Anotherpower.com Forum
Renewable Energy Questions/Discussion => Renewable Energy Q&A => Topic started by: MadScientist267 on March 12, 2012, 12:16:19 pm
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I am looking to determine the general consensus for correct float float voltages for flooded lead acid cells in extended standby applications. The voltages are different for standby than they are for cyclic use.
By "standby", I am referring to use where the bank floats for at least a week straight at a time, without interruption.
I realize that many will not have this usage, but since batteries are the core of any completely off-grid system, there is bound to be some useful data to be collected here! :)
Thanks ahead of time for your input...
Steve
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For 12v Flooded Lead acid batteries Trojan recommends . . .
Daily Charge 14.8
Float 13.2
Equalize 15.5
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It seems very dependent on the maker.
I have set my banks float based on how much out gassing seems to happen. This seems to be at 13.4 volts for these.
I go through about a gallon every six months with 16 golf cart style batteries, and they are 9 years old this coming September.
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Need to factor in Temperature as well.
My Morninstar TS 45 mppt varies the float based on temp
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My Xantrex equipment with chargers also vary based on the temp, if you install the temp sensors.
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Mad, in your case I would suggest you place the pot accessible from the outside of the case when you do your mods.
Then you can adjust in case what you do decide on is still boiling or not optimal.
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Most definitely.
I'll be recessing it behind the cover, but accessible from the front, on both most definitely.
My problem lies in the fact that determining what is charging vs what is allowing them to sulfate. Considering a manually operated multi-stage setup, since there are two units. A switch on each to allow a different setting other than what is "standard".
In this way, I can change the voltage to known values without the issues that tweaking a pot (or 2) can bring.
But the question still remains, what's the right voltage? The difference seems to be in opinion amongst the manufacturers. The actual makeup of the insides of the batteries across OEMs can't be all THAT much different, can it?
So far, so good on the input... keep 'em comin... I'd like to resolve this one :)
Steve
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mad-
hopefully Ghurd chimes in here. i seem to remember him saying something along the lines of backing off the voltage a bit for longer term storage. somehow this made them last longer??
adam
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Most definitely, trick is, how far? :)
Steve
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I just watered my bank, it takes about 1/2 gallon/battery every 6 months, so 12 gallons for all 24 L16s bulk/absorb 58.8v, float 55.6v My bank runs cold, around 55-60f in the basement
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hopefully Ghurd chimes in here. i seem to remember him saying something along the lines of backing off the voltage a bit for longer term storage. somehow this made them last longer??
OK, by request.
"the general consensus for correct float float voltages for flooded lead acid cells in extended standby applications...
By "standby", I am referring to use where the bank floats for at least a week straight at a time, without interruption".
This is a 24/7/365 grid fed charger? Then 13.2V is fine.
Solar has interuptions I like to refere to as "night", so 14.4V.
Wind is about like solar, so also 14.4V unless it is some crazy windy place when I would back it down to maybe 13.8V.
I have seen very abused SLAs still work fine after 5 years, but most 'never' used SLAs floated at 14.2V 24/7/365 do not last more than about 2 years?
On my front porch, I just got a pair of 7.2AH SLAs (glued together into a 24V pack for a nice UPS) that register about 7V. They are less than 2 years old, were in a major name brand UPS, in an area that probably never lost power for more than a couple minutes since they were installed. They are from a UPS a company that does software/internet type stuff.
I believe most (maybe all?) 24/7/365 chargers float the battery too high.
RE specific devices from a good name brand do not, because the person buying the charger is more knowledgable?
Stepping on toes expected here... Present company excluded.
Most computer geeks know nothing about batteries. UPS companies can get away with murdering batteries intentionally because the target demographic (computer geek) knows nothing about batteries.
They don't know about batteries. I don't know about computers.
G-
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UPS companies can get away with murdering batteries intentionally because the target demographic (computer geek) knows nothing about batteries.
They don't know about batteries. I don't know about computers.
If I wasn't quite so cynical, quite so jaded and quite so experienced, I probably wouldn't say this.. but I am, so here goes!
Many suppliers seem to rely on said companies and "geeks" ignorance and/or reluctance to do anything other than just order the "special UPS battery pack from (supplier)" every 18 months. It's well known that UPS batteries don't last 2 years, and "need to be replaced". Some UPS manufacturers or their agents buy insane quantities of those standard 7AH cells, use double-sided foam tape to put them in "blocks" of 2 or 4, with hideously complicated sets of series/parallel connection jumpers that scare the average person silly - and charge 3 or more times what the batteries are worth (and add shipping on top)... it's a nice earner. And if they sell them every 18 months, to every UPS owner.... it's just like the cheap printers (sell them at cost) - but make a killing on the ink! Batteries are "consumable items". They rely on people to "learn" and maintain this mentality, because its how many of them make their profits.
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"Most computer geeks know nothing about batteries. UPS companies can get away with murdering batteries intentionally because the target demographic "
For anyone working in IT... that's more than an opinion.... I have had my fair share of dead UPS units... some cheap, some not so cheap.... in the case of the cheap ones (200$) a unit, corporately.. when calculating staff time, overhead expenses for ordering, yada.... its actually cheaper to just buy a new one.
Of course with our more expensive units, it flips the other way.... cheaper to find batteries.
However... even our most expensive units... er I figure 24 months max ... on the batteries.
Bad news for the el cheapo units.. is when the batteries go, hmm so does your normal power from an outlet.. they just shut down.
Rover
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Gents,
Has anyone sent this question to 2-3 battery manufacturers? In another life, I was involved with some of the same concerns all here are talking about. The manufacturers are very helpful and will provide lots of data you all are trying to figure out. Maybe it's worth asking if they would have one of their engineers / technicians answer questions from a representative from the Forum. You would then have facts to discuss.
Don't mean to step on anyones toes in the Forum. When in doubt-- go to the people that make them.
Bill
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Yep, learned a LONG time ago that the UPS itself very RARELY fails, it's always the batteries.
Had a couple that let the magic smoke out, but just grabbed another one from the attic, ran the connector out the back, and got on with my day...
But the one thing that they have always managed to do is inevitably boil the batteries dry. Now that I know the fix, I'm gonna mod a bunch of them... but gotta get that "magic number"... which is where you guys come in. :)
Steve
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which is where you guys come in. :)
FLA? 13.2V.
G-
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I can't even decide who I am replying to, but here goes:
These LOOK like 7 or 7.2AH glued together (for a UPC PRO-1500), but they are marked 9.0AH.
These replacements were purchased from 'the' UPS manufacturer for about $125 with S&H.
The repacements I sent them to cost about $38 a pair, though they were not 'glued together'.
If the computer geeks want them glued together, they can do it themselves.
G-