/ Distr.
GENERAL
18-20May2010
Original:ENGLISH
LithiumBatteryInformalWorkingGroup
Washington, DC
18-20 May2010
Definition ofRated Capacity
Transmittedby RECHARGE
Watt-hour and Rated Capacity for Lithium-ion Batteries in UN Model Regulations
The UN Model Regulations regulate lithium ion batteries based on their Watt-hour rating and also require alllithium ion batteries to be marked with the Watt-hour rating starting 1st January 2011.
“Watt-hour” is defined in the UN Model Regulations as follows:
Watt-hour rating, expressed in Watt-hours, is calculated by multiplying a cell's or battery's rated capacity, in ampere-hours, by its nominal voltage.
“Rated Capacity”is defined in the UN Model Regulations as follows:
Rated capacity means the capacity, in ampere-hours, of a cell or battery as measured by subjecting it to a load, temperature and voltage cut-off point specified by the manufacturer.
Capacity Marking Requirement in EU Batteries Directive
The European Union (EU) Batteries Directive (2006/66/EC)requires the “capacity” (Ampere-hours) to be marked on all types of portable rechargeable batteries, including lithiumion batteries, butnot the Watt-hourrating.
In order to establish a basis for the marking of the “capacity” of portable rechargeable batteries in the EU Batteries Directive, the rated capacity is measured according to the International Standard (IEC 61960)[1] which is a globally recognized technical basis for the evaluation of the “rated” capacity ([2]) .
Harmonization of Capacity Measurement for Portable Batteries
As noted above, the UN Model Regulations defineRated capacity as the capacity, in ampere-hours, of a cell or battery as measured by subjecting it to a load, temperature and voltage cut-off point specified by the manufacturer.
By making no reference to the type of measurement method that needs to be followed to evaluate the capacity, which is the basis for the calculation of the Watt-hours, the UN Model Regulations may open the route to many types of rating of the capacity of a portable battery; in particular it can be any value of “rated” capacity determined under any discharge (non-standardized) conditions. This is particularly problematic when determining if a battery is eligible for the exceptions provided in Special Provision 188 of the UN Model Regulations.
This means that in case of conflict of interests there is no standard technical basis for comparison, which could lead to unfair competition. Furthermore, the Watt-hour value is approximate since the voltage (V) may not be constant during discharge of a battery under non-standardized conditions.
Conclusion
As a consequence of the non-harmonized requirements of the UN Model Regulation and of the EU Batteries Directive,“double labelling”will be required for Lithium ion batteries (Ah + Wh).
To promote harmonization between the UN Model Regulations and EU Batteries Directive,RECHARGE is proposing to amend the definition of Rated Capacity by including a reference to the IEC 61960Standard for measuring the “rated capacity” of batteries subjectto Special Provision 188.
PROPOSAL
Rated capacity means the capacity, in ampere-hours, of a cell or battery as measured by subjecting it to a load, temperature and voltage cut-off point specified by the manufacturer.
NOTE: The rated capacity of lithium ion cells with not more than 20 Watt-hours and lithium ionbatteries with not more than 100 Watt-hours shall be measured based on IEC 61960 Standard.
1
[1]IEC 61960 – Secondary cells and batteries containing alkaline or other non-acid electrolytes; Secondary lithium cells and batteries for portable applications.
[2] IEC 61960 - § 3.5 definition of rated capacity: quantity of electricity C5 Ah (ampere-hours) declared by the manufacturer which a single cell or battery can deliver during a 5-h period, when charged, stored and discharged under the conditions specified in 7.2.1.