Battery tub tester

A battery tub tester is disclosed that tests the individual batteries, battery accessories and connections as they are being assembled into a battery tub for an electric vehicle. The batteries and battery tub accessories, including temperature sensing devices and battery monitor modules, are mounted and electrically connected in the battery tub in accordance with a known battery tub assembly scheme. As the assembler mounts and connects the batteries and battery tub accessories, the tub tester determines the battery voltages of each battery after it is mounted and connected within the tub to determine if the batteries have the desirable voltage and will operate as they are intended and are connected properly. Additionally, the tester determines the temperature readings as the temperature sensors are being mounted, to determine if the temperature sensors will operate as intended and are connected properly. In this manner, the assembler will know that the battery tub is assembled properly and the components will operate properly prior to the battery tub being mounted to the vehicle.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to a battery tub tester for testing 
battery tub components during tub assembly and, more particularly, to a 
battery monitor and tester for testing batteries and battery tub 
components as they are being assembled in a battery tub for an electric 
vehicle, to determine whether each individual battery and component is 
acceptable prior to the battery tub being connected to the vehicle. 
2. Discussion of the Related Art 
Electric vehicles which run on electrical power stored in multiple 
batteries within a battery housing or tub are known in the art. The 
popularity of electric vehicles is on the rise as a result of many factors 
including consumer demand, emission concerns with internal combustion 
engines and increased government regulations. An assembled battery tub 
includes a certain number of batteries and battery components mounted and 
electrically connected in the battery tub in accordance with a particular 
assembly scheme. Once assembled, a lid is bolted to the tub and the tub is 
then bolted to the vehicle. 
In one example, twenty-seven 12 volt batteries, three battery monitor 
modules (BMMs), and fifteen temperature sensors (thermistors) are mounted 
and electrically connected within the battery tub. The batteries are 
electrically connected in series, and a group of batteries is connected to 
each BMM such that an electrical connection is made between each adjacent 
battery and the particular BMM. A single temperature sensor is used to 
sense the temperature of two adjacent batteries. During vehicle operation, 
the BMMs monitor the battery voltage and battery temperature of the 
individual batteries within the tub, and provide a signal indicative of 
these values to a controller to be processed for visual indication to a 
vehicle operator. U.S. Pat. No. 5,646,534 issued to Kopera discloses a 
battery monitor module for an electric vehicle of the type being discussed 
herein. 
A problem exists with the above-described technique of assembling a battery 
tub for an electric vehicle. That problem has to do with the lack of 
ability, in the known art, to test the batteries, BMMs, and thermistors, 
and the various connections, as they are being assembled in the tub. 
Occasionally, one or more of the batteries being mounted and connected in 
the tub may be defective, and not be able to produce its intended charge. 
Additionally, it is typically necessary that the batteries all have 
approximately the same voltage capacity (generally on the order of 
12-131/2 volts) and voltage spread. Further, other tub components, such as 
the BMMs and the temperature sensors, may be defective and not operate 
properly. Also, the various connectors and leads may be defective or not 
connected properly, and not provide the desired electrical connections 
between the tub components. 
Currently, no technique exists for determining whether the battery tub is 
being assembled properly, and whether the batteries and electrical 
components being inserted in the tub will operate as intended. Thus, the 
assembler of the tub would not know that the battery tub will not operate 
correctly until the battery tub was completely assembled, mounted to the 
vehicle, the vehicle was started, and the readouts from the BMMs were 
determined. After the battery tub was secured to the vehicle, and it was 
determined that there was some problem with the battery tub operation, it 
was necessary to remove the battery tub, and individually check each of 
the connections, batteries and other components to locate the problem. 
Because the battery tub is extremely heavy and is connected to the vehicle 
by several bolts, the manpower required to connect and remove the tub is 
intensive, as well as the manpower and lost time required to test the 
individual batteries and components once it has been removed. 
What is needed is a system and method for sequentially testing the 
individual batteries, battery tub components and connections in a battery 
tub as the battery tub is being assembled, so as to insure that the 
battery tub will operate correctly prior to the tub being connected to the 
vehicle. It is therefore an object of the present invention to provide 
such a system and method. 
SUMMARY OF THE INVENTION 
In accordance with the teachings of the present invention, a battery tub 
tester is disclosed for testing the individual batteries, battery 
accessories and connections of a battery tub for an electric vehicle as 
the battery tub is being assembled. The batteries and battery tub 
accessories, including temperature sensing devices and battery monitor 
modules, are mounted and connected in the battery tub in accordance with a 
known battery tub assembly scheme. As the assembler mounts and connects 
the batteries and battery tub accessories, the tub tester determines the 
battery voltages of each battery after it is mounted and connected within 
the tub to determine if each battery has the desirable voltage, will 
operate as it was intended and is connected properly. Additionally, the 
tester determines the temperature readings of each temperature sensor as 
it is mounted in the tub, to determine if the temperature sensors will 
operate as intended and are connected properly. In this manner, the 
assembler will know that the battery tub is assembled properly and the 
components will operate as intended prior to the battery tub being mounted 
to the vehicle. 
Additional objects, advantages and features of the present invention will 
become apparent from the following description and appended claims, taken 
in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following description of the preferred embodiments directed to a 
battery tub tester and method of testing batteries and battery tub 
components of the battery tub as it is being assembled is merely exemplary 
in nature, and is in no way intended to limit the invention or its 
applications or uses. 
FIG. 1 is a schematic-type diagram of a battery tester 10 connected to a 
battery tub 12 by an electrical lead 14. Once assembled, the tub 12 is 
covered by a lid (not shown) and bolted to an electric vehicle (not 
shown). A plurality of stacked batteries 16, BMMs 18 and thermistors 20 
are assembled, mounted and electrically connected within the battery tub 
12 in accordance with a particular tub arrangement scheme. The arrangement 
of the batteries 16, the BMMs 18 and the thermistors 20 in the tub 12 is 
intended to depict all types of battery tub assemblies for electric 
vehicles. 
The tester 10 is a computer system that includes a microprocessor 22, a 
keyboard 24, and a monitor screen 26. The computer system can be any 
suitable system for the purposes of the present invention. The tester 10 
is programmed to operate in accordance with the testing scheme described 
below. The electrical lead 14 is intended to represent a plurality of 
electrical leads connected to the various BMMs 18 within the tub 12. When 
the tub 12 is connected to the vehicle, the electrical lead 14 is 
connected to a controller (not shown) within the vehicle that monitors the 
BMMs 18 during normal operation of the vehicle. The lead 14 is connected 
to the tester 10 during assembly of the tub 12 before each of the 
individual batteries 16 are mounted in the tub 12 and electrically 
connected to the BMMs 18. The operation of the BMMs 18, including the 
controller, is described, in one example, in the '534 patent. 
FIG. 2 shows a flow chart diagram 30 depicting the operation of the tester 
10 in accordance with a testing algorithm of the invention. The 
microprocessor 22 is programmed to prompt the tub assembler to perform 
certain functions while he is assembling the tub 12. The BMMs 18 are first 
mounted within the battery tub 12 in the conventional manner and then are 
connected to the tester 10 by the lead 14. The tester 10 is switched on, 
and the testing sequence is initiated to go through it's start-up routine 
at step 32. Each of the individual batteries 16 mounted within the tub 12 
includes a plurality of bar codes (not shown). The plurality of bar codes 
give information such as the serial number of the battery 16, the 
manufacture date, the part number, etc. The first step that the testing 
algorithm prompts the assembler to do on the computer screen 26 is scan 
the appropriate bar code to determine the battery's serial number at step 
34. The testing algorithm then determines if the scanned serial number 
matches the predetermined criteria stored in the tester 10, at decision 
diamond 36. The testing algorithm compares the scanned serial number to 
stored serial number data so as to eliminate certain errors, such as using 
the wrong battery type or double scans of the same battery. If the serial 
number does not match the predetermined criteria, the testing algorithm 
returns to the step 34 of prompting the assembler to scan the battery bar 
code. 
If the serial number matches the predetermined criteria, then the testing 
algorithm prompts the assembler to insert the battery into the tub 12 and 
connect the sense leads of the appropriate BMM 18 to the positive and 
negative battery terminal connections in accordance with the tub assembly 
scheme, as indicated by step 38. At the appropriate time in the assembly 
scheme, the assembler will also connect a temperature sensor at this step. 
Once the sense leads of the battery and/or temperature sensor are 
connected, the testing algorithm determines the voltage and temperature 
values of the just connected battery or temperature sensor on a bus 
protocol, such as Motorola Component Area Network (MCAN) on the lead 14 
through the BMM, at step 40. Next, the testing algorithm determines 
whether the measured battery voltage of the just installed battery has an 
acceptable voltage at decision diamond 42, so that the tester 10 knows 
that the battery will operate properly and be suitable for the tub 12. 
When the batteries are ready to be mounted in the tub 12, they are fully 
charged, and therefore, all of the batteries should have about the same 
voltage, for example, within a range of about 12.25 to 12.75 volts. It is 
important that all of the batteries in the tub 12 have about the same 
voltage capacity so that the charging and discharging of the batteries 16 
during vehicle operation is as efficient as possible. 
If the measured battery voltage, as determined at decision diamond 42, is 
not within the accepted range, then the testing algorithm prompts the 
assembler to visually inspect the battery connections to make sure that 
the battery is in fact connected properly at decision diamond 44. The 
battery connectors may be defective or the battery may not be connected 
properly, resulting in an improper voltage reading. If the battery is not 
connected properly or one or more of the connectors is broken, the testing 
algorithm prompts the assembler to attach the sense leads at step 46 to 
connect the battery properly, and then returns to the step of determining 
the battery voltage at step 40. If the battery is connected properly and 
the connectors are good at the decision diamond 44, the battery is not 
acceptable, and the testing algorithm prompts the assembler to remove the 
battery from the tub 12. The testing algorithm stores the serial number of 
the defective battery in a bad battery file in the microprocessor 22 at 
step 48. The testing algorithm then returns to the beginning of the 
algorithm for scanning and insertion of a new battery in the place of the 
defective battery at step 34. 
If the testing algorithm determines that the measured voltage value of the 
battery has a value within the acceptable range at decision diamond 42, 
i.e., is fully charged to the right level, the algorithm then determines 
if the voltage range of all of the batteries mounted in the tub 12 so far 
have an acceptable voltage spread, here 0.5 volts, at decision diamond 50. 
Not only do the batteries have to be fully charged to an acceptable 
voltage level range, the fully charged battery voltage of each battery in 
the tub 12 must be within a certain value of every other battery in the 
tub 12 for proper operation of the tub 12. The actual voltage values that 
set the spread to determine if the most recently inserted battery falls 
within the spread are defined by the already mounted and accepted 
batteries. Of course, a spread of 0.5 volts is by way of example in that 
other voltage spreads may be applicable. If the voltage value of the 
battery is not within the accepted spread, the algorithm prompts the 
assembler to remove the last inserted battery at step 52 as being 
inadequate. Even though the battery does not have an acceptable voltage 
value compared to the other batteries already inserted, the battery may be 
able to be used for other applications. The algorithm then returns to the 
step 46. 
If the voltage value of the battery is in the acceptable range, the testing 
algorithm then determines if the measured temperature is within an 
acceptable range, at decision diamond 54. The expected temperature range 
can be any predetermined range around ambient temperature, and as long as 
the temperature sensors are within this range, the connection of the 
thermistors is acceptable, and the thermistors are operating correctly. If 
the temperature measurement is not within the acceptable or expected 
range, then the testing algorithm prompts the assembler to determine if 
the thermistor sense leads are connected properly and the connectors are 
good at decision diamond 56. If the thermistor leads are not connected 
properly or the connectors are broken or defective, the testing algorithm 
prompts the assembler to properly attach or replace the thermistor leads 
at step 58, and then returns to decision diamond 50 to determine if the 
temperature measurement is now in the expected range. If the thermistor 
leads are connected properly and the temperature reading is not at the 
right level, then the thermistor is probably defective, and the testing 
algorithm prompts the assembler to change the thermistor at step 60, 
attach the new thermistor connection at the step 58, and then return to 
the decision diamond 54 to determine if the temperature measurement of the 
new thermistor is in the appropriate range. 
If the thermistor is in the expected temperature range, then the testing 
algorithm records certain data, such as location of the batteries and 
thermistors inserted so far, under the vehicle identification number (VIN) 
at step 62, because all of the batteries and thermistors that have been 
assembled so far are suitable. This information is retained for warranty 
purposes. The testing algorithm then prompts the assembler to determine 
whether the last battery has been inserted in the battery tub 12 at 
decision diamond 64. If it is not the last battery, the algorithm returns 
to the step 34 to scan the next battery to determine its serial number. If 
it was the last battery, then the testing algorithm prints out a record of 
the assembly at step 66. At the end of the process, the assembler knows 
that all of the batteries, thermistors, BMMs and the connections 
therebetween are good, and once the battery tub 12 is bolted to the 
vehicle, will know that any problems will not be within the tub 12. 
The foregoing discussion discloses and describes merely exemplary 
embodiments of the present invention. One skilled in the art will readily 
recognize from such discussion, and from the accompanying drawings and 
claims, that various changes, modifications and variations can be made 
therein without departing from the spirit and scope of the invention as 
defined in the following claims.