Download Fall Design Report - Senior Design

SENIOR DESIGN – BATTERY REJUVENATION PROJECT
Shock Therapy Report
Battery Rejuvenation Design
Timothy Blake, David Bankhead, Travis McMillen
Contact: [email protected] or [email protected]
12/9/2011
University of Idaho
College of Engineering
Moscow, ID 83843
December 15, 2011
Acoustic Research Detachment
33964 N. Main Avenue
Bayview, ID 83803-9750
Attention: Jim Klein, LSV Propulsion Engineer
Subject: Battery Rejuvenator project team design report
We are submitting an interim design report cataloguing all that we have accomplished this semester.
Our planned actions to develop a procedure are included in this report. The planned testing procedures
are explained in detail in the system architecture section of this report. Also contained are the proposed
final product including various other directions we thought about taking the project and reasons why
this direction was not taken. These are outlined in the concepts considered and the concept selection
sections of this report. The final section details where this project could be taken after our planned
portion of this project is completed.
Thank you for all the suggestions you have given us on this project (especially after our design review).
As always feel free to contact us with questions or concerns about where we are going with the project.
We appreciate everything that you have done to help make this project possible.
Yours truly,
Battery Rejuvenation Team
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Executive Summary
The Shock Therapy team is in the process of designing an algorithm that the NAVY can use
to characterize their rejuvenators. The project began when it was realized that the NAVY needed
a more efficient way to recharge their batteries. The NAVY purchased rejuvenators to
investigate the plausibility of doing this and in so doing gave the Shock Therapy team an analysis
project.
The Shock Therapy team was given this equipment and tasks which the team turned
into forming a design project from this analysis project. This was done by deciding that the team
should implement or create an algorithm that the NAVY could follow which would characterize
their rejuvenators. This was deemed the most efficient and cost effective solution to the
problem the NAVY is facing. Many tests have been developed with the goal in mind of forming a
null hypothesis to create a procedure or algorithm useful to the NAVY. The Shock Therapy
team’s plan to implement this project is further outlined in system architecture.
In the future it would be possible to take this project even further by making it fully
automated. This could be done through the use of a microprocessor or other means, but this
will most likely come from a future senior design team.
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Contents
Executive Summary...................................................................................................................................... iii
I.
Background ........................................................................................................................................... 1
II.
Problem Definition ................................................................................................................................ 1
III.
Project Plan ....................................................................................................................................... 1
IV.
Concepts Considered ........................................................................................................................ 2
V.
Concept Selection ................................................................................................................................. 3
VI.
System Architecture .......................................................................................................................... 4
Discharging................................................................................................................................................ 4
Recharging ................................................................................................................................................ 5
Internal Resistance.................................................................................................................................... 6
Test Results ............................................................................................................................................... 7
Discharge Tests ......................................................................................................................................... 7
Rejuvenation Tests .................................................................................................................................. 10
VII.
Budget Summary............................................................................................................................. 11
VIII.
Future Work .................................................................................................................................... 12
Appendix A .................................................................................................................................................. 13
Data obtained ......................................................................................................................................... 13
iv
v
I.
Background
The NAVY personnel stationed at the Bayview acoustic testing center is responsible for
testing how loud their vehicles are in the water. The goal of this testing center is to create the
quietest NAVY vehicle possible. To this end they run their vehicles that are currently under
testing on the power of lead acid batteries. The problem facing the NAVY is that these batteries
die off every 4 years or so. This is quite costly for the NAVY, and they want to see if the life of
their batteries can be extended. From this they will determine how beneficial this will be as well
as if this is cost efficient. To this end the shock therapy team has been tasked with testing the
battery rejuvenators and batteries under question and forming a procedure or algorithm that
the NAVY can follow to characterize their rejuvenators.
II.
Problem Definition
Having one of the best NAVY branches in the world, the US NAVY wants their aquatic vehicles to
be as quiet as possible. One way to accomplish this is running the vehicles on electric power instead of
engines. This is where the US Navy Acoustic Research Detachment base in Bayview comes into play.
One of the downfalls of having a fully electric vehicle is that the batteries need to be changed out every
so often and that can become quite expensive. One option to help with expenses is to extend the
battery life and to do this a different type of charging system is required. One type of charging that they
are looking at is a type of rejuvenation that combines AC and DC voltages and currents. They NAVY
would like this team to see if this is a viable solution to their problem.
When the NAVY gave this project, it was more of an analytical project where they wanted to see
if this specific type of battery rejuvenator was better than the conventional charging method. This,
however, was not a design project. As a result, part of this design project was to quite literally design a
design project. After much thought the team decided the best course of action was to design a process
or algorithm that the NAVY could follow, step by step, to decide if the rejuvenator actually worked.
Going more into depth on the subject, a major goal the NAVY wishes to see out of this project is
if rejuvenating the batteries can extend the life of the battery. Even if the rejuvenator extended that
batteries life for just an extra month, that alone would save money for the NAVY in the long run. Along
those same lines, these rejuvenators also claim to not only extend the life of the battery, but also bring
batteries back to life which brings us to the second goal of this project.
The NAVY also would like us to prove if a dead battery can be cycled with the rejuvenators and
eventually brought back to a working condition. Right now the batteries are disposed of when they are
dead but if some of the batteries can actually be rejuvenated back to life, it would be a great
improvement.
III.
Project Plan
Below is the timeline we plan to follow for the rest of the project.
For this project it was somewhat difficult to catalog which responsibilities belonged to each
individual person because this semester has largely been spent designing our design project which
required all of us to work together almost the entire time. However, the official team responsibilities are
as follows:



IV.
David Bankhead: Website Technician, Treasurer
Tim Blake: Manager
Travis McMillen: Recorder
Concepts Considered
There were a variety of concepts considered throughout this project, but the main one being
focused on was the idea of designing a process that the NAVY can follow to characterize their
rejuvenators. This was a little more difficult than usual considering that we were originally given an
analysis project. Before each of these concepts are described, it would be prudent to detail how this
procedure would be formed which will further be outlined in system architecture, but will first be
introduced here.
As can be imagined with this project, there will be a lot of testing that needs to be accomplished
before any detailed process can be formed. This process that will be given to the NAVY will be formed
from extensive testing of the rejuvenators and batteries. The data obtained so far in our testing
procedures is given below in the Appendices. This data will then need to be statistically analyzed by the
formation of a null hypothesis. For the sake of argument consider that our null hypothesis is “The
BatteryMinder Rejuvenator works the best for the Genesis XE lead acid batteries”. As it so happens, this
is in fact what our data shows. The procedure can then be further expounded upon once this null
hypothesis is verified. So far, not enough testing has been done to form a null hypothesis that would be
valid for all types of testing that the NAVY will do on these batteries. Depending on whether the null
hypothesis is verified or falsified, the procedure would then detail what to do next. This procedure will
then allow for the NAVY to make the most efficient use of their time and money. This is the intended
goal of where we are headed with the project.
2
To this end, there were several ideas considered for this project. The first of these was designing
a procedure for testing the battery rejuvenators. This procedure would be able to accomplish several
things among which would be the ability to identify the compatibility of different rejuvenators with
different kinds of rejuvenators. To accomplish this we would develop a specific test setup which would
then be utilized by the NAVY. As explained before this procedure would result from the testing of the
null hypothesis we are working towards. This procedure would then output how compatible a certain
rejuvenator is with a certain type of battery. It would also characterize the rejuvenator by outputting
things regarding how fast this battery can be expected to charge as well as the life expectancy of the
battery. Another side goal of this procedure would be to determine if there are parameters of a battery
that indicate whether a battery is beyond any hope of being charged.
So let us consider the pros and cons of this approach. The pros of this approach are that the
NAVY can continue our research as well as determine the best type of rejuvenator for a given task at
hand. The cons of this approach are that it would be labor intensive for both the designers and those
utilizing the procedure. Ideally we would like to find something that would require minimal labor on the
NAVY side of things as this would be the most efficient and result in the best design. Another con of this
is that we might not have enough chargers to get conclusive results, something we are still looking into.
The biggest con of this approach, however, is that it is not a “set it and forget it” approach. In other
words, it is not an automated procedure which is something that we would greatly desire. To this end,
we have another option that is explained below to attempt to automate this procedure as much as
possible.
The second option we are considering and leaning more towards is the creation of a software
algorithm. This would involve creating a program that would monitor the interaction of the rejuvenators
and the batteries. Ideally this procedure would also automate the rejuvenator testing process. This
program would result from creating the procedure entailed above with our first design option, except it
would be completely run by a program. Currently we plan to accomplish this by using LABVIEW.
LABVIEW would be used because it would nicely record all the data necessary and would allow for a
nicely programmable process. This option would be quite a bit faster than other options in obtaining
results. However, it would also maybe have some unexpected compatibility issues with the operating
systems used by the NAVY and could also be more expensive since if the NAVY does not already possess
LABVIEW, they may have to purchase it. Overall, however, this does seem to be the best option. Why we
made the choice we made will be explained below in more detail.
V.
Concept Selection
In order to turn our given analysis project into a design project, we decided to provide the Navy with
a detailed process or algorithm they can follow to charge/rejuvenate their batteries. The NAVY provided
us with three “pulse” rejuvenators to test and also batteries that they are currently using. It took us a
few months to clearly define our project and decide what would be the best way to provide something
to our client instead of just raw data from testing and analyzing these results. We will compare the
rejuvenators with the Navy’s current charging methods and see which way is most beneficial for the
batteries. Then we will build the procedure based on our findings.
The procedure would allow NAVY to continue their research to characterize pulse rejuvenators and
would allow them to find the best rejuvenator for whatever task is at hand for them. This procedure
could include a software interface, most likely LABVIEW, but we are still working on finding all of the
different components to get it up and running. A software interface has the potential to make the
procedure a lot more user friendly and less time consuming. A procedure to check if batteries are dead
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or not is also another concept considered. This was a secondary of the project, and this procedure may
come about from our testing and analysis.
VI.
System Architecture
We will determine these characteristics during the next three months by carefully testing the
rejuvenators given to us with different types of batteries. The data obtained from tests will allow us to
observe behavior of batteries and how the rejuvenators interact with them. From these observations we
will determine which characteristics of a rejuvenator is the most desirable for the batteries given and
which rejuvenator is the most effective. The rejuvenators and batteries being tested were already
provided to use, so our main job was to develop a test setup. This will lead to the identification of
important characteristics for a good rejuvenator that the Navy can expand upon to develop a new
charging system for their batteries that will increase battery life and rejuvenate batteries that are
considered “dead.”
We have developed several different setups that we will use based on if we are discharging,
recharging, and also the battery type.
Discharging
When discharging batteries, we have developed a test setup that includes the battery, a resistor,
and a DAQ. The DAQ will measure the same things as when we charge the batteries. Figure 1 shows the
basic discharge setup.
Figure 1: Battery discharge setup
(for 12 V and 2 V)
Since the 2 Volt batteries need to be recharged in series, we have decided to discharge them in
series as well. This means that the series 2 Volts have a much higher amp hour rating than the 12 Volt
batteries by themselves. We are currently using a 1 ohm resistor as our resistance, but we decided later
to decrease this resistance in order to have more current drawn from the battery. This will in turn
decrease the amount of time it takes to discharge the batteries. We are thinking of doing this for the 2
Volt batteries in order to decrease the discharge time, because right now we are predicting about a 30
hour discharge rate for the 2 Volt batteries using a 1 Ohm resistor.
4
Recharging
When recharging batteries, our setup will include the charger or constant current or constant
voltage source, the battery, and the DAQ will be attached to the terminals of battery as well. The open
circuit of the battery will be measured before connecting it to the setup. Then the DAQ will be used to
take voltage, temperature, and hopefully current measurements across the terminals of the resistor at
set intervals. We are still in the process of getting the DAQ set up so we’re not entirely sure of its
capabilities. It is known that it will acquire data and send to the program LABVIEW, where we can
compile and analyze the raw data. The temperature will be constantly monitored so we don’t exceed
the maximum battery operating temperature. The battery charging setup for a 12 Volt battery can be
seen in Figure 2.
Figure 2: Battery Charging setup (for 12 V)
Since our rejuvenators provided by the Navy are specified to work only for 12 Volt batteries, we
needed to develop a way to get it to charge our 2 Volt batteries. To do this, six 2 Volt batteries are put in
series. The voltage between the terminals of the first and last battery is 12 Volts, and that is how we
plan to recharge these batteries. The test setup is shown in Figure 3.
Figure 3: Battery Charging Setup
(for 2 V)
5
The voltage at each of the battery terminals will be measured at set intervals so we will be able
to find discrepancies between the batteries and how they take a charge. If there is a bad battery in the
string, it can disrupt the charging characteristics of the other batteries. We need to be able to identify
this and replace batteries as needed. This is a challenge we may have to overcome if it is a problem.
Internal Resistance
Our other test setup we have developed will be used to determine the internal resistance of our
batteries. A battery’s internal resistance is said to change depending on the state of the battery. A fully
charged battery has a lower internal resistance than a discharged battery and a used, sulfated battery
has a much higher resistance than a new battery. This increased internal resistance is due to the
chemical reactions within the battery. Over time, sulfate builds up on the lead acid plates within the
battery, and this build up of sulfate decreases the batteries performance and it is also said to increase
the internal resistance of the battery.
The pulse chargers claim to remove the sulfate build up within the batteries, so that is why
measuring internal resistance will be an important characteristic in testing these claims.
Figure 4: Internal resistance
test setup
The process we will use to measure the battery’s internal resistance is as follows:
1.
2.
3.
4.
5.
Measure the open circuit terminal voltage of the battery
Connect the battery to a resistance
Measure current through the circuit
Measure the voltage as close to the terminals of the battery as possible
Use equation 1 to calculate the internal resistance of the battery
Equation 1
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6. Repeat steps 1-5 for varying the load resistance in order to verify findings
This process will require multimeters that are accurate up to the third decimal place. This is because
of the very small internal resistance of the batteries. We are hoping to find that using the pulse
rejuvenators will decrease the internal resistance of the batteries, thus increasing the capacity.
Test Results
Testing will play a big role in helping us identify important characteristics of these rejuvenators.
This semester our tests are being used to make sure our test setup will get us the result we expect. Next
semester is when we plan to do heavy testing. By then we will have the DAQ set up and working and
precise instruments to use for resistance testing. This will provide us with more accurate results that can
be easily manipulated and analyzed.
So far we have performed five tests with our batteries and rejuvenators, three discharge and
two rejuvenation tests. We have done two full discharges and the rest of the tests are not fully
completed due to the large amount of time required to complete these tests. Refer to the Appendix for
the gathered data from testing. The results of our tests are explained below:
Discharge Tests
Discharge Battery #1
12
Voltage
11
10
9
8
7
6
0
20
40
60
80
100
120
140
160
Minutes
Figure 5: 1st discharge test (USED & Previously Rejuvenated Battery#1)
Figure 5 shows a discharge test performed on a used, previously rejuvenated 12 V red Genesis
XE Battery #1. This battery was down to 5.2342342 Volts before being rejuvenated by the Navy’s contact
in Sandpoint. It started with and open circuit voltage of 12.83 Volts. For this battery we performed a
deep discharge to determine just how well it would hold its rejuvenated charge. It performed as
expected until around 10.5 Volts, which is the normal discharge stopping voltage. This battery had a
little longer discharge than the unused spare we discharged addressed in the next section. This was
most likely due to the fact that it was discharged in several sessions and we started off with a higher
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resistance until we were told about the 1 ohm resistor in the lab that we have used for the rest of our
discharges. Then its voltage level decreased very quickly. The expected behavior up until 10.5 Volts is
very promising because it does show that the rejuvenation did work on this battery, and it can now hold
a charge again. Hopefully we will be able to demonstrate this type of discharge after rejuvenation in
future tests.
Discharge Battery #2
Voltage
12
10
8
6
0
20
40
60
80
100
120
Minutes
Figure 6: 2nd discharge test (UNUSED Spare Battery #2)
Figure 6 shows a discharge test that was performed on an unused spare 12 V red Genesis XE
Battery #2. This linear discharge curve meets the specifications for this battery and is a good test to
compare the discharges of the used batteries we will be testing.
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Voltage
String of 2 Volt Batteries
11.82
11.8
11.78
11.76
11.74
11.72
11.7
11.68
11.66
11.64
11.62
0
15
30
45
60
75
90
105
120
Minutes
Figure 7: 3rd discharge test (6, 2V unused batteries in series)
Figure 7 shows a discharge test that was performed on six unused 2 Volt batteries connected in
series. Figure 7 shows the voltage between the terminals of the first and last batteries, adding up to 12
Volts. After two hours a linear discharge curve could be seen. These batteries weren’t fully discharged;
they were brought down to a total of 11.69 Volts from 11.8 Volts. From this test one can see that it will
take a lot longer to discharge these 2 Volt batteries. In the future we plan to monitor the voltage on
each battery, so we would be able to identify bad batteries. We don’t have the datasheet for these
batteries either, but we think the amp hour rating for them is along the lines of 40AH, which is this same
as the 12 Volt genesis batteries. This is why it will most likely take six times as long to discharge this
string of batteries.
9
Rejuvenation Tests
Rejuvenation Battery #1
13
12.8
Voltage
12.6
12.4
12.2
12
11.8
11.6
11.4
0
15
30
45
60
75
90
105
Minutes
Figure 8: 1st Rejuvenation test (Battery #1)
Figure 8 shows a rejuvenation test that was performed on the used, previously rejuvenated 12 V
red Genesis XE Battery #1. This was the battery that was deep discharged. The open circuit voltage was
9.86 Volts before charging, which is below the recommended 10.5 Volts for these batteries. This battery
was connected to the BatteryMINDer Model 12248 rejuvenator. This rejuvenator has three different
voltage settings of 2, 4, and 8 volts and can also charge different types of batteries. For this test we set it
to the 8 Volt setting for lead acid batteries. After just under two hours of charging, it brought the voltage
up from 11.91 to 12.74 Volts when connected to the charger. The battery wasn’t fully charged, but the
data we gathered showed a linear voltage increase as we graphed it. It also charged the battery a lot
faster than the second rejuvenator test.
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Battery #2 Rejuvenation
12.2
12.1
12
Voltage
11.9
11.8
11.7
11.6
11.5
11.4
11.3
435
405
375
345
315
285
255
225
195
165
135
105
75
60
45
30
15
0
11.2
Minutes
Figure 9: 2nd Rejuvenation test (Battery #2)
Figure 9 shows a rejuvenation test that was performed on an unused spare 12 V red Genesis XE
Battery #2. This rejuvenation was performed by the small Renaissance RC-2A12-2. This is a single setting
rejuvenator that outputs 2 Amps to the battery. After about 7 hours of charging the rejuvenator
increased the voltage from 11.5 Volts to 12.08 Volts. This is the smallest charger we have and it looks
like it will take the longest to rejuvenate the batteries, based on the small amount of current it’s putting
out.
VII. Budget Summary
The team applied for the Kenneth-Corbett grant and was awarded a sum total of $1,000.00. As
shown, there are two main totals. The first total describes the trip up to Bayview and if need be, a
second trip is accounted for in case of unforeseen problems. The second total accounts for parts
and miscellaneous items that might be needed as the year progresses. Figure 10 shows this
breakdown of the budget.
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Budget Total
# of People Rate
Sub Total
Lunch
4
$10.00
$40.00
Dinner
4
$20.00
$80.00
# of Miles (round trip) Rate
Driving
230
0.445
$102.35
Total:
$222.35
Total x 2:
$444.70
Parts
$500
Miscellaneous
$55.30
Total:
$555.30
Grand Total:
$1,000.00
VIII. Future Work
This was a unique project, in which we created our own project definitions. This allowed us to
have some freedom in where we wanted the project to eventually go. As previously stated earlier, the
plan was to have a process that will quantify rejuvenators and batteries but the next step to that would
be to make this process fully automated. A “black box” design would be created in which that wanted
data would be printed out to a computer screen. To do this a team of not just Electrical Engineers but
also one or two Computer Engineers/Computer Science. This way the programming aspect would be
accounted for and the project would get done in another year or so.
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Appendix A
Data obtained
st
1 discharge test (USED & Previously Rejuvenated Battery#1)
Time (min) Voltage (V) Current (A)
0
11.8
11.7
15
11.71
11.7
30
11.51
11.9
45
11.43
11.9
60
11.22
11.8
75
11.09
11
90
11
11
105
10.87
11.1
120
10.59
10.7
135
9.84
9.9
140
9.15
9.1
145
7.85
7.9
2nd discharge test (UNUSED Spare Battery #2)
Time (min) Voltage (V) Current (A)
0
11.44
11.5
15
11.37
11.4
30
11.25
11.2
45
11.13
11.1
60
10.97
11.1
75
10.82
10.8
90
10.6
10.7
100
10.5
10.6
13
3rd discharge test (6, 2V unused batteries in series)
Time (min)
0
15
30
45
60
75
90
105
120
Voltage
Current
(V)
(A)
11.8
11.8
11.8
11.6
11.79
11.5
11.78
11.4
11.77
11.6
11.75
11.4
11.73
11.7
11.71
11.3
11.69
11.3
1st Rejuvenation test (Battery #1)
Time
(min)
0
15
30
45
60
75
90
105
Voltage Current Temperature (F)
11.91
8
83.7
12.05
8
85.5
12.24
8
87.3
12.29
8
87.5
12.42
8
88
12.5
8
88.6
12.62
8
89.1
12.74
8
90
2nd Rejuvenation test (Battery #2)
Time (min) Voltage (V) Temperature (deg F)
0
11.7
73.3
15
11.83
73.6
30
11.87
73.8
45
11.9
73.8
60
11.92
74
75
11.93
73.9
105
11.96
74.1
135
11.98
74.2
165
12.01
74.2
14
195
225
255
12.03
12.06
12.08
74.4
74.2
74.2
15