Bad Cell?

[Westbranch]

We went to bed at ~ 9 pm and woke up at 7 am to what you see...  and it kept coming for the rest of the day albeit at a bit slower rate.  It was freezing rain when it started so a bear to get the vehicle doors open...  not much overnight and then another 2 inches of sloppy wet stuff! took 3 days of scooping to clear it all away so I could get tot the quad, and attach the snow blade...

cold? it's ~Zero F right now and clear skies, so it will drop a bit lower (15 below) overnight. Nice part is when the temp drops this low or down to 30 below, we get clear skies, with no wind,  and it counteracts the cold, in the daytime that is..., snow just sublimates and the ice slowly just disappears, no slush etc.

My dog (Chow/Collie) keeps the deer away so would do well on sheep, no barking till he is at the heels, he'll get those Big Horns off your 'lawn'.

[vtmaps]

What's got me lay'n awake at night now is the charge imbalance between strings. There is actually a couple of amps difference from the interconnect on string 1 and string 2. Add them together and you get the amperage on the big feed line to the inverter.

All the interconnects and crossovers were meticulously removed, cleaned and gooped up with that wazoo anti-corrosion stuff in a can. There is no connection problem there, it just has to be the resistance in the batteries (I'm out on a limb here and guessing). 

Good guess.  The internal resistance of the batteries is greater than that of the cables.  You can make your cables perfect but the VARIATION in the resistance of the individual batteries will steer the current. 

At first there is normal variation, but over time the small imbalance in charging caused by the small variation will cause uneven use of the parallel strings, which will cause further variation in the resistance of the batteries which causes further imbalance of the current flow... Positive Feedback!   Go back and reread Reply #12 in this thread.  Sooner or later... it happens. 

The battery string with the higher current flow warms up more than the other string.  This lowers its internal resistance which causes it to receive even more of the current flow, which makes it warmer which lowers its resistance which makes it receive more current... Positive Feedback!

Its amazing that parallel batteries can work as well as they do.  Here's how its done:  with some high energy density batteries (lithium, for example) a battery management system (BMS) is used...  each cell has its own battery charger.  That solves the problem of charge imbalance.  These cells must have a BMS because they will explode if overcharged.

Flooded Lead Acid batteries are remarkably tolerant of abuse and rarely have a BMS.   No two cells are identical, and the manufacturer calls for a charging protocol that will charge more than 99.9% of their cells, even though that means most of their cells are being overcharged.  These flooded batteries take a lot of abuse! 

If you're lucky you will find that you can reduce the absorb time or voltage, and keep all your cells charged, and you will have a longer than average lifespan for the battery.   The presence of a weak cell will determine the life of the battery, so a battery manufacturer must know what percent of their cells are on the 'weak' tail of the production curve.  Note that if a cell has a 0.02% chance of failing before the warranty period, a battery with 3 cells has almost 3 time the chance of failing before the warranty period.

The more cells you have, the greater the chance you have a weak cell that will result in a shorter life for the whole bank.  Therefore, the fewer cells you have, the better.  Of course, reducing system voltage to 2 volts is not practical.  What is practical is reducing the number of cells to the minimum: one string, at whatever voltage.

--vtMaps

[plongson]

Arggggh...

Nothing like learning from experience     You can read about this stuff forever but you really start to understand it when you live it. What a pain, and the worst of it is, it seems no matter what you do or how obsessed you are you're still at the mercy of the batteries. So what happens now? You just live with these things until they won't charge or discharge? Within reason, is there anything that can be done to extend the life? With just two years on the set, I'll bet I'm lucky to make five years, man that's pretty pricey power.

I have a neighbor that hasn't a clue about batteries, runs them down to the inverter cutoff nearly everyday and thinks it's normal. They just keep plugging away on the same set. I guess ignorance is bliss, and what you don't know won't hurt you.

It's like we're on the Titanic and she's leaking and going down. It's gonn'a sink and there is nothing that can be done but hope you get a lifeboat.   

Paul

[Westbranch]

Paul, this thread is right on topic for you, ....and a bunch of the rest of us.

http://midniteforum.com/index.php?topic=1528.msg12874;topicseen#new

[plongson]

Here's a follow-up...It looks like Surette is going to warranty the bad S-530 battery based on the info I produced. I don't have the money yet...but the emails have been flowing and it was apparently approved. Fortunately for me, I was able to get a replacement in Las Vegas. It shipped from California and I hauled it to Utah but at least it's in...Just keeping my fingers crossed now. Its taking about two weeks.

I'm off to read the link right now WestBranch...

THANKS!

[vtmaps]

Arggggh...

Nothing like learning from experience     You can read about this stuff forever but you really start to understand it when you live it.

It might be a good time to reread this: http://www.wind-sun.com/ForumVB/showthread.php?14674

--vtMaps

[plongson]

FWIW...I'm still waiting on a warranty check from Surrette for the battery they deemed junk in early November. I can't believe this is the way they do business.

Talked to Steve and he said he is in the tech side of things and Mary in the money side handles these things...

Ya, I know...Thanksgiving, Christmas, New Years, Hanukkah, Quanza throw in a birthday somewhere and you have dozens of excuses to not cut a warranty check for $400.

Grumble, Grumble, Gumbel...

Does anyone here see an advantage to taking a gamble with these guys? Usually a company that cannot pay its bills is on the rocks, maybe there is more to this than I think...

[Westbranch]

Hi Paul,  how is that bank doing with the new cell?

HNY too!

[plongson]

So far...Fingers double crossed...the system is back to performing great. It will support my setup just fine in these short winter days and long nights. Getting the gravity to 1.265 (as listed on the battery tag) is all but impossible but I do come close. I do have some cells that are always a few points lower, but that's just the way the cookie crumbles. No amount of charging or EQ'ing will drag them up to the desired mark...

We just keep trucking along in this imperfect world of off-grid solar...LOL    BUT GUESS WHAT, the days are getting longer...HaHA

Paul

[plongson]

Another little followup on this thread.

The replacement battery seems to have fit in just fine. As you may know, it was right at two years old when it failed and lost a cell. So far all is well...but

It failed the first week of November, I contacted Surrette and after filling out the required forms, they honored the warranty claim. Because I needed a battery NOW for the system. I purchased, from an authorized Surrette dealer, a replacement S-530 battery. Then came the fun part...getting reimbursed.

Long story short, it took 5 long months to get my $400 back. First it was Surrette dragging their feet for 4 months then the authorized dealer stringing me along for another month.

Actually I was very pleasant and understanding through the whole ordeal, full well knowing they all had me at a disadvantage until I got my cash. A gentle reminders every few weeks doesn't seem unreasonable.

If it had not been for my tenacity with calls and email every couple of weeks, I'd never seen the $$. I also feel I was being taken for a ride and both parties had no intention of coughing up the money and hoped I'd just go away. I personally think there is no excuse for this kind of service, no matter how busy you think you are.

Guess what, my next battery won't be a Surrette and I wont purchase a Trojan from this YaHoo locally either.

Paul

[TomW]

I personally think there is no excuse for this kind of service, no matter how busy you think you are.

Guess what, my next battery won't be a Surrette and I wont purchase a Trojan from this YaHoo locally either.

Paul

Paul;

Agreed this is unacceptible behavior from a supplier or manufacturer but seems to be the norm these days.

I agree to vote with your $$. Locally we have a few companies (non RE) that drag their feet or simply refuse to provide customer service. We simply do not buy from them unless there is absolutely no other option.

Got WildBlue sat internet a few months back and the installer / order taker messed up and got us on the Obama net economic recovery plan which I specifically said I was NOT interested in. They had to cancel the subscription and redo the order and WildBlue charged us for unreturned equipment that we never had because the installer reused the same gear for the correct subscription.

Upshot was I had to open a case with my card company and it took almost 4 months to get reimbursed. Letters from us, the installer explaining the issue. Many promises from WildBlue to reimburse us all just a tactic to get you to give up. $400 was just too much to walk away from for us. Even at minimum wage it took more than $400 worth of time to sort it out. Absolutely none of it my fault.

Luckily, I learned my lesson another time and immediately filed a claim on the charge otherwise my window of opportunity would have vanished to force them to give us our money back. I think that is their method of operations, put you off until you have no way to force the issue and you never communicate with the same person twice (or one that can do anything). Luckily the access is pretty good / fast and reliable. Locked in on a contract so glad it works as advertised.

Glad you got it sorted out.

Tom

[mahendra]

That is very true all of it no wonder big brand names keep crumbling because dishonesty = failure in the long term -Karma will catch up with you eventually.

[mahendra]

I am also a musician or would like to think i am.  The quality of the products i have seen for the past 10 years or so is of very poor quality and next to useless customer support,next to useless warranties (which the charge ridiculous sums for additional years) and poor repair feedback,assistance and service. all useless.I don't buy certain brands anymore even if they are better than the cheaper less better ones because at the end of the day i need a product that will do the job,of decent durability  and one that is of a good price.I would say that's pretty unprofessional of Surrette given the price for their batteries.I was anticipating to getting some surrettes based on the features but now i am sure i wouldnt.It would be nice if midnite solar go in the battery business too. . I know i am over  the edge here a little , but Midnite solar is one of the best where quality and customer service i have ever came across.

[plongson]

+10 A+++ x10 for Midnite staff and products. I totally agree!!!

I've got response from email and thread post ON A MAJOR HOLIDAY when I needed help!!!

Unbelievable service...

Paul