The Max Smoke charging model

[inetdog]

... With a NiFe battery bank, I'm mostly trying to save distilled water, low charge is not a killer on them like it is for Pb H2SO4 cells

Just out of curiosity have you ever calculated the cost per kWh that you can attribute to distilled water purchase?

[Rainwulf]

This has been extremely informative!

I didn't get a chance to get my temperature comped hydrometer today but will try and get it tomorrow.

I have reset my MPPT controller to the voltages indicated, 14.8 absorption for now, and see if i can either get gassing or hydrometer indicating 100 percent SoC, turn down the voltage, or if the hydrometer indicates less then 100 each afternoon, wind the voltage up a bit more.

What would be ideal is a charge controller that can actually do its own hydrometer tests and then adjust to suit!

I now know what killed my last set of batteries, i only got 3 years out of them, and it was simply lack of charge. The first year of their life was on a PWM controller! Those poor batteries, i feel so guilty.

I still have them, they are probably sulfated up bad.

[Willy T]

Just having a Hydrometer and knowing how to use it is half the the battle. Knowing the fill strength of the electrolyte is the other, don't assume. A good example is the Trojan RE line as of June of 2012 ( F2 date ) the electrolyte strength was changed to 1.280 and many dealers sold mixed stock. To assume that one battery manufactured has all the same requirements that another has is a mistake. Example : Trojan Smart Carbon alloy is much different that their regular deep cycle batteries and has different charge requirements so you have to know your batteries and not what is always posted here.

[Rainwulf]

Just having a Hydrometer and knowing how to use it is half the the battle. Knowing the fill strength of the electrolyte is the other, don't assume. A good example is the Trojan RE line as of June of 2012 ( F2 date ) the electrolyte strength was changed to 1.280 and many dealers sold mixed stock. To assume that one battery manufactured has all the same requirements that another has is a mistake. Trojan Smart Carbon alloy is much different that their regular deep cycle batteries and has different charge requirements.

Hmm. Thats a good point. I am not sure what the actual strength is, i cant find it anywhere on the limited datasheets i have. At least every battery i have is an identical date and batch.

[Willy T]

The basic standard here ( USA ) has been 1.265 for most batteries, but some are different. By using the wrong number if it is to low you could be giving up capacity by leaving the plates partially sulfated. When you do a commissioning charge before using them you get your constant, it's the foot in the sand you can always return to, but to do that you have to know what it filled with.

[Rainwulf]

The basic standard here ( USA ) has been 1.265 for most batteries, but some are different. By using the wrong number if it to low you could be giving up capacity. When you do a commissioning charge before using them you get your constant, it's the foot in the sand you can always return to, but to do that you have to know what it filled with.

Ah, well thats what im doing now then. I got them installed on saturday, and just dialing in some things like my charge controller and my diode isolation. Today they got a full charge with no load, and tomorrow i will do the finishing charge to find out what the SG is before the gassing starts. They are sitting at 1.265 right now, but they havent been conditioned yet.

edit: 1.270 is what they ended up with 2 days of float and conditioning charge.

[Rainwulf]

Well... im at 1.265 (100 percent is 1.270) by 11am.

Im ALREADY in float mode, with at least another 5 hours of daylight available.
I think i have too many panels. Is that a thing?

[Mike90250]

Well... im at 1.265 (100 percent is 1.270) by 11am.

Im ALREADY in float mode, with at least another 5 hours of daylight available.
I think i have too many panels. Is that a thing?

Winter is coming!

Summers, I have 300 minutes of float, with my irrigation pump running for about 2 hours a day.
Winter, no irrigation, some days I'm lucky to even start absorb, 5Kw PV, about 11KWh daily use.

[PNjunction]

I now know what killed my last set of batteries, i only got 3 years out of them, and it was simply lack of charge. The first year of their life was on a PWM controller! Those poor batteries, i feel so guilty.

I still have them, they are probably sulfated up bad.

Since you still have them, check electrolyte and let an Optimate 6 charger do it's thing with nothing else connected to the battery. If they are really big, then charge them up with a bigger charger, let them rest, and then let the Optimate 6 have a go. Critically, let it FINISH the 12 hour testing cycle, indicated when the led's are *solid* and not flashing.

Some pull the Optimate 6 off too early when they notice the charger has finished, but don't follow through with the test - which will go back to a charge mode, or give you an indication if your recovery was successful, or you just have a heavy zombie on your hands.

While I think that proper battery maintenance from the start is the best way to go, I don't often recommend wasting time with typical consumer hail-mary's. The Optimate 6 is MUCH smarter than that. And if you are so inclined, be mesmerized by the blinkenlights.

[SunEagle]

Winter is coming!

Summers, I have 300 minutes of float, with my irrigation pump running for about 2 hours a day.
Winter, no irrigation, some days I'm lucky to even start absorb, 5Kw PV, about 11KWh daily use.

Winter is coming!!! Better build the wall higher to keep out them blue eyed guys.

[Sunking]

Well... im at 1.265 (100 percent is 1.270) by 11am.

Im ALREADY in float mode, with at least another 5 hours of daylight available.
I think i have too many panels. Is that a thing?

If 1.270 is 100% then 1.265 is about 90%, no where near fully charged. What was the temp of the electrolyte. You did do Temp Compensation right?

[Rainwulf]

If 1.270 is 100% then 1.265 is about 90%, no where near fully charged. What was the temp of the electrolyte. You did do Temp Compensation right?

i did to temperature compensation yes. I also slightly upped my float voltage a bit more to make sure i got full charge in before sundown.
Now i have to wait a few days to make sure there are no bad trends in the SG.

I also discovered that the batteries in the high part of each shelf have different SG to the bottom, and also take and give more charge.

I have to put them all at the same level this weekend.

[Sunking]

I also discovered that the batteries in the high part of each shelf have different SG to the bottom, and also take and give more charge.

That right there tells all of us your panel wattage is to low. When the heavier acid sinks to the bottom of the Jar and water floats on top is called Stratification. In mobile applications Stratification is not an issue because the electrolyte is stirred up with each drive by physical movement.

In Stationary applications Stratification can become a problem especially if charge current is TOO LOW. With at least C/12 charge current you cause the electrolyte to agitate toward the end of the charge as the batteries approach Gassing Stage. There has to be enough current so when the gasing starts the electrolyte begins to boil and roll a bit if charge current is at least C/12 to C/10 range.

So if you have Stratification problems is caused from too low of a charge current which is caused by not enough panel wattage. With a Solar system the window of charge current is very small. With FLA the min = C/12, and maximum = C/8 to C/6.

So what is your charging current, and what is your battery AH rating? I would bet your charging current is too low.

[Rainwulf]

That right there tells all of us your panel wattage is to low. When the heavier acid sinks to the bottom of the Jar and water floats on top is called Stratification. In mobile applications Stratification is not an issue because the electrolyte is stirred up with each drive by physical movement.

In Stationary applications Stratification can become a problem especially if charge current is TOO LOW. With at least C/12 charge current you cause the electrolyte to agitate toward the end of the charge as the batteries approach Gassing Stage. There has to be enough current so when the gasing starts the electrolyte begins to boil and roll a bit if charge current is at least C/12 to C/10 range.

So if you have Stratification problems is caused from too low of a charge current which is caused by not enough panel wattage. With a Solar system the window of charge current is very small. With FLA the min = C/12, and maximum = C/8 to C/6.

So what is your charging current, and what is your battery AH rating? I would bet your charging current is too low.

Sorry i think you mis-understood.

I have batteries on a 2 tier shelf, 2 at the bottom and 2 at the top. I have no way of measuring the SG at the bottom of the battery heh.
its sorted itself out now, the batteries are slowing starting to synchronise. I have put a current meter on each battery string and i can tell which strings are charging/discharging heavier.

As of now, all SGs are the same, lower and upper. I have 1 string out of the 4 drawing about 10 percent more current which charging and discharging.

Parallel batteries are a pain and the next time i get batteries im going the individual cell route.

Charging current is 25 amps per string. Each battery is 200ah.

[inetdog]

Sorry i think you mis-understood.

I have batteries on a 2 tier shelf, 2 at the bottom and 2 at the top. I have no way of measuring the SG at the bottom of the battery heh.
its sorted itself out now, the batteries are slowing starting to synchronise. I have put a current meter on each battery string and i can tell which strings are charging/discharging heavier.

As of now, all SGs are the same, lower and upper. I have 1 string out of the 4 drawing about 10 percent more current which charging and discharging.

Parallel batteries are a pain and the next time i get batteries im going the individual cell route.

Charging current is 25 amps per string. Each battery is 200ah.

Get a clamp-on DC ammeter (~$50 from Sears) and measure the load current and charging current for top and bottom shelf. Or do you have that already and that is how you got the 10% difference?
There may be a difference in wiring resistance that causes an unequal current flow.
If the load currents are unequal but the charging currents are balanced do you have inverter and charger connected at the exact same place?
Are you using a bus bar or trying to make do with a wiring harness? That does not work for multiple parallel batteries.
Once the batteries get out of balance they will just get worse unless you separate the two banks and charge them separately to 100% SOC or beyond.