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Thread: What is a good, inexpensive charger for SLA batteries?

  1. #1

    Default What is a good, inexpensive charger for SLA batteries?

    Hello;
    I've got two 12V 8Ah SLA batteries that I purchased a couple years ago for an APC Back-UPS. I didn't use the batteries to power anything - they just sat there in the unit receiving whatever automatic charge was programmed. Then I replaced the entire UPS, and now have the two batteries sitting on a shelf. I have kept them more or less charged using a B&D automobile charger which has a setting for 'GEL', which I assume is same as SLA.

    The other day, after these batteries have been sitting at least 6mos on the shelf, I wanted to check their state, and found that one of them has an unloaded voltage slightly lower than 12V, which would indicate to me that the battery needs to be recharged. So I connected the B&D charger, set it to GEL, and to the lowest (2A) charge rate.
    The charger immediately stopped with the display 'FUL'. But the battery is not full.

    Next thing I did was to connect a variable voltage power supply directly to the battery, and set the voltage to 14V. Unfortunately, this power supply has a capacity of only 500mA, which is not enough for these 8Ah batteries.
    So now, I'm trying to find a suitable charger - or perhaps it's not worth the money? Should these 2yr old batteries be recycled instead?

    Thanks for your advice
    Ultrarunner

  2. #2
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Hello Ultrarunner2015,

    SLA and GEL are actually two different types but the difference in charging is minimal.

    Your power supply supplying 500 mA should top off these batteries although it make take some aditional time.

    The Battery Tender brand of chargers seem to offer quality and flexibility to meet your needs.

    Apply a load and measure the performance of your batteries. If they fall short, recycle them. If the perform well, charge them up and hold on to them.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

  3. #3

    Default Re: What is a good, inexpensive charger for SLA batteries?

    Thanks for the info. I'll check out Battery Tender.
    I guess it would be wise to first charge them up with what I already have, so I won't be spending money on a new charger that I won't use, in case the batteries turn out to be bad.

  4. #4

    Default Re: What is a good, inexpensive charger for SLA batteries?

    I use SLA batteries every day and also like I suspect yo are asking about,they are a go to for Ham for sure!

    There is no real difference between the charger you already have and a Battery Tender brand charger as long as yours is a modern multi-stage charger that is what the BT are.

    I also don't know why you think you do not have enough current with 1/2 amp for an 8ah battery?

    You should be fine with that and in fact I think they prefer a longer slow charge in general?

    If you still have the UPS that you got them from I would think it is an ideal charger for them too.

    I use cheap Burglar Alarm supplies for these all the time because I have them and they are not high current chargers at all but work just fine but I also have several 1 and 2 amp chargers like you describe too and they work well for these smaller SLA batteries as long as they will start the charge=ing on them at all.
    If yours won't them I imagine the charger thinks your battery is bad and it mat=y well be,SLA do not like being discharges and stored that way and that seems to kill more of them on me than running a charger on them all of the time.

    I buy my batteries at Alarm Supply Wholesalers and they are 1/3 of the street price usually so I suggest you look into that if looking to replace some.

    73

  5. #5

    Default Re: What is a good, inexpensive charger for SLA batteries?

    Do also take a look at Battery Minder brand. I have their 2012 model and it has saved me many times of having to buy new batteries.

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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Hello Gaudi,

    Thanks for bringing that up. I actually have the Battery Minder and it works great.

    The advantage of these chargers is their float charge system. They bring the charge up to full voltage, then shut off. This seems to be better for the battery than supplying a constant current which can overcharge and break down the electrolyte.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

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    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    I use this the Deltron Battery Tender Jr., which has a 750mA charging rate. It won’t charge a car battery, but it works well on my 22Ah and 12Ah SLA/AGM mother batteries. They make the Battery Tender, which has a 1.5Ah rate, for faster charging.

    Chris
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Sadly, to this day sealed batteries are a mystery to many - not helped by the manufacturers which threw up their hands.

    VRLA aka sealed-lead-acid batteries come in two types:

    AGM and GEL. You do NOT open the caps on any of them. Do NOT try to "refill" duds with water.

    AGM, or Absorbed Glass Mat have lead plates placed very close to each other, separated by a glass mat (think paper towl) soaked in electrolyte.

    GEL have lead plates spaced a bit further apart from agm, and the electrolyte is solidified, like jello.

    Charging requirements:

    AGM - typically used with a cc/cv charger that has a CV or absorb voltage limit of 14.4 to 14.7v. Use 14.4v unless you have a "pure lead" type like Optima, Odyssey, Cyclon. Most others are "conventional" agms, made from recycled lead. 14.4v is what you want.

    GEL - the absorb limit voltage should be no higher than 14.1v. Otherwise you will create bubbles in the gelled electrolyte. Like seeing bubbles in a jello desert, these are detrimental when the bubbles are right next to the plates.

    Current considerations: Conventional recycled-lead AGM's can take up to about 0.3C as a max safe charge rate so as not to start to warp / distort the plates. Gel on the other hand, should be charged at no more than about 0.1C. Similar to flooded. This makes gel much more unsuitable for solar, where charge time is commonly an issue.

    MARKETING HOODWINKS about Gel!

    Since the average consumer doesn't know the difference between gel and agm, they are often confused about which is which, and what the charging requirements, such as cv voltage is. Like only 14.1v for gel, and NOT 14.4v.

    However, manufacturers have even thrown up their hands not being able to distinguish the difference and even take advantage of the consumer by telling consumers they are the same. They may even label their batteries with the wrong info!

    The reason they can get away with this, is because a gel won't *immediately* die when charged at the agm-specific 14.4v voltage. But it is damaging, and the secondary effect is that if you do this with a gel, you'll be buying a replacement battery even sooner! It's a win-win for manufacturer and sales! And salesman don't have to deal with knowing the difference either.

    But, now YOU know. Don't rely solely on a charger's "label". Look up what *voltage* that label really is, and apply it to your battery chemistry.

    Example: Blindly using the "gel" or "sealed" setting on a charger, without knowing the voltage from the owners manual, will UNDER charge an agm if that label's value is 14.1v.

    If you use an "agm" setting with a gel - EVEN IF THEY SAY IT IS OK - and that agm voltage is 14.4v, will overcharge a gel quickly. Buckled plates and bulging tops and sides are total giveaways with gels charged at agm voltages.

    It's a bummer that it's been this way for a few decades now, but with knowledge you'll save some bucks by charging at the right voltage - and knowing about the "gel is the same as agm" scam.
    Last edited by IonicBond; 07-17-2019 at 01:20 AM.

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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Back to the original question:

    Battery Minder highly recommended.
    Battery Tender also recommended. They have different models for gel or agm, so get the right one!

    Pulsetech XC-100-P. Another outstanding choice.

    Tecmate-Optimate Also highly recommended. Notable for a VERY smart float algo, smarter than most. It's the only one I tell people to use if they are just going to park a battery in the garage and not use it for years. Decent SAE connectors.

    SAE connectors: most of the sae pull-apart connectors are total crap. I usually replace them with my own powerpoles.

    However, just make sure that when you get a maintenance charger, to exercise the sae connectors a few times to get rid of the oxidation that occurs during retail storage. And be sure they are TIGHT when you push them together. Once a year or so, exercise the sae connectors once or twice.

  10. #10
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    What about "maintenance free" batteries? Aren't they sealed?

    Yes, but they operate differently as compared to a sealed-vrla like agm or gel.

    Essentially, maintenance-free batteries are just standard flooded batteries, with extra electrolyte added in an attempt to demonstrate a typical 4 year lifespan of a starter battery without any maintenance.

    Any standard flooded battery needs electrolyte maintenance, such as topping off with de-ionized or distilled water or the tops of the plates become exposed, which is bad. Most consumer don't do that, so the manufacturers came up with the maintenance-free version with more electrolyte than necessary to try and work under the typical consumer condition.

    They are physically sealed like vrla's, but operate just like a standard flooded battery, far different from a sealed-vrla which is sealed by necessity of providing the recombinant process, and not losing electrolyte. This is why when you break the seals of a gel or agm, you destroy that capability and it is no longer doing what it was designed to do.

  11. #11
    Flashaholic* vadimax's Avatar
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    BatteryMINDer® Model 2012: 12V 2 AMP Charger-Maintainer.


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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Quote Originally Posted by vadimax View Post
    BatteryMINDer® Model 2012: 12V 2 AMP Charger-Maintainer.
    Yes, that is very good. The ambient temperature sensor that comes with most BM's make them serious. Even better, get the "on battery" temperature sensor accessory to truly do it right and attach it to either the positive or negative terminal while charging. It isn't just for safety, but for additional life by being so exacting with temperature-compensation.

    Be sure to doublecheck that it retains the settings after an accidental power-outage or mistaken switch off from an outlet. Like ALL batteries being charged, never leave them unattended.

    And, at only 2A output like most maintainers, it is *never* a good idea to use in a cyclic fashion where you really need a charger with more bulk capacity. Many modern maintainer manuals (not just from this manufacturer), have gotten smart and warned consumers about doing that too often. What they found is the consumer "babying" the battery to death.

    Using a dinky maintainer when a charger with a larger current is actually necessary (like using one of these to recharge a non-damaged large capacity battery, say >45 ah) that takes DAYS to do so, is actually harming the battery by being so inefficient. That is, most of the energy is so inefficient and is heating the battery (even though you may not feel it), warping plates and so forth internally without you even knowing.

    If you find yourself cycle-charging a healthy normal battery often, then consider at least the 8A version, which I think is the largest amperage model they make.
    Last edited by IonicBond; 07-19-2019 at 04:12 AM.

  13. #13
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    Default Re: What is a good, inexpensive charger for SLA batteries?

    You might want to look at the NOCO GENIUS line of Smart Chargers. Depending on the optimal current you'd like which may reflect on your choice.

    I have the following models:

    G1100 - 1.1A DC 7 step charger which has a selection for winter cold or normal
    G3500 - 3.5A & 900mA charge modes also supporting Lithimum batteries in their latest builds and and 8 step charger

    There are lower versions such as the G750 and personally too small for most and my applications which can handle 1.1A current. There is a lot of info on the company website. They are sold in many Auto part stores like Canadian Tire here and can be purchase direct from NOCO. These are all sophisticated charger and AC adapters with battery clips pumping out low mA DC current with minimal if any smarts.

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    Default Re: What is a good, inexpensive charger for SLA batteries?

    I generally like NOCO Genius chargers, especially the ones from years past where I feel build-quality and QC were better.

    Like any product, I may have run into a batch of poor QC models when the new ones that support lithium arrived. Perhaps they have improved since then, or I just ran into a manufacturing run that wasn't up to snuff, despite return and replace.

    Note that the lithium support is ONLY for LiFeP04, and even with their largest amperage models, in LFP mode, they only supply about 2A maximum. So if you have a custom built 12v / 200ah battery made of large prismatic cells - yeah not sufficient. So really only useful for motorcycle-sized starter LFP's.

    Thing is, lead-acid battery charger discussion seem to turn into religious discussions. Unless one is trying to revive already-trashed batteries, using any sort of maintenance charger *at all*, puts one 90% ahead of the curve.

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    Default Re: What is a good, inexpensive charger for SLA batteries?

    I only buy these for Lead Acid anyway but notice the LiION mentioned on the labels and its a heavier unit than the old one I replaced under warranty.

    They don't gas cells so you can leave them on indefinitely as I use either on my ATV, Lawn tractor, Auto Battery etc which have various size cells. All much better than many automotive store automatic chargers. I read a lot about them years ago and they worked wonders on my snowmobile battery. I got almost 4 more years out of it.

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    Default Re: What is a good, inexpensive charger for SLA batteries?

    Heh, I've tracked many automotive speed-chargers and found them not well suited for long-term maintenance. Oh, they'll charge the battery alright - but at voltages that differ wildly from the display / chemistry voltages (usually by about 0.7v!) where that can mean burning up a gel, or undercharging an agm. And I *NEVER* advise using them with new batteries, unless you chart and track what they are REALLY doing.

    But they *will* get that tired brick in the garage, or shelf-queen to start a vehicle with enough cycles to get you to the battery store.

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