Granted Patent B2

US 12,613,266 · App. 18/243,261 · Granted Apr 28, 2026

Inventors: Reagan P. Zimmerman (Bloomfield Hills, MI); Craig E. Esler (Plymouth, MI); Shormin Razzaq Chowdhury (Northville, MI)

G01R31/007G07C5/008G07C5/0816

Abstract

Claims (45)

1 . A method of setting current limits for detecting anomalous current drain of a battery in an electrical system during a Key-Off state of a vehicle, the method comprising the steps of:

selecting a plurality of test vehicles which are operational without any anomalous current drain;

identifying a plurality of time intervals according to a plurality of predetermined Key-Off-Load (KOL) modes which are activated successively after initiation of the Key-Off state;

measuring Key-Off interval currents during each of the time intervals in each of the test vehicles;

determining a respective average current of the interval currents in each respective time interval;

determining a respective standard-deviation current of the interval currents in each respective time interval; and

setting a respective current limit corresponding to each time interval according to the respective average current plus a respective incremental value determined according to the respective standard-deviation current.

2 . The method of claim 1 wherein each respective average current is comprised of a mean value of the respective interval currents of each respective time interval.

3 . The method of claim 1 wherein each respective incremental value is comprised of two times the respective standard-deviation current.

4 . The method of claim 1 further comprising the steps of:

measuring Key-Off interval currents during each of the time intervals in a purchased vehicle not included in the plurality of test vehicles;

comparing the measured Key-Off interval currents to respective current limits; and

detecting an excessive current drain when one of the measured Key-Off interval currents is greater than the respective current limit.

5 . A method of monitoring a fleet of vehicles for excessive Key-Off Load (KOL) current drain while in a Key-Off state, the method comprising the steps of:

selecting a plurality of test vehicles which are operational without any anomalous current drain;

identifying a plurality of time intervals according to a plurality of predetermined KOL modes which are activated successively after initiation of the Key-Off state;

measuring Key-Off interval currents during each of the time intervals in each of the test vehicles;

determining a respective average current of the interval currents in each respective time interval;

determining a respective standard-deviation current of the interval currents in each respective time interval;

setting a respective current limit corresponding to each time interval according to the respective average current plus a respective incremental value determined according to the respective standard-deviation current;

transferring the respective current limits to each vehicle of the fleet of vehicles;

measuring Key-Off interval currents during each of the time intervals in each of the vehicles in the fleet of vehicles;

comparing the measured Key-Off interval currents to the respective current limits to determine respective Key-Off load scores for each vehicle of the fleet of vehicles;

combining Key-Off load scores from the fleet of vehicles; and

detecting an abnormality of the vehicles in the fleet of vehicles when the combined Key-Off load scores exceed a predetermined threshold.

6 . The method of claim 5 wherein each respective average current is comprised of a mean value of the respective interval currents of each respective time interval.

7 . The method of claim 5 wherein each respective incremental value is comprised of two times the respective standard-deviation current.

8 . The method of claim 5 wherein each respective Key-Off load score is comprised of a root sum of squares taken of each of differences between respective measured Key-Off interval currents and respective current limits.

9 . The method of claim 5 wherein each time interval is associated with a respective first current limit and a respective second current limit, and wherein each respective Key-Off load score is determined according to a compilation of respective time intervals in which the respective measured Key-Off interval current is greater than the respective first current limit and in which the respective measured Key-Off interval current is greater than the respective second current limit.

10 . The method of claim 9 wherein each first current limit is comprised of the respective average current plus the respective standard-deviation current, and wherein each second current limit is comprised of the respective average current plus two times the respective standard-deviation current.

11 . The method of claim 5 further comprising the step of:

when the abnormality is detected, then matching the time intervals and measured Key-Off interval currents to electronic modules in the fleet of vehicles capable of malfunctioning to create the measured Key-Off interval currents.

12 . A vehicle comprising:

a battery configured to supply electrical current during a Key-Off state of the vehicle;

a plurality of electrical loads each configurable to receive the electrical current flowing from the battery during the Key-Off state depending upon predetermined Key-Off-Load (KOL) Modes active according to respective time intervals;

a battery monitor measuring Key-Off interval currents during each of the time intervals;

a controller configured to (1) compare the measured Key-Off interval currents to respective current limits, and (2) indicate an excessive current drain in response to one of the measured Key-Off interval currents being greater than the respective current limit;

wherein the respective current limits are obtained from:

selecting a plurality of test vehicles which are operational without any anomalous current drain;

measuring Key-Off interval currents during each of the time intervals in each of the test vehicles;

determining a respective average current of the interval currents in each respective time interval;

determining a respective standard-deviation current of the interval currents in each respective time interval; and

setting a respective current limit corresponding to each time interval according to the respective average current plus a respective incremental value determined according to the respective standard-deviation current.

13 . The vehicle of claim 12 wherein each respective average current is comprised of a mean value of the respective Key-Off interval currents of each respective time interval.

14 . The vehicle of claim 12 wherein each respective incremental value is comprised of two times the respective standard-deviation current.

Assignments (1)

Continuity (1)

References Cited (21)