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Battery Powered Vacuum repair

Discussion in 'Troubleshooting and Repair' started by Justin417, Jul 29, 2015.

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  1. Justin417

    Justin417

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    Jun 26, 2015
    Hello! First real post on here, excited to see the feedback.

    So recently my mother was gifted a "Royal model BD10200" Hand Held battery powered vacuum.
    [​IMG]

    It took only 5 months before the batteries wouldn't even hold a slight charge. The motor dies after about 3 seconds and no matter how long you charge for it dosen't hold its charge any longer. Unable to find any information whatsoever online about the internals of the unit, I took it apart.

    Inside I found 5 Ni-Cd battery cells that look like their in parallel (I'm not certain, still a novice at electronics).

    [​IMG]
    [​IMG]
    [​IMG]

    Any ideas as to what I could replace the battery cells with? I've tested a few options but they seem to have reached the true end of life.

    All the cells seem to be 1.2 V, 1100 mAh, can I just find replacement cells and wire them like they are currently?

    Any advice would be greatly appreciated as I don't want anything exploding in my face when I do get replacement battery cells.
     
  2. Tha fios agaibh

    Tha fios agaibh

    2,083
    694
    Aug 11, 2014
    I have one of those in my garage.
    (Piece of junk)
    In my opinion it's not worth messing with. You can find replacement batteries online but there is a good chance the motor is shot. If you have a 6vdc adapter disconnect the batteries and try hooking up directly to the motor. My guess is the motor brushes are warn down and the motor draws too much power. Another problem is the charging circuit on those tends to fry the batteries if its plugged to an ac adapter all the time.
    If your determined the parts can be found, but you'd be doing yourself a favor by pitching it.
     
    Justin417 likes this.
  3. Justin417

    Justin417

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    Jun 26, 2015
    I agree it is quite junk. I was just doing this for the heck of it, since I normally don't have many electronics to play around with :)

    I could power the motor of direct DC power, although I never thought of the idea that the motor may be faulty and drawing too much power. Thanks for the suggestion. I'll look into that.

    My other question, if I did manage to get it working again from a 6v source, would it matter if they are still Ni-Cd batteries? Thinking of selecting a different battery type and possibly making modifications to the case to contain it.
     
  4. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    You could do that but then you'd have to alter the charging circuit. If you run the motor off an external 6vdc ps you could then measure how much current the motor is drawing.
    Again, by the time you but the parts to fix it you could buy another vacuum.

    Btw, welcome to the forum Justin.

    If your looking for something to tinker with, you might have some luck scouting your neighborhood during trash pick-up day?
    Regards, John
     
  5. Justin417

    Justin417

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    Jun 26, 2015
    Good point. Always worth a shot I guess :)

    Hey maybe I'll just take the motor out of here and call it done, maybe will come in handy some day.

    Thanks for the replies
     
  6. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    As you can see in the photograph, the NiCd cells are clearly wired in series, daisy-chain fashion. So the terminal voltage, end-to-end, should be 1.2 x 5 = 6 V. You might want to check that with a digital multimeter (DMM) before throwing them away.

    I agree with you and the other poster (@Tha fios agaibh ): this is a piece of junk. I have a Shark Cordless that I purchased at a big-box home improvement store last year that is still working. It sits on its recharging stand all the time and is used only once in a while, so I don't know what the condition the batteries or the motor is. But, so far, it has worked every time I picked it up and turned it on. When it quits working I will pitch it and maybe buy another one... or not. We have a similar-sized hand vacuum with a long cord that plugs into a wall outlet, so cordless operation is only convenient until it isn't.

    I am not a big fan of NiCd batteries. They have short life-times, experience "memory" problems where they will not take a full charge if not fully discharged between charge cycles, and have a poor energy-to-weight ratio. In other words, not much bang for the buck with NiCd batteries. Much more preferable are rechargeable lithium ion cells, IMHO.
     
    Justin417 likes this.
  7. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    And, likely the main reason NiCad batteries die quickly, is because people don't follow that discharge/full recharge cycles.
    Oh, and when we say "throw them away" we really mean recycle please.

    Btw, I like that line Hop; "(It's) only convenient until it isn't" Lol.

    John
     
  8. Justin417

    Justin417

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    Jun 26, 2015
    Interesting. I've never dealt with batteries other than sealed lead acid (SLA) batteries and LiPo batteries.

    Just out of curiosity, why would a company (like the vacuum manufacture) use NiCad batteries in a device which they know probably 90% of the users won't follow the proper charge/discharge cycle? I know its probably to cut costs but would there be any advantages?

    Sorry for the silly question, but how do you guys normally calculate how much mAh those batteries in series would produce? I assumed I would multiply 1100 mAh x 5, but that seems a bit high just for a motor. I'm probably going about this wrong.

    Of course ;)
     
  9. Gryd3

    Gryd3

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    Jun 25, 2014
    Cost coupled with capability.
    NiCd can handle higher charge/discharge rates than NiMH, and splurging on the cost for Lithium based cells would be out of the question for most consumer goods unless they can use it to their advantage.
    Cordless Drills for example are commonly NiCd, and the ones that use Lithium are usually marked up and advertised as such.


    mAh = Milliamp Hours.
    All components in a series circuit will share the same current...
    Which means that 5x batteries in series will result in a larger 'equivalent' battery that has 5x the voltage, but only 1x of the mAh rating.

    All components in a parallel circuit will share the same voltage...
    Which means that 5x batteries in parallel will result in a larger 'equivalent' battery that has 5x the mAh rating, but only 1x the voltage.

    This is true with loads as well... Two 12V lights in series will require 24V to light, but will still only use the same current as one of them. Alternatively, two in parallel will take twice the current to light.


    Please note that regardless of the connection method, you will still be using more power!
     
    Justin417 likes this.
  10. Justin417

    Justin417

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    Jun 26, 2015
    Thank you so much, that clears up alot not only for this project but for others I've been working on.

    And thanks everyone else for all the replies! Wasn't expecting such nice responses. Very awesome community on this forum!
     
    Tha fios agaibh and Gryd3 like this.
  11. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    You will find one of the cells is faulty. Charge them all and get a globe (3v to 6v) and try each cell. You will find one does not light the globe.
     
    Justin417 likes this.
  12. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Probably right Colin, but it would not be wise to only replace the shorted cell.
     
  13. Gryd3

    Gryd3

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    Jun 25, 2014
    Still a good thing to bring up.
    Many times simply connecting batteries in series like that lead to the individual cells in the pack becoming unbalanced...
    Some cells charge faster than others, so you end up overcharging some and undercharging others... Ideally, there will be a circuit to balance this, but it's usually skipped over for cost savings.
     
    hevans1944 and Tha fios agaibh like this.
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