Download Lithium Ion-Battery

Project
Muscle Activated Prosthesis
Project Record:
Battery Research and Decision
Version 2
10.17.16
Erin Cressman
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Version History
Version
Date
Description/Notes
1
10.11.16
Initial Research
2
10.17.16
Decision on Type
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Table of Contents
Abstract ........................................................................................................................................... 4
Goal ................................................................................................................................................. 4
General Battery Research…………………………………………………………………………4
Lithium Ion-Battery..................................................................................................................... 5
Lithium-Polymer Battery……………………………………………………………………….5
Conclusion ...................................................................................................................................... 6
References ....................................................................................................................................... 6
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Abstract
This document discusses the different battery options for our myoelectric hand to help
determine the best fit for our project. We start by comparing Lithium-based batteries, Nickelbased batteries, and Lead Acid batteries and deciding that Lithium-based are the best option.
Then we compare Lithium-ion batteries to Lithium-polymer batteries to decide what type of
Lithium battery will best suit our hand. In the end, we decide that a Lithium-ion battery will be
the best option and lay out some possible battery choices.
Goal
The purpose of this report is to document research of myoelectric hands to find what type
of battery is typically used and use this information to focus on finding which battery would best
fit our needs of being lightweight, powerful, fairly high voltage, small size, with a long life
cycle, and a low cost.
General Battery Research
The ideal battery for a myoelectric prosthetic hand is lightweight (< 100g), small as to not
make the arm too bulky, has a high voltage capacity to allow for as many different voltage
thresholds as possible (for assigning different hand positions), a long discharge cycle to allow the
arm to last all day, and is easily rechargeable.
The most common battery types are Nickel-based, Lithium-based, and Lead acid
batteries. Majority of the myoelectric prosthetic hands on the market use either a Li-ion or Lipolymer battery [4,5]. This is because the Li-based batteries are light-weight, have higher energy
densities than the other options, and have the greatest electrochemical potential. These batteries
have high cell voltages that allow for simple, one cell battery packs, and the cell itself has a low
resistance. Another important characteristic of Lithium batteries is that it requires little
maintenance. These batteries do not need to be fully discharged over time, and keep their charge
when not in use. Lithium batteries are more expensive, mostly due to the protection circuit that
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they require to prevent the voltage of the cell from getting too high or too low while the cell is in
use, but a prosthetic hand needs a powerful lightweight battery with as little maintenance as
possible, making Lithium batteries a great fit [3].
Based on this research, we decided that Lithium-based batteries are the best option for
our prosthetic hand. Now the decision is between using a Lithium-ion battery or a LithiumPolymer battery.
Lithium Ion-Battery
Lithium-ion batteries are lightweight since Lithium is the lightest metal and they are able
to have a higher cell voltage than other batteries due to their composition. These batteries also
have a flat discharge curve to allow for optimum use of the voltage. Another advantage of Li-ion
is that it is low-maintenance with no memory, so there is no need to completely charge or
discharge the battery to keep it healthy and it does not need to be primed before use. This type of
battery is very similar to the Li-polymer battery, but it is bigger and cheaper, with costs
continuing to lower. It does need a protection circuit and is expensive, but the lightweight
capabilities to go along with the powerful voltage it provides makes it extremely useful for
powering small devices [2].
Lithium-Polymer Battery
Lithium-polymer batteries are very similar to Lithium-ion batteries, but are made to be
even smaller. These batteries use laminated sheets that do not need a rigid case like Lithium-ion
batteries which causes these batteries to be lighter and able to be formed into any shape. Many of
the Lithium-polymer's other characteristics match the Li-ion's, for example they both need
protection circuits and both have a high energy density. However, because the Li-polymer is so
small, it cannot produce as much power as a Li-ion battery and it is also more expensive. It is a
good application for very small devices that do not need a lot of power, and it is becoming very
popular in phones and devices [1].
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Conclusion
After comparing the different types of batteries, I believe that a lithium ion battery will be
the best option for our myoelectric hand. It is lightweight, small, and has a high battery density
that will allow it to power our system well. Lithium-polymer batteries are harder to come by and
are too small to provide enough power to move the hand. In order to get enough power, the size
of the hand and the cost of a Li-polymer batter would be greater than a Li-ion battery. We will
decide the exact Lithium-ion battery we will purchase based on our budget and technical
requirements. Table 1 shows different examples of the kind of battery we would buy.
Table 1: This table shows examples of specs of Li-ion batteries we could use in our hand [6].
Type
Current
(A)
4
Capacity
(mAh)
2200
Dimensions (mm)
Li-ion
Voltag
e (V)
7.4
Power
(Wh)
16.25
Cost ($)
72 x 38 x 19
Weight
(g)
99
Li-ion
Li-ion
7.4
7.4
5
5
2600
2800
72 x 38 x 19.5
70 x 38 x 27
99
91
19.24
20.72
19.99
37.99
Li-ion
11.1
4
2200
70 x 55 x 18
150
24.4
26.99
Li-ion
7.4
5
2800
70 x 38 x 27
91
20.72
37.99
13.99
References
[1] Buchmann, Isador. "BU-206: Lithium-polymer: Substance or Hype?" Li-polymer Battery:
Substance or Hype? – Battery University. Cadex Electronics Inc., n.d. Web. 18 Oct. 2016.
[2] Buchmann, Isador. "Lithium-based Batteries Information." – Battery University. Cadex
Electronics Inc., n.d. Web. 18 Oct. 2016.
[3] Buchmann, Isador. "What’s the Best Battery?" Basic to Advanced Battery Information from
Battery University. Cadex Electronics Inc., n.d. Web. 18 Oct. 2016.
[4] "Michelangelo Prosthetic Hand." Michelangelo Prosthetic Hand. Ottobock, n.d. Web. 18
Oct. 2016.
[5] "Power Options." Bebionic. Steeper, n.d. Web. 18 Oct. 2016.
[6] "Rechargeable Batteries." All-Battery.com. N.p., n.d. Web. 18 Oct. 2016.
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