Help me in choosing toy car battery

Discussion in 'General Electronics Chat' started by sachin1101, Jan 4, 2014.

  1. sachin1101

    Thread Starter New Member

    Jan 4, 2014
    1
    0
    Hi,

    I need to replace Sealed Lead acid battery(SLA).
    SLA specification - 6v X 700mAh


    If I use my understanding then Total power of the battery
    = 6 x 0.7 = 4.2 (I forget the power unit )

    I am thinking of using commonly available NiMH 1.2v AA batteries.

    however these AA batteries has high mAh ( 1900 to 2500) when compared.

    So my basic question is can 4 AA batteries of 1.2v 1900 mAh can be used in place of the original battery (SLA) ?

    Please confirm my understanding -
    The current drawn from the battery depends upon the resistance of the circuit. The NiMH battery combination ( 4.8 x 1900 mAh) wont burn the RC toy car circuit as it would draw ~700 mAh.

    :) Please help.
    thanks
    Sachin
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    mAh is the size of the fuel tank, not the pressure at its outlet, nor the pipe coming out of it.

    Your new battery must have nearly the same resting voltage as the old one. (6V=the pressure at the fuel tank outlet).

    If your 700mAh battery lasted 2 hours, then a 1400mAh battery will last twice as long (the size of the fuel tank).
     
  3. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    mAh is the battery can be discharging how many Ampere current for one hour that it shows as mA/h or mA/hr are more easy to understand.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    If 4.8V is enough to cover the 6V power source needed then it's ok.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    That would be watt•hours. The electricity entering your home is usually metered in kW•hr. For whatever reason, we usually stick with mA•hr or A•hr with batteries. As noted, it's a capacity rating. More capacity equals more run time (as long as the current
    required can be maintained).

    I think the 4 AAs will work nicely. There's no reason not to try. In my opinion there would be little risk of using 5 AAs, but there may be no need.
     
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    YES, but you need five cells since the nominal cell voltage is 1.25V.
     
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,006
    3,763
    One other thing to watch out for is the C-rating of the batteries. That is, how much resistance is in the battery (internal resistance) and, therefore, what load (amps) can be drawn from the batteries power and still be at 12 volts (near 12 volts).

    The higher the C rating for RC cars - especially with brushless motors - the better.
     
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    By an interesting coincidence, the mA-hr rating for a AAA size Ni-MH cell is also 700 mA-hr. That means you could use five AAA cells and have just about exactly what you have now except it would probably be smaller and lighter.

    http://www.all-battery.com/aaa700ma...22_a_7c10407&gclid=COHW48v75bsCFcJqfgodD24AAA
     
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