Battery to run Electric Sofa Recliner

Discussion in 'The Projects Forum' started by ahchah08, Sep 26, 2012.

  1. ahchah08

    Thread Starter Member

    Nov 13, 2008
    11
    0
    Hello all,

    I have a project to work on. I have three electric recliners that have to be plugged into a wall outlet to work. But the sofas are in the middle of the room and it's a bit annoying having the wire running to the wall. I'm thinking about installing a battery system, but don't know how exactly.

    The motor say it's intermittent. 24V and 3A.

    I am thinking about using maybe a 12v car battery with an inverter. Then plugging in the power cable into the inverter. What type of inverter should I get and I guess I would need a sealed battery of some sort. Does anyone know how much amp-hours I would need for the battery?

    Thanks. I'm a bit new to this
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    A battery produces DC. Mains electricity is AC and can feed a transformer to reduce its voltage to 24VAC. A rectifier can convert AC to DC.

    Inverters have an AC output (120V or 240V) but nobody makes a 24VAC inverter.

    We don't know if the motor is AC or DC.
     
  3. DMahalko

    Senior Member

    Oct 5, 2008
    175
    14
    An inverter generally converts DC to 120v/240v AC. If the motor only needs 24v, then you can probably power it directly at 24v without an inverter.

    If the drive motor is DC 24v then you don't need anything more than a few batteries wired in series, connecting to the power wires into the chair power input in place of the wall-wart or power-brick power supply.

    Bigger batteries will last longer with more life.

    In general you probably don't want lead-acid cells, because if they sit discharged a long time, then the plates become permanently damaged.

    In this application, discharge tolerance is needed because you won't recharge until the batteries are almost dead and the recliner motor is running really slow. This generally points to something like lithium-ion cells or perhaps Nickel-Metal-Hydride.



    If you want to skip the need for recharging altogether, you may be able to pull this off with simply a pile of 16 alkaline D-cells (16 * 1.5v = 24v DC) and throw them all away when the recliner motor slows down.

    Though, I do not know what the max amperage is for D-cell alkalines, 3 amps may be too much.
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    No.
    Lithium batteries are destroyed if they are discharged to a fairly low voltage. A low voltage cutoff circuit is needed.

    Though, I do not know what the max amperage is for D-cell alkalines, 3 amps may be too much.
    The Chinese D-cells at The Dollar Store are leaking already before being sold.
    They might not work.
     
  5. ahchah08

    Thread Starter Member

    Nov 13, 2008
    11
    0
    Thanks a lot for the responses! But see, I don't want to cut into any of the $2500 couch's wires! I just want to make a battery and inverter circuit that I can just plug the couch's wire into the outlet of the inverter.

    I was just thinking about it, and I guess telling you about the motor's specs are useless if I'm just doing the above method.

    All I would need is a big 12Vdc battery going into an inverter that outputs 120Vac and then I can just plug in the couches? Is that correct?

    All I want to know, now, is how big of a battery I should get (in terms of amp-hours). I have three couches each with their own 24Vdc, 3A motor with their own wall outlet plugs. (I'm assuming I can just get an extension cord and plug all 3 going into the inverter?) How much do you think, say a 5 AH, battery would last?
     
  6. DMahalko

    Senior Member

    Oct 5, 2008
    175
    14
    Okay, if you don't wanna hack up the electronics then, you basically need an AC inverter capable of (24v * 3a) 72 watts output for each recliner. I have a 300w inverter in the car that cost me $50.

    You will want a switch on the inverter to turn it off when you aren't using it because even if the chair controls are not used, it still takes a small amount of power to continuously produce the AC wave output in the inverter.

    This could be a handheld wired remote power switch for the inverter's battery input, so you can turn the inverter on/off while sitting in the powered recliner.

    Or turn the inverter on before sitting, let it run the battery down while in the chair, then turn the inverter off when done with the chair.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    Only if each couch runs on 120VAC.

    Why wasn't this extremely important information in your first post that said "24V motor". It did not say that the couch is powered by 120VAC.
    I thought that the couches were used on a bus that has a 24V battery.

    The couch probably has a transformer and rectifier to convert the 120VAC to 24VDC. The power of the motor is 24V x 3A= 72W but it is not used continuously, it is only used occasionally. So a small battery will last a long time.

    A car battery is quickly killed if it is discharged too low and if it is not recharged immediately after being used. If not used then its charge leaks away in about 2 to 3 months.
    A deep discharge battery should be used.
     
  8. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
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    One thing that hasn't been addressed in this - What will the out-gassing of charging a lead -acid battery do to the surrounding fabrics? Ever stored a battery in a closed environment? The gasses are rough on wood, paint, and carpet.
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    The out-gassing is a severe fire hazzard. Hydrogen and oxygen.
     
  10. DMahalko

    Senior Member

    Oct 5, 2008
    175
    14
    It's just another reason why lead-acid should not be used for this application. Deep discharge for long periods tends to ruin them, and they vent explosive gases while charging.

    Alkaline batteries still sound good, perhaps wired in series-parallel groups to get the amperage high enough. Put them in a plastic tub so they don't leak and eat the floor.

    Six strings of 9 D-cells plus a blocking diode in each string to prevent string imbalances, 12-13v 6a output, 72 watts


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    How much does it cost for 54 D cells? Per chair? :D
     
  11. Audioguru

    New Member

    Dec 20, 2007
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    It doesn't take 72W to recline a chair. That is the maximum power allowed from the motor. It might use only 5W.

    I think Ni-MH rechargeable AA cells will be fine and only one string, not 6 strings. Each chair should have 10 cells. The chairs need a current-limited charger producing at least 15V. A timer to disconnect the charger will work OK.
     
  12. ahchah08

    Thread Starter Member

    Nov 13, 2008
    11
    0
    That sounds like it could get expensive to get a bunch of AA or D batteries. Could I just get a Home Alarm Battery such as http://www.amazon.com/Volt-Alarm-Battery-12v5ah-Hour/dp/B0010Z4MDK

    It's lead acid, and I feel like it's safer since it is non spillable and sealed. Does it still emit gasses you think? I was planning on keeping this battery underneath the couch and then pulling out the cable to plug it in every now and then.

    Would this battery still be bad if I run it all the way down and then charge it all the way up?

    Where could I find a cheap deep cycle battery that I could buy online?

    Also are the inverters loud?
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    I have never played with a sealed lead-acid battery. When charging if it is sealed then where do the hydrogen and oxygen gasses go? KA-BOOM?

    If the battery is discharged too low then it might not ever work again or for its next few times it might not last long.

    Most deep-cycle batteries are huge and expensive.
     
  14. pityocamptes

    Member

    Jul 25, 2012
    75
    0
    The cheapest alternative is to re-arrange your living room so that the chairs are closer to outlets ;)
     
  15. pityocamptes

    Member

    Jul 25, 2012
    75
    0

    They do vent, and the gases will corrode everything around it. Bad choice to use larger 12v car m/c batts...
     
  16. ahchah08

    Thread Starter Member

    Nov 13, 2008
    11
    0
    Darn. So the best bet and safest way is to use Dcells or AA batteries.
     
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