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Electric vehicle battery question

  1. Mar 17, 2007 #1
    i really hope someone can help me with this...
    what type of battery that is suitable for an electric vehicle(slow walking speed,electric wheel barow)? is it a deep cycle marine?
    I have a problem on how to choose the correct battery.
    i have choose a motor which can produce a max mechanical power output of 400Watts.

    if you look at the characteristic curve, my working torque would be around 2-3Nm, the corresponding current required is about 100A. The problem is due to the fact that the vehicle need to be as compact as possible, i can only choose one 12V battery 100Ah battery. i initially try to pick the right motor by using the assumption that, stall torque>torque require.This i know is not efficient+the rpm is slower near stall torque.
    Right now the motor that ive choosen got the right working torque(2-3Nm) and rpm, and is >50% efficient but the power source could not supply more than (2-3Nm), what happens if the required torque is more than 2-3Nm??
  2. jcsd
  3. Mar 19, 2007 #2
    There are two solutions. One is to use cells with high peak currents such as Li-Ion or Molibnium, but these are expensive and generally only used in Electric Cars as opposed to Electric Wheelbarrows unless weight is a driver above cost.
    The other option is to use motor control circuits to deliver the very high starting currents from resevoir capacitors whilst keeping the average current drawn from a Pb-Acid cell near the optimum for capacity. This slows your acceleration but gives you good running times.
    The motor control solution also protects the motors when the going gets tough as they can be used to limit the average current seen by the motor and switch out if a dead stall occurs.
    Unless you are looking for a lightweight wheel barrow with good 0-60 times I would look at building a motor controller using IGBTs such that peak current is delivered to the limit of the motor and average current is delievered at no greater than 2-3C of the Battery.
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