Method and apparatus for predicting the available energy of a battery

• US 6,618,681 B2
• Filed: 05/02/2001
• Issued: 09/09/2003
• Est. Priority Date: 05/02/2001
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Honeywell International Inc.
• Inventors: Hoenig, Steven, Palanisamy, Thirumalai G., Singh, Harmohan, Eagan, Margaret
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Desta, Elias
• Application Number:
  US09/847,823
• Publication Number:
  US 20020193953A1
• Time in Patent Office: 860 Days
• Field of Search: 702/31-32, 702/57, 702/60, 702/63-65, 702/85, 702/86, 702/108, 702/117, 702/127, 702/182, 320/127, 320/130-136, 320/147, 320/148, 320/153, 320/FOR.101, 320/103, 320/108, 320/121-133, 324/426, 324/430, 324/433, 324/600, 324/601, 324/605, 324/608, 324/691, 324/713, 324/720, 324/721, 700/52, 700/89, 700/91, 700/108, 700/291, 700/293, 700/295, 700/297, 700/299, 700/286, 307/18-21, 307/24, 307/31, 307/46, 307/48, 429/61, 429/62, 429/63, 429/121, 429/123, 429/125, 429/126
• US Class Current: 702/63
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/379 for lead-acid batteries
• CPC Class Codes: G01R 31/3835 involving only voltage measurements

Abstract

A method of predicting by non-invasive testing the available energy of a battery at any state of charge by acquiring data of the parameters of internal resistance (IR), open circuit voltage (OCV) and temperature (T), the points of voltage and current of the slope on a positive current ramp of V_up and I_up at the transition from charge to overcharge and on a negative current ramp of V_dn and I_dn at the transition from overcharge to charge for a plurality of batteries. Next an algorithm in the form of a linear equation is developed using this data. The available energy of a battery under test is predicted by acquiring from it the numerical data values of these parameters and applying them to the algorithm.

Claims

1. A method of predicting the available energy of a battery comprising the steps of:

determining the battery internal resistance (IR);

measuring the battery open circuit voltage (OCV) and temperature (T);

calculating the voltage and current points (V_gas and I_gas) at which the battery transitions from one of a charge to overcharge or overcharge to charge state in response to at least one of battery charge and discharge; and

predicting the available energy on the basis of the parameters OCV, T, IR, V_gas, and I_gas by developing an algorithm of prediction of available energy as a function of OCV, T, IR, V_gas, and I_gas and acquiring an applying the values of OCV, T, IR, V_ga, and I_gas of the battery under test to the algorithm.

2. The method of claim 1 wherein the step of calculating the V_gas and I_gas comprises:

applying to the battery a ramp of current (I) in each of the positive and negative directions;

monitoring the voltage response (V) in response to the applied current;

calculating the slope of the response as dV/dI; and

determining the maximum points of the slope.

3. The method of claim 1 wherein the step of developing numerical weighting factors comprises subjecting the data of OCV, T, IR, V_up, I_up, V_dn, and I_dn to an analysis to produce a linear equation having a numerical value as a weighting factor associated with each of the parameters.

4. The method of claim 3 wherein the analysis comprises a linear regression and the algorithm produced also includes a numerical setoff value.

5. The method of claim 3 wherein the equation of the algorithm is of the form

6. The method of claim 5 wherein for a lead-acid storage battery the algorithm is:

7. The method of claim 3 further comprising the step of acquiring the parameters of OCV, T, IR, V_up, I_up, V_dn, and I_dn and developing an algorithm with weighting factors for batteries in each of different ranges of battery Amp-hour rated capacity.

8. The method of claim 1 further comprising the step of determining the Time to un to discharge of a battery under test based on the predicted available energy in accordance with the equation:

9. The method of claim 8 further comprising repeating the steps of determining the Time to Run over a period of time as current is being drawn from the battery by subtracting the current drawn from the battery between successive Time to Run determinations and using the result of the subtraction in recalculating the available energy for the latter Time to Run determination.

10. A method of predicting the available energy of a battery comprising the steps of:

determining the battery internal resistance (IR);

measuring the battery open circuit voltage (OCV) and temperature (T);

calculating the voltage d current points (V_gas and I_gas) at which the battery transitions from one of a charge to overcharge or overcharge to charge state in response to at least one of battery charge and discharge, said step of calculating comprising

applying to the battery a ramp of current (I) in each of the positive and negative directions;

monitoring the voltage response (V) in response to the applied current (I),

calculating the slope of the responses as dV/dI, and

determining the maximum points (V_up and I_up) of V_gas and I_gas of the slope on the positive current ramp at the transition from charge to overcharge and the maximum point (V_dn and I_dn) on the negative ramp at the transition from overcharge to charge; and

predicting the available energy on the basis of the parameters OCV, T, IR, V_up, I_up, V_dn, and I_dn by developing an algorithm comprising the parameters OCT, T, IR, V_up, I_up, V_dn, and I_dn, developing weighting factors for each of the parameters, acquiring for the battery under test numerical values of each of the parameters, and applying the acquired numerical values of the parameters to the algorithm.