UN/SCETDG/33/INF.34

page 3

Annex

UN/SCETDG/WG/INF.

COMMITTEE OF EXPERTS ON THE TRANSPORT OF

DANGEROUS GOODS AND ON THE GLOBALLY

HARMONIZED SYSTEM OF CLASSIFICATION

AND LABELLING OF CHEMICALS

Sub-Committee of Experts on the

Transport of Dangerous Goods

Lithium Batteries Informal Working Group

Washington D.C.

11 -13 November 2008

LISTING, CLASSIFICATION AND PACKING

Transport of Lithium Batteries

Test Equipments and Criteria

Transmitted by the experts from China

Background

During tests according to UN38.3, we sometimes faced arguments on test results due to inconsistent on equipments. Also, based on criteria in text, some problems may come forth in actual testing. Listed as following:

1.  Requirements on T.6 test equipment

Experience shows different equipment used for T.6 could lead to different test results. The difference of these results could be huge. The following factors may cause influence on results:

a)  Resistance when mass dropping;

b)  Perpendicularity of the dropping tract;

c)  Departure of strike point and center of gravity on sample;

d)  Materials of the bar (different rigidity);

e)  Length of the bar;

f)  Materials and rigidity of flat surface.

2.  Observation for venting and leakage

In the text of UN38.3, “no venting” and “no leakage” are the test criteria for T.1~T.4. However, it is difficult to observe the phenomena of venting and leakage during the test especially for battery pack.

a)  leakage

For the battery pack (such as notebook battery), it is impossible to observe the phenomena without detach the case if cell leaks. In addition, the leakage does not result in the decrease of voltage absolutely. When the cells connected in parallel, the leakage for one cell may not decrease the voltage of the pack. And, the mass loss may not achieve 0.1% of the pack mass.

b)  venting

According to definition, venting means the release of excessive internal pressure from a cell or battery in a manner intended by design to preclude rupture or disassembly. This phenomenon is really hard to observe during the test. For instance, generally a 18650 cell has a reducing valve itself. Moreover this valve cannot be observed from outside.

3.  Temperature threshold for thermal fuse

Some battery pack set the threshold of thermal fuse at 70℃ in design for improving the safety performance. However, after T.2 test which at 75℃, the thermal fuse goes to open circuit. As a result, no open circuit voltage will be measured. According to requirement, it is failed. This takes puzzle to the manufacture since they actually enhance the safety performance for the battery pack.

4.  Temperature measurement for very small battery/cell

For some very small batteries/cells (biggest size of one dimension is less than 1cm, see annex), it is not easy to fix the thermal couple on surface of battery/cell for some tests (T.5 external short-circuit, T.6 impact etc.). It makes temperature measurement and monitor rather hard.

Proposal

1.  Amend 38.3 with requirements on equipment. For example to the T6 equipment:

a)  Suggest using 316 stainless steel to make bar and flat surface;

b)  Regulate the length of the bar as 12cm;

c)  The drop of 9.1kg mass should be free without traction, using tract-oriented, and there are should be definite requirement on roughness of contact surface;

d)  The horizontal level of flat surface and vertical level of oriented tract shall be calibrated;

e)  The center of gravity on mass, bar and dropping track shall be on a straight line.

2.  For observation of leakage and venting, temperature measurement for small battery/cell, and design temperature of thermal fuse, we propose to discuss and get a consistent and suitable judging procedure.

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Annex