It listed among the possibilities a manufacturing flaw, a design defect or problems with external systems that charge and discharge the battery.

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By using a capacitor instead, Mazda saves weight and space and, unlike a battery, it can charge and discharge instantly without deteriorating during prolonged use.

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Last month, the most exciting news was from UCLA, where a small team of researchers developed a micro-scale graphene-based supercapacitor that can charge and discharge a hundred to a thousand times faster than current batteries.

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The chemical that allows the battery to charge or discharge is held in vessels outside of the battery and it flows between the electrodes when it is time to do some work.

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So last fall, Bello's team began a special clinic where nurses check heart surgery patients about a week after they go home, at no extra charge and have a chance to re-teach those discharge instructions when people are more ready to listen.

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