. You can adjust the FM80 to match this. There seems to be a 1 Volt difference between the FM80's screen and the DMM at the batteries. Leave out the 0.7 Volts and that is a 0.3 Volt drop across the wires, which is not very much but still can be a bit off for getting right charge Voltage set points. What size wire have you got?

I hate to be pessimistic, but to me that picture looks like severely warped battery plates. Might be my increasing astigmatism, or it might be time to call the undertaker.

waynefromnscanada · January 2012

Re: More Surrette problems

Cariboocoot wrote: »

I hate to be pessimistic, but to me that picture looks like severely warped battery plates. Might be my increasing astigmatism, or it might be time to call the undertaker.

OUCH! Same here Coot, looks like those plates are screwed, or at the very least they've taken on the shape of a screws thread

terrynew · January 2012

Re: More Surrette problems

Argghhh, this story just keeps getting worse, eh? I hadn't ever looked at the plates before, just the fluid depth. I've just done some surfing and confirmed what Wayne and Coot pointed out, this is baaaad. It gets worse -- all sixteen batteries (both strings of eight) have these warped plates. Interestingly, so does the one that failed after just 3 months and was replaced by Surrette. So either something done during the first 3 months (and possibly since then as well) caused this, or (very unlikely) they came that way. Almost time to talk with Surrette.

But first, detective time. So tell me, please, what can cause this plate warping? My surfing has turned up some causes that I've ruled out (low fluid levels, freezing, overheating) and one more-likely cause, overcharging. Can anyone think of other causes? Does 'overcharging' mean voltages too high or gravities too high? Both are unlikely in my case since the voltage never got above 63.2 for an EQ, and I've never observed a single cell above 1265 (and few that high). Or does 'overcharging' mean absorbing or equalizing for too long or too frequently? Below are two cases where I did that:

1. On July 27 (7 weeks after installing all 16 new batteries) I did a big charge, suggested by a local solar installer and first approved by Surrette's Tech Support guy -- I did 4 hrs of solar absorb, then 2 hrs of solar EQ, then 4 hrs of generator EQ. Air temp was 84 F. It didn't solve things: right after this, most cells were still around 1250 (using a refractometer with auto temp adjust) but this was when I first noticed one bad battery had a cell with 1150 -- this is the battery that was replaced under warranty two months later, Sept 28. Unfortunately I didn't check for warped plates before or after The Big Charge. Thereafter I went back to 4-hr EQs monthly, so could this one day's charging have caused such plate damage?

2. Surrette's Tech Support had me change absorb hrs from 3 to 6 (when by solar) and from 3 to 4 (when by gen) back on July 7 (1 month after installing all 16 new batteries). After 3 months with no improvement, this was reduced back to 3 hrs Sept 28, when I replaced the bad battery and took one of the two strings of 8 offline. Could this worsen the plate warpage?

So does this two-pronged scenario explain my situation? First, the difference between the FM80's displayed vs. actual V-out means continuous under-charging and thus the gravities never reached 1265. And second, perhaps The Big Charge damaged the plates and so the undercharging has gotten even worse since then. Or are there other causes of warped plates that need to be considered?

One outstanding question is, why do you (Coot & Wayne) and some other websites say the bad warping means the batteries are toast, when they appear to have been working (albeit undercharged) since The Big Charge 5 months ago? How long might I expect to get value from them? Is it that they risk shorting out any day and causing, uh, what would happen if they short out?

Humbly thanking y'all for your thoughts,
...Toasted Terry
P.S. Coot, I'm not sure we have a 0.3 V drop across the battery wiring as you suggested in your last post. On Jan 3 I had a 1.0 V difference between the FM80 display and the battery box, but I didn't measure the battery cables in the FM80 that day; is it possible the difference between the FM80 display and the actual voltage inside the FM80 could vary day-by-day? Today I measured 51.8 on the V-out display, 51.1 on the cables inside the FM80, and 51.0 in the battery box, so that's only a drop of 0.1 V across the lines. I'll check this again tomorrow before changing the V-Batt parameter on the FM80. (I'm sorry, I don't know how to tell what size the wires are; should I just do a width measurement in sixteenths of an inch? I promise I won't use a metal ruler.)

Vic · January 2012

Re: More Surrette problems

tn,

I am not familiar with the exact batteries that you are showing in the pic, BUT,

I wonder is what we are seeing in the photo, are the separators. They do not look like any plates that I have seen. Although, have not seen separators that high above plates, if the warped thingies are separators.

Will go back and look at the pic again.

EDIT: If voltage drop is caused by the resistance of the interconnect, then the voltage drop is dependant on the amount of current flowing. One of my MX-60s required a 0.5 volt adjustment in the CC to have it agree with my good DMMs reading.
Vic

mike95490 · January 2012

Re: More Surrette problems

What causes plates to warp? I thought it was mostly heat. (from fast discharge, fast recharge, long cooking in Eq)
What were battery temps during those long hours of Absorb and Eq ?

Cariboocoot · January 2012

Re: More Surrette problems

Hmm. I wonder if Surrette always advises people to deep-fry their batteries?

"Absorb for 4 hours on medium, then increase heat to high and Equalize for six more hours. Serve warm."

Things like that, to my knowledge, will warp plates. "Overcharging" can be: too high Absorb or EQ Voltage or too long in a high Voltage state (even if correct Voltage), or too high a current (yes it is possible). A shorted cell will also cause an overcharging condition in the other cells (think of it as dropping 2 Volts from the battery's nominal rating and figure what that would mean).

Even if the plates are warped the batteries may still work, but only by the good grace that they didn't warp so that plates short together. The likelihood that something catastrophically bad will happen in the future is still increased.

Anyone who has ever read me droning about Equalization has seen the dictum of doing it for one hour at a time and allowing the battery to rest between "bouts" of high Voltage. Check the SG again, then repeat. If there's no improvement or SG stops rising on the low cell(s), it's time to stop. Repeatedly hammering batteries with high Voltage isn't good for them.

As for the controller to battery wiring ... it ought to be labeled. Some tiny little print on it that hopefully says "6 AWG" or such. The thing about the Voltage difference is that the higher the current flowing through the wires the greater that difference will be. So with full batteries you may see an inconsequential difference (0.1 Volts) but when they need that full current the difference rises to where the controller no longer reads close to what the batteries actually are (like that 1 Volt difference you saw). You read the Voltage at the controller's output with the DMM to see how close the two meters agree. Then check it at the batteries when the current is high to see how much V-drop is occurring in the wiring.

terrynew · January 2012

Re: More Surrette problems

Thanks for this info, Coot. To clarify your EQ method, am I right that I start by measuring the SG of the lowest cell in the string, EQ for an hr, and only do another hr if the SG has gone up? Should I decide to continue or not based on the EQs of any other cells as well? Is that lowest cell what you've referred to as the 'pilot' cell in past messages? And is an increase of .0005 (e.g. 1240 to 1245) enough to continue?

Thanks also for the AWG tip. The V-out cable is marked 4 AWG and is aluminum. Is that okay? The V-in from the panels is copper and looks the same thickness but I can't read its AWG#.

The Outback Tech Support agree with you that I should measure the V-out wire inside the FM80 using a high-quality DMM, what he calls a true RMS meter. I'll try to borrow one from a nearby electrician tomorrow. He also says the difference between the V-out display and the actual wire inside the FM80 may be due to the RTC but shouldn't the display already be adjusted for that?

Hmm, am I missing any info? I think it's time for me to call Surrette.
...Terry

Cariboocoot · January 2012

Re: More Surrette problems

Yes, you want to watch the cell with the lowest SG - but also the others. You do not want the "good" cells charging too much, which can happen if the "bad" cell is really bad (shorted). If you can read a hydrometer to 0.005 .... well I can't. But any increase in the bad cell justifies continuing. It is unfortunate that EQ is best done with zero loads and the batteries out of service. It is also best done on individual cells, but few batteries support that. So we deal with what we've got and hope.

4 AWG is good. Aluminium is not. You couldn't swap that out for 6 AWG copper, could you? The aluminium will have a higher V-drop and problems with corrosion at the connections. Personally I don't like aluminium wire. It's usually only used for very high gauge applications where the additional weight of copper becomes problematic. Still, what you've got shouldn't present more than a 0.5 Volt drop at 48 V & 80 Amps over 6'.

I do not recall exactly, but I think the Outback RTS alters the Voltage set points, not the Voltage readings. This may seem backward, but in essence it works. Unplugging the RTS will eliminate it having any affect on Voltage readings and negate the issue.

terrynew · January 2012

Re: More Surrette problems

Good news: I showed the plates photo to Surrette's Tech Support Manager and he said "What you see that is warped is the separator material and not the plates. No worries!" Phew, it shows we shouldn't jump to conclusions, eh?

What this does mean is that we return to the original purpose of the plates photo -- can you see any sulfur crystals? If not, then we can still do something to clean up the batteries, right?

One possible recovery method is a suggestion from Surrette's Tech Support: "I just finished 'reviving' a set of batteries for a local customer. They are 6 years old and happened to be low on capacity and SG. All I did was put the S460s on charge at 15A for 36 hours and then did 2 charge-discharge cycles. After this, the batteries were back at 80% capacity tested, which is acceptable. Is this something you think you could achieve?" May I ask what you guys think of this suggestion, and how it might be achieved? 36 hours sounds like trouble for my generator, and I don't know how I'd tell the inverter to drop the current to 15 A.

...Terry
PS Thanks for the EQ,cable, and RTS info, Coot. I'll ask a local electrician if he can replace the aluminum with copper. And I'll measure the voltages with the RTS unplugged and get back to you.

Cariboocoot · January 2012

Re: More Surrette problems

Couple of things.

You can't see all of the plates (or even all of one) looking through the filler hole. You can see that you can't see any sulphation. That doesn't mean there isn't any, but it does mean if there is it hasn't got to the point where it's about to start climbing out the holes. Hopefully Surrette is right about that just being warped separators, although why they should be warped I don't know. Plates & separators tend to be a sandwich of parallel flat bits.

Trying to do a constant current charge is tricky, because the equipment you've got isn't designed to charge that way. You'd have to rig up a charger you could watch the current and adjust the Voltage on to keep the current at spec. I'm not familiar with Magnum's programmability, but I suspect it's based on Voltage set points like most others are.

I don't agree with Surrette that 80% capacity is "acceptable". It's 20% depleted. Whereas we know battery capacity goes down over time, 20% is a lot of capacity to be out.

Do what you can with them with what you've got to work with. Use them 'til they're unquestionably incapable of providing the power you need. Then buy some Trojan or Crown batteries. I'm completely disillusioned with Surrette. Others are free to make up their own minds.

waynefromnscanada · January 2012

Re: More Surrette problems

Given Surrette's apparent desire to deny any and all problems with their batteries, when in reality they do indeed have problems, some of them very sever at that, causes me to consider their statement that the twisted mess showing through the filler hole to be OK, is highly suspect at the very least. Pure BS at worst.
I have never in my life seen such a twisted mess in any good battery, nor would I ever purchase any battery in that condition. Sorry Surrette, I just don't buy your story, I'm convinced there's a lot more to that mess than you're letting on to your customer

Vic · January 2012

Re: More Surrette problems

tn,

Glad that you got the official work from Surrette. I felt that those must have been separators, as they almost could NOT have been plates. At least have never seen any plate that looked like that, or that color.

Have placed some Surrette S-530s in service, about 6 years ago, and the separators are not visible, as the Moss Guard is between the Vent Well and the guts of the battery. Looks like this newer separator performs the Moss Guard/Separator function, being as tall as they are.

Glad that you do not have to concern yourself with warping of plates!

Good Luck with your batteries, Vic

terrynew · January 2012

Re: More Surrette problems

Thanks for your support, Vic -- good call on the plate separators. More good news: I've ruled out the possibility that I was undercharging due to voltage loss between the charge controller and battery box. Taking the advice of Coot and Outback's Support, I used two true RMS meters to read both ends of the battery cable. The FM80's V-out display agreed exactly with the DMM's values inside the FM80 at the lugs and inside the battery box at the other end. My own DMM continued to show a 0.8-1.0 V drop, meaning it's a piece of garbage or at least needs recalibration.

The only bad news in ruling out the two above problems is that it still leaves our mystery unresolved: why aren't my SGs getting up to 1265 with either solar or gen charging, even after 4 hrs of equalizing? After all, I've observed 42 A going in at the start of solar charging, and my MS4448PAE says it's continuous charger output is 60 A, both of which are good enough for the batteries.

Should I bump up the absorb voltage like Jeff suggests beyond 57.6? And/or should I bump up the absorb time from 3 hrs to 4.5 hrs? That 4.5 figure comes from Surrette's recommended equation, t = 0.42 * C / I where 0.42 = 20% / 50% + 5% losses and where my C=450 and I=42.

Or can anyone think of anything else that might be leading to this undercharging?
Thanks again,
...Terry

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