Best way to store unused batteries?

BilljustBill
BilljustBill Solar Expert Posts: 219 ✭✭✭
Just thinking about how our state and national economies are not as "stable" as they were ten years ago, and considering future needs, possible shortages, and future pricing for deep cycle batteries of all types for our stand-by or off grid solar projects....

Starting with flooded lead acid deep cycle batteries, like the L-16's, is there a "best" way to buy now, place in storage for months or years from now, and then bring them out expecting them to perform as if they were brand new?

Thanks,
Bill
Bill

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Best way to store unused batteries?

    From NAWS' Battery FAQ:
    The lifespan of a deep cycle battery will vary considerably with how it is used, how it is maintained and charged, temperature, and other factors. In extreme cases, it can vary to extremes - we have seen L-16's killed in less than a year by severe overcharging, and we have a large set of surplus telephone batteries that sees only occasional (5-10 times per year) heavy service that are now over 25 years old. We have seen gelled cells destroyed in one day when overcharged with a large automotive charger. We have seen golf cart batteries destroyed without ever being used in less than a year because they were left sitting in a hot garage without being charged. Even the so-called "dry charged" (where you add acid when you need them) have a shelf life of 18 months at most. They are not totally dry - they are actually filled with acid, the plates formed and charged, then the acid is dumped out. These are some typical (minimum - maximum) typical expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. that it is almost impossible to give a fixed number.
    • Starting: 3-12 months
    • Marine: 1-6 years
    • Golf cart: 2-7 years
    • AGM deep cycle: 4-7 years
    • Gelled deep cycle: 2-5 years
    • Deep cycle (L-16 type etc): 4-8 years
    • Rolls-Surrette premium deep cycle: 7-15 years
    • Industrial deep cycle (Crown and Rolls 4KS series): 10-20+ years
    • Telephone (float): 2-20 years. These are usually special purpose "float service", but often appear on the surplus market as "deep cycle". They can vary considerably, depending on age, usage, care, and type.
    • NiFe (alkaline): 5-35 years
    • NiCad: 1-20 years

    Short answer--I don't think you can store standard batteries in any meaningful manner...

    If one wanted to try... Keep the batteries charged and refrigerated/very cold. In theory, battery life goes up by a factor of 2x for every 10C (18F) reduction in temperature... Instead of storing at +20C (room temp), store at -20C and they should last (if kept properly charged):
    • 2^4 (-20C)= 16x longer
    • 2^2 (0C) = 4x longer
    Do I believe it? Not sure. Is it practical--Got any permafrost near by? Is it cost effective? Probably not.

    Go back and figure out what the power is for? Radio, TV (will anyone be broadcasting?). Fridge/Freezer (electronics/inverters/compressors will probably only last 10-20 years).

    Run equipment? Pumps, washer, tools? Perhaps solar panel only motors during sunlight? Tools/pumps/etc. have limited life too... Especially the DC versions (brushed motors or electronic drivers, pump seals, etc.).

    Get a low power LED flash light and CR123 Lithium primary cells... The Lithium should last 10+ years at room temp (longer if cold?). The LED on very low power will run ~700 hours per pair of CR123 (enough light to not trip around the home).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    Re: Best way to store unused batteries?

    I've bought Lead-Acid batteries before that were sold dry with a bottle of acid. Just fill and use.

    Not sure if oxidation of the grids is any concern, but if not, then it seems to me that emptying the acid out (or buying dry batteries) is probably the best for long term storage of Lead-Acid batteries.

    If they are flooded Nicads, then you store them shorted out and recharge when needed.

    Of course if you're really concerned about everything going to heck, then what you want to do is find a set of Edison Cells, Nickle Iron batteries. They basically last forever, well for decades at least, and usually they are designed to be easily rebuilt.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Best way to store unused batteries?

    Probably not a good economic idea.

    If you are forced to store for long periods, keep them as cool (or cold) as possible on a proper float charge.

    Tony
  • oil pan 4
    oil pan 4 Solar Expert Posts: 767 ✭✭✭✭
    Re: Best way to store unused batteries?
    Peter_V wrote: »
    I've bought Lead-Acid batteries before that were sold dry with a bottle of acid. Just fill and use.

    I have herd that dumping the acid doesn't work that well, I think buying dry batteries, just add acid is the way to go.

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    Re: Best way to store unused batteries?

    I'm pretty sure I've read that there's still a shelf life for dry stored batteries (can't remember what the life was though). Something about the plate paste oxidizing when in air instead of electrolyte.

    Best bet would be to ask the tech/production department of a large battery supplier.

    Ralph
  • jagec
    jagec Solar Expert Posts: 157 ✭✭
    Re: Best way to store unused batteries?
    Ralph Day wrote: »
    I'm pretty sure I've read that there's still a shelf life for dry stored batteries (can't remember what the life was though). Something about the plate paste oxidizing when in air instead of electrolyte.

    Best bet would be to ask the tech/production department of a large battery supplier.

    Ralph

    I have to wonder how gas-tight the seals are on flooded batteries. Obviously they have to vent hydrogen, but if you dumped the acid and filled the cells with pure nitrogen, how much time would you buy before enough oxygen permeates the cells to damage them?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Best way to store unused batteries?

    The naws battery faq lists 18 months maximum shelf life in the second post.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    Re: Best way to store unused batteries?
    jagec wrote: »
    I have to wonder how gas-tight the seals are on flooded batteries. Obviously they have to vent hydrogen, but if you dumped the acid and filled the cells with pure nitrogen, how much time would you buy before enough oxygen permeates the cells to damage them?

    It's been a while since I last bought dry batteries, but IIRC they were sealed in shrink wrap, so maybe filling them with nitrogen or argon and then sealing them in plastic, etc. is a viable option.
  • System2
    System2 Posts: 6,290 admin
    Re: Best way to store unused batteries?

    Storage recommendation for various battery types in the manufacturer's words.

    It makes a lot of sense to read what the battery manufacturers say about long term battery storage. The following is a selection of several manufacturers who have put information in their catalogs. Please read the disclaimer below:

    Sealed Lead Acid Battery Storage

    Power-Sonic Batteries should not be stored in a discharged state or at elevated temperatures. If a battery has been discharged for some time or the load was left on indefinitely, it may not readily take a charge. To overcome this, leave the charger connected and the battery should eventually begin to accept charge. Although Power-Sonic batteries have a low self-discharge rate which permits storage of a fully charged battery for up to a year, it is recommended that a battery be charged 6-9 months after receipt to account for storage from the date of manufacture to the date of purchase. Otherwise, permanent loss of capacity might occur as a result of sulfation. To prolong shelf life without charging, store batteries at 10 degrees Celsius or less.

    Gaston: Lead-acid batteries previously were affected by long term storage after charging. But Gaston SLA batteries are not so affected. This battery offers longer extended storage than conventional batteries (referenced curve shows 3% per month self discharge rate at 20 degrees C.) During storage, carry out supplementary charging according to Table 3 (below 20 degrees charge every 6 months, 20 to 30 degrees C charge every 3 months, over 30 don't store). Although the self-discharge rate is low, specific precautions must be taken against the battery over discharging itself by self-discharge when in storage or not operating. In general, to optimize performance and service life, it is recommended that Gaston batteries which are to be stored for extended periods of time be given a supplementary charge, commonly referred to "top charging" periodically. The top charge referred to is a charge of 20-24 hours at a constant voltage of 2.4 volts per cell.

    Spiral Wrapped Lead Acid Battery Storage
    Hawker Energy Products

    When a Cyclon battery is kept in storage, i.e. on open circuit, the ambient temperature should be controlled to prolong storage time and maintain maximum capacity over time. To get the best storage results, batteries should be charged at room temperature or below, and charged prior to being put back in service.

    The OCV (open circuit voltage) of each battery must be monitored on an individual basis. If the OCV measures 1.93 Vpc, it has zero effective capacity and should be boost charged immediately. Even if the OCV reads higher than 2.00 Vpc at the end of 12 month's storage, the battery should be recharged before use. Thus, to maintain maximum reliability, batteries should be boost charged once every 12 months, or when the OCV reads 2.00 Vpc, whichever occurs earlier.

    If the OCV is allowed to drop between 1.93 and 1.80 Vpc, some permanent damage may occur to the battery. However, if it drops to less than 1.80 Vpc, the battery will most likely be unchargable by conventional methods. Therefore, under no circumstances must the OCV be allowed to drop below 1.80 Vpc.

    Just as high temperature accelerates the aging of a battery, so does it accelerate the self-discharge rate. Thus, when the storage temperature exceeds 25°C, one must monitor the open circuit voltage more frequently. . .

    Flooded Lead Acid Battery Storage

    Trojan: Periods of inactivity can be extremely harmful to lead acid batteries. When placing a battery into storage, follow the recommendations below to insure that the battery remains healthy and ready for use.

    NOTE: Storing, charging or operating batteries on concrete is perfectly OK. The most important things to avoid:

    1. Freezing. Avoid locations where freezing temperature is expected. Keeping battery at a high state of charge will also prevent freezing. Freezing results in irreparable damage to battery's plates and container. [Freezing can happen between -19 F (40% charge) and -98 F (fully charged)]
    2. Heat. Avoid direct exposure to heat sources, such as radiators or space heaters. Temperatures above 80° F accelerate the battery's self-discharge characteristics.
    3. Step by step storage procedure: 1. Completely charge the battery before storing. 2. Store the battery in a cool, dry location, protected from the elements. 3. During storage, monitor the specific gravity (flooded) or voltage. Batteries in storage should be given a boost charge when they show a 70% charge or less. Completely charge the battery before re-activating.

    For optimum performance, equalize the batteries (flooded) before putting them back into service. Refer to the Equalizing section for this procedure.

    Continental Battery Storage:
    Q: Will a battery rapidly self discharge if placed on concrete?
    A: No, placing a battery on concrete will not cause it to discharge any faster than any other surface.
    Q: Can I store a battery indefinitely?
    A: No, a battery will self-discharge slowly over time. Allowing a battery to sit in a discharged state will ultimately lead to severe positive grid corrosion and battery failure. An unused battery should never be allowed to sit over 6 months without a recharge.