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US 5,214,370 AGranted
Battery charger with thermal runaway protection
AssigneeAT&T Bell Laboratories
InventorsCharles E. Harm, Kenneth J. Timm
Life of this patent
Estimating the term…
Abstract
A battery charger control includes a thermal sensor attached to the battery being charged. If the temperature readings indicate a thermal runaway condition the charging current output is adjusted in accord with the temperature reading by means of voltage injeciton into an output sense lead of the charging circuitry as a means of achieving a control that prevents thermal runaway of the battery while still permitting continuous charging of the battery.
Claims4
A battery charging circuit comprising:
- a power input for accepting an AC energy source;
- a power output connected to a battery to be charged and supplying the regulated voltage to the battery;
- and
- a rectifier charging circuit for supplying current at the regulated voltage to the power output, and including a regulation control for controlling teh voltage;
- a temperature sensing device located proximate to the battery;
- scaling circuitry for converting a value of the temperature sensing device to a voltage magnitude;
- a voltage output of the scaling circuitry connected to the regulation control;
- wherein the improvement comprises:
- voltage sensing leads connected to terminals of the battery being charged and to the rectifier charging circuit;
- circuitry included in series with one of the voltage sensing leads for injecting a voltage into a path of the voltage sensing leads;
- whereby the voltage injected into the path of the voltage sensing leads alters the charging voltage supplied by the rectifier charging circuit to the battery to compensate for a temperature sensed by the temperature sensing device.
8 more elements
A battery charging circuit as claimed in cliam 3;
- wherein the improvement further comprises:
- the thermistor being connected in series with a resistor to form a voltage divider, and
- the scaling circuitry includes an amplifier responsive to a divided voltage output of the voltage divider.
Dependencies are inferred from the claim text.