FLA battery wiring / config ?'s

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lamplight
lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
Hi folks..
i probably have to replace my battery bank this year before winter. i abused the heck out of them. i do not want agm's after much consideration.

anyhow after reading pretty much all winter since last fall (lucky i made it through winter with them) i'm leaning towards FLA's again. I recently picked up an "automatic" battery watering jug that makes it 10X easier and faster than the old bulb method , so i figure if i can get a configuration with less cells to water and a bigger bank (ive exanded the PV) I'm moving forward.

so i'm looking for about 900-1100AH in 12v config and my question is simple: is there any technical/longevity advantage one way or the other of going with

3 4v in series or 3 12v batteries in parallel?

I want to go with trojan or surrette.
unfortunately from what I can see so far , if i want to stay with 3 batteries i have to go surrette in this capacity range. the price jumps quite a bit between brands, but i do not think i want to keep watering 6 batteries.

thank you as always ! :-)
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
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    Re: FLA battery wiring / config ?'s

    Is there some magic about three batteries? Six Trojan L16RE-2V in series would give you 1110 amp hrs, six cells to check & water. If three is a magic number, then the three 4 v in series would be a better choice ... no balancing issues.

    As to watering, I use a siphon from a gallon jug. 1/4" clear tube and a 1/4" brass ball valve does the trick! As you can see I have 72 cells to service!
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    thanks, no magic other than less work :)
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s

    What is it with these 1000+ Amp/hr 12V banks turning up these days? :confused:

    I hope you're planning to add panels, as 875 Watts isn't going to cut it on a bank that size. You'll also need two good charge controllers to handle the 120 Amps of current. Remember; if you're using those "tall cell" batteries you must have the higher charge current to keep the electrolyte mixed. Stratification is a problem with these.

    BTW, this is one of the reasons why we go up in Voltage when power requirements start to climb.
  • audredger
    audredger Solar Expert Posts: 272 ✭✭
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    Re: FLA battery wiring / config ?'s

    Marc, as you always say and, you and I know loads grow over time .. so does the battery bank. Just look at mine ... 24 - L-16's in a 24 v system. I should have a 48 v or higher and, big 2 v's. When these batts are dead then we will upgrade to a higher voltage system.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    Thanks for the suggestions, but how are you coming up with 120amps of current?

    can you also explain higher current for the taller batteries? i had assumed they have similar charge cycles and voltages as existing small golf cart batts. of course it will be more current with a larger bank but what are you saying in regards to the sizes ?

    What is it with these 1000+ Amp/hr 12V banks turning up these days? :confused:

    I hope you're planning to add panels, as 875 Watts isn't going to cut it on a bank that size. You'll also need two good charge controllers to handle the 120 Amps of current. Remember; if you're using those "tall cell" batteries you must have the higher charge current to keep the electrolyte mixed. Stratification is a problem with these.

    BTW, this is one of the reasons why we go up in Voltage when power requirements start to climb.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s

    If you have a bank of Trojan L16RE-2V's http://store.solar-electric.com/trl111ah2dec.html they are 1110 Amp/hrs @ the 20hr rate. Following the recommended charge rate of 5% - 13% of the Amp/hr rating you get a need for charge current of 55.5 Amps to 144.3 Amps. "120 Amps" is a middle-of-the-road approximation: roughly 10% of a nearly 1200 Amp/hr bank. With these "tall case" (L16) batteries you need to 'lean towards' the higher end of the recommended charge rate to keep the electrolyte stirred. This type is more likely to suffer from stratification (and therefor sulphation) if you don't.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    ok gotcha and thanks for the clarification. im leaning towards c/5 so i can have less depth of discharge. i guess i will have to keep that in mind re: the large batteries if i want to be closer to the c/5 side of things.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    ok gotcha and thanks for the clarification. im leaning towards c/5 so i can have less depth of discharge. i guess i will have to keep that in mind re: the large batteries if i want to be closer to the c/5 side of things.

    Just to clarify, the charge rate whether expressed as C/X or as a percentage is the rate of recharging. It has nothing to do with the Depth Of Discharge which is how much you used up. If you go with 50% DOD or 25% DOD the re-charge rate is the same. The time it will take to 'put back' the 'used Amp/hrs' will vary.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    i know. thanks.

    i plan to go on the larger size of what i can handle recharging(closer to c/5 instead of c/13 in order to do that) . but now im thinking if i plan to go with larger batteries i may have to rethink that, or the size of my bank.

    this is the first ive heard of larger batteries needing a higher charge rate, is this common knowledge or your experience (both?).

    if i did have a bank on the largish size and i was on the lower end of suggested charge rate, i wonder if regular (say monthly) EQ's would be a good alternative to a higher charge rate? or do you think the stratification could happen without a regular charge rate thats higher?
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    ... this is the first ive heard of larger batteries needing a higher charge rate, is this common knowledge or your experience (both?). ...

    I have seen this discussed here before. It makes intuitive sense. (to me. :-))
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    ok thanks folks, much to think about..
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,781 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s
    If you have a bank of Trojan L16RE-2V's http://store.solar-electric.com/trl111ah2dec.html they are 1110 Amp/hrs @ the 20hr rate. Following the recommended charge rate of 5% - 13% of the Amp/hr rating you get a need for charge current of 55.5 Amps to 144.3 Amps. "120 Amps" is a middle-of-the-road approximation: roughly 10% of a nearly 1200 Amp/hr bank. With these "tall case" (L16) batteries you need to 'lean towards' the higher end of the recommended charge rate to keep the electrolyte stirred. This type is more likely to suffer from stratification (and therefor sulphation) if you don't.

    For most users this is solid advice! But there are strategies to get around it. Most of my experience is from the marine electrical world and I have to tell you they have crossed these strategies long before RE. Having big batteries to make it thru many days and nights at sea is where this all comes from.

    So what do you do? As Marc says a big battery that is not charged well can suffer.
    In a small RE system as long as your load is the same and you go to a bigger capacity battery you just increase the EQ cycles from 4 per year to 6. The key to this strategy is you can take a system that charges on a regular basis and use a bigger battery than is intuitive. You do have to complete charge on a regular basis and do the extra EQ's.

    The risk of this is that you will be tempted to consume more energy! If you are smart you will add solar or charge sources as you go and you can get 10 to15 years of battery life. The 2V that Marc likes is not the one that I am sure Arizona Wind and Sun would get for my client. Offgrid is all about strategy and rules of thumb often have nuances.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    <clip> Offgrid is all about strategy and rules of thumb often have nuances.

    Boy-oh-boy is that ever true!

    One of the most difficult things about explaining solar set-ups to people is how utterly site-specific they are! You can start with the nominal numbers and calculations tempered with rules-of-thumb and get some idea of what you'll need, but in every case the systems have to be tailored to the individual requirements.

    This is why there's no off-the-shelf, one-size-fits-all "kit" that actually works.

    Maybe we should make a list of all the site variables that have to be considered for design. It'd be quite lengthy.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    i know. thanks.

    i plan to go on the larger size of what i can handle recharging(closer to c/5 instead of c/13 in order to do that) . but now im thinking if i plan to go with larger batteries i may have to rethink that, or the size of my bank.

    this is the first ive heard of larger batteries needing a higher charge rate, is this common knowledge or your experience (both?).

    if i did have a bank on the largish size and i was on the lower end of suggested charge rate, i wonder if regular (say monthly) EQ's would be a good alternative to a higher charge rate? or do you think the stratification could happen without a regular charge rate thats higher?

    As battery Amp/hrs go up, the charge rate goes up. Whether expressed as C/x or %. I'm pointing out that when you deal with the "tall case" batteries you want to lean towards a higher rate because the physical design of that type tends to make them a bit sluggish in re-mixing electrolyte. Really, really massive batteries used in forklifts have air pumps in them to keep it stirred - and also dissipate some of the resultant heat.

    Equalization can make up for this, at least in part. That's what it's for; to knock the sulphation off and re-mix electrolyte so that SG evens out across the cells. Trouble is, EQ involves higher than normal charge Voltage and leads to excess water loss and potential heat-related problems such as plate warping. Too much EQ - as in length or frequency - can cause more trouble than it solves. It is best to get your results from regular charging and keep EQ cycles to a minimum. This is almost more art than science, though! :cry:
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,781 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s
    Just to clarify, the charge rate whether expressed as C/X or as a percentage is the rate of recharging. It has nothing to do with the Depth Of Discharge which is how much you used up. If you go with 50% DOD or 25% DOD the re-charge rate is the same. The time it will take to 'put back' the 'used Amp/hrs' will vary.

    I swear I am not picking on you but this thread... This one is often not true all of the time. Example a tracked 2KW array charging a large battery bank is not often going to see anything near the C10 that it may be capable of. The reason is all the slow charging that is going on in the early hours of the day. By the time the sun power is peaking, the battery SOC is past the steep current peak of the array. This often happens in systems that have charge capacity set for winter charging. It does not hurt the battery one bit! It is a strategy for long battery life. This also happens with fixed arrays but is not as apparent.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s

    Okay, Dave; from now on I'm putting the ultimate caveat in all my posts:

    "The information provided in this post is probably correct, except in those instances when it isn't."

    :p

    Or; "Every rule has its exceptions."

    I always go for the most likely scenario when gauging my responses.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s
    As battery Amp/hrs go up, the charge rate goes up. Whether expressed as C/x or %. I'm pointing out that when you deal with the "tall case" batteries you want to lean towards a higher rate because the physical design of that type tends to make them a bit sluggish in re-mixing electrolyte. Really, really massive batteries used in forklifts have air pumps in them to keep it stirred - and also dissipate some of the resultant heat.

    hi
    i do know this and am not sure why you keep saying it. i understand as i said. like i said im playing around with the 5% - 13% number to get the largest bank i can safely charge. my loads on this system are such that i dont need to use them (other than a very small always on load) if weather is uncooperative. i do appreciate the info on larger physical batteries needing more current to mix them up, and your efforts to help. this is not going to be an easy decision. i really want less cells to water, but dont want to go agm. i may have to think of a smaller bank or smaller batteries. was hoping to eek out the ability to charge at least 900ah.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    While I agree that a larger battery prefers a higher charge rate, if it were me I would go with the larger bank and charge at C/5 rate with plans in the future to add more panels. My second bank was sized to my panels and load at the time and quickly the panels were at a C20 rate.

    So as long as you have the ability to keep the bank charged and have a way to EQ when needed I would go for a larger bank so you can "grow" in to it.

    Just my $.02
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    thats my plan thanks Brock, but on the other hand I don't plan to grow this one TOO much more.. then as Marc said ill be looking at needing a second controller.. etc etc.. really will have to think about all this.


    really good info as always from all you guys thanks!
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    hi
    i do know this and am not sure why you keep saying it. i understand as i said. like i said im playing around with the 5% - 13% number to get the largest bank i can safely charge. my loads on this system are such that i dont need to use them (other than a very small always on load) if weather is uncooperative. i do appreciate the info on larger physical batteries needing more current to mix them up, and your efforts to help. this is not going to be an easy decision. i really want less cells to water, but dont want to go agm. i may have to think of a smaller bank or smaller batteries. was hoping to eek out the ability to charge at least 900ah.

    Sorry, but when you get older you start to repeat yourself when you get older and start repeating yourself because you are getting older and repeating yourself just because you're getting older and repeating yourself.

    :p

    No, actually I was doing my usual poor job of explaining the difference between the actual Amps going up as the bank gets bigger and the need for those Amps to be a greater percentage of Amp/hrs in the tall case batteries.

    In other words, if you had 1000 Watts of T105's you could charge them at 50 Amps and successfully mix the electrolyte (in theory; in practice it's a whole 'nother kettle of fish - wires, really) but the L16's are more likely to stratify/sulphate at 5% and would remix better at 10-13% (100-130 Amps).

    If you have an abundance of panel and a good charge controller you can always set a limit of Amps so the batteries won't receive too much current. Pretty sure the FM60/80 still have that feature, and the Xantrex unit is likely to as well.

    One of the other problems of getting old is you start to forget things. :cry:
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    thanks!

    Im not going to have a "too much current" problem anytime soon. :)

    along the lines of this topic i was just looking at my new tristar mppt60 manual and one of the presets is for L-16's, and it has it's auto EQ'ing (if you choose to use it) every14 days as opposed to 28 days for the other battery charging presets, this is all making more sense :)


    im thinking i might want to get a smaller bank now so that i can handle keeping those larger batts mixed up. still thinking i want the larger wet cells vs agms or smaller wet cells.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    Just to finalize this thread with what I actually did: ordered 3 4v surrette batteries for 1104 AH. Looks like I may have to add more panels , :) :roll:

    now im hoping i can get them in the cellar, at 300lbs each. :)
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    matt,
    i am a bit confused here. as my memory recalls, you were straight gt with a fronius. what changed and why?
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    HI Neil

    its understandable as i havent really hung out here much, no need, everything works GREAT :)

    no. i have gridtie and a inverter made from a company in MA (forget name at the moment). i had 4 185w panels installed GT, then a year or so later 6 more.

    i started a small offgrid system prior to all that with 2 175w sharps. and 4 t-105's. within the 1st year i added 2 more t105's. ive added a panel here and there and am now up to 5 of them (1 just this spring). you and many of the original people on this site helped me get going as i recall :) I'm considering adding a 6th panel if needed, which it looks like will be. i'm hoping for very low battery discharge , and frequent eq's of every couple weeks.

    I do have serious concerns getting them to the cellar. i really hope we can tip 45deg and slide them down.
  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    I do have serious concerns getting them to the cellar. i really hope we can tip 45deg and slide them down.
    You could build a simple wooden sled with a pitch corrected for the angle of your stairwell I suppose. This way you wouldn't have to tip the batterys. Just drop an extension ladder section for it to slide on on top of the stairs. I would add a rope to the sled so you can lower it down from the top just in case one gets away.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    thanks Mike thats exactly what i was thinking but your ideas are firmer than mine , now i have some concrete ideas to play with.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    HI <snip>i'm hoping for very low battery discharge , and frequent eq's of every couple weeks.

    Um,no. You do not want frequent equalization cycles. You only want to EQ if necessary; it's hard on batteries (higher Voltage in EQ cycle means higher temps and more water loss as well as stress on plates). Batteries that are not heavily discharged and are properly and timely recharged will not require much equalization.

    Just thought I should mention that. :D
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: FLA battery wiring / config ?'s

    Thanks Marc
    well i was thinking of doing that to supplement the fact that i cannot offer the bank c/13 of charge rate for now, but since i can very likely keep it regularly charged by not discharging too deeply, i thought more frequent eq's might be good as someone was mentioning in this thread as being a successful approach.

    i understand what you're saying. i just didnt know if regularly getting the bank voltage to proper levels was still good enough - IF my BULK rate is on the (very) low side.

    i will invest in a battery monitor so i can closely watch the health as this bank i s a big investment.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: FLA battery wiring / config ?'s
    lamplight wrote: »
    Thanks Marc
    well i was thinking of doing that to supplement the fact that i cannot offer the bank c/13 of charge rate for now, but since i can very likely keep it regularly charged by not discharging too deeply, i thought more frequent eq's might be good as someone was mentioning in this thread as being a successful approach.

    i understand what you're saying. i just didnt know if regularly getting the bank voltage to proper levels was still good enough - IF my BULK rate is on the (very) low side.

    Well, no it isn't enough to just replace the Amp/hrs. You're absolutely right there; if your charge rate is truly deficient you need to keep a close eye on the SG and equalize as needed. What you don't want is regular/automatic EQ 'no-matter-what'.
    i will invest in a battery monitor so i can closely watch the health as this bank i s a big investment.

    100% correct. :D You won't regret having a battery monitor.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,477 admin
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    Re: FLA battery wiring / config ?'s

    Yes, there is a difference between giving the batteries a "full charge" one every week or so, vs giving them an equalization charge every two weeks...

    Technically, you cannot equalize a battery until it is 100% charged (specific gravity to maximum value for your batteries). Equalization is (typically) a 5% rate of charge of a full battery bank just long enough to bring any "lagging cell" specific gravity backup up with the rest of the cells (typically, equalize when cells are 0.030 or farther apart in s.g.).

    Equalization is hard on the battery (and plates). Also, it generates oxygen at the positive plate and can/will cause plate grid corrosion).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset