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 relay controlled by an Arduino will be used to apply the loads. A Fluke Scopemeter will datalog the output of 2 channels to a computer once per second.

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. Fluke Scopemeter
  5. Arduino
  6. Relay board
  7. Large wattage adjustable wirewound 4.7ohm resistor
  8. Dual AA battery holder
  9. 4 L91 AA batteries
  10. Nichrome wire for resistance of 15 ohms
  11. Low wattage resistance of 2x 0.35ohms

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. Connect Channel A to collect voltage from the battery terminal and the middle of a voltage divider circuit.
    3. Connect Channel B to directly measure cell voltage.
    4. Set up resistors in breadboard/clipleads to form loads and voltage divider circuit
    5. Start datalogging, set to autosave to dropbox
    6. connect loads and start arduino
  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. Convert the voltage measurement of Channel A to current

Observations

Data Collected / Results

  • CSV Data file of raw data output
  • Graph of raw data

Conclusion

testing/cryogenic/compmat/cryo24.1.txt · Last modified: 2010/12/04 17:19 (external edit)
 
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