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Thread: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

  1. #1
    Flashaholic*
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    Default Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Picked up an old "3335 lumen" dual 100W beam incandescent spotlight and it uses one of these old dinosaur SLA batteries. I looked into some of the more current "Litebox" type Streamlights and was surprised to see they still use these old SLA batteries.

    I know under load these type of batteries aren't going to perform great. But how bad can I expect a good, fresh, quality SLA battery to perform against modern Li-ion when under load? Do they do ok with loads of 2Amps+? How about reliability?

    I'm someone who primarily uses incandescent lights, and am very sensitive to the color shift that easily happens in them (white to yellow) when they sag under load, so I can be a bit OCD when it comes to driving bulbs hard and getting them as white as possible. Which is why I love HKJ's battery comparator, except there's no chance of finding these on there!

  2. #2
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    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    A good SLA battery will be able to deliver a lot of amps, usually more than lithium-ion can. They're also very reliable, and cost less than lithium-ion. Their downside is weight, and lower usable capacity (they don't like to be drained too far).

  3. #3
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    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Thank you WITL. Perhaps I misjudged this old technology's capabilities.

    The market is littered with different brands, and performance/datasheets aren't always easy to find, but I'm on the search now for the highest quality battery I can find.

  4. #4

    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Power output capacity is rated in "C".

    7.4Ah capacity, 2A is only 0.27C

    Ordinary lead batteries usually strain to put out much over 2C continuously, and the total capacity would be much lower

    but no problem for your use case.

    But LI has **much** higher power density, many packs can put out well over 20C no problem, so a tiny 0.1Ah / 100mAh capacity pack would work fine from a power POV

    but of course only for a couple minutes.

    In energy density, most modern LI chemistries pack at least 3x the Ah capacity in the same weight & volume, compared to even the best lead cells.

    For longevity, the lower your avg DoD% the better. Most LI users normally go down to 80% or more. Lead you really want to stay above 50%

    so **usable** energy density is even lower.

  5. #5
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    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Seems like the sheer size and weight is the biggest negative against SLA. I wonder why they are not completely phased out by now? Perhaps it's the low cost in many applications.

  6. #6

    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Yes good LI will cost at least 5-6 times more per Ah

    plus extra infrastructure costs not usual for lead

  7. #7

    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    And lead **is** pretty much gone from propulsion use cases for many years now.

  8. #8
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    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Ok, you want the very best in small sla? The one that started it all: Enersys / Hawker Cyclon spiral D-sized (approx) agm. (Even though today they use flat plates in their much larger consumer Odyssey agm line.)

    Pure-lead, not recycled lead. Ability to be hammered at 1C if you know what you are doing. Most commonly used in "monoblocks" of varying voltages, although one can string them together diy if necessary.

    The extremely low internal resistance makes them hold voltage under load waaay better than your conventional agm.

    I've used them when I needed extremely fast solar turnaround for small projects, but just like their much larger consumer / commercial counterparts, don't abuse them.

    Be sure to buy from reputable battery dealers - some online sources may be selling 15 year-old nos, so get fresh ones that aren't hard sulfated already

    If voltage drop is a concern, then also consider a motorcyle-agm starter batt if sla is your need, rather than the usual knock-off general purpose cheapie. But that might cost more than the light itself.....

    Just ... maybe HKJ might make an exception to test out one of these D-sized or small monobloc Cyclons....
    Last edited by IonicBond; 07-11-2020 at 12:32 AM.

  9. #9

    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Quote Originally Posted by DayofReckoning View Post
    Seems like the sheer size and weight is the biggest negative against SLA. I wonder why they are not completely phased out by now? Perhaps it's the low cost in many applications.
    It is the low cost and also in some devices the ability to continually top off the battery. I've seen SLAs replaced in most flashlights and lanterns but when you start needing a lot of Ahrs in a battery that is where the cost soars and more attention to safety concerns arise in design. The only things that I have lead acid in now is a UPS and car battery. My lawnmower battery died and I'm not spending $25 on a tiny SLA so that I can twist a key to start rather than pulling a rope once or twice a week as my mower isn't hard to start.
    I often also wonder how many cycles you could get out of lithum ion where SLAs are being used they may not last as long as some people using phones find the batteries fading after a few years with decent SLAs can last 4-7+ years.
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  10. #10

    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Some LI chemistries last decades over 10000 cycles treated well.

    Others only 150-200.

    Proper deep cycling lead - FLA better than AGM - usually are rated 600-1500 cycles.

    Standard crap SLA from consumer retail channels, might get 200 if you're lucky.

    Of course a lot depends on at what SoH metric you define EoL as determined by precise CC load testing.

    Industry standard is 80%, but even cautious knowledgeable owners proactively replace by 65-70%.

  11. #11
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    Default Re: Quality 12V 7.2ah SLA Batteries, How bad do they suck?

    Quote Originally Posted by Lynx_Arc View Post
    It is the low cost and also in some devices the ability to continually top off the battery.
    Lithium-ion doesn't like being kept at full charge, whereas lead-acid prefers to always be kept at full charge. So, lead-acid makes a lot of sense in emergency applications, where you hardly ever use the battery but want it at full charge if something happens. Stuff like UPS, sump-pumps, security backup, car starter, etc. Lead acid has a really simple charging system, compared to a BMS for lithium-ion.

    Of course, if cost is no option, lithium-ion can serve a similar purpose, and you can extend its life by only charging it to 70% or 80%. That's what I do on my laptop, for example.

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