Doesn't need to be an "inverter" just a booster. Which could be a step
down transformer coupled switcher making a variable output to be wired
in series with the battery, or just a boost regulator where there's a
series coil and the switch transistor to ground on the output side of
the coil, plus a diode to the filter capacitor. Energy is stored in the
coil and when the transistor opens, the voltage raises to that of the
capacitor. There are single chip high efficiency solutions for just that
where the switch is a FET and the "diode" is a FET for less voltage
drop. So takes the control chip, two fets, a coil and a filter
capacitor, plus a few small parts. Likely there's a MAXIM chip and
circuit in one of their publications already worked out and there's one
such circuit been mentioned here that is on the market. The boost energy
should be 75% efficient so the overall efficiency from 12 in to 13.8 out
ought to be about 97%.
73, Jerry, K0CQ
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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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