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Anonymous
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Driven by the laptop and PDA markets, EDN Magazine has published a comprehensive article on battery technology: "Battery Management Included", Joshua Israelsohn, EDN 18 January 2001, pages 65-74.
Although NiCads have been the traditional solution in pulse induction metal detectors, I have to wonder if a LI-Ion (coke) battery plus a large capacitor (to supply the pulse currents) would be a better solution that straight NiCad batteries, as the Li-Ion (coke) batteries have 90/40= 2.25 times the energy per kilogram, and 210/100= 2.1 times the energy per liter, of a NiCad.
Big capacitors take a lot of space, but are not that heavy, so the energy-per-kilogram figure of merit, even with the capacitor included, may be sufficiently favorable.
One can also buy "supercapacitors" that have capacitances of up to one half of a farad in battery-level voltages, which is almost a battery in its own right One supplier is AVX (www.avxcorp.com), which offers its "BestCap" electrochemical supercapacitor line. There are other suppliers, one of which advertises in NASA Tech Briefs.
Joe
Although NiCads have been the traditional solution in pulse induction metal detectors, I have to wonder if a LI-Ion (coke) battery plus a large capacitor (to supply the pulse currents) would be a better solution that straight NiCad batteries, as the Li-Ion (coke) batteries have 90/40= 2.25 times the energy per kilogram, and 210/100= 2.1 times the energy per liter, of a NiCad.
Big capacitors take a lot of space, but are not that heavy, so the energy-per-kilogram figure of merit, even with the capacitor included, may be sufficiently favorable.
One can also buy "supercapacitors" that have capacitances of up to one half of a farad in battery-level voltages, which is almost a battery in its own right One supplier is AVX (www.avxcorp.com), which offers its "BestCap" electrochemical supercapacitor line. There are other suppliers, one of which advertises in NASA Tech Briefs.
Joe