Cryo test of Various Lithium Battery Performance

DESCRIPTION

Due to the extreme cold temperatures encountered, and importance of saving weight, currently lithium batteries are the best single-use choice for balloon flights. Lithium batteries perform well in cold, are lighter than other types, and store more power per unit mass. Rechargeable battery technologies generally have poor cold performance. For reference, a chart of rechargeable battery performance information is available at http://batteryuniversity.com. Battery University has a great deal of information on battery technologies, and is recommended reading.

Example specifications for the Energizer Ultimate Lithium AA are:

 Capacity (mAh)	 Voltage	 Weight (g)
 3000	         1.5	         14.5

Setup

Four battery sizes will be tested in this test. Each battery will be loaded with 50mA continuous resistive load for the test. The batteries are all rated to supply this current continuously. An arduino is used to read A/D values and output them to a serial capture program on a PC, RealTerm. Realterm provides timestamping. The Arduino outputs the values approximately once per minute. The data for 6v inputs only will need to be converted to volts based on this circuit. Realterm is time-stamping voltage data captures using Unix Time.

Format:

time,sampleNumber,Analog0,Analog1,Analog2,Analog3,Analog4,Analog5,

A/D output range is 0 to 1024.

Striped Color = Positive
Solid Color = Negative

Battery Type Voltage mA Wire Color Analog Port
CRV3 3 Orange 0
2x L-91 3 Green 1
2CR5 6 Blue 2
CR-P2 6 Brown 3

The 6v batteries were wired using a voltage divider to allow the 0-5v arduino A/D to measure them. The divider is made of a 20ohm resistor at the positive side, and a 100ohm resistor at the negative side. The 20ohm resistance was made from two 10ohms in series. The Arduino measures the 3v batteries directly.

Anthracite web scraping performed on Dan's MacBook Pro to allow capture of temp log.

OBJECTIVE

Capture discharge curves for 4 different battery types at -56C using 50mA load.

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. Breadboard to make voltage dividers on
  5. Arduino
  6. Backup temperature sensor

PROCEDURE

  1. Connect the 50mA load to the 6v batteries until the voltage divider circuit output is below 5v
  2. Remove 50mA load
  3. Add dry ice into reservoir, if necessary. Be sure to wear the dry ice handling gloves.
  4. Place one type of each battery in cryo chamber.
  5. Connect 50mA load
  6. Connect voltage outputs to arduino
  7. Start chamber fan system
  8. monitor voltage and temperature remotely
  9. Restock dry ice if needed
  10. Continue test until all batteries reach their exhaustion voltage
  11. Retrieve batteries from cryo chamber
  12. Measure and record the voltage of batteries immediately
  13. Let the batteries return to room temperature
  14. Measure and record the voltage of batteries

Notes

Start Date: October 31, 2010 Dry Ice Mass at chamber entry: 2.65kg + 2.52 kg
Dry ice Chamber entry time 18:02 Eastern 20101031

  • Removed Vcc line and resistor from ANALOG2 at sequence 221
  • At sequence number 241 reconnected ANALOG2's load and sense line, and added 50ma loads to ANALOG0 and ANALOG1. It was discovered that the loads had been left out of those two battery channels. This resulted in no appreciable drop over the course of the test up to this point for those two channels
testing/cryogenic/compmat/cryo1.txt · Last modified: 2010/11/01 02:30 (external edit)
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 3.0 Unported
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki