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US 6,556,020 B1Granted
Battery state of charge indicator
AssigneeThe Raymond Corporation
InventorsPaul Patrick McCabe, Dean Harvey, Daniel Robert Driscall, Augustus R. Baldini
Life of this patent
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Abstract
A state-of-charge indicator system monitors the battery current and voltage during operation of a lift truck. Selected current and voltage samples are used to calculate the internal battery resistance and this is employed to calculate a “dynamic” battery voltage. This dynamic battery voltage is used as input to a stored look-up table which provides a battery state-of-charge value.
Claims13
A state-of-charge indicator system for a battery which comprises:
- a voltage sampling circuit coupled to the battery to measure its voltage;
- a current sampling circuit coupled to the battery to measure its current;
- battery resistance calculations means coupled to the voltage and current sampling circuits and being operable to calculate a battery resistance value (Rbattery) based on a change in measured battery current and the corresponding change in battery voltage;
- dynamic voltage calculation means for receiving measured battery current (1) and voltage (V) and calculated battery resistance (Rbattery) and calculating a dynamic battery voltage
- Vdynamic=V+I(Rbattery);
- and
- means for converting the dynamic battery voltage Vdynamic into a battery state-of-charge value.
4 more elements
A method for indicating the state-of-charge of a battery connected to a variable load, the steps comprising:
- periodically sampling the battery voltage V;
- periodically sampling the battery current I;
- detecting a battery current change event in which the sampled battery current changes a preselected amount during successive samples In and In−1;
- calculating a battery resistance value
- Rbattery=|Vn−Vn+1/(In−In+1);
- calculating a dynamic voltage value
- Vdynamic=Vn+1+In+1(Rbattery);
- and
- converting the dynamic voltage value to a battery state-of-charge value.
6 more elements
Dependencies are inferred from the claim text.