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I wonder what size battery for this Merc?

AncientMariner

From the June E&T magazine, A Mercedes-Benz EQXX prototype has been driven from Sindelfingen in Germany to Cassis on the French Riviera, a distance of more than 1,000 km, on a single charge.

Whilst certainly a good range, is it energy efficient considering the weight of the battery, which could have been reduced in return for a lesser range?

Whilst on the subject, does a fully charged battery weigh more (or even less) than a fully discharged battery?

Clive

  • 0

    A smaller battery would be cheaper to buy, and less weight to carry around, thereby reducing energy used if other factors remain equal.

    It would in my view be worth producing two versions of most electric vehicles, one with say a 350 km range and one with a 1,000 km range, let the customer choose.

    I would expect the battery to weigh the same [within the limits of measurement] whether charged or discharged.

  • 0

    And the price is?

  • 0

    the only batteries that change weight by a lot are things like Zinc Air and any chemistry that either out-gasses or absorbs from the air during run down or charging.

    There is also a very very  small change in weight in sealed cells that is not detectable with normal instruments, and is based on E=mc2

    In practice a few greasy finger prints will have more effect.

    For example, an electric car battery that may store 16 kWh. Multiply it by 1,000 and 3,600 to get the value in Joules; then divide it by 1017 which is (approximately) the squared speed of light and you get the mass difference in kilograms. It's about

    16×1,000×3,600/1017=0.6*10−9kh

    kilos, or a touch over half a microgram !

    A fully charged battery does have more mass, as it has more energy, but there is no normal instrument that can detect that sort of change on a thing that big.

    Mike.

  • 0

    Hi,

    According to two physical theories of Einstein, mass and energy are just different manifestations of the same phenomenon, and therefore a battery contains energy in the form of its atomic mass and the electrical energy inherent in it. A battery when charged is more energetic or in other words 1 trillion times heavier and this shows an uncharged battery. The difference is so small that a standard scale will always show the same weight whether the battery is charged or not.

  • 0

    There comes a point where you're making the car heavier and thousands of pounds more expensive, only to save 30 minutes each way on a journey that you might do once a year.

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