1. Rechargeable Batteries and Battery Testing for Hospitals
Cadex Electronics Inc.
December 13th, 2005
Bruce Adams

2. Overview Introduction – Cadex Electronics
Common Rechargeable Battery Types
Which chemistries are most common?
Global demand data, Freedonia
Advantages and limitations of the common chemistries: Nickel Cadmium, Nickel Metal Hydride, Sealed Lead Acid and Lithium Ion.
Why batteries fail.
Guidelines for Battery Maintenance
Selecting the Right Battery Analyzer/Tester
Summary –
- Battery Testing. What to Expect

3. Cadex Electronics Inc. – Overview
Cadex designs and manufactures battery chargers and battery analyzers/testers for professionals.
Established in years of manufacturing and design excellence.
Cadex products are sold in over 100 countries worldwide.
Cadex products and practices comply to CSA/UL/CE/FDA standards for safety, and ISO 9001/13485 and GMP for quality.

4. Common Rechargeable Battery Types – by Global Demand
Lead-acid batteries account for approximately ½ the worlds’ total demand for rechargeable batteries. Mostly for automotive, and power back-up applications (UPS) including medical equipment.
Lithium ion batteries shows the fastest growing demand.

5. Common Battery Types - Advantages & limitations
Nickel Cadmium
Advantages
Fast and simple charge.
High number of charge/discharge cycles — if properly maintained, the NiCd provides 1000+ charge/discharge cycles.
Forgiving if abused — the NiCd is one of the most rugged rechargeable chemistries.
Best chance of recovery following prolonged storage.
Limitations
Relatively low energy density.
Memory effect — the NiCd must periodically be exercised to prevent memory.
Has relatively high self-discharge — needs recharging after storage.

6. Common Battery Types - Advantages & limitations
Nickel Metal Hydride
Advantages
30%+ higher capacity compared to standard NiCd.
Less prone to memory than NiCd — fewer exercise cycles are required.
Limitations
More complex charge algorithm needed — the NiMH generates more heat during charge and requires a longer charge time than the NiCd.
High self-discharge — typically 50% higher than NiCd.
New chemical additives improve self-discharge but at the expense of lower energy density.
Performance degrades if stored at elevated temperatures.

7. Common Battery Types - Advantages & limitations
Sealed Lead Acid
Advantages
Inexpensive – lowest cost/watt hour of all common batteries.
Low self-discharge.
Low Maintenance — no periodic discharge is needed.
Limitations
Low energy density - poor weight-to-energy ratio. Mostly used mostly in power back-up (UPS) or in wheeled applications.
Can not be stored discharged – cell voltage must be maintained above 2.10V/cell.
Lowest number of full discharge cycles compared to other battery types.

8. Common Battery Types - Advantages & limitations
Lithium Ion
Advantages
High energy density — potential for yet higher capacities.
Relatively low self-discharge — self-discharge is less than half that of NiCd and NiMH.
Low Maintenance — no periodic discharge is needed; no chemical memory.
Limitations
Requires protection circuit to maintain voltage and current within safe limits.
Subject to aging, even if not in use — storing the battery in a cool place and at 40% state-of-charge reduces the aging effect .
Expensive to manufacture — about 40% higher in cost than NiCd.
Fuel gauge recalibration required periodically.

9. NiCd NiMH Li-ion Lead-acid Gravimetric Energy Density (Wh/kg) 45-80
60-120
30-50
Internal Resistance in m (includes peripheral circuits)
V pack
V pack
< V pack
Less than V pack
Cycle Life (to 80% of initial capacity)
1500
Service Life
5 years +
3-4 years
2-3 years
Fast Charge Time
1-2h
2-4h
½-4h
8-16h
Self-discharge / month (room temp.)
20%
30%
5-10% 5%
Cell Voltage (nominal)
1.2V
3.7V 2V
Load Current peak best result
20C 1C
5C 0.5C or lower
2-5C 1C or lower
5C 0.2C
Operating Temp. (discharge only)
-40 to 60C
-20 to 60C
Maintenance Requirement
30-60 days
60-90 days
6 months
Typical Battery Cost (US$, ref. only)
$50 (7.2V)
$60 (7.2V)
$100 (7.2V)
$25 (6V)
Cost per Cycle (US$)
$0.04
$0.12
$0.14
$0.10
Commercial use since
1950
1990
1991
1970

10. Common Battery Types - Why Rechargeables Fail
Every battery has a finite life. Choose hardware (charger) and a field service program (Battery Maintenance) that maximizes the number of charge/discharge cycles from your batteries.
Poor charging or storage… “ Heat ”Choose a battery and charger to compliment usage patterns and ambient conditions.
NiCd charges cooler than NiMH – if you work in a hot climate NiCd is a better choice, if you charger supports both.
Nickel Cadmium and Nickel Metal Hydride batteries develop “Memory” Choose a conditioning charger and professional battery maintenance product.

11. The Battery Problem - So What Can You Do?
Weak batteries are picked more often than good ones because weak batteries are charged more frequently and remain on “Ready / Green Light On” longer.
In an emergency situation, the only batteries that are on “Ready / Green Light On” could be the duds.

12. Guidelines for Battery Maintenance 1. Isolate Date Expired Batteries
Ward A St. Joe’s Hspt
Expire Date Today
85% Batt ID# 1234
Date Expired
TO BE
SERVICED
Before use the service date on the battery label is checked and if expired, the battery is isolated so it can be serviced.

13. Guidelines for Battery Maintenance 2. Test/Service Battery
TO BE
SERVICED
Printer
Battery Analyzer
Batteries are serviced on a battery analyzer/tester to restore lost capacity or recalibrate the fuel gauge. Batteries that do not reach target capacity are properly discarded. All batteries with acceptable capacity (80%, or facility defined target) are relabeled.

14. Guidelines for Battery Maintenance 3
Guidelines for Battery Maintenance 3. Relabel Battery and Return to Service
Ward A St. Joe’s Hspt.
Expire Date 3 Months Later
84% Batt ID# 1234
New Label
NEW BATTERIES
SERVICED
BATTERIES
After service batteries are returned to service. All batteries now meet expected performance standards (no weak batteries)

15. Selecting the Right Battery Analyzer/Tester
Choose a tester that matches the number and type of batteries in your facility;
How many batteries can be tested at the same time?
Are all chemistries supported?
Are all pack voltages (1.2V-30V+) supported?
Does it perform the right tests (Service tests along with priming programs for new batteries)?
Warranty period and upgradeability?
Easy to connect the battery?
How much time will it take?

16. Selecting the Right Battery Analyzer/Tester
Choose a tester that allows you to collect service data and record/report the results appropriately. PC software and accessory label printer may be required.
Choose a tester that can be updated to support batteries for future medical devices. Interchangeable adapters make it easy to accommodate new battery types.

17. Summary – Battery Testing What to Expect
Test Time/Battery.
6-10 hrs. for NiCd, NiMH hrs. for Li-Ion. 24 hrs. for SLA.
Recommended Service Period/Battery Type.
NiCd – every days. NiMH –every days. SLA and Li-Ion every ~6 months.
Amount of Operational Time Required – Once installed, less than 30 minutes per day.
The bottom-line line: Battery testing will improve reliability of medical equipment and minimize the expense of unnecessary battery replacement (lower cost of operation).

18. Thank You! bruce.adams@cadex.com
For more on battery-related products and information visit the following websites:
Corporate website
Educational website; offers practical information for battery users in essay form.
Informational website; carries articles and the book: "Batteries in a Portable World — A handbook on rechargeable batteries for non-engineers”