Amps

Discussion in 'General Electronics Chat' started by New123, Jan 3, 2013.

  1. New123

    Thread Starter New Member

    Jan 3, 2013
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    How does a portable jump starter produce up to 1000amps from a 12v battery. Also what type of batter is it
     
    Last edited: Jan 3, 2013
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
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    1000 amps could be produced from even a 1V battery. Likewise a 1000V battery may not even be able to produce 1A. it depends on the internal resistance of the battery in question. Very low internal resistance = very high amp output, and vise versa. Google ohm's law.

    I don't know what type of battery is common in a car jump starter, but I suspect it's some variant of the lead acid battery like the one that is already in your car. The lead acid battery in your car is also likely able to produce 1000A, as it is a low resistance battery.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Lithium polymer battery is small and very low internal resistance.

    Remember, a real battery is the same as an "ideal battery" plus a resister in series with the battery.
     
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  4. vrainom

    Member

    Sep 8, 2011
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    Most I've seen use a 19ah sealed lead acid battery.
     
  5. New123

    Thread Starter New Member

    Jan 3, 2013
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    Ok. So if I were to remove all resistance from a lithium ion battery ( ex. Laptop battery 11.1v) could I produce similar amperage
     
  6. WBahn

    Moderator

    Mar 31, 2012
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    Sure, but how do you propose to remove all of the internal resistance?
     
  7. Papabravo

    Expert

    Feb 24, 2006
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    With a "Magic Resistance Elimination Wand" of course. Are you guys living under rocks? -- LOL
     
  8. New123

    Thread Starter New Member

    Jan 3, 2013
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    I don't know. I'm just wondering if its possible to produce 200amps from a 12v lithium ion battery.
     
  9. New123

    Thread Starter New Member

    Jan 3, 2013
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    Or lithium polymer
     
  10. JMac3108

    Active Member

    Aug 16, 2010
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    19Ah is the battery capacity in amp x hours. This is unrelated to the amount of current the battery can source. As others have said, this is only limited by the internal resistance of the battery. I once designed a UPS battery pack with individual sealed-lead-acid cells and they actually specified a "short-term short-circuit current" in the datasheet. I remember it being about 400A.
     
  11. JMac3108

    Active Member

    Aug 16, 2010
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    Nope. Regardless of internal resistance, the internal safety circuit in a LiIon battery will disconnect the battery before allowing an excessive current.

    And if you tried to use raw LiIon cells and draw a very high current from them you would heat them up and find out why we always use a safety circuit!!!
     
  12. WBahn

    Moderator

    Mar 31, 2012
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    Of course it's possible. Put enough cells in parallel and you can produce whatever current you want. A quick search revealed this site:

    http://www.claytonpower.com/products/lithium-ion-battery/
     
  13. vrainom

    Member

    Sep 8, 2011
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    I was answering op's question "what kind of battery is it". And most jump starters I've seen use that particular battery capacity. Sure, they can give an instantaneous huge amount of current.
     
  14. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    This URL is about Energizer AA battery Internal Resistance but it gives you an idea of the deciding factor for what a battery can deliver.

    For example, a CR2032 Lithium coin battery and a CR123 Lithium Cell (half length AA battery and a bit fatter) both have about 3 Volts at the terminal.

    The Coin Cell, due to construction and physical size, can only output about 20mA when terminals are shorted.

    A CR123 Cell can provide >10 Amps when the terminals are shorted.

    The downside of Lithium Cells, especially rechargeable Li-ion, is during heavy current flow, they heat up and tend to catch fire or explode. This can happen either in discharging (both types), and especially in Li-Ion Rechargeable (Flaming notebooks).

    Lead Acid is the best chemistry for very low internal resistance for short bursts of very high current. When a battery goes "bad", it is due to the internal resistance climbing, for one reason or another.
     
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