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Thread: Battery issues

  1. #1
    Variable Bitrate
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    Battery issues

    Guys,
    I need a battery that can give 12V at 5A to power the PSU of the Via C3 Epia motherboard. Would it be possible for me to use a pack of nicad batteries...one is around 1.2V at 0.60 Ah. That means i'll need 10 to get 12V and 6ah. Is that correct? Then can i use a simple circuit with the max787 to regulate the voltage to 12V at 5A? Or would i need higher ( around 40% more)voltage/amperage rating?

    The battery would have to be kinda small because of the limited space.

    I welcome all opinions.

    Paladin

  2. #2
    Raw Wave Rob Withey's Avatar
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    With 10 you would get 12 V and 0.6ah, or 1.2V and 6ah. You can't have it both ways.

    I seriously doubt you could pull a sustained 5A from nicads anyways.


    Rob
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  3. #3
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    Nickel Metal Hydrides might do it, but that may set you back 100 bucks or more, you would be better off using a sealed lead acid battery.....
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  4. #4
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    EDIT:
    (Sorry for the double posting, when I wrote this reply, you guys posted before me I thought I was the first one)


    Hi
    Im afraid your calaculation is wrong.

    If you connect batteries in a serial way, that means:

    (+)==(-)(+)==(-)(+)==(-)

    You add the voltages. In this case 3 x 1,5V = 4,5V

    If you wire them parallel:

    I -(+)==(-)- I
    I -(+)==(-)- I
    I -(+)==(-)- I


    You add their Capacities. 0.5Ah x 3 = 1.5Ah

    You would need more than 10 batteries to get 12V and 5 Ah.

    But there are batteries with 12V and 5 Ah. I think you can get them in a RC-Car-Shop. They are much smaller than car-batteries.

    Anyone correct me please if this was wrong!

    Greetz

    Golf_MPIII
    VW GOLF III GT 93
    [Xenarc 700TS] [Epia M10000]
    [256Mb RAM] [20Gb IBM 2,5" HD] [WIN XP Pro] [Bicker PSU] [Soundblaster Extigy] [######### -] 90%


  5. #5
    Variable Bitrate
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    Sorry...my mistake......i've seem to have forgoten what i learnt in college.hehe.

    Golf_mpIII,
    I've been to my local Tamiya Distributor and what they have are 7.2V and 9.6V at 1.7Ah

    Paladin

  6. #6
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    Also, (I am abit BORED) Nikel Metal Hydrides have a MUCH higher amp storage.. while your AA Nicads hold .6amps AA NIMH can hold upto 1.7amps.. so, if you want to use AAs, these would be MUCH better.... perhaps you can explain WHY you need a battery pack..??
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  7. #7
    Variable Bitrate
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    Themp3kid,
    well if i must, i must..hehe

    Ok, I've been asked by my local via distributor to make something to showcase the Via epia boards for a PC Fair which will be held end of this month. He likea the jellybean idea
    (http://www.viaarena.com/?PageID=120)
    and wants something similar to that.

    What i plan to do is to have the board powered by a battery pack and then hook up the rc motors to the parallel port. I would then be able to control the car movements through wireless keyboard or if possible wireless lan. I've just bought the shell of the car...the guy chose a f360 modena. I've looked at sealed lead acid battery and they are simply too heavy. I'm currently looking through the farnell catalogue to find something useful.

    Oh ya.....why 12V and 5A? because thats what the ATX psu needs.

    Keep em coming guys. Rob and golf has already spotted one mistake....anymore?

    Paladin

    i forgot to add that marauderz would be working on the software....so if u have any bright ideas, u can forward it to him

  8. #8
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    You wont get far with AA-batteries. You should either try Li-Ion Notebook-batteries or lead-gel or lead-acid batteries.

    I have an old 12V lead-acid battery from my motor-cycle in my 'Ghetto-Blaster'! Great thing, just a bit heavy!

  9. #9
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    hmmm... interesting.. what do you think is the max weight/size of the battery then??
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  10. #10
    Variable Bitrate
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    Frankly speaking....i dont know.... the smaller and lighter the better. the 1/10 shell aint that big. The battery will have to sit in the rear like a real life mid engined modena to maximise the traction since its rear wheel driven. The torque of the motors arent that great either so if its too heavy, it wont budge .

    Paladin

    p/s: just read that the sealed gel lead acid baterry, 12V 6.5A...its expensive and weighs 2.6 kgs!!!!

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