Golf Car BATTERIES at SAMS?

2

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  • bryanlbryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    That's a graph you can find in many other resources about lead acid batteries. It shows why the general recommendation is to not discharge batteries below 50% SoC as a routine thing.

    I think it interesting that the graph lists 10% but not 80% (a usual deep cycle definition point) or 90% (symmetry with the 10%) depth of discharge (DoD). From what I can tell, discharge under 10% is considered float service and lead acid batteries don't do well at that, either.

    Consider that you have about 2000 days in the nominal lifespan for a lead acid battery. That puts the average daily DoD at about 20% and that is a measure to use to plan battery bank capacity in an RE system. In an RV system, the discharge frequency is much lower so the calculations can differ.
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?

    One reason that people recommend not to discharge a battery below 20% state of charge is that the cells in a series string may not have identical capacities (age, mfg. defects, normal mfg. variations, etc.)...

    When a battery is discharge deeply--there will usually be at least one cell that hits "zero" capacity before all others. If the battery continues to discharge (other cells still have >0% capacity), the one cell actually changes polarity and begins to "reverse charge". For most rechargeable cell chemistry--that is an instant death sentence to that cell.

    On a low voltage battery bank, say 6 volt... You would notice when the battery discharged to 4 volts (one cell flat) or if it went to 2 volts (the one cell being reversed charged).

    On battery banks with large numbers of cells in series (say 48 volt, becomes 46 volts with one flat cell, or 44 volts when the cell is reversed charged--still well above the 42 volt of a "dead battery")--it is much more difficult to "notice" that one cell has failed.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    so wait... you are saying we can mix... but just dont go below 20%?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    so wait... you are saying we can mix... but just dont go below 20%?

    Actually Bill is saying there will be a mix - even when you start with brand new batteries. It is impossible to manufacture a battery so that every cell is absolutely identical and will remain so throughout the life of the battery. It is even more impossible that any two cells from two different batteries will be identical, regardless of date of manufacture or how good the quality control is. To start with, these variances are inconsequential. The older the batteries get, the more/deeper they're cycled, the greater the differences become. As this happens the effect of one "weak" cell has on the others increases. As Bill mentioned, the worst case scenario is actual reversal of polarity of one cell - which will ruin the rest of them in short order.
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    ah thanks. another point i dont understand is how/why will a dead cell reverase polarity. what exactly does that mean?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    ah thanks. another point i dont understand is how/why will a dead cell reverse polarity. what exactly does that mean?

    Electro-chemical magic!:p

    Basic battery chemistry: one plate is made of a metal with a (+) charge, one with a (-) charge (electron balance of the metal). Stick 'em in acid, connect a circuit between 'em, the electrons start to flow from one to another. Push current 'backwards' across the plates and the electrons go back to where they were (recharged).

    When you do this in the real world, the chemical nature of the plates changes. In a FLA battery the acid is sulfuric, which is why when you re-charge and boil off the water component (hydrogen and oxygen) you're left with sulphur which bonds to the plates - "sulphation". This is also why the plates (lead/antimony) break down over time (or sometimes suddenly with catastrophic results). The positive plates are usually the first to go, because they attract the oxygen molecules - leading to oxidization of the metal.

    If you discharge a battery too much, too many electrons flow across and the make-up of the plate changes from metal having a (+) charge to having a (-) one (and vice versa).

    Fun, eh? :D
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    thanks for the laymen description... everything makes sense except the last paragraph.

    isnt it like a magnet - sure the polarity changes but why cant you change it back?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    thanks for the laymen description... everything makes sense except the last paragraph.

    isn't it like a magnet - sure the polarity changes but why cant you change it back?

    Theoretically you can. But it's like trying to change rust back into steel. Simply applying voltage won't do it. Remember batteries actual produce voltage as a result of the chemical reaction; they don't store it. Applying voltage back to the battery will reverse some of the process, but not all of it.

    This is the same problem as a heavily sulphated battery refusing to release the bonded sulphur even though you crank the voltage to it. There are battery desulphators which claim to work by applying pulses to the plates to knock the sulphur off, but they have their detractors as well as proponents.

    Eventually all batteries fail because the chemical reactions inside are only reversible to a certain degree. Each 'cycle' of a deep cycle technically takes the battery's capacity down a bit, and every time it's recharged it does not come back to 100%. This loss is miniscule until you add it up over several thousand cycles.

    Trying to explain this in terms anyone can understand - and it's getting a bit wonky.:p
  • bryanlbryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?
    One reason that people recommend not to discharge a battery below 20% state of charge is that the cells in a series string may not have identical capacities (age, mfg. defects, normal mfg. variations, etc.)...
    This is why equalizing is an important adjunct to a full and proper charge as well.

    But the point gets out into the fringes of the distribution, I think.

    _Maintenance and proper usage_ is the first factor to control in being happy with your batteries.

    Interesting point about reverse forming cells. That gets into initial battery forming and the interesting fact that both the negative and positive plates start out as the same stuff. But, again, problems related to that are getting way out in the fringe of the distribution, I think.

    When we get back to within a standard deviation or two from the mean, I think the number of factors to be concerned about diminishes to a very small set that can be resolved by readily available specifications and measures. The other stuff is fun, but not really worth promulgating confusion when trying to answer a query about "golf car batteries at Sam's" for the average Joe.
  • bobdogbobdog Solar Expert Posts: 191 ✭✭
    Re: Golf Car BATTERIES at SAMS?

    Back to the OP question....you other guys go off to a pub and have some cocktails and jib-jab all you want.

    I bought 4 of them and plan on 4 more. 1st 4 have lasted over a year, no problems, left alone in winter, seasonal use in summer. I know a few that have used them and they last 5-6 years before falling off quickly. BUT, learn to take care of them.

    Apparently Sam's buys batteries from various manufacturers close to their distribution centers and then re-labels them. At least I've read that on this list before. Mine aren't Eveready, but something else.

    Edit: Mine are Interstate re-branded

    Here's a helpful link: http://www.batteryfaq.org/

    For the money and as TRAINERS I think you can't beat 'em. If I mess up, I'm out $65. If I buy a Trojan right off the bat, and then mess up? I'm out a lot more.

    As far as marine vs GC...some might say it's a tough choice, but for someone who actually OWNS a boat and has used them, they are not IMHO useful for RE systems. Just my 2 cents.
  • soloronesolorone Solar Expert Posts: 254 ✭✭✭
    Re: Golf Car BATTERIES at SAMS?
    solorone wrote: »
    I will qualify my post by saying that my experience with GCB is 26 years old, but I do not think much has changed.
    Batteries are engineered for a particular use, and GCB are designed to give up the necessary power that is needed for the cart, no more no less, and this is a known load range, unlike what you are going to be drawing with an inverter.. Inverter loads can momentarily hit 600 amps, with out any trouble, and you can not see it on a Fluke amp meter, it is not quick enough, I have personally seen it run up to 470 Amps, before the load display disappeared.

    .
    Kamala wrote: »
    There has been no mention, so far, in this thread regarding loads. It is very difficult to evaluate the performance of any component while not knowing what it is expected to do!

    To say that "Inverter loads can momentarily hit 600 amps..." without specifying planned/expected loads isn't very helpful. 600A X 12V = 7.2 kW! I understand that this may be "start-up" loading, but we don't know.

    For myself, and it is just for myself, I have come to think of "golf cart" as a battery size rather than suited to the application of powering a golf cart. I have a bank of East Penn 8AGC2s. A for AGM and GC for golf cart because of the size. That is, physical dimensions. They are actually an RE battery. If I am not mistaken, Trojan T105s, a standard in RE apps, are GC dimensioned batts.

    Previous post regarding the "freshness" of products offered by SAMS should be heeded.

    Craig

    Informative thread here.

    Craig I did not make my post clear, and was assuming a good bit, such has the loads, well pumps can draw at start up, esp. at 12V.

    Also I could have been clearer on the battery construction as I understand it. For inverter use and typical large loads in a home, microwave, toaster, dryer ignition and start up. Some of these need a lot of power fast and some batteries are designed to give up that amount of power and have construction designed, such as holes in plates, to allow for good circulation and keep fresh acid on the plates. Sorry I was too brief in my early post.
    As i noted, my exp. with GCB is rather dated, and they may have changed, but it seems unlikely. The loads would be quite different for home use.

    It is much the same as when I started, everyone was after telephone batteries, I have 5 tons, no really I do. These were designed for a known load and quickly became useless as soon as the Trace 1512 hit the market, they could not give up enough power fast enough.

    I am not saying GCB do not work, obvisiouly they will, but how well and for how long, that is what I meant to point out.
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    here is what johnson control wrote back:

    "Sam's Club is supplied by either JCI's product made in Mexico or else CrownBattery. We purchase the Crown Battery and supply it to Sam's Club. Thespecs for both batteries will be the same. 220Ah at the 20 hour rate and 105 minutes at the 75 amp rate. "

    i guess this is very good news for us?
  • bryanlbryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    re "some batteries are designed to give up that amount of power and have construction designed"

    It used to be (a long long time ago) that 'deep cycle' as applied to a battery also meant current limited but one of the changes in the last decade or two is a bit of optimization in battery design. Even the more rugged (aka 'deep cycle') batteries in common use can provide fairly healthy currents.

    That gets me to wondering about the history of CCA and reserve minutes specifications. It seems there was a governmental or industry standard agreed upon that these measures were to be readily available. (anyone have cite to resource on this?)

    The need for large peak power draws for small battery banks also brings up the issue of parallel versus serial bank configurations.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?
    bobdog wrote: »
    Apparently Sam's buys batteries from various manufacturers close to their distribution centers and then re-labels them. At least I've read that on this list before. Mine aren't Eveready, but something else.

    Edit: Mine are Interstate re-branded

    Mine are Interstate not re-branded, and one of them failed in the first year (collapsed plate). This is the first time I've had a catastrophic battery failure ever. Doesn't give you confidence. But the point is, when you buy a "house" brand you have to do a bit of digging to find out who really made them. Besides that, they are not necessarily made to the same standards as one with the manufacturer's name on it (this happens a lot in industry).
    For the money and as TRAINERS I think you can't beat 'em. If I mess up, I'm out $65. If I buy a Trojan right off the bat, and then mess up? I'm out a lot more.

    True enough, provided you understand going in that there is a possibly greater potential for premature failure. If you buy cheap batteries and they last and last and last ... smile and know you're lucky! :D
    As far as marine vs GC...some might say it's a tough choice, but for someone who actually OWNS a boat and has used them, they are not IMHO useful for RE systems. Just my 2 cents.

    100% agreement there! :D
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    a few battery questions now that i have real batteries!

    * if the plate collapses, would that be reflected right away in the specific gravity or voltage (which one)?
    * i took a look at the inside of the battery (peering through the energizer watering hole)... the plates looked warped/crooked/ridged. is that normal? i am guessing it is because all my batteries looked like that. what does a collapse plate look like?
    * i recharged all night until float... after waiting 5-10 mins the water inside was still bubbling a little - looked like mosiquitoes in the pond. thats normal right?
    * how much water do i add into the battery (specifically tghe sams club battery). no instructions or labels or markers telling me where to stop watering
    * the specific gravity (temp adjsted) after float [10mins wait] with no equalization on 9/09 batteries were ~1290 is that normal? or did i do something wrong? also the spec gravity varied between batteries - varies up to 0004. is that normal?
    * also battery temperatures varied by quite a few degrees celcius
    * during equalization... is it normal to have this musty smell in the air?

    btw i my setup is 2/0 - one set of battery is 3ft... 3 sets of battery at 4ft to the buss bar; 2 interconnects are 6awg; 2 are 2/0 - all 1ft. thats not recommended but it doesnt hurt anything right? during charging max amp through any of the wires were 20A which is much lower than the max current the wires supports

    i ran out of wires/budget.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    a few battery questions now that i have real batteries!

    * if the plate collapses, would that be reflected right away in the specific gravity or voltage (which one)?

    The first thing you'd probably notice is a voltage drop: two plates touching eliminates their ability to produce electricity (shorted). Even this may take a while to show up.
    * i took a look at the inside of the battery (peering through the energizer watering hole)... the plates looked warped/crooked/ridged. is that normal? i am guessing it is because all my batteries looked like that. what does a collapse plate look like?

    This is normal: the ridges add strength to the plate structure. Lead/lead oxide is pretty soft stuff, even when 'reinforced' with antimony or other substances. You won't actually be able to see a collapsed plate or sulphation through the fill hole.
    * i recharged all night until float... after waiting 5-10 mins the water inside was still bubbling a little - looked like mosiquitoes in the pond. thats normal right?

    Yes. The Bulk & Absorb cycles will cause quite a bit of 'bubbling' - that's actually the electrolytic process converting water to hydrogen & oxygen (the bubbles). Float voltage doesn't do this as much, but some bubbling may still occur - it takes a while for the process to "slow down".
    * how much water do i add into the battery (specifically tghe sams club battery). no instructions or labels or markers telling me where to stop watering

    Usually it's to the bottom of the fill tube. That's hard to explain in words, but look at the level when you first get the batteries - it should be about there. :p Under the caps there's a bit of plastic tube that's part of the top of the battery. It will probably have slits in the sides. The water should come up to the bottom of this tube. Another way of looking at it is "enough to cover the plates (roughly) + 1/8". Do not over-water; it dilutes the acid and reduces capacity.
    * the specific gravity (temp adjsted) after float [10mins wait] with no equalization on 9/09 batteries were ~1290 is that normal? or did i do something wrong? also the spec gravity varied between batteries - varies up to 0004. is that normal?

    The important thing with new batteries is to charge & equalize to begin with. Let them rest (it's hard to get a good SG reading while bubbles are still forming) for about 3 hours, then read. Take that as your base number: the thing to compare all future readings to. The truth is, SG varies from battery to battery and location to location, to say nothing of the difficulty of reading a hydrometer down to 0.004. Up here all my SG readings are 0.050 low due to altitude.
    * also battery temperatures varied by quite a few degrees celcius
    * during equalization... is it normal to have this musty smell in the air?

    Don't sweat the small stuff. A few degrees Celsius measured how? And how many is "a few"? Variations in batteries are always present. The "musty smell" is probably you breathing in hydrogen sulphide gas, which is present in small quantities above batteries of this type.
    btw i my setup is 2/0 - one set of battery is 3ft... 3 sets of battery at 4ft to the buss bar; 2 interconnects are 6awg; 2 are 2/0 - all 1ft. thats not recommended but it doesnt hurt anything right? during charging max amp through any of the wires were 20A which is much lower than the max current the wires supports
    i ran out of wires/budget.

    A foot of even 2/0 is going to make a difference in the resistance to that set of batteries. That set (on the shorter wires) will be doing most of the work. The interconnect wires should be as short as possible (no sense adding resistance, even tiny amounts). The 6 AWG will again cause unbalance problems eventually. We are talking very small amounts of resistance here, but the effect will accumulate over time. The most important thing is to keep the wires equal size/length so that the current flow in and out and through each battery is as close to equal as possible. I'd say your biggest wiring problem is the use of 6 AWG, followed by the one set with the leads being 1 foot shorter.

    We all run out of budget. Otherwise I'd have 8 more panels on my roof and wouldn't be running the generator right now! :cry:
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    thanks for all the replies. as a way to show gratitude... heres more followups :)

    [Usually it's to the bottom of the fill tube. That's hard to explain in words, but look at the level when you first get the batteries - it should be about there. Under the caps there's a bit of plastic tube that's part of the top of the battery. It will probably have slits in the sides. The water should come up to the bottom of this tube. Another way of looking at it is "enough to cover the plates (roughly) + 1/8". Do not over-water; it dilutes the acid and reduces capacity.]

    is there a way for me to know FOR SURE what you mean? right now when i peer into the hole i see plates with water, then there is a gap of maybe 1/8 or 1/4 inch between the water line and the lowest point of the side of the plastic edge. so you are saying water the hole until the waterline meets the lowest point of the plastic siding. that is quite some amount of water. what happens if i just keep the plates covered w/ water (it is now) but not all the way up to that suggested mark?

    [The important thing with new batteries is to charge & equalize to begin with. Let them rest (it's hard to get a good SG reading while bubbles are still forming) for about 3 hours, then read. Take that as your base number: the thing to compare all future readings to. The truth is, SG varies from battery to battery and location to location, to say nothing of the difficulty of reading a hydrometer down to 0.004. Up here all my SG readings are 0.050 low due to altitude.]

    wait 3 hrs. do i take measurements before or after i add new distill water? how much of a variation is "too much" - basically exchange another new battery? how much of a variation is "too much" - as in use as core?

    [Don't sweat the small stuff. A few degrees Celsius measured how? And how many is "a few"? Variations in batteries are always present. The "musty smell" is probably you breathing in hydrogen sulphide gas, which is present in small quantities above batteries of this type.]

    a few degrees celcius measured in the hydrometer; variation of temp enough for 0004 adjustment in specific gravity


    as for 3ft vs 4ft 2/0AWG being a big deal... at what point is it 'ok' - 6inches of difference? 2inches? 1/8? my plans are to replace the 6AWG w/in a week.
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    is there a way for me to know FOR SURE what you mean? right now when i peer into the hole i see plates with water, then there is a gap of maybe 1/8 or 1/4 inch between the water line and the lowest point of the side of the plastic edge. so you are saying water the hole until the waterline meets the lowest point of the plastic siding. that is quite some amount of water. what happens if i just keep the plates covered w/ water (it is now) but not all the way up to that suggested mark?

    It depends on the construction of the "fill vent" of your battery... Some are a "pipe" that hangs down a 1/2" or so, with slits in the side that allow gasses to pass through the slit and out the cap.

    The "slit tube" is nice when filling as you can see when the electrolyte "touches the sides of the tube" (surface tension).

    If your battery is filled so full (or did not have "slits") and there is no "space" for gases to escape--the cell will pressurize and force the electrolyte out the top of the cell when charging/equalizing (also, if very near full when cell is cold, expansion of the electrolyte as the battery heats can also overflow the electrolyte.

    The idea is to always keep the plates covered, but the liquid level down enough to prevent overflow (gasses and heat).

    Check the battery before filling that the plates are covered by at least a 1/4" of electrolyte (SWAG), and after charging/equalizing that the level is not "too full" (as described above).

    If you have a lot of cells to maintain, a battery filler may be worth getting. Saves having to keep looking into the cells with a bottle in one hand, a flashlight in the other, and the cap in the other.
    wait 3 hrs. do i take measurements before or after i add new distill water? how much of a variation is "too much" - basically exchange another new battery? how much of a variation is "too much" - as in use as core?
    The Specific Gravity is most accurate after the electrolyte has mixed--resting for three hours is the recommendation.

    Adding distilled water will dilute the electrolyte at the top of the cell and will "read low specific gravity" until the electrolyte has remixed (may require charging/equalization to fully/quickly remix electrolyte). Water is lighter than sulfuric acid and tends to "float" at the top of the cell if not "mixed".

    From Trojan's battery manual (PDF):
    Equalizing (flooded/wet batteries ONLY) 3.4.2.

    Equalizing is an overcharge performed on flooded/wet batteries after they have been fully charged. Trojan recommends equalizing only when batteries have low specific gravity, below 1.250 or wide ranging specific gravity, 0.030, after fully charging a battery. Gel or AGM batteries should never be equalized.
    • Confirm that the batteries are flooded/wet
    • Check electrolyte level to make sure plates are covered with water before charging
    • Check that all vent caps are secured properly on the battery before charging
    • Set charger to equalizing mode
    • The batteries will gas (bubble) during the equalization process
    • Measure the specific gravity every hour. Discontinue the equalization charge when the gravity no longer rises
    WARNING: Do not equalize gel or AGM batteries.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Golf Car BATTERIES at SAMS?

    Bill has answered the electrolyte questions so ...

    I'll just say that the thing with the wiring is not so much the length, per se, it's the equal lengths/sizes. The 1' interconnects is a very minor resistance issue compared to the use of 6AWG on some. The extra foot of 2/0 on the leads to other batteries will show up over time, but not right away. It's a difference of "it will work" vs. "less than the best it could be". When you're fine-tuning for maximum efficiency (or in this case, lifespan of the batteries) every little bit counts.

    But then these batteries were cheap, and it's always good to start out with (and make your learning mistakes with) inexpensive components.
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?
    mshen11 wrote: »
    as for 3ft vs 4ft 2/0AWG being a big deal... at what point is it 'ok' - 6inches of difference? 2inches? 1/8? my plans are to replace the 6AWG w/in a week.

    From a mathematical point of view... We all remember V=I*R or I=V/R

    Assuming that all of the batteries are equal voltage, then if R is 2x higher in one string than the other, then the current "I" will be 1/2 as much...

    Lead Acid batteries themselves have very low resistance... For example the Optima Blue Top Marine/RV batteries are around 0.0025-0.0030 Ohms. (note that this is a "car sized battery marine/rv battery--others will have different resistances)

    And copper wire is also very low resistance per foot... Here is a chart (note, resistance is per 1,000 ft, so divide by 1,000 for Ohms per foot):
    • "00" 0.077 Ohms per 1,000 ft (0.000077 Ohms per foot)
    • 6awg 0.4028 Ohms/1,000' (0.0004 Ohms per foot)
    So--in this case, 1 foot of 6 awg wire and 1 foot of "00" wire is still way less than 0.003 ohms of a single battery. But the 1 foot of 6 awg will have an effect on the amount of current flow because:
    • A general engineering rule of thumb--things that are 10x or more different--the "bigger" number only applies. Things that are 2x or less difference--they are almost the same.
    If you have 10' of 6 awg wire--its resistance is the same (or slightly) higher than the battery itself--so I would expect the current flow to be 1/2 that of a "00" cable.

    Now--if all cables were 6 awg of the same length--then all strings would share loads equally--However, with some energy lost to Power=(I^2)*R "I squared R" heating of the 6 awg wire.

    Notice that heating losses go with the R (2xR is 2x heating loss). However, go with the square of the current I (2xI is (2^2)=4x heating loss). Heavy currents have more effect on losses than just high resistance because of this relationship.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,046 ✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    Here's Crown Batteries Maintenance for Deep Cycle batteries. They are one of the suggested manufacturers.

    http://www.crownbattery.com/PDF/Safety.First._Deep%20Cycle%20Batteries.pdf

    I think it's interesting that they follow Associated Press (AP) style rules for abbreviations except for RE (renewable Energy?) Where they have RE (RE), I guess someone was going to look it up and forgot...

    They say something like above the plates but not higher than the bottom of the vent tube.

    Also interesting to note, they suggest monthly equalizing in RE use.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    here are sp gravity numbers after 3hrs of rest after equalization. all batteries at 6V.

    battery1[4ft 2/0; 1ft 6AWG] = 1304 1304 1306
    battery2[4ft 2/0; 1ft 6AWG] = 1306 1309 1304
    battery3[3ft 2/0; 1ft 2/0] = 1296 1295 1296
    battery4[3ft 2/0; 1ft 2/0] = 1295 1297 1295
    battery5[3ft 2/0; 1ft 2/0] = 1296 1300 1305
    battery6[3ft 2/0; 1ft 2/0] = 1315 1312 1313
    battery7[4ft 2/0; 1ft 6AWG] = 1315 1314 1314
    battery8[4ft 2/0; 1ft 6AWG] = 1310 1314 1309

    buss bar is closest to batteries 3-6, explaining the shortened wire
    - what can one say about these data? is the 6AWG interconnect causing higher sp gravity?
    - why are these numbers so high - a lot higher than sp gravity charts. i told the prosine i had 800AH even though i have 880AH [it was either 800 or 1000 and i was advised to under count as oppose to over count]. does it mean i have super healthy batteries (as i should)?
    - so are these my basline? and if these numbers deviate significantly i should equalize?
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?

    All the batteries appear well charged.

    The batteries with the 00 cable may be cycling more--a lot depends on the current and AH drawn as to whether or not there is significance between the specific gravity.

    But, since your spread is less than 0.030 -- then further equalization would be a waste of energy and battery life (over equalization is not good either).

    For flooded cell batteries I have seen recommendations from every few weeks to 4x a year maximum...

    If the batteries are charged and have little spread in specific gravity--then I would not do the equalization very often.

    If the batteries are "tall" -- I would probably do a short equalization a bit more often to ensure the electrolyte is well mixed (especially if you see your specific gravity is low after charging--may indicate a layer of "water" / light s.g. electrolyte at the top of the cell. And equalization would then bring the s.g. back up.

    Reasons it is handy to write down your s.g. readings -- you will quickly notice when something is not right (low s.g. overall, vs one cell/battery/string with low s.g., etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    [f the batteries are "tall" -- I would probably do a short equalization a bit more often to ensure the electrolyte is well mixed (especially if you see your specific gravity is low after charging--may indicate a layer of "water" / light s.g. electrolyte at the top of the cell. And equalization would then bring the s.g. back up.]

    i thought equalization shortens the life of the battery and should be done as little as possible? i read somewhere if you can tolerate a little loss of capacity - its better not to equalize so frequently

    im curious as to why there is such a variation in sp gravity between the batteries?

    thanks for everyones help - i think now i understand batteries enough to maintain it.
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?

    Well mixed electrolyte is important--so if you notice all cells not coming back to "full charge" level of s.g., then there is a good chance that "mixing" (equalization) will bring the s.g. back up to your logged readings (keep these as your "good batteries" / "fully equalized" numbers.

    The amount of variation you are seeing is not that great (less than 0.030 between all cells). And having "high" s.g. is not always a good thing either.

    I ran across this page on why different types of batteries have different starting s.g. fills... Is pretty interesting:
    Specific Gravity vs Applications
    1.285 Heavily cycled batteries such as for forklifts (traction).
    1.260 Automotive (SLI)
    1.250 UPS – Standby with high momentary discharge current requirement.
    1.215 Geral applications such as power utility and telephone.

    As mentioned earlier, the specific gravity (spgr.) of a fully charged industrial battery, or traction battery, is generally 1.285, depending on the manufacturer and type. Some manufacturers use specific gravities as high as 1.320 in an attempt to gain additional Ah capacity, but at the cost of a shorter cycle life.

    ...

    Higher Gravity = vs Lower Gravity =
    More capacity / Less capacity
    Shorter life / Longer life
    Higher momentary discharge rates / Lower momentary discharge rates
    Less adaptable to "floating: operation / More adaptable to "floating" operation
    More standing loss / Less standing loss
    Also on that page is the formula between cell resting voltage and specific gravity:
    Specific gravity = single-cell open-circuit voltage - 0.845 (example: 2.13v – 0.845 = 1.285)
    Or
    Single-cell open circuit voltage = specific gravity + 0.845.
    The web + google/search engine is great! :D

    Thank you for asking the questions--I am learning more myself.

    -Bill

    PS: If you want to quote some text:

    [HTML]
    text to be quoted
    [/HTML]
    text to be quoted

    Also, in the "edit window"--up at the upper left you will see a box A/A -- that toggles between "code" and "wysiwyg" (what you see is what you get).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    well... IF i had a preference i rather have less AH capacity and longer life (since i overbought for my purpose). and since it seems these battery have high sp gravity it is contrary to my ideal situation.

    can i 'adjust' the sp gravity and lower it [by diluting it - throwing away some acid water and replacing it w/ pure water]. that way i get less AH and longer life?

    or it doesnt quite truly work that way?
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    more battery questions:

    ok. specific gravity is "relative" that is why you take initial measurements and compare of it those initial numbers. how about voltage? mine starts off at 12.9V... does that mean if it drops to 12.8, its 90% full (as oppose to 12.5 or 12.6V for some charts)?

    [more questions to follow - depending on the answer]

    Figure 1 - Battery State of Charge
    Charge Voltage Voltage Specific
    Level (12v) (6v) Gravity



    100% 12.7 6.3 1.265
    75% 12.4 6.2 1.225
    50% 12.2 6.1 1.190
    25% 12.0 6.0 1.155
    0% 11.9 6.0 1.120
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?

    Assuming the batteries are "rested" and "well mixed"--the formula is:
    Specific gravity = single-cell open-circuit voltage - 0.845 (example: 2.13v – 0.845 = 1.285)
    Or
    Single-cell open circuit voltage = specific gravity + 0.845

    And the fill specific gravity can vary between battery vendors and distributors (see my previous post with this information).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mshen11mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    Re: Golf Car BATTERIES at SAMS?

    what about voltage? seems like voltage may vary for definition of 100% charged.

    is voltage relative in measurement - ie. if a new battery has 12.9V as full... then the next time around it is also full at 12.9V

    and if it drops to 12.7V it is no longer full (even though charts say anything above 12.7V is considered full).


    followup question:
    i thought batteries discharge at the same rate when not in use - like 5% a week?
    my new batteries are at 12.9V and in 4 days it went down to 12.8V... so assuming the rate is linear, it will take 12 days to go to 12.6V which is slightly less than 100% capacity.

    an older battery starts off at 12.7V and it takes 3 days to go down to 12.6V... something doesnt add up - does this mean newer battery stay at 100% full longer?
  • BB.BB. Super Moderators, Administrators Posts: 29,887 admin
    Re: Golf Car BATTERIES at SAMS?

    That is why it is recommended that batteries for a bank be purchased as a set (same model, same lot code, all filled by the same distributor, etc.).

    Also, remember that batteries are temperature sensitive and their output voltage changes with temperature.

    5% self discharge per week sounds a bit on the the high side... Such a battery is probably pretty old. Hot batteries would tend to self discharge faster too.

    Also, different battery consruction/design will have different self discharge levels. AGM tend to have a very low rate. Old fork lift batteries tend to have a higher rate.

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