Diversion setpoint for 24 volt sealed cells?

[Boss]

Howdy folks
The wind has been blowing like mad here in northern NM for the last 48 hours
Ever since I installed the preowned sealed cell battery bank shown below:

These are  C&D UPS12-475FR sealed cell lead acid batteries
In an attempt to understand how these units operate I downloaded the spec sheet
http://www.powerprosinc.com/descriptions/brochures/cd-dynasty-ups-batteries.pdf
I've heard this term float charging voltage" mentioned here but I really do not know what it means
anyway it says float charging voltage for the 12volt units is 13.75 +or- 1.5 VDC
Actually, I pretty much don't know what any of the values in the specs  are used for. Please help
with real world info I need to help keep these batteries healthy.
Crap I almost for to to state my boggle
When I had our 10 foot turbine connected to 6 (matched date and AH) 12 volt flooded cell deep cycle batteries I saw 25 amps @ 27 volts fairly regularly on the amp meter in similar winds such as we have had over the last few days.
I decided to disconnect the load and let the measly 10 to 15 amps flow into the battery bank, in the hope that equalization would occur at some point.
I checked this morning after good wind all night and indeed the bank was finally up past 24. 5 volts and now it is at 25.5 volts
perhaps it did equalize, but the turbine still seems to be held back not spinning as fast cranking out higher wattage as it was with the wet cell battery bank .
Question is could the doubling of storage cause less amperage to flow, and hold the output of the turbine down?
Perhaps I ought  to let the voltage increase upwards to the float charge voltage 13.75 X 2 =27.5  volts before I put the load on again?

[hydrosun]

You don't want to equalize sealed batteries. You want to keep the batteries below the venting point. With non sealed batteries you can add water to replace what is lost while overcharging.
 The highest voltage you want is the manufacturers charging voltage. You said the float voltage is 13.75 +- 1.5 volt. I'd guess that the 13.75 is the max voltage you want to leave the batteries charging constantly at 75F room temperature.  Higher voltage at lower temps and lower voltage at hotter temps. The specs should also have a voltage and a time length to get a full charge.  With 13.75 as the float I'd guess about 14.1 volts as a full charge for 1 or 2 hours. With a Trace C-40 you would set the full charge for 14.1 and float for 13.75 and manual equalize. Other controllers set similarly.
Chris

[Boss]

Thanks
My Ghurd's diversion controller is currently set at 27 volts to begin dumping
It sounds like I can leave it there
on the equalizing issue with sealed cells is the only consideration the venting point?
I ought to buy a charge controller, but I have not worked since I tweaked my back 10 days ago, in my  case no work, no pay
I need to make what I have work, optimally
Being home does mean I can observe my system
What I need to know is what to look for, besides smoke I mean, grin

[Volvo farmer]

Equalizing to me means.. "boiling the electrolyte for a couple hours" It mixes up the electrolyte and puts any residual sulfate on the plates back into solution.  If some cells are higher in specific gravity than other cells, the equalization can help bring them all back to the same SG.  This is generally accomplished by bringing the voltage up to 2.5V per cell or so.

Since you are not supposed to equalize (read: boil) sealed batteries, none of this applies to you.

As an aside. I just noticed an interesting phenomenon with my wind turbine today. When my batteries are low, around 25V, it seems to stall the machine more. When I get up around 28V, I noticed a marked improvement in power into the batteries, at lower wind speeds. The thing just flies better. Perhaps this was the same thing you were observing?

[Boss]

thanks Volvofarmer
I appreciate the clarification on equalization. It doesn't matter what I thought it meant, I suppose, but I said to an observer of my system that it had to do with bringing the individual batteries  to the same voltage, so that electricity was not moving from less charged batteries from the batteries with a good charge, as they were before I rewired my system so that each battery has precisely the same length of cable run.

I wired up our old deep cycle batteries for 12 volts to use for our remote stage lighting system and I did not have enough cable to repeat the pattern I used on the new set seen below:

The voltage was different at the terminals further from the charger!
You guys really know what you are talking about
I can see from the stats on my site that a lot of you have looked at this already:
http://outfitnm.com/alt-energy/bmn-battery-bank-wiring-or-how-i-learned
thank you all so much, this makes me so happy, while sciatica has me floored with pain and fear of not being able to do stuff, this attention gives me back my rosy disposition, thank thanks thanks.
Chiropractor, med doc, and now physical therapy are bringing me back to life
 

[zap]

I've heard this term float charging voltage" mentioned here but I really do not know what it means
anyway it says float charging voltage for the 12volt units is 13.75 +or- 1.5 VDC

Float charge is holding the battery voltage at it's charged voltage... i.e. it's replacing whatever power is lost to self discharge.

I didn't see the UPS12-475FR listed in the pdf you provided but it listed 13.65 +/- 1.5vdc as a float voltage for the MR series from Dynasty so 12.15 to 15.15 would be the range?
Another pdf I found listed the float voltage for the FR series as 13.3vdc minimum.

That same pdf (www.cdtechno.com/custserv/pdf/7135.pdf also listed an equalization charge of 2.4v/cell or 14.4vdc (28.8 vdc in your case) and state this (also found at: http://www.longwaybattery.com/en/displaynews001.html?newsID=159083):
"BATTERY PREPARATION FOR ACCEPTANCE TESTING
The battery system should be assembled at the manufacturer's site, simulating the user's installation, or completely installed at the user's location following relevant installation instructions.
1. Measure and record all cells1 units open circuit voltage to assure minimum acceptable voltage prior to interconnecting.
2. The individual cells1 units should be interconnected using the intercell/unit cables or bus bars specified for the application and with which the battery's performance is rated.
It is important that all cell1 unit terminals and contact surfaces of the intercell/unit connecting cables and bus bars be properly cleaned and greased prior to installation and the bolted connections be properly torqued. Improper connections can result in low measured capacity due to voltage drop at the connections.
3. Equalize the battery for 24 hours at the recommended voltage (e.g., 2.4 volts/cell) to assure the battery is fully charged.
4. Following equalization, the battery should be place on float charge at the recommended voltage (e.g., 2.30 volts/cell) for 3 to 7 days prior to the acceptance test.
5. Just prior to initiating the acceptance capacity test, measure and record the individual cell/unit float voltages. "

Battery University has lots of good info.

...but I said to an observer of my system that it had to do with bringing the individual batteries  to the same voltage, so that electricity was not moving from less charged batteries from the batteries with a good charge, as they were before I rewired my system so that each battery has precisely the same length of cable run.

That description is good enough although it has more to do with individual cells.
From Battery University:
"Equalizing Charge:
With time, the charge levels of individual cells of a large battery tend to become slightly unbalanced. The equalizing charge applies an elevated charge voltage for a few hours to balance the cells. Used mainly for large lead acid cells."

[DanG]

Sorry Boss, I hate to say this but your string should be solar charged - wild 3-phase from turbines will be hard on them. The info in the form you found must be a typo error - see the 6V as having 0.15VDC range?

13.65 ± 1.5 VDC average per 12V unit (6.75 to 6.90 per 6V unit)

-- The 12V range should be 0.30 as found in many other C&D tech support documents.

http://www.cdtechno.com/custserv/techsupport.html

http://www.oksolar.com/pdfiles/battery_dynasty_12_475.pdf

-- The batteries you have are designed for "constant voltage variable current" charging versus a flooded lead acids "constant current variable voltage" and can accept a C/5 rate - so 122AH/5 = 24.4 is their recommended current limit though C/4 at 30.5 should be okay for occasional inrush when you finally get wind with discharged batteries. The high surge currents is needed to help circulate the semi-gelled electrolyte through the glass mats...

--The batteries you have are sensitive to voltage ripple:

Maximum AC Ripple (Charger) 0.5% RMS or 1.5% P-P of float charge voltage

which suggests you should get some solid DC filtration in place.

--The Batteries have a free-air space specification:

Note: Batteries to be mounted with 0.5 in. (1.25 cm) spacing minimum and free air ventilation.

which suggests you scoot the batteries around from the close stacked array you have. (summers coming)

--Look at the attachment chart, high-rate charge not recommended for your set. Lets clarify the high-rate (cycle-service) charge spec as explained in my battery manual: If the battery is deeply discharged and you know you have a limited time of charging before the next discharge cycle THEN using the high-rate charge would be less harmful than allowing the batteries to go flat or near flat, an example would be telecom back-up where grid has failed with only one generator assigned to multiple strings or has limited propane fuel, etc. before the next outage. I think equalization as mentioned in the chart should be avoided unless you have a crippled system and need the power as mentioned above.

--Temperature compensation is absolutely necessary, their service temperature range is huge and has guaranteed gassing if over 90-something degrees and hit with base float voltage.

Anyway - out of time here, I'm needed for chores - back later with anything I missed...

[Boss]

Quote
Maximum AC Ripple (Charger) 0.5% RMS or 1.5% P-P of float charge voltage
which suggests you should get some solid DC filtration in place.

I can do this, thanks
Thanks Dan, I too need to get to work, finally after 10 days off, I will read this again when I have time

[ghurd]

"can accept a C/5 rate - so 122AH/5 = 24.4 is their recommended current limit"
I don't think he has to worry about too many amps.

24.4A x 6 pair = 146.4A, x 26V = 3800W.
I am guessing it is a 10' turbine and brief power spikes will be maybe 1.2KW?  Or about 7-8A per battery.

"Maximum AC Ripple"... I always figured they threw that in there meaning 'use a high quality charger'.

"which suggests you should get some solid DC filtration in place."
How would it be practical to filter the ripple on a turbine?
The only thing I can think of is a Giant cap, after the rectifiers, before the long wire run to the batteries.

Those batteries wouldn't have come out of UPS delivery trucks by chance?
That's what they were using around here a few years ago.  No idea if they still do.
Doesn't seem like the best choice for a diesel.
G-

[Boss]

"Maximum AC Ripple"... I always figured they threw that in there meaning 'use a high quality charger'.

Sort of a release of liability, right?

Those batteries wouldn't have come out of UPS delivery trucks by chance?

I was told they were from a Qwest central office UPS system.

"which suggests you should get some solid DC filtration in place."
How would it be practical to filter the ripple on a turbine?
The only thing I can think of is a Giant cap, after the rectifiers, before the long wire run to the batteries.

I was thinking the same thing, I used to know where I had two gigantic capacitors left over from my old electronic service shop, Two problems with that as far as I can see right now. 1. Don't even remember why or what I bought them for, power filtering perhaps. 2. I haven't seen them in years, they could be in any number of out-buildings.

[Ungrounded Lightning Rod]

As I understand it:

In normal operation some cells leak more power than others.  If nothing is done about it the states of charge of the cells will track with progressively greater offsets until you have only a small fraction of your rated capacity between the point where the most charged cells are fully charged and the point where the least charged cells are minimally charged.  You don't discharge beyond lowest-cell-at-minimum and usually don't charge above highest-cell-at-maximum, so this reduces the effective battery capacity.  To avoid this you periodically "equalize" the cells.

Equalization means overcharging until you drive enough current through the fully charged cells so the lower-charged cells are brought up to full charge, too.  But driving current through a fully charged cell electrolyzes the water into hydrogen and oxygen.

In flooded batteries you can just go ahead and drive a high equalizing current through them, then top off the lost electrolyte in the less-leaky cells after a few equalization cycles.  Meanwhile the bubbles mix the electrolyte up, reducing stratification and temperature differences (which lead to self-discharge due to differing voltage at different levels of the battery, with the higher-voltage parts discharging to charge the lower voltage parts.)

In sealed batteries you can't replace the lost electrolyte.  But they do get unequalized.  Fortunately, if you don't generate the gas TOO fast there are side reactions at the plates that will recombine it back into water.  Also, some SLAs have catalysts to assist this process (like the catalytic cap accessories for flooded batteries.)  These reactions speed up with higher pressure.  So the batteries are rated so the float voltage also "wastes" a little power trickle-equalizing the cells, at a rate that will not raise the pressure to the point that the valves must open and vent the gas to prevent an explosion.

The ripple limits seem to be to avoid having a charging system (such as a transformer and half-wave rectifier but no filter) which has so much ripple that when the average voltage is at float the peaks are driving excessive equalization current into the battery, making it generate gas faster than it can recombine it and thus causing it to vent.