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  • Newbie battery question

    I recently was able to purchase some AGM batteries for a pretty low price (140ah each for $70) and I'd like to eventually use them to build a small solar energy system. I'm still learning the basics of how to put it all together. This is my first time buying AGM batteries, and these do not have terminals (just a couple of holes, which I assume I need to buy a threaded terminal post for). Any suggestions or advice on what I'm supposed to buy, what I need to know, and where to buy?

    Any and all advice is appreciated. Thanks!!

  • #2
    Ok, that's basically going about it backwards by purchasing batteries first - many do this by mistake, so you are forgiven.

    Basically, one needs to figure out how much power - over time - that their devices use during the period you need them battery powered. THAT will determine the capacity of the batteries you need and you build the rest of the system around that. Otherwise, you either have way too much, or way too little in capacity. Rarely is one lucky enough to take a stab at it.

    That being said, if you just are playing around and want to be able to use them for other things if they are totally improper, get a decent charger just to make sure you can keep them alive.

    Let us know exactly what the battery model and make is, and we can steer you towards a decent charger. There are many inappropriate chargers one can get from the automotive department that will get you out of the driveway, but repetetive use with a fixed solar system can actually harm them if the specs don't meet the manufacturer's ratings.

    Aside from that, stop spending any more money NOW, and take a gander at the faqs and stickies at the tops of each forum. They condense a lot of very useful information into a short space. But let us know what the batteries are, (unless you just want to return them) and we'll consider those your "learner set".

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    • #3
      Originally posted by PNjunction View Post
      Ok, that's basically going about it backwards by purchasing batteries first - many do this by mistake, so you are forgiven.

      Basically, one needs to figure out how much power - over time - that their devices use during the period you need them battery powered. THAT will determine the capacity of the batteries you need and you build the rest of the system around that. Otherwise, you either have way too much, or way too little in capacity. Rarely is one lucky enough to take a stab at it.

      That being said, if you just are playing around and want to be able to use them for other things if they are totally improper, get a decent charger just to make sure you can keep them alive.

      Let us know exactly what the battery model and make is, and we can steer you towards a decent charger. There are many inappropriate chargers one can get from the automotive department that will get you out of the driveway, but repetetive use with a fixed solar system can actually harm them if the specs don't meet the manufacturer's ratings.

      Aside from that, stop spending any more money NOW, and take a gander at the faqs and stickies at the tops of each forum. They condense a lot of very useful information into a short space. But let us know what the batteries are, (unless you just want to return them) and we'll consider those your "learner set".
      Thanks for the advice, but as you said this is just me learning and playing around. I'm not actually building a system yet. I saw these batteries for sale from a local tech company and figured this would be a lower cost way to learn about AGM batteries. These are the batteries: http://www.batterysharks.com/C-D-Tec..._-caAvc08P8HAQ

      Like I said, the first question i have are what kind of terminals do I use? Is there a basic, threaded terminal I am supposed to use with these? If you can point me towards exactly what to get that'd be great. That's the first thing I need b/c I'd like to charge these asap (I have one of these I use for my car battery http://www.amazon.com/Schumacher-SSC...attery+charger) but w/o a terminal to connect to I can't.

      Again, thanks for the advice, and be assured I'm probably months (maybe years) from actually building a system. This is definitely a learner set.

      Comment


      • #4
        Originally posted by Living Tribunal View Post
        Thanks for the advice, but as you said this is just me learning and playing around. I'm not actually building a system yet. I saw these batteries for sale from a local tech company and figured this would be a lower cost way to learn about AGM batteries. These are the batteries: http://www.batterysharks.com/C-D-Tec..._-caAvc08P8HAQ

        Like I said, the first question i have are what kind of terminals do I use? Is there a basic, threaded terminal I am supposed to use with these? If you can point me towards exactly what to get that'd be great. That's the first thing I need b/c I'd like to charge these asap (I have one of these I use for my car battery http://www.amazon.com/Schumacher-SSC...attery+charger) but w/o a terminal to connect to I can't.

        Again, thanks for the advice, and be assured I'm probably months (maybe years) from actually building a system. This is definitely a learner set.
        According to the battery link you need to find what is called "IT" terminals. I am presuming they are threaded at both ends. One side screws into the battery openings and the other side allows you to use a nut and lock washer to attach a cable with a terminal on the end. Maybe you can get them at the same place as where you found the batteries.

        Now the bad news is that battery is designed to be used in a UPS system. Which means they pretty much just sit there at full charge and then when needed can deliver a lot of power very quickly. Since they only have 300 cycles (which is very short life for a solar battery system) they are not something you want.

        They also need a charger that is designed for UPS AGM style batteries. That Schumacher charger is not a good charger for those batteries.

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        • #5
          First thing you will learn is those are UPS batteries. They are made to be used in standby operation and able to deliver very high discharge rates as high as 15 minute discharge. With that said they are not inteneded to be cycled, only used as emergency power. If you press them into cycle service you are only going to get maybe 100 cycles vs 1000 to 1500 cycles for a deep cycle battery.

          Second thing which you may already know those are used batteries. What telecom and data centers do is turn a liability into an asset. Normally they would have to pay a rather significant fee to dispose of spent batteries. EPA requires them to track the batteries. So what they did is unload them on you and put the i Own it on your and all the liability that comes with it. They turned their liability into an asset and recovered some losses.

          As for the terminals they are made to attach either a battery term plate with lead plated stainless steel hardware.
          MSEE, PE

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          • #6
            Sorry, but those batteries are intended for long-term float, and not cycling. If you can, return them pronto. However, i must say that C&D has some extensive battery documentation. On par with Enersys. I like it. Still, those are the wrong batteries for solar, even for just playing around.

            Schumacher "Speed Chargers". This is the reason I mentioned it earlier. These types of automotive chargers are basically designed to help badly discharge / abused / old recuperate to a point where they are somewhat serviceable, and then placed back into the vehicle for normal charging thereafter.

            In the case of the Schumacher speed-chargers, they are highly aggressive - too aggressive for use on batteries that are new or are performing ok.

            While they have high-voltage desulfation spikes early on when meeting a badly discharged / sulfated battery, (which is good), at the end of charge, despite being "smart", they more often than not go MUCH higher in voltage than the industry standard specs. To the tune of about 0.6 to 0.7v! Which means essentially that they will take them into EQ voltages, which most AGM manufacturers recommend against. This may be beneficial for BADLY abused batteries, but not necessary for good ones! My own blown-out overcharged perfect Deka Intimidators and other high quality lead-calcium agm's met an early demise this way - with blown out cases to boot. Many GEL owners (not appropriate for solar in most cases) have witnessed this, and have documented it online.

            Of course Schumacher is pretty quiet about their smart algorithm. You have to try and interpret their patent. Suffice to say that the user has NO control over whether it decides to go into high-voltage EQ, or stay normal. I have witnessed this high-voltage among nearly ALL their speed-charger line, as I was intent on finding out if I just had a bad apple. Nope. Needless to say, I won't let them anywhere near my good batteries.

            Adding to the confusion is the normal consumer not understanding why they seem to "stall" at 80%. This is normal due to the absorb cycle that takes time, but most consumers don't know that. They then pull the plug and reset the unit, which detects what appears to be a full charge, and stops. Those are the lucky ones. The ones that actually let it totally finish the charge may be in for a higher than spec surprise - especially if they track the charging behavior with their own metering.

            I've written about the speed-chargers before, so I'll just say that if you already own one, and have an AGM, and have NO other choice, then you want to PURPOSELY set the speed-chargers for the wrong chemistry to compensate for their extreme aggressiveness. That is, select GEL, even if you have an AGM. To top it off, that agm had better be able to accept voltages up to about 14.7v, since that is what the speed charges reach even in the "gel" setting. And gel owners - well, 14.7v will kill most of them.

            I could almost accept this for use in cases where I wanted to EQ, with agm's that allowed for it. Unfortunately, what I found with my metering is that this high voltage is not done at the END of absorb, but seems to activate right before or slightly into the START of absorb. That is not how it is usually done.

            My advice is to keep the speedcharger for use with abused batteries, not for ones that have already proven to be good and are presenting no problems.

            Note - the SC1500 ship n shore may also seem to endlessly cycle on and off at the end of charge, unlike some other models that eventually stop. At least the two I owned did this. I was not willing to let the relay do 1000 cycles each time I wanted to use it.

            I hate to say it, but take it ALL back if you can. Don't worry - we've all had to just cut our losses and start over.

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