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using a power supply to charge a battery.

Discussion in 'General Technical Questions and Answers' started by KC9NEQ, Oct 28, 2008.

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  1. W5DXP

    W5DXP Ham Member QRZ Page

    I don't "only work SSB" but I use the amp only for SSB. Who needs an amp for CW or PACTOR II? I'm a man of few words and have never run the battery down below a level acceptable to the SG-500 amp. The battery is a "Walmart special" EverStart maxx marine battery rated at 125AH and 205RC. They have all outlived their warranty periods.
  2. K1VSK

    K1VSK Ham Member QRZ Page

    Even battery mfgs have marketing departments and have no problem marketing specifically to boaters who have no clue what battery construction they art buying. Putting "marine" on the case does essentially nothing except allow them to charge more money.
    It is a truck battery hybrid that sometimes may have thicker plates but definitely not a true deep cycle and definitely not any better at taking the pounding to which a boat may be subject.
    A true marine deep cycle will always be rated at amp/hrs and not CCA or any other meaningless designation when it comes to constant load with intermittent recharge.
    In fact, you will not find marine batteries on most boats as their owners all know the difference and virtually all have a true, dedicated start battery isolated from everything except the engine and a "house" bank of deep cycle batteries to handle the boat's load from refrig, electronics, etc.

    From being both a ham and boater for decades, I constantly find it ironic how boaters always seem to know more about batteries than hams.
  3. K1VSK

    K1VSK Ham Member QRZ Page

    Sorry to disillusion you but labels sometimes hides what is inside. There is nothing magical about powering an electric trolling motor - it should be designed to withstand multiple deep discharges prior to recharging and only deep cycle batteries do that. If you prefer to verify this yourself, I invite you to look into the specs of various battery mfgs such as Johnson Controls, Trojan, Rolls, et. al.., all of which make a wide variety.

    Regarding charge rate and frequency of charging, I similarly invite you to read one of a number of good battery primers on the internet, the Ample Power Primer being one of the better ones. In it and others, you will learn how to prematurely kill batteries, one way being to constantly charge them. Parenthetically, charging them at a constant rate is another injurious method.
    The conventional wisdom for deep cycle batteries is they should last, depending on which mfg you believe, up to 3000 cycles - do your's?
  4. NA0AA

    NA0AA Ham Member QRZ Page

    Ah, the bi-monthly battery charging arguement!

    Look, there's a million ways to charge batteries, and there is more than one way that yields 90%+ results. Heck, there must be a few ways that achieve 95% of some technical ideal. Cool.

    What matters to me is that the system works well enough to keep the batteries on line for a reasonable period - I figure I want 5 years minimum out of a battery in constant standby service. After that, it's a bonus.

    FWIW, mine is in parallel with a power supply, diode isolated so that the entire 12 volt station is on full UPS power. Personally, I have a generator, so my battery is sized for 5 or so hours - there are not many outages in my area longer than that and if there are, then I can fire my generator, which I would have to do for the Fridge and freezer anyway.
  5. KJ4HAY

    KJ4HAY Ham Member QRZ Page

    WB2WIK already addressed the cleaner power part but, managing 13 CO's in East TN, I can assure you, we are using more power now. We've had to add strings of batteries in a few of the offices and even beef up the AC units due to the amount of heat the newer equipment generates. It's mostly due to all the broadband equipment (which is a bad thing by no means!) ;)
    Every one of the CO's also has an emergency generator, some of the bigger ones have 2, so there's not much chance of a Central Office failing. Remote sites are a whole other story...and I've already taken this further off topic than I should have. :)

  6. K7JEM

    K7JEM Ham Member QRZ Page

    While floating, batteries are not really charging. That is why CO batteries can be floated for years, and still work fine. The float voltage needs to be pretty tightly regulated, so as to not boil out water, yet keep the battery near a 100% charge.

    So they really aren't being constantly "charged" in the sense of current flowing through them.

    That 3000 cycle thing seems high, but it all depends on the depth of discharge. I don't think many batteries would survive 3000 cycles, if discharged 80%. If the discharge was only 10%, it could easily happen.

  7. K1VSK

    K1VSK Ham Member QRZ Page

    Here's the chart that Trojan posted showing maximum life of batteries, versus % of capacity discharge. I've never independently verified this data but 3000 cycles seems conservative based on this one reputable battery manufacturer's data. (DoD = Depth of Discharge)

    10% DoD (100 A-H x 0.10) x 6,200 cycles = 62,000 Amp-Hours (lifetime)
    20% x 5,200 = 104,000
    30% x 4,400 = 132,000
    40% x 3,700 = 148,000
    50% x 2,900 = 145,000
    60% x 2,400 = 144,000
    70% x 2,000 = 140,000
    80% x 1,700 = 136,000

    As far as how floating effects capacity, the float doesn't necessarily have to transfer charge to effect sulfation which occurs at a constant rate unless you are using a PWN pulse charger..
    Last edited: Oct 30, 2008
  8. K7JEM

    K7JEM Ham Member QRZ Page

    That doesn't make sense. Sulfation occurs when the battery is undercharged or left sitting for a long time. A battery on float won't sulfate, look at the thousands of telecom sites that use float systems.

    A pulse charger is not needed to prevent sulfation, just a charger that will maintain the float voltage without going over, or under, the fully charged voltage. There is no "magic" in a pulse charger, at least relative floating batteries. Telecom systems do not use pulse type chargers, what they have is essentially constant voltage power supplies with current limiting at some point.

    Those of us that have actually worked with float systems for decades know what they will or won't do, and what chargers are actually needed. People try to make this harder than it actually is, either because they don't understand how float charging works, or they've bought into some "magic" scheme.

  9. K1VSK

    K1VSK Ham Member QRZ Page

    The only "magic" scheme under discussion is that of the battery manufacturers with whom you can feel free to disagree based on your experience using whatever you are used to working on. I hesitate to continue this as it sounds like you are taking everything I say personally so I'll end my participation thinking you may be basing your suppositions on a limited set of circumstances but regardless, I think we both conveyed our respective views.
  10. K7JEM

    K7JEM Ham Member QRZ Page

    OK, it's just that the manufacturers I deal with have never specified any sort of "pulse charger" or suggested that float charging a battery will result in sulfation, or somehow shorten it's life. Most of them recommend constant voltage float charging, and will specify what that voltage needs to be.

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