Golf cart batteries from Costco.

Lefty WrightLefty Wright New UserPosts: 111Solar Expert ✭✭✭
The Costco store near me has golfcart batteries for $75. This is $25 cheaper than at any other place I can drive to.

But the batts have no amphour rating listed. Just a cold cranking rating of 100 minutes.

The guy selling them didn't know what an amp hour is.

I'm wondering if these are even deep cycle batteries. Could these be some kind of automotive starting battery in a golf cart battery case?

I'm looking for about 400 AH @ 12V. Four of these would do if they are really deep cycle batts.

Anyone seen these?
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Comments

  • BB.BB. Just some guy Posts: 24,220Super Moderators admin
    Re: Golf cart batteries from Costco.

    They probably are deep cycle batteries... Try contacting the battery buyer for Costco... Others have contacted the buyers on other products (and batteries) and found them to be pretty forthcoming on who the vendor is and more info about the product.

    Obviously, do not confuse these batteries with the Kirkland dual purpose/smaller batteries sold in the car battery racks--Which are not true deep cycle types.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • WindsunWindsun Solar Shogun Posts: 1,164Solar Expert admin
    Re: Golf cart batteries from Costco.

    You might want to look at this post http://forum.solar-electric.com/showthread.php?p=43717#post43717
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    Where Costco shines is in cost and warranty. Those mean a whole lot more than 'true deep cycle' and other marketing hype. The Costco batteries are pretty much on par with other mid line batteries such as the Trojan T105 or SCS220.

    Capacity in lead acid batteries falls in a narrow range of about 22 watt hours per pound and the variance is a very minor issue in practical terms. Very many factors will influence battery capacity by 10% or more and it is best no to use lead acid batteries on the extreme margin so fussing about small differences in battery capacity is not a very productive use of effort IMHO.
  • gclarsengclarsen New User Posts: 1Registered Users
    Re: Golf cart batteries from Costco.

    My Costco 6v batteries are 220AH each, bought about 10 months ago
  • Lefty WrightLefty Wright New User Posts: 111Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.

    The batts I saw at Costco had white cases with red tops, just like U.S. Battery Co.'s 220 Amp hour 6V golf cart batts. But they had no manufacturers label and no Amp hour rating.

    The lack of an Amp hour rating is what makes me suspicious. After having some Kirkland tires fly apart I'm not too crazy about the quality of the merchandise at Costco.

    The cost of those batteries is good if they are really what they appear to be.
  • machinemanmachineman New User Posts: 123Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.

    Anyone have or find the charging specs for these 6V costco batteries? I have 8 of them since last September making ~440ah 24V bank. Mine are white with red top and on say GC2 on them. Wondering if I should be more critical with my bulk/absorb/float settings. For discharge I set my low cut-off voltage to 23.5V.

    Thanks..
  • System2System2 Posts: 6,290 admin
    Re: Golf cart batteries from Costco.

    The Costco here in Santa Rosa, Ca. has Marine Deep Cycle batteries for $75.00 plus $15.00 core charge. They are 12 volt, 115 Amp Hour. About 7" Wide, 13" Long, 9.5" High. They were on the rack along with the car batteries. I've searched all over the Internet for storage batteries for my 27 ft. Newport sailboat and this is the best price by far. Plus, Costco has a hard to beat return policy. And no freight charges!! I'm buying 4 of these and 2 205 watt solar panels will be next.
  • solarvicsolarvic New User Posts: 954Solar Expert
    Re: Golf cart batteries from Costco.

    Isn,t that core charge kind of high? I was shoping for some new l-16 and they only wanted to give me 3 bucks core charge. S:Dlarvic
  • dagr51dagr51 New User Posts: 72Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.

    $15 is pretty standard around here (Michigan).
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.
    Where Costco shines is in cost and warranty. Those mean a whole lot more than 'true deep cycle' and other marketing hype.
    this one needs emphasis, I think, as many just can't seem to see it.

    Available energy capacity is a bit more than 10 watt hours per pound for lead acid batteries (22 -24 wh/lb rated 20 hour rate).

    Thinking that a few amp hours capacity one way or another is going to make any difference in your batteries is a fools errand. There are too many variables involved in practice to make such minor differences meaningful.

    The 'deep cycle' thing in modern terms also goes way overboard too often IMHO. The differences between batteries are more of degree than of kind.

    What will make the most difference in the satisfaction you get from batteries is your use and maintenance.

    Cost and warranty from a reputable retailer who stands behind what he sells and sells a lot to folks like you is a very good start on making a good and effective battery buying decision.
  • PhotowhitPhotowhit Old and in the Way Posts: 3,121Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.
    bryanl wrote: »
    The 'deep cycle' thing in modern terms also goes way overboard too often IMHO.

    As it is generally excepted that deep cycle batteries will out last a standard thin plate lead calcium car battery, you need to support this claim.

    Unless suppoprted stick with deep cycle batteries.

    Good battery information can be found here;

    http://www.windsun.com/Batteries/Battery_FAQ.htm
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • russruss New User Posts: 593Solar Expert
    Re: Golf cart batteries from Costco.

    Came across a blog on batteries - This Week İn Batteries - by Venkat Srinivasan.

    His background:

    I work with a team of researchers at Lawrence Berkeley National Lab as part of the Batteries for Advanced Transportation Technologies (BATT) program. We're solving the problems that prevent lithium-ion batteries from being widely used in electric, hybrid-electric, and plug-in-hybrid-electric vehicles.

    A little away from direct solar but not all that much. He answers questions put to him on the blog.

    http://thisweekinbatteries.blogspot.com/
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    The FAQ is one of the very resources I consider credible that actually tries to list battery life. The problem is that not many folks actually read it for what it says and what it does not say.

    My assertion was that the difference between SLI and 'deep cycle' is more a matter of degree rather than of kind. To be a matter of kind, there would need to be a sharp and clean delineation such as one could find in a spec sheet. I have yet to find any.

    I do know I can buy SLI batteries with 5 and 7 year warranties but those intended for 'deep cycle' are often warrantied for 3 years max while those for commercial may have a 1 month warranty, if any. The issue isn't the battery, it is the anticipated use. Warranty is a manufacturer's (or retailer's) way of telling you how long he thinks your battery will last for how he thinks you will be using it. The big variable is the latter one.

    I do know that all lead acid batteries show similar life with repeated discharge depth curves. I do see patterns in line cards that show the capacity, cost, ruggedness trade-off. I see differences of degree but not of kind.

    What I don't get is the human factors. It never ceases to amaze me the degree to which some folks are invested in their beliefs about batteries.
  • PhotowhitPhotowhit Old and in the Way Posts: 3,121Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.
    bryanl wrote: »
    ... amaze me the degree to which some folks are invested in their beliefs about batteries.

    Been around a long time and watched people make mistakes. Even made a few myself, though not with batteries.

    I can tell you a Yamaha RD-350 is not a touring bike, ie is not designed to take long trips on. It's 2 cycle, chain driven and red lines at 13,500. I'd say a Yamaha SX750 while not a pure touring bike, is 4 cycle, shaft driven, and for this example has a cafe' faring.

    I've owned both of these bikes, and what your telling me is they are the same.

    SLI batteries have thin plates, calcium is added to the lead, this is to increase the Cold Cranking Amps, the design is different, as is the use.

    I've riden the SX750 from Tallahassee, FL to Denver, CO in 2 days, but the longest motorcycle trip I ever made was from Tallahassee FL, to Panama City FL on the RD350 I paid for it for weeks even though I was a young health kid.

    If you need me to I can find links to back up my explaination, but my explaination is the excepted one, Please show links if you can find them, backing up your position.

    Forums are a dangerous place for the distribution of misinformation, support your claim!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    re: "SLI batteries have thin plates, calcium is added to the lead"

    have you ever looked at a battery's internals? They don't have solid plates. They have grids filled with paste. In any battery, lead that is not exposed to electrolyte is just dead weight. That is why the whole plate thickness thing is such a misleading concept as thick plates means low lead efficiency and that is to be avoided in any battery. (note how consistent the energy density by weight is in a battery line to see how 'plate thickness' is optimized).

    Calcium, antimony, and other dopants are used to control properties. Between these two, the trade-off is gassing versus electrode strength. Guess which is used in sealed, maintenance free and which is not.

    Again, my point is that the difference is one of kind and not of type. If you want to think of batteries with plate thickness, think that there aren't just 2 thicknesses but rather a whole range.

    The fact is that lead acid batteries are more similar than not and that the major factors influencing their service life involve their use profile.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: Golf cart batteries from Costco.
    bryanl wrote: »
    re: "SLI batteries have thin plates, calcium is added to the lead"

    have you ever looked at a battery's internals? They don't have solid plates. They have grids filled with paste. In any battery, lead that is not exposed to electrolyte is just dead weight.

    Not quite. Automotive batteries are like this, and the extra lead is not 'dead weight'; it is there to continue to provide power as the plates slowly erode over time.
    That is why the whole plate thickness thing is such a misleading concept as thick plates means low lead efficiency and that is to be avoided in any battery. (note how consistent the energy density by weight is in a battery line to see how 'plate thickness' is optimized).

    Again, not quite. Thicker plates mean the battery will last longer - the main point to deep cycle. True Deep Cycle batteries have plates that are solid, not 'spongeform' like the automotive type. They have a wavy shape to them to add structure.
    Calcium, antimony, and other dopants are used to control properties. Between these two, the trade-off is gassing versus electrode strength. Guess which is used in sealed, maintenance free and which is not.

    Actually things like antimony are added to improve teh structure of the plates - lead is pretty darn soft stuff. Some substances, such as cadmium, are added to the electrolyte to improve the recharging capability.
    Again, my point is that the difference is one of kind and not of type. If you want to think of batteries with plate thickness, think that there aren't just 2 thicknesses but rather a whole range.

    Again, the problem is there's no industry standard or Gov't spec to follow: any manufacturer can stick the label "Deep Cycle" on any battery. It does not have to be capable of being discharged to 20% SOC 'X' times under 'Y' load over 'Z' hours at 'T' temperature with a recharge of 'A' Amps @ 'V' Volts for 'H' hours.

    A perfect example of this misleading labeling are the RV/Marine batteries. "DEEP CYCLE" is proclaimed in large letters, but most of them are the automotive style plate design, just extra thick so they last longer. Some don't bother with that distinction. Manufacturers get away with this because there's no way for the average consumer to tell the difference. If they use it in a RE application, the battery isn't warranted for that so any failure is the consumer's problem, not the maker.
    The fact is that lead acid batteries are more similar than not and that the major factors influencing their service life involve their use profile.

    Yep. Very similar with slight variations that can make the difference. But even two batteries from the same maker can have different internals and therefor one is superior to the other for a given application. Also, even though the 'big box' department store units are made by a famous manufacturer, they are made to the retailer's specs. This usually makes the #1 consideration "profit", rather than "performance".

    Some companies are now marketing batteries specifically intended for Renewable Energy applications, and designate them with the RE tag. As far as I know, they aren't much different from their standard Deep Cycle; they're just 'admitting' they can be used for such purposes.

    I think Windsun could give us some better data as to how well these batteries do, and how well the different manufacturers stand behind their product. Bottom line; that's what counts.
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.
    Again, not quite.
    yes, well really, this is where these threads often go ...

    What we are talking about is the same basic point. There is a lot of hype and marketing terms when it comes to batteries but the batteries themselves are more alike than different. Manufacturers provide batteries over a range that trades off capacity, ruggedness, and cost. There are no clear delineations between the various use types described in the marketing terms.

    As for the esoterica and the 'thick plates' bull, see Understanding batteries, start with these links for a start on where I come up with what I offer. Restating what I said in a slightly different manner with a 'not quite' to try to refute just isn't doing much clarification.
    I think Windsun could give us some better data as to how well these batteries do, and how well the different manufacturers stand behind their product. Bottom line; that's what counts.
    As for the first, that depends upon the user much more than the battery so getting anything useful for how batteries do would not have much value. As for the second, there is this thing called a warranty offered by manufacturers and retailers that stands as a reliable guide for the purchaser.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: Golf cart batteries from Costco.

    So you're saying the only reason manufacturers put thicker plates in Deep Cycle batteries is to fool people who equate the weight of the thing with its power capacity?

    Maybe we should all just be buying El Cheapo car batteries for our RE systems.
  • KamalaKamala Solar Aborigine Posts: 452Solar Expert ✭✭✭✭✭
    Re: Golf cart batteries from Costco.
    bryanl wrote: »
    ... batteries themselves are more alike than different. ...

    As are golf clubs. All have a grip, a shaft and a head, (I'm not a golfer) making them very much alike. Different heads make each club more suited for a particular task than another. The task, of course, is to hit the ball. Which can be done with any club. But you wouldn't drive with a putter and you wouldn't putt with a driver.

    bryanl, I understand and accept your point but do not share your disdain for the term "deep cycle."

    Kamala
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    re: "So you're saying the only reason manufacturers put thicker plates in Deep Cycle batteries is to fool people who equate the weight of the thing with its power capacity?"

    what I am saying is that this "thick plates" idea is a teaching fiction and not in touch with reality. It is used to try to sell marketing hype like "deep cycle" with a false rationalization. It may have been somewhat useful long, long ago but no today IMHO.

    re: "fool people who equate the weight of the thing with its power capacity?"

    the weight and capacity of a battery are two measures commonly found in line cards. If you use them to calculate energy density by weight, you will see that all lead acid batteries fall into a vary narrow range. (again, caveat: context. open minded beware of the tendency to bring in extremes to refute, examine 'logical fallacies' for the phenomena)

    This is one of the primary means by which one can infer that 'thick plates' is a fiction.

    If there were 'thicker plates' then batteries with those plates would be much heavier for the energy they could store. Since this is not the case, they do not have 'thicker plates'

    Also note that corrosion is a problem of excess charge while sulfation is the problem of age. Cycling a battery doesn't cause plate material to shed and wear down as a primary life shortener, it causes it to accrete sulfate crystals which reduces the effective exposure of plate lead which causes a reduction of capacity over time.

    And yes, I am aware this leaves open the expansion and contraction nitpicking on shedding for those in a state of dissonance to try to grab upon so readers with an open mind - be prepared. The age via sulfation is well established and the key in modern batteries in this context.

    As for the golf clubs - note that very few people use such things as compared to how many use batteries and that of those that do use the clubs, not many are going to be able to illustrate a difference in performance with very high end clubs versus the run of the mill clubs. The high end stuff may feel better and make one able to hold the nose a bit higher, but they don't do much to help out any except the serious golf devotee, if then. (i.e. very big expense for very little performance difference)

    People have enough trouble trying to get an idea of what they are looking to purchase without misleading 'teaching fictions' or marketing myths. I noticed that Costco now has their 6v T105 sized batteries in bright yellow with "Golf Cart" in big black letters. That tells me they read the (especially RV) forum discussions about batteries and know that the sell point is not on specifications, warranty, or other measurable stuff but rather a collection of myths deeply held, for which many are willing to pay a premium.

    I have nothing against people spending their money how they want but it does bother me if they do so out of ignorance or deception because that is why I get bright yellow batteries with bold nonsense labeling in my face instead of good reliable and comprehensive measure.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: Golf cart batteries from Costco.

    In other words, I'm stupid.
    Well that's me and a whole slue of electrical engineers and physicists going back over 100 years, as well as everyone else who believes what you call "marketing hype", "false rationalization", and "fallacies".

    At least I'm in good company.

    I do agree with you about the Deep Cycle label: would either of us be surprised to cut open some manufacturer's DC battery and find it identical to their SLI model? Nope!
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    re: "In other words, I'm stupid." - I don't think personalizing the discussion is a good idea, especially when it involves putting words that weren't said or intended into the mouths of others.

    I have not said anyone is stupid, I have not said that SLI batteries are identical to those intended for other service types, and I have not said anything about those who engineer or design batteries.

    I wish I had retained the link to a PDF for an owner's manual for a manufacturer's industrial batteries. It had instruction about replacing the plates in those batteries along with pictures and diagrams - and a good rundown on just how battery plates are designed and built and the materials used. It would have been a good resource for this discussion.

    The key point for my interest is that those looking for batteries of the sort you can find in Costco should stick to measurables such as warranty, specifications, and retailer volume and reputation. They should avoid terms that don't have clear objective definitions and they should be aware that their use and maintenance of batteries is going to be a major influence on the satisfaction they get from its performance.
  • PhotowhitPhotowhit Old and in the Way Posts: 3,121Solar Expert ✭✭✭
    Re: Golf cart batteries from Costco.

    Well I've been polite, to this point you have provided one link that I followed that goes to generic information aabout batteries, if fact a link to NAWS FAQ.

    You've talked a lot but not provided any evidence, even antidotal.

    Forums are great places for bad information to get a foothold, so I say,

    Put up, or sh...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • BrockBrock New User Posts: 612Solar Expert ✭✭
    Re: Golf cart batteries from Costco.

    Regarding thin plate vs. thick plates, a thick plated cell doesn't weigh more. As has been mentioned the weight is a good rule of thumb for capacity. The thing is a "deep cycle" battery usually has the same amount of plate weight, just thicker plates and fewer of them, where an automotive or starting battery has thinner plates and more of them.

    As far as battery being the same simply walk in to a store with both types, the same weight and number of cells. Taking a simple battery tester with a 200 amp resistive load in it and try this out for yourself. The starting battery will stay up at 12v for 30 seconds or so and then start falling off, a deep cycle battery will start about 11.5v and stay there much longer. I have even run them at the same time and after a few minutes the "thicker" plated cells will have a higher voltage and the voltage will have stabilized while the voltage on the starting battery continues to fall.

    Now how can those two batteries not be made differently? Why would a manufacture make them different, each has their own purpose and task and are designed accordingly.

    Bryanl, if I didn't have the experience I do I would have implied that a Costco unbranded battery, a Trojan and a Rolls are all created equil and I can attest they are not. I am not saying what anyone should or shouldn't purchase, but I can assure everyone they are not all the same, similar yes, the same, not by a long shot.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • KamalaKamala Solar Aborigine Posts: 452Solar Expert ✭✭✭✭✭
    Re: Golf cart batteries from Costco.
    bryanl wrote: »
    ... As for the golf clubs - note that very few people use such things as compared to how many use batteries and that of those that do use the clubs, not many are going to be able to illustrate a difference in performance with very high end clubs versus the run of the mill clubs.

    Quality of manufacture was not an element of my post. I was typing metaphorically. :roll:
    bryanl wrote: »
    ... it does bother me if they do so out of ignorance or deception because that is why I get bright yellow batteries with bold nonsense labeling in my face instead of good reliable and comprehensive measure.

    Knowledge is a weapon against ignorance. And this forum is an armory. Those here who use the term "deep cycle" are not inferior warriors. The term is just that, a term. It is used here to signify a, perhaps subtle, difference in battery construction, and thereby, usage. I will admit that when someone says "true deep cycle" the implication is that "deep cycle" alone is deceptive. I won't attempt to enumerate the weapons to be used against deception.

    byanl, I admire your zeal in demanding meaningful measurement. Sadly, you may be "on a hill seeing [sic] the world spinning 'round."

    Regards,
    Craig
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    re: "As has been mentioned the weight is a good rule of thumb for capacity. The thing is a "deep cycle" battery usually has the same amount of plate weight, just thicker plates and fewer of them, where an automotive or starting battery has thinner plates and more of them."

    There are both factual and logical problems with this. First is that the energy density of lead acid batteries is not a rule of thumb, it is a property of the battery. This is easily determined by examining any manufacturer's line card (see also BatteryUniversity.com on this). Second is that the capacity of a battery depends upon reaction of lead with the electrolyte. Lead that is buried within a 'thick plate' and does not have exposure to the electrolyte cannot add to capacity.

    This basic reality is that lead cannot react with sulfuric acid to provide energy unless the two come into contact. Batteries manufactured with solid plates that can be thick or thin for ruggedness are going to be inefficient in use of resources. Thick plates means that there is more lead that is not exposed to electrolyte and, therefore, cannot contribute to battery capacity. If 'deep cycle' batteries had 'thick plates' then they would suffer from this decrease in capacity for any given weight of battery.

    The fact is (as you can see from manufacturer specifications), that there is only minor and insignificant variance in energy density by weight. Therefore there is minor and insignificant difference in lead that is within the structure compared to exposed to electrolyte and that, in turn, means that there aren't any significant variances in thickness of the electrode materials in terms of bulk as thought of as being needed to create stronger plates.

    re: "You've talked a lot but not provided any evidence, even antidotal." it is interesting how a link sheet of selected battery information available on the web is so cavalierly dismissed, not to mention the manufacturer's data sheets and a very straightforward logical inference.

    Keep in mind that the 'deep cycle' and 'thick pates' thing being promoted is about a matter of kind whereas my perception is that it is, instead, a matter of degree. Find me a specification that can be used to classify batteries as suggested; one that has good merit and is readily available to consumers. (the only one I have found to date is warranty)

    Rather than impugn, denigrate, and deny, why not answer my logic and show me what is wrong with it? Show me how you can get battery capacity from lead that is not available for reaction. Show me how a thick plate has as much surface area for weight as a thin one and how strength can be improved in such a thick plate as needed to support the suggestions about thick plates.

    That's all you need to do to get me out of your hair. Show me where my logic is faulty. Provide a competent and pertinent reference that competes with the list I provided. Provide me with better logic, better data, better models, or concepts that make sense and fit with what I can see and experience.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: Golf cart batteries from Costco.

    No one ever said thicker plates contribute to a battery's current producing ability. They don't. It is the exposed plate surface that adds up to higher current capacity. That is the reason for the 'spongiform' plates of automotive batteries; large surface area to deliver high Amperage for starting purposes. Deep Cycle batteries often fall short in this function and can sometimes be over-whelmed by the sudden need to produce high current, resulting in a drop of available Voltage which (if conditions are borderline all around) can even cause inverter shut-down.

    The so-called deep cycle Marine/RV or 'hybrid' types tend to have the same plate form as automotive, only slightly thicker so they will stand up longer. Sometimes they fail to perform well in either application because of this compromise design.

    The thick, sometimes (but not always) 'solid' plates of a "true" deep cycle are built that way to provide cycling life for the battery. Every time a battery is discharged and recharged, to what ever degree, some plate erosion occurs. In automotive applications this is so minor as to be unnoticeable for years of service. But it's different if current is steadily drawn over hours and then pushed back in. A battery that has failed of old age will have quite an accumulation of dissolved metal at the bottom. Manufacturers provide space at the bottom below the plates for this material to settle in to without it causing shorts (hopefully - doesn't always work).

    You can't really trust makers' warranties either. Since RE is usually not "an approved application" the warranty is often not applicable. Some companies will stand behind their product regardless of this technicality. And that is how you know you're dealing with a quality product: by the public reputation they've earned for performance. And remember that sometimes "warranties" are just insurance money paid to off-set the potential future replacement.

    One thing I think we all agree on: the "Deep Cycle" label is bandied about and put on products without there being any true, legally binding definition. It would be nice if there were some sort of spec companies had to meet, but I wouldn't be surprised to one day open up a DC and find it's nothing but a case stuffed full of penlight cells. :p
  • bryanlbryanl New User Posts: 175Solar Expert ✭✭✭✭
    Re: Golf cart batteries from Costco.

    re: "only slightly thicker so they will stand up longer." -- this is the issue at hand, except here it is only "slightly" - the reason given for thick plates as a distinctive property of a deep cycle class of batteries in so many places is that these thick plates are (supposedly) what make the deep cycle class of battery stronger and more rugged in a way that sets them apart from SLI batteries. As I noted, the model just doesn't withstand even the basic logic that buried lead is useless lead.

    Slight is a good qualifier because it acknowledges that the differences are not worthy of the claims made for them. Battery ruggedness is enhanced in many ways and the differences are 'slight' even then.

    re: "sometimes (but not always) 'solid' plates of a "true" deep cycle" -- what we are talking about here are the sorts of battery in common circulation at places like Costco. If you find a modern lead acid battery that has solid plates, even for industrial use, please let me know as I'd be curious as to why the manufacturer would waste so much lead.

    re: "Every time a battery is discharged and recharged, to what ever degree, some plate erosion occurs." -- as I understand it, plate corrosion is primarily a problem with overcharging. Cycling a battery wears them because they shrink and expand depending upon state of charge. This is another good reason for not making solid plates because a solid plate would suffer more than other designs in expansion and contraction (i.e. crack and big chunks break off).

    The primary failure mode for modern batteries is sulfation that is built up over time in the discharged state. Shedding and cell shorting from corrosion is rather far down the list from what I can tell in modern batteries.

    re: "You can't really trust makers' warranties either." -- these things are commercial contracts and subject to enforcement. That is why they get so short unless the usage is clearly identified as a condition of the warranty. This leads to the advice that you buy batteries from a retailer who offers a good warranty, sells a lot to folks who use them like you do, and will stand behind what he sells.

    re: "the "Deep Cycle" label is bandied about and put on products without there being any true, legally binding definition." -- not only legally binding but measurable in any reasonable way. The only explicit 'legally binding' thing about batteries is their warranty.

    What is sometimes measured is the cycle life expectancy. That is usually determined by cycling a battery down to 80% DoD and seeing how many times the battery handles this before performance degrades in some measureable way. It is a destructive test. SLI batteries tend to handle 200- 400 cycles or so and those intended for deep cycle use maybe 2 or 3 times that at most. When you use a DoD of 50% the numbers start to converge in the thousands somewhere.

    This cycling life expectancy is why it is recommended that batteries not be taken below 50% DoD as that gets to about the point where shorter life and battery cost start to cross over as capital cost impacts on other factors involving battery life expectancy.

    When you get the cycle life expectancy at this 50% DoD point and consider a typical 5 year life expectancy with nominal use patterns, the differences get down into esoteric concerns. Many solar systems tend to float so deep cycle aging isn't the problem. Most RV systems only get periodic (weekend) service and there are only 260 weekends in 5 years. It is industrial service where they run the batteries down daily where warranties are really short and battery replacement every few months or so is not considered unusual.

    Use and maintenance are a primary factors in battery service satisfaction. People that sell batteries put "deep cycle" or "RV/Marine" or "solar" labels on their products to indicate their focus suggesting that they have tweaked the design for this particular type of use. I don't think it does a service to exaggerate differences, especially with rationales that don't make sense when examined.

    There are many things than can be tweaked which is why we have so many options available to us. We need to keep in mind that, if the differences were clear cut and actually significant and useful, there wouldn't be so many discussions asking about what is the best battery.
  • KamalaKamala Solar Aborigine Posts: 452Solar Expert ✭✭✭✭✭
    Re: Golf cart batteries from Costco.

    Just as a thought experiment, what if the plates were "foil" thin? Perhaps all of the Pb would go into ionic solution as PbSO4. In other words, the plate is destroyed, entirely consumed and no longer exists. In the recharge process there would be no place for the Pb ions to "go back to." So it would seem that plate thickness might be a factor.
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: Golf cart batteries from Costco.

    As this extended argument is upsetting Bill, I will first of all apologize to him and all other forum members for allowing this obviously pointless discussion to drag out so long. :blush:

    In future I shall try to be more circumspect in my posts.
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