Please Help me to understand FLA battery.

[ChrisOlson]

That was my point earlier... you notice these things much sooner if you have only one string...there are no other strings to mask the problem.

Yep. A good battery monitor with midpoint sensing can keep track of multiple strings for you. And that's what we have now - two of them. It's actually best to have a monitor on each string if you run lots of parallel strings (or buy a PentaMetric that can track three strings). The nice thing about a good battery monitor is that it keeps a detailed history so if there is a warranty problem you have the data (along with your logs) to back up your warranty claim. Without the detailed data that shows everything that has gone on with your batteries, you are pretty much screwed on warranty no matter what company you deal with. I've heard that Trojan is reasonable on warranty claims. But Rolls is most definitely not - sometimes taking two months to process a claim on a defective battery or cell where good records have not been kept, and flat out denying some claims. If you have detailed logs and data Rolls will process a warranty claim much faster.

[mapmaker]

We had one on our old batteries many years back that shorted out.
<snip>
Had three parallel strings and the two good strings handled all the loads on discharge, and the string with the dead cell took the gaff on charging and boiled all the water out of the 11 good ones.

That was my point earlier... you notice these things much sooner if you have only one string...there are no other strings to mask the problem.

--mapmaker

[ChrisOlson]

It is not BS Chris. PbC is the real deal and changes a 3000 cycle battery to a over 10,000 to 100% DOD.

Sunking - my hope has always been that when our current batteries go south that they'd come up with something better to buy the next time. We're only in our early 50's and plan on living here at least the next 15 years yet before we give up on the rigors of the off-grid lifestyle and can't do it anymore. So I expect we'll have to buy one more bank of batteries at some point. By the time we retire from off-grid living, they'll probably have the cat's meow in batteries, making all the money we spent to live here for 30 years look ridiculous (which it is probably is now).

[ChrisOlson]

I think I would notice a shorted cell pretty quick... but then I don't really know because I've never had one

We had one on our old batteries many years back that shorted out. These days, with the equipment I got now, I'd notice it immediately because alarms would go off on battery monitors indicating the midpoint voltages aren't right. Back then I didn't notice it right away (24V system) and smoked the rest of the string because the shorted cell was just like completely removing it and running the whole string on 11 cells. Had three parallel strings and the two good strings handled all the loads on discharge, and the string with the dead cell took the gaff on charging and boiled all the water out of the 11 good ones. I didn't have a good battery service plan then, no logs, nothing. Didn't discover it until my wife said the batteries are going dead all the time, so checked water one day and had a whole string bone-ass dry (and 900 pounds of scrap lead).

That's one of them "live and learn" deals where you decide that the cost of a good battery monitor is less than a string of batteries. And even then I didn't put in a real battery monitor - I installed some cheap volt meters to keep track of the midpoint voltages. A couple months later I had another cell in another string go bad and the voltmeters caught that one. But it was too late - the bank was due for replacement because I only had one good string left, and stuck a used battery in where the second cell had failed. The next month was spent trying to come up with $10,000 to buy new batteries. And this time I spent the money on good monitors.

I've heard it said that all off-grid people go thru this - wreck your first set due to gross negligence to learn how to take care of the next set that cost more money.

[Sunking]

It becomes marketing BS when you call it Smart Carbon. Carbon is dumber than a rock.

It is not BS Chris. PbC is the real deal and changes a 3000 cycle battery to a over 10,000 to 100% DOD. They are the only lead acid battery that can work PSOC range without damage. They could easily knock Lithium out of the market. Kia motors has already tossed lithium out and uses PbC in their EV.

They are quite real and 4 manufactures are making them who are Furukawa DEKA, Axiom, and now Trojan. There is a ton of info from reliable sources out there I suggest you go look at them like this one from Sandia National Labs. If they can deliver half of what they claim is a Quantum leap in battery tech. Test results from Sandia indicate 30,000 cycles to 100% DOD.

[mapmaker]

With a single series string, a cell can go bad, but you'll know it right away.

Not if a cell shorts out.

OK. I was assuming that the operator would notice voltages were not right. Why is the voltage only 49.8 volts an hour after sundown? Why did the low voltage disconnect (which is set to 48.0) get triggered during the night? Doesn't everyone have a trimetric in the living room?

I think I would notice a shorted cell pretty quick... but then I don't really know because I've never had one

--mapmaker

[ChrisOlson]

So Chris, You tell me that you keep discharge your batteries from 85%SOC to 50% SOC and charge them back to 85%SOC repeat for days and have no problem with sulfation? what voltage do you set your absorption start? 48 volt system.

Absolutely zero problems with sulfation - BUT we use three-stage bulk/absorb/finish charging, which most controllers can't do. Absorb V is 2.45VPC (58.8V). Finish V is 2.58VPC (61.9V) with net amp exit from finish stage at 2% C(20hr). XW solar controllers with firmware at or newer than V01.05.00-0006 can do three-stage bulk/absorb/finish charging with float at end of charge, or optional no-float end of charge.

Edit:
Absolutely zero problems with sulfation
I should clarify this. If the battery has been in a short cycle (less than 2 days) it can reach 100% SOC in about 1.5 hours from start of absorb. A medium length cycle of 5 days or so will take 4-5 hours from start of absorb. If it has been in a long cycle (7-10 days or more) it can take two days to charge to 100%. The first day the 5 hour max timer will time out before it gets to 100% SOC. The second day might take an additional 3 hours or so to finish.

That long time to get back to 100% SOC is the effect of sulfation on a long PSOC cycle. So when I say we have zero problems with it, I mean we have zero problems fully desulfating the battery to keep it healthy. Use of the normal 2.45-2.50VPC absorb charging will NOT charge a Rolls battery back to 100% after a long PSOC cycle. The higher voltage is necessary to achieve full 100% SOC. This can be accomplished with most controllers by using a EQ cycle set at recommended finish voltage instead of EQ voltage. But I like the XW controllers, and that's why I ended up switching from Classic 150's to the XW's - the XW system has quite precise net amp measurement capability and does not over-charge the battery. And the XW system does not have to be closely monitored to take care of the battery correctly with our cycle regimen, as is necessary when using an EQ stage in other controllers for the finish charge.

So I'm not going to set here and tell you that we do will work for you. It takes the right equipment, and to have it set properly and calibrate the charging with a hydrometer over several cycles to make sure you have it set right. If you run several cycles and find that your system is exiting absorb and you got a couple cells that "lagging" at 1.250-1.255 then your finish voltage is not set high enough. If you let those "lazy" cells "lag" for a long time, guess what you got? A battery with a sulfated cell that now needs several hours of EQ to "fix" it.

So setting up your system to run PSOC cycles by design is not a set it and forget it thing. It is a thing you manage every single day that you live with it. Some days you have to make the decision that, hey, the battery has gone two weeks and we're just not getting enough RE to charge these things up. So you end up running the prime genset for a few hours for two days in a row to take some of the load off the system so the solar can get them to 100% before they go too long.

And it means continued monitoring with the hydrometer from time to time. Our TriMetric has a Days Since Equalized thing on it that flashes. I have that set for 60 days. When we notice it flashing that means it's time to run the batteries to a full 100% SOC, then whip out the hydrometer and check every cell and write down the readings in the logs to make sure they are all reaching 1.260-1.265.

I guess these are the things that off-grid folks should be doing anyway, but few do. No matter what, living off-grid is more work (and way more expensive) than living with utility power and just throwing the switch. That's why I don't understand why some people have this desire to move off-grid when they got utility power. To do so is just plain ludicrous. There is no logical reason for it - you are inventing problems (and expense) that you don't have to have. Some say they want to do it in case the power goes out, and I say just buy a freakin' standby generator. The generator is WAY less expense and problems than what we have living off-grid full-time with batteries and solar panels et al. And us off-gridders STILL have to have a standby generator (or two or three).

[paulcheung]

So Chris, You tell me that you keep discharge your batteries from 85%SOC to 50% SOC and charge them back to 85%SOC repeat for days and have no problem with sulfation? what voltage do you set your absorption start? 48 volt system.

Thank you

[ChrisOlson]

Chris Lead Carbon batteries (PbC) is not marketing

It becomes marketing BS when you call it Smart Carbon. Carbon is dumber than a rock.

[Sunking]

For folks wondering about PSOC cycling, there is standard that battery manufacturers can certify to for PSOC cycling for RE applications. Trojan, as far as I know, is the first to certify to it coming up with their latest marketing scheme called "Smart Carbon" in their batteries:

Chris Lead Carbon batteries (PbC) is not marketing, it is a battery technology using Carbon in the negative electrode. The positive electrode is just like any Pb battery consisting of lead dioxide. However the negative electrode instead of being made of sponge lead is made of activated carbon. It still uses acid as the electrolyte.

The whole point of PbC batteries is to enable PSOC where conventional Lead Acid batteries cannot without sulfation issues. Trojan is not the first to come out with PbC batteries, that honor goes to East Penn (DEKA division) and a new start up call Axion. The technology is targeted at the EV and utility scale storage.

[Sunking]

With a single series string, a cell can go bad, but you'll know it right away.

Not if a cell shorts out.

[ChrisOlson]

For folks wondering about PSOC cycling, there is standard that battery manufacturers can certify to for PSOC cycling for RE applications. Trojan, as far as I know, is the first to certify to it coming up with their latest marketing scheme called "Smart Carbon" in their batteries:

http://www.trojanbatteryre.com/About_Us/Press_Releases/SmartCarbonPR.html

Well, our Rolls batteries must have regular old Dumb Lead because PSOC cycling has not hurt them at all in 7 years. I got a new Swiss-made hydrometer called a Hydro Volt that MidNite Solar is marketing now as the MNHydrometer. I had to check this new thing out because it has built-in automatic temp compensating. Our batteries are at 24.7C so no temp compensating anyway. But I checked every cell with it to see what we got on our latest PSOC cycle where our batteries once again reached 85% SOC for the day before they started to discharge at nightfall again.

Every single cell shows 1.242 - 1.245. Fully charged is 1.265 for our batteries. That pretty closely agrees with Rolls' published figures for 85% SOC SG. We use two-stage absorb/finish charging here with the finish stage at 2.58VPC, and consequently we never equalize because our cells never vary by more than 5-10 points after a full charge cycle.

So I don't know exactly what Smart Carbon does. But I find it hard to believe that it's any better than good old Dumb Lead that has proven itself to work fine here on PSOC cycles time after time. As far as I'm concerned, these battery companies can come up with all sorts of BS market speak. But the basic technology in the flooded lead-acid battery has not changed in over 150 years.

[ChrisOlson]

1. I know you have a very complex setup and use a lot of equipment to monitor your battery system and don't cycle the battery daily, but for forks like me are using the battery every night down to 20 to 35%DOD sometime even 50% occasionally. how the 260 cycles per year coming? isn't that 365 cycles per year? Can you explain?

Our battery is sized to use roughly 13 kWh of its 39 kWh capacity on a daily basis. This amounts to 33% of its capacity. Assuming we would fully charge every day we would discharge our battery to about 67% SOC every day. However, we don't do that. We use opportunity loads in the form of electric water heating to use up our solar capacity for that instead of charging batteries every day. We have a device called a Morningstar RD-1 Relay Driver:



That RD-1 is a programmable logic controller and it controls our water heating system and limits battery charging. It turns on progressively more water heating load as voltage tries to rise to Absorb V by operating SSR's. This sends the solar power to the water heater instead of batteries, and the RD-1 constantly adjusts how much load is on the system to match incoming RE power with loads to keep the voltage below Absorb V and "float charge" the battery instead of absorbing it. Once every week to 10 days or so, historically we get an exceptional RE day where the water heaters kick out due to the thermostats shutting off the elements and the batteries get absorbed and back to 100% SOC.

The reason we do this is because batteries do not live their lives based on the sun rising and setting like humans do. So quit trying to associate the solar cycle, and your daily cycle, with a battery cycle. Example: you discharge a fully charged battery at the 100hr rate, how long does it take to discharge it? 4 days. Then you spend a day charging it. This is a five day cycle. This is what we do here, and have been doing it for many years. Although in perfect conditions we will cycle our battery from about 50% SOC to 85% SOC on a daily basis for many days, using the RD-1 to control it (I have used many methods, including Waste Not in Classics, but the RD-1 is the latest method because it has way more flexible programming than a Classic does).

The reasons I do this are many. But in a nutshell we achieve very high cycle efficiency with our battery bank here. And our batteries run nice and cool for many days at a time, never exceeding 25C temp even in very hot weather. Batteries that are cycled to only 80% SOC, then recharged every day are being cycled on the most inefficient part of their discharge/charge curve and they run hot because of it. Running hot shortens the battery's life drastically from over-charging it (or charging it when it doesn't need to be charged).

This goes into quite a bit more detail, as I have spent years tweaking and tuning this system to get maximum kWh return from our battery investment, and I use one of the most sophisticated logging systems in the RE business to track it. But it is a different topic - the above is just in a nutshell.

2. One battery fail on the 4000 series didn't get caught and kill the whole string, so the 5000 series doesn't do that? they have different structure that prevent that happen? I know you can replace one cell but if it didn't get caught in time then what happen?

People that spend the money on 5000-series batteries are usually not going to have a low-end RE system. That means you will have battery monitors on the individual strings, do your battery service on a regular basis with logs, and you know what you are doing. You will catch a bad cell long before it becomes a problem and replace it.

People that tend to buy the lower-end batteries are usually not going to take care of them properly. They just buy them and hope for the best based on they read on forums (where they usually get bad information from people that don't have the experience to be providing the information). Off-grid systems are a whole different world than telecom battery backup systems, or grid-tie battery backup. There aren't many of us that live off-grid. And fewer yet that have been at it enough years to know what to do, and how much it really costs. Until you been there done it, you don't realize the implications of buying this new place you just bought that is miles from any utility lines and now you have to figure out how to survive and live a somewhat "normal" lifestyle. That's the position I found myself in many years ago, with a wife that was not quite sure about the whole thing. I've made my share of mistakes, but overall we've done pretty well here and would not give up our off-grid lifestyle even if ALGOR donated one of his mansions to us.

[mapmaker]

2. One battery fail on the 4000 series didn't get caught and kill the whole string, so the 5000 series doesn't do that? they have different structure that prevent that happen? I know you can replace one cell but if it didn't get caught in time then what happen?

It's a matter of serial vs parallel. When you have a bad cell in a parallel bank, the good string(s) can mask the problems in the bad string. Meanwhile, real damage is being done to the the good string(s).

With a single series string, a cell can go bad, but you'll know it right away.

--mapmaker

[paulcheung]

OK understood, two questions though.

1. I know you have a very complex setup and use a lot of equipment to monitor your battery system and don't cycle the battery daily, but for folks like me are using the battery every night down to 20 to 35%DOD sometime even 50% occasionally. how the 260 cycles per year coming? isn't that 365 cycles per year? Can you explain?

2. One battery fail on the 4000 series didn't get caught and kill the whole string, so the 5000 series doesn't do that? they have different structure that prevent that happen? I know you can replace one cell but if it didn't get caught in time then what happen?

Thank you.