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  • Another battery question for small boombox

    Hey everyone, I've searched and searched and learned quite a bit, but still had some questions. I'm used to using 12v SLA batteries for my boomboxes, but my current project is very small and there's really not enough room inside for an SLA battery (unless I could use a 1.4ah, but that's way small, right?).

    The box will use the TA2024 amp, and two 3" 8ohm full range speakers.

    All I need is about at least 4-6 hours of battery life. I'm happy with that. I would like the battery to be as small as possible because of the box dimensions. I had a 5ah SLA sitting around that I thought I could use, but test-fitting it in the box proved that it would just take up way too much space. So I need something smaller than that.

    So Li-On is no good because they're too dangerous?

    What would you use?

    Thanks!

  • #2
    You want a 3S (e.g. 3 cell) LiPo pack and charger. Try the online hobby sites (e.g., TowerHobbies.com, etc.). Battery and charger will be in excess of $100. Pay attention to dimensions. You need to buy a compatible connector for the battery (an additional couple of bucks). The LiPos will save weight over the SLA.

    If you push the system to max on the 1.4 AH battery, you'll get a couple of hours, maybe 2+ in my estimation. Will two 1.4ah SLA's fit? Connect them in parallel. That might get you to 4+ hours. You also need a 3-stage charger of the proper amp rating (like 0.5a for each 1.4ah SLA). A 3-stage charger will keep them in peak condition and extend their lifetime. Do not leave SLAs on a "Battery Tender" type charger. Always charge SLAs as soon as possible and never leave them discharged - it will keep them in short order. Be mindful of the battery voltage when in use. It should never be allowed to go below 10.5v. Many put a digital DC voltmeter (try eBay) on their control panel to manage that (a LiPo pack will shut itself down automatically).

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    • #3
      So is LiPo safe? Any downsides? They all seem to say 11.1v....is that enough?

      http://www.ebay.com/itm/Turnigy-2200...UAAOSwQM9UainA

      Would that be good?

      Thanks for the input!

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      • #4
        How loud do you want the boombox to be? Have you considered the new Dayton KAB series amp/battery combos?
        "A dirty shop is an unsafe shop, if you injure yourself in a clean shop you are just stupid" - Coach Kupchinsky

        The Madeleine
        The Roxster
        Swopes 5.0
        Acoustic Panels
        Living Room Make Over

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        • #5
          Originally posted by shibby View Post
          So is LiPo safe? Any downsides? They all seem to say 11.1v....is that enough?

          http://www.ebay.com/itm/Turnigy-2200...UAAOSwQM9UainA

          Would that be good?

          Thanks for the input!
          The Turnigy is a 2200 maH (2.2 aH) battery. Not much more than your 1.4 aH SLA. My first choice was a 5000 maH (5 aH) battery. It will cost that much more.
          Due to the nature of the cell chemistry, 3S LiPos are rated at 11.1V. Fully charged 3S LiPos are 12.6 V and run down to 9+ V depending on the battery electronics. Compare that to an SLA that hits 13+ V fully charged and ends at about 10.5. You get a little less power out with the slightly lower voltage. You would't notice it.

          This batteries are safe when used with the mating charger. The charger uses the extra connector to balance the cells and insure no cell gets over charged, Though there could always be a failure ...

          You can double the power out by choosing 4 ohm drivers instead of 8 ohm. Of course, you'll drain the battery faster at the higher output.

          Gordy has a point. At 12 V the Dayton KABs should perform nicely and the LiPo battery charging and management is integrated into the solution..You just add three 18650 dumb cells (!~$6 each for 3 aH capacity at 11.1 V). Beware of fake battery claims - Authentic Panasonic 18650 BD or BE cells would be my pick.

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          • #6
            Originally posted by Millstonemike View Post

            The Turnigy is a 2200 maH (2.2 aH) battery. Not much more than your 1.4 aH SLA. My first choice was a 5000 maH (5 aH) battery. It will cost that much more.
            Due to the nature of the cell chemistry, 3S LiPos are rated at 11.1V. Fully charged 3S LiPos are 12.6 V and run down to 9+ V depending on the battery electronics. Compare that to an SLA that hits 13+ V fully charged and ends at about 10.5. You get a little less power out with the slightly lower voltage. You would't notice it.

            This batteries are safe when used with the mating charger. The charger uses the extra connector to balance the cells and insure no cell gets over charged, Though there could always be a failure ...

            You can double the power out by choosing 4 ohm drivers instead of 8 ohm. Of course, you'll drain the battery faster at the higher output.

            Gordy has a point. At 12 V the Dayton KABs should perform nicely and the LiPo battery charging and management is integrated into the solution..You just add three 18650 dumb cells (!~$6 each for 3 aH capacity at 11.1 V). Beware of fake battery claims - Authentic Panasonic 18650 BD or BE cells would be my pick.
            ^This. The Panasonic is a solid 18650. I am partial to Samsung 25R cells. They will last near triple the hours of what you are expecting with the KAB amps. IMRBatteries has a good selection and they sell guaranteed genuine name brand cells and they ship fast as while.
            "A dirty shop is an unsafe shop, if you injure yourself in a clean shop you are just stupid" - Coach Kupchinsky

            The Madeleine
            The Roxster
            Swopes 5.0
            Acoustic Panels
            Living Room Make Over

            Comment


            • #7
              Hmm, I don't know what to do now. lmao I already have the amp and speakers, so I'd like to stick with them for this.

              With the LiPos, is there any physical size differences between, say, the 2200mah and the 5000mah? Or ar ethey all the same size?

              I've been reading up on the LiPos, and I'm still so unsure about them. The battery wont be easily accessible when it's in the box, so is it ok to leave in there all the time, even during charging?

              Thanks for all the tips so far guys!

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              • #8
                I was thinking, and I've seen it discussed before...what about the little Li-ion packs used in small cordless tools? Milwaukee makes a 2.5ah pack. Is that possible to use in a boombox? Of course I'd have to make the battery easily removable so it can be charged in the charger.

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                • #9
                  Originally posted by shibby View Post
                  I was thinking, and I've seen it discussed before...what about the little Li-ion packs used in small cordless tools? Milwaukee makes a 2.5ah pack. Is that possible to use in a boombox? Of course I'd have to make the battery easily removable so it can be charged in the charger.

                  See this thread ....

                  http://techtalk.parts-express.com/fo...aker-questions

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                  • #10
                    Thanks, yea I saw that thread yesterday. It's still a little confusing to me as I'm not really up on all the techy terms and such (still learning). I guess what I really need to know is, can one really use one of these batteries (like the one pictured below...just picking this one because I actually have the same battery for my oscillating tool ) in a boombox? It's clearly stated which is the positive and negative, but what are the other slots for? Is there anything else I would need, or can I just connect to the pos and neg and be done with it? I'm new to all this Li-Ion battery stuff so I really have no clue. lol

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                    • #11
                      Does anyone know about the inner workings of these li-ion batteries? Are the protection circuits only inside the batteries themselves, or is there something inside the tools that communicate with the batteries? Would it be as easy as just connecting the + & - of the battery to the amp, or is it more involved? I don't want to ruin the batteries.

                      Thanks for any help!

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                      • #12
                        Maybe wire one of these lcd voltage meters to make sure you don't run it too low.

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                        • #13
                          Yea, I had one of those planned either way.

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                          • #14
                            Also, if I did have to monitor it manually with the voltage meter, what is the voltage one should start to recharge at with Li-ion batteries?

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                            • #15
                              http://batteryuniversity.com/learn/a...ased_batteries

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