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Home made battery packs

Discussion in 'Power Electronics' started by Protoman, Apr 24, 2021.

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  1. Protoman

    Protoman

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    Dec 30, 2020
    I've been wanting to ask this since I was interesting in using homemade battery packs like 6 D cell batteries soldered together. I realize that this something that would give 9vs, but the amount of mAh would be greatly higher than any 9v could do. Would such a pack be safe for small electronics like this? https://www.aliexpress.com/item/32408914467.html?spm=a2g0s.9042311.0.0.4cbb4c4dA2eSPh

    Someone told me on a project I made using that RF switch that I should invest in a Li-On battery since they are small and can provide a good amount of electricity for most small projects, but I want to tinker around homemade battery packs of various sizes before doing that.

    I just want to make sure I am not overloading anything else will still providing ample power. I'll be buying some cheap alkaline D and C cell batteries to make some packs and see how much amps I can get out of them.
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    If you look on battery university it is more than likely they will already have that information.
    https://batteryuniversity.com/
     
  3. ChosunOne

    ChosunOne

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    Jun 20, 2010
    Just wanted to add my 2 cents worth because I've seen this too many times among novices. Why would anyone solder D cells together when there are readily available holders to combine most common cell sizes? Soldering would make sense if you want to put it together as cheaply as possible and it's for a one-time use---like if you're powering a flashing LED for a message in a bottle that you're about to throw in the ocean and probably never see again. But for any project where you intend to replace (or even recharge) the cells, why wouldn't you design it with the appropriate holder?

    Looking on eBay, my quick search didn't find any 6-D-cell holders---AA is apparently a more popular size for that---but modifying an 8-cell holder is as simple as soldering a wire between two empty spaces in the holder, thus creating a 6-cell holder.
    https://www.ebay.com/itm/401500860729?hash=item5d7b50f139:g:QeYAAOSwvs9amI7H
     
    dave9 likes this.
  4. Protoman

    Protoman

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    Dec 30, 2020
    I think it would be just for fun. I know I can get a battery holder for them (There's an electronics supply store in my city that sells all manner of battery holders). I also like the makeshift appearance of it all.
     
  5. Protoman

    Protoman

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    Dec 30, 2020
    Ooh nifty! Thanks.
     
  6. Audioguru

    Audioguru

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    Sep 24, 2016
    Few products today use huge C and D size batteries so if you find a store that has them then the batteries might be many years old.
    Cheap batteries have very poor quality and are probably 60-years-old-technology "Super Heavy Duty type but marked Alkaline.

    The Chinese receiver needs 12V, not 9V and eight battery cells produce 12V only when they are new.
    Why does the receiver use 6mA all the time then uses much more current to turn on the old-fashioned relay?
     
  7. Protoman

    Protoman

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    Dec 30, 2020
    I have a maglite flashlight that needs D cells. That's why I had them lying around. I also gave some to friends of mine who just got a hot wheels track that needed 2 D cells.

    I would have to disagree slightly with the brand. while the carbon-zinc are obviously inferior, the dollar stores in my area have Panasonic batteries (cheaper carbon-zinc and slightly more expensive alkaline). I've seen battery tests on youtube that show that the alkaline Panasonics tend to compete fairly well with brand names like duracell and energizer.

    Yes it does say 12V not 9V, but from everyone I asked who used that switch they said it is a 9V minimum and a 12V maximum. I hooked up an energizer 9v to it and it works just fine. I realize that if I am to keep my toy functioning for more than a few hours without the battery draining I will need a decent quality 9V. Those 3 or 4 button cells that I tied together with electrical tape? My experiment showed me just how fast those batteries drain. I left them attached last night to see how long they last. They didn't have enough power left to work the switch by noon and I had to swap them. I'm trying to see how long a regular energizer lasts with it.
     
  8. Audioguru

    Audioguru

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    Sep 24, 2016
    It takes a lot of battery power to activate that antique relay. The last time I used a relay was 50 years ago.
    A Mosfet for a DC load or a Triac for an AC load activates with a much lower current.
    The receiver circuit draws 6mA which is high for today.
     
  9. Bluejets

    Bluejets

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    Oct 5, 2014
    There are, never the less applications where a relay is a much simpler answer to an application.
    And no, I don't intend to go into any detail.
     
  10. Protoman

    Protoman

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    Dec 30, 2020
    I'll be looking into those. I've had a starter Arduino kit lying around and I did tinker with some of the tutorials. I think I will use that next for some exploration.

    That being said. The little RF switch, as flawed as you say it is (and I will agree with you) is fine for my purposing of making a light up toy. Right now I am just trying to see how long the batteries last before packing it (batteries disconnected) in the body of the rubber ducky. Hopefully this situation with COVID-19 will improve and I can show it off to cosplayers at comic con...
     
  11. Audioguru

    Audioguru

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    Sep 24, 2016
    The light in the toy also uses battery power. Make the circuit turn it off after a short on time.
     
  12. Protoman

    Protoman

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    Dec 30, 2020
    There won't be much need. The whole point of this toy is just a novelty. Once it's turned on, keeping it on for long period is not necessary.

    That being said. Yes, that RF module is a drain. The energizer max I used to power it lasted about 36 hours before it could not deliver the voltage needed to run it. My DROK shows it delivering around 7.6 volts, so it's still usable for all sorts of other things. Or I could try to hook it up to a booster to see if I can still make it work just as another bit of mild practice.
     
  13. Technomaniac

    Technomaniac

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    Oct 31, 2020
    I have had a number of battery packs made up by a local firm, come into my workshop after failing, and the problem has been failure of the seals of the cells, all because the person making up the pack had SOLDERED to the top end terminal. If you decide to solder, buy the cells with the spot-welded tabs and solder the tabs rather than the cell terminals.
     
    dave9, Harald Kapp and Protoman like this.
  14. Protoman

    Protoman

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    Dec 30, 2020
    OK so I was tinkering around with my Arduino and I was thinking of how long I could keep the thing running when plugging it into an outlet might be inconvenient, and I read this article:

    https://hwstartup.wordpress.com/201...clone-on-aa-batteries-for-over-a-year-part-2/

    Specifically this part:

    Now I feel like I have gotten over my fascination with soldering home battery packs, and I have lots of AA battery holders (1, 2, 3, and 4 AA battery holders) but they are all your typical series ones. Anyone got a good link or instructions to making a one for parallel battery holders? I think I'll want to make one for my Arduino.
     
  15. Audioguru

    Audioguru

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    698
    Sep 24, 2016
    An AA alkaline battery cell is 0.9V to 1.5V. A bunch of battery cells in parallel still produce only 0.9V to 1.5V.
    Your Arduino needs at least 3.0V. So you need 4 battery cells in series to produce at least 3.6V or you can use 3 cells in series if you let the Arduino stop working when they discharge to 3.0V.
     
  16. Protoman

    Protoman

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    Dec 30, 2020
    OK, so I'm going to try to visually wrap my head around the step-by-step process in order to do it (to make sure I have at least 5 volts going into my Arduino) by connecting 8 AA batteries in parallel to see if I can keep it going for the time it said it can.

    A: Make two 4 AAs in regular series to get 6 volts.
    B: Connect the two sets in parallel (negative to negative, positive to positive).
    C: Connect negative from one pack and positive from the other into the Arduino (will need to get another barrel pin connector for that).
    [​IMG]

    Am I on the right track?
     
  17. Audioguru

    Audioguru

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    698
    Sep 24, 2016
    You are assembling 8 AA cells in series/parallel making one fairly long lasting 3.6V to 6V battery. The total battery has only one negative and only one positive for one barrel connector.
     
  18. Protoman

    Protoman

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    Dec 30, 2020
    I think I got it to work. I used my two 4 AA battery holders and twisted the negatives and positives of each packs to one another. After that I stuck wires from the negatives of one pack and the positives of the other (like in the illustration I linked) and I tested it with a multimeter. I got a 6.5 voltage from the whole 8 pack. I think I did it. Best part, no soldering or permanent modification of the packs, so I can reuse them for other devices as needed.
     
  19. dave9

    dave9

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    283
    Mar 5, 2017
    I'm glad you're working with small alkaline batteries instead of Li-Ion, let alone AC mains power. :oops::eek:o_O
     
    ChosunOne likes this.
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