Do SLA batteries need to be vented?

Discussion in 'General Electronics Chat' started by foolios, Aug 14, 2014.

  1. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    Do SLA batteries need to be vented? As in fanned to the outside?
    I thought AGM and SLA batteries were the same, and bought a 12v/55amphour SLA battery. The product site stated that:
    No Spills
    No leaks
    No water to check
    Longest life-cycle product on the market
    This maintenance-free design allows for the most powerful, highest amp hour capacity. Fiberglass mat separators and high cell compression extend battery life by delivering superior vibration resistance from the most extreme conditions

    At: http://www.chromebattery.com/12v-55ah-sealed-lead-acid-battery-nut-and-bolt-connector-945.html
    So I thought this could be charged by my solar panel in the garage while hooked up to my Renogy charge controller.
    I've noticed a battery type smell in the garage near the battery.
    Is this normal when charging SLA batteries? Is it safe to keep it in the garage while charging/discharging?
    EDIT: Actually, I just reread their product description for this and it also stated:
    absorbed glass mat technology
    Thanks in advance for any info.

    Edit: Looking back at another battery I ordered from them off Amazon, I see why I was confused and thought it was an AGM battery. According to their product description for a different battery, 35ah that I bought:
    Chrome Battery SLA batteries are 'the workhorse of ALL batteries' and are constructed with lead calcium alloy and absorbed glass mat technology
    at: http://www.amazon.com/gp/product/B008D5YG3G/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

    But I am seeing articles about AGM vs. SLA.

    I'm so confused.
     
    Last edited: Aug 14, 2014
  2. MrChips

    Moderator

    Oct 2, 2009
    12,415
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    SLAB, sealed lead acid battery, by definition is sealed. Hence no venting is required.
    However, it is important that you use a properly functioning intelligent charger.

    This is what happens if the charger does not switch to a float charge at a lower voltage once the battery has reached full charge:

    [​IMG]
     
    Last edited: Aug 15, 2014
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    You are overcharging the SLAs. If you religiously obey the voltage limits printed right on the battery, they should never vent.

    Grab your voltmeter, and measure the voltage every thirty min or so during the charge cycle. You should never see >14.4V, and then not for more than a few minutes...


    Likely, your charger is set up for flooded batteries; not SLAs
     
  4. NorthGuy

    Active Member

    Jun 28, 2014
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    AGM is SLA. LA may be of 3 types - flooded, gel and AGM. Flooded batteries has caps which can be open and you can see acid inside. Others are sealed. The battery linked from Amazon is AGM.

    It has a valve, so it may vent a little bit out, but it really shouldn't. If it vents frequently, it'll loose all the water and becomes useless. Read the battery data sheet for recommended voltages and adjust your charge controller accordingly.
     
  5. snav

    Active Member

    Aug 1, 2011
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    All batteries are vented to prevent explosions but if the charger is properly regulated you will get a good long life(4-6yrs). We regulate our 12v chargers to maintain no more than 13.63v on float.
     
  6. RichardO

    Well-Known Member

    May 4, 2013
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    From a safety point of view you do need some venting. At minimum you need a blow-out plug.

    This is in case there is a catastrophic failure in the battery or charger that causes the battery to vent. The last thing you want is hydrogen gas in a tightly sealed container with an electric arc waiting to ignite it.
     
  7. foolios

    Thread Starter Active Member

    Feb 4, 2009
    160
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    Wow! Nowhere for it go?
     
  8. foolios

    Thread Starter Active Member

    Feb 4, 2009
    160
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    I have seen 15.2v on the Renogy charge controller. It was so highly reviewed. Now I realize it is killing my batteries.
    This one:
    http://www.amazon.com/gp/product/B00BCTLIHC/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
     
  9. foolios

    Thread Starter Active Member

    Feb 4, 2009
    160
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    So the batteries should be ok, right? I should just replace the charge controller with something better then.
    I think I have only smelled them twice and I've only had them about two weeks.
     
  10. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    What does that mean, on float?
     
  11. foolios

    Thread Starter Active Member

    Feb 4, 2009
    160
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    How do you use/do this?
     
  12. NorthGuy

    Active Member

    Jun 28, 2014
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  13. foolios

    Thread Starter Active Member

    Feb 4, 2009
    160
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    http://renogy.com/wp-content/uploads/2014/04/PWM30CC-Manual1.pdf

    It does say max 14.6v but apparently I have a bad one. I know the inverter I am using has a cut off when the voltage reaches over 15v and I did see it red light and shut down once. So I can use that to help verify that the voltage is going too high.

    I don't see anything about adjusting the voltage, but I do see the caution of loading it at no more than 80%. I am prolly getting 25 amps out of the 30 that is its max. Do you think that going into the upper range that that is causing the higher voltage?
     
    Last edited: Aug 15, 2014
  14. MikeML

    AAC Fanatic!

    Oct 2, 2009
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  15. NorthGuy

    Active Member

    Jun 28, 2014
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    The controller has an ability to lower current when battery voltage is too high. If its voltage goes above the expected settings, something is wrong.

    Where and how do you measure the voltage?
     
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  16. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    If a battery charger is designed to charge 100Ah LA batteries (which can accept a max charge rate of 40A), and you connect it to a small SLA that can only tolerate a max charge current of <5A, you should expect that the charger might have a problem...

    You are using the wrong charger for such a small battery...
     
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  17. BobTPH

    Active Member

    Jun 5, 2013
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    Float is a constant voltage that is the max voltage the cell can be charged to safely. After the battery is fully charged, this float voltage is applied and it keeps the battery fully charged as it loses to self-discharge.

    Bob
     
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  18. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    I have a digital voltage meter display that is connected to each bus bar that the batteries are connected to.
    And I take a voltage reading at the connection terminals for the positive and negative wires on the charge controller itself.
     
  19. foolios

    Thread Starter Active Member

    Feb 4, 2009
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    Ok, so a problem may be that I am getting more amperage incoming than what the batteries can handle.
    With all batteries connected;
    26ah+35ah+35ah+35ah+55ah = 186ah total.

    How do I figure out how many incoming amps this collection can handle at one time?
     
  20. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    You are not supposed to parallel batteries with dissimilar capacities and try to charge them as a group. If charging a bunch of batteries in parallel, they should all be the same model/make, same capacity, bought at the same time...

    Say the charger is capable of delivering 40A. The battery with initial lowest state-of-charge is going to get hit with 40A while the others take not much. The 40A charge rate for the single battery taking it all could be 5X the max allowed charge rate for that one battery...
     
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