Best way to determine the value of a used battery

rene26
rene26 Registered Users Posts: 5 ✭
in General Solar Power Topics #1
Hi all,

First-time poster, here.

I'd like to hear your opinions on a question I have. I work for a start-up solar company, and we're having a tough time determining what value is left in used batteries that we get from clients after installing new systems. There seems to be a pretty wide range of states that a used battery can be in, from completely dead to moderately ok. I realize that the minimum value of a battery is whatever the scrap yard is offering for it--that part is easy, and that is the price on which we base our offer to clients for their old batteries. But I feel like there is much more to this story. I realize there is no guarantee with used batteries, but there must be some way to at least approximate their worth, right? I have had a fair amount of people approach me to purchase one or two of the old batteries, and we have trouble determining a fair price to charge.

I've done a good deal of research online but haven't had a lot of luck in finding a satisfactory method. I'm not confident that a generic load tester gives you the full picture. Does anyone out there have a method for determining this? I'd like to be able to fairly confidently say "This battery has about 50% capacity left, this one 30%, this one 70%, etc."

I've heard of people applying say, a 10 or 11A load to a 225Ah battery, adding a small electric clock, and seeing how many hours the battery can support the load (indicated by whatever time the clock stops at). You would then compare this time to 20hrs (since 10-11A should be held for about 20hrs with a new 225Ah battery) and determine what percentage capacity is left. Sounds pretty cool. Has anyone tried this? Are there other methods?

Eager to hear your thoughts. Thanks in advance for any and all advice!

Rene
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Best way to determine the value of a used battery

    Welcome to the forum.

    My formula is this: # lbs. weight of the battery * current scrap price for mixed lead.

    No I'm not kidding. Used batteries are the ultimate 'pig in a poke'. A complete gamble. You can not really test them to know what shape they are in. The actual method of load testing is with a fixed current draw over time, and simply applying a load does not a fixed current draw make; as the Voltage goes down while the battery discharges the current goes up. Furthermore, because of the Peukert effect it is not easy to compare capacity between different rates of discharge.

    Before you buy used anything look at the price of its new equivalent. Lots of people try to sell used solar equipment for considerably more than it can be had retail.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #3
    Re: Best way to determine the value of a used battery
    rene26 wrote: »
    I realize that the minimum value of a battery is whatever the scrap yard is offering for it--that part is easy, and that is the price on which we base our offer to clients for their old batteries.

    I pretty much agree with 'Coot, to give someone more, from a business stand point, would be taking on resopnsiblity and liability. You would need to maintain the batteries as well as be liable for their working if you resold them. I would continue to buy them, and resell them with the understanding that they have NO warranty at the scrap price. Be very clear to those you purchase from and those you sell to what you are doing. It maybe that you can help some people out in this way. If someone has a failed L16 you might help them get by for a short term, and build good will.

    Once you have explained it a few times, I think there could be some small benifit to your company in building good will, but there is a whole lot of down side if and when problems arrise.

    There are exceptions NiCD(wet cells) and NiFe I think can be rejuvinated with a change of electrolite, dropping to novoltage and fast charging (NiCD) but there is a bit of a science to this but you could read up and be the local expert! Still not sure if I would want to sell them as a business, perhaps on Ebay They both have a cult following.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #4
    Re: Best way to determine the value of a used battery

    Hi Rene,

    My opinion is that almost any customer should be happy if you folks would haul them away, and recycle them, for NO CHARGE. And, at that you might loose money. Do not need to tell you that this removal/hauling/unloading them is a PITA. Just MHO. vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Organic Farmer
    Organic Farmer Solar Expert Posts: 128 ✭✭
    #5
    Re: Best way to determine the value of a used battery

    Why not recycle them?

    When I lived in Bremerton Washington, there was a business there who recycled lead-acid batteries. I met the guy and watched him do it. The 'big' thing is to get the molds to pour the liquid lead into. It is all pretty lo-tech.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #6
    Re: Best way to determine the value of a used battery
    Organic Farmer wrote: »
    Why not recycle them?

    When I lived in Bremerton Washington, there was a business there who recycled lead-acid batteries. I met the guy and watched him do it. The 'big' thing is to get the molds to pour the liquid lead into. It is all pretty lo-tech.

    It is pretty low tech until you have to comply with all of the EPA and other regulations associated with legally recycling lead batteries. (They are concerned about such things as dust and vapors, contamination of the soil with bits of lead or lead compounds, etc.)
    Also not completely low tech if you are concerned about your own health. Common sense and sufficient knowledge can take care of that part though.
    SMA SB 3000, old BP panels.
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  • Organic Farmer
    Organic Farmer Solar Expert Posts: 128 ✭✭
    #7
    Re: Best way to determine the value of a used battery

    All of the lead gets recycled, so your not putting any lead into the soil. That is the whole idea behind recycling. :)

    Exhaust hoods should meet OSHA standards for worker health.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #8
    Re: Best way to determine the value of a used battery
    Organic Farmer wrote: »
    All of the lead gets recycled, so you're not *intentionally* putting any lead into the soil. That is the whole idea behind recycling. :)

    Exhaust hoods should meet OSHA standards for worker health, *but what about the people downwind?*.

    As I said, it gets complicated. Especially when the regulations do not offer any shortcuts for small volume operations or location in a remote area.
    SMA SB 3000, old BP panels.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #9
    Re: Best way to determine the value of a used battery
    inetdog wrote: »
    It is pretty low tech until you have to comply with all of the EPA and other regulations associated with legally recycling lead batteries. (They are concerned about such things as dust and vapors, contamination of the soil with bits of lead or lead compounds, etc.)
    Also not completely low tech if you are concerned about your own health. Common sense and sufficient knowledge can take care of that part though.
    I worked on an pre (EPA) audit assessment of a secondary lead smelter (battery recycler) 20+ years ago. It was nasty. Sulphuric acid mud was all over the place and everyone had to wear a respirator at all times because of the fumes from the smelter and from the incinerators they used to burn off the plastic. I hated that job.
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  • rene26
    rene26 Registered Users Posts: 5 ✭
    #10
    Re: Best way to determine the value of a used battery

    Thanks so much for your replies, everyone.

    I understand where you guys are coming from: it's important to keep up the reputation of the company. I also did not know that load testing was based on a fixed current draw. That's interesting and would definitely be relevant in this case. In case you are interested, here is a link to the type of "tester" I was interested in building:

    http://www.instructables.com/id/AmpHourTest/

    My bosses aren't so much concerned with liability in this case. I think they plan on selling the batteries "at your own risk" but just want to be able to guide clients toward making some quasi-informed choices. Certainly, should the batteries completely fail to perform satisfactorily, we would refund the client their money and take the battery back to send off for recycling.

    I was just curious to see if anyone was doing anything like this and might have a recommendation.

    It never occurred to me to do the recycling ourselves. That sounds wildly interesting, but a bit beyond our means at the current time ;-)

    Your comments are all greatly appreciated!
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #11
    Re: Best way to determine the value of a used battery
    rene26 wrote: »
    It never occurred to me to do the recycling ourselves. That sounds wildly interesting, but a bit beyond our means at the current time ;-)
    Wildly interesting? Really? Not to me. Lead, sulphuric acid, and molten/burned plastic are all very nasty substances. But whatever blows your skirt up. ;^)
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