Cryogenic test of Energizer L91 Battery

Description

This will test the capacity, and voltage response under sudden load, of the Energizer Ultimate Lithium L91 battery at several different low temperatures.

Background Info

From the Energizer Lithium L91 Battery Handbook.

Although the higher OCV of the LiFeS2 system is 1.8 volts, the nominal or rated voltage is 1.5 volts which makes it a suitable replacement for alkaline and nickel systems. The battery voltage will drop when it is placed under load. For this reason, the higher OCV will typically not damage electronic components, but device designers should take into consideration that the OCV of fresh batteries can range from 1.79 to 1.83V. LiFeS2 batteries fully meet the ANSI specification for a 1.5V battery. When a drain has been applied to the battery, the OCV drops dramatically and then slowly recovers with time. The OCV for a battery can be misleading. A “good” battery will generally have an OCV >1.74 volts. Any battery with an OCV <1.70 (after it has been allowed to recover) is completely discharged. Although an alkaline battery may read “good” at 1.6 volts, this reading on a LiFeS2 battery indicates the product has been discharged.

Setup

One cell will be used for these tests. It will be placed in a spring contact holder. A PROTEK RC Charger 1010B Battery analyzer will be used to apply the loads, and to datalog the output to a computer. The PROTEK charger will provide a current equivalent to the estimated normal operating current

Idle current calculated with the following conditions:

  • Sat modem at receive only
  • Xbee receive only
  • Strobe off
  • Ballast closed
  • FC CPU running
  • Comm Comtroller CPU running
  • Sensor Board CPU running
  • GPS running
  • Openlog running idle

Pulsed load will simulate the following conditions:

  • Satellite modem transmit for 5 seconds

Objective

At -40C

  • Find capacity under simulated idle 100mA load + 2A pulsed load every 10 minutes

Equipment

    1. styrofoam dry ice reservoir
    2. mounted fan
    3. temperature sensor
    4. web portal that displays temperature readings
  1. dry ice
  2. dry ice handling gloves
  3. Volt meter
  4. Protek RC iCharger 1010B
  5. Large wattage adjustable wirewound 4.7ohm resistor
  6. Dual AA battery holder
  7. 4 L91 AA batteries

Procedure

  1. Prep
    1. Set up battery holder in cryo chamber
      1. Add fresh battery
      2. Attach thermo sensor from charger to battery
      3. Run wires out of chamber
    2. Attach switched load to battery
    3. Set discharge current to 100mA
    4. Start datalogger, set to autosave to dropbox
    5. start discharger
  2. Observe
    1. Watch current draw and voltage, adjust pulse current resistance to make sure 2A are being pulled.
  3. Abort
    1. If battery cannot provide 2A pulse draw at any point.
  4. Analysis
    1. Using the resistance value on the external load, calculate add the missing current/power/capacity to the data

Observations

Data Collected / Results

  • CSV Data file of raw charger output
  • Graph of raw data
  • CSV Data file corrected for pulsed load current

Conclusion

Voltage never dropped below 1 volt during test. Dry ice ran out before battery ran out. Time resolution was only 2 seconds, would like more accurate Due to measurement device limitations, current was only estimated. Will re-perform using a better setup as Cryo24.1

testing/cryogenic/compmat/cryo24.txt · Last modified: 2010/12/04 17:06 (external edit)
 
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