Transcript Diapositive 1 - Recharge Batteries

Market growth
300 Wh exemption for ADR transport
Claude Chanson
6th WRBRF, March 23-24, Berlin
background
 The power tools industry observes an increase in the energy of
the batteries. The limit of 100 Wh of battery exemption
according UN SP 188 should be enlarged to 300Wh for ADR
(for excepted rechargeable lithium-ion batteries shipped under
the SP188 , transported by road, rail and inland waterways).
 In US, this 300 Wh exemption for road transport is granted.
 The first proposal in UN December 2015 session has been
refused,
 But further work was accepted, particularly about
 The multimodal issue
 The safety characterisation of the 300 Wh batteries.
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On going activity
Multimodal approach.
• Air = Not allowed. Propose an additionnal dedicated
marking : “not allowed for air transport”.
• Sea = any particular recommendation?
• Road and Rail= basic tolerance
Safety characterisation of the 300 Wh batteries.
• Safety assessment test
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Safety issue: what are the main reasons in case of a local fire/runaway
• Dangerous case example ( FAA tests): the cells are closely pack in a
battery or package of flammable material: a single cell event propagate to
a whole pallet, due to heat propagation and fire propagation.
• In case of use of fire extinguishing systems (halon), flames can be
stopped, but the runaway is still progressing and producing flammable
gas, due to heat propagation
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Safety issue: the advantage of thermal protection
In case of thermal insulation between the cells or the batteries (minimum
distance between cells/batteries or use of thermal insulation material), then
the flame extinguishing system is a sufficient to stop the event.
Ignition and fire-> fire extinction and heat evacuation-> no propagation
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Safety assesment approach: the earlier the protection,
the smaller the event
The key mechanism possibly leading to the hazardous
situations is the risk of heat and flame propagation
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The heat propagation can be modelled
RECHARGE has created a simplified thermal propagation model
Objective:
•
•
A simple static thermal model was not sufficient to analyze the results of the
testing
The testing was limited to one type and size of battery: there is a need of a
model allowing a good prediction of the thermal behavior in case of different
battery and packaging sizes or other cushioning materials.
Model description:
-
-
A dynamic model has been created: simplified finite
elements calculation under Excel, using heat
propagation in isotropic spherical conditions through 4
layers of material.
Boundary conditions can be adjusted
Heat source size and layer thickness can be adjusted
cushioning material
heat
source
heat tranfert
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Cushioning calculation: Minimum Safe Distance (MSD)
to avoid heat propagation can be calculated.
-
-
The « Minimum safe distance » MSD, is the thickness of the cushioning
material layer allowing to stop the propagation to the next battery in case of
one battery runaway
It has been shown that Li-ion batteries do not release significant amounts of
heat up to 100°C ( ref 1). It is then considered that the distance where the
cushioning material is heated at 100°C maximum is the MSD.
MSD for a Li-ion 18650 layer
-
ACCUREC has conducted
experiments (ref 1) to measure this
MSD with different cushioning
materials.
-
Results obtained with the model
are quite comparable to the
experiments, except for
pyrobubbles: the test result is not in
relation to the thermal properties
measured in this case.
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Other example: cushioning calculation avoiding heat
propagation for a large battery runaway.
-
Case of large batteries in packaging with limited cushioning:
• boundaries conditions of the model adapted:the key parameter
is the cooling efficiency of the packaging.
•
Example of a 100 kg battery surrounded by 7 cm vermiculite thickness in a
metallic drum, in conditions allowing the natural convection cooling (i.e. single
drum on a pallet).
•
the max. external temperature is 100°C, and decreases after 5h.
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Safety assesment approach: what are the different cases
case
Batteries type
Flame
emission
during
thermal run
away
Runaway
propagation
Casing and
packaging
type
Flammable
casing/packa
ging
1N
No
No
No
1F
No
No
Yes
Yes
No
No
2N
2F
Yes
No
Yes
3
Yes or No
Yes
Yes or No
Hazards in case of fire
Complementary risk mitigation
recommendation
In case of fire, limited
amount of gas, selfextinguishing flame.
Risk of fire propagation
throught casing/
packaging flames
Limited amount of heat,
self exitinguishing flame.
No specific need.
Risk of fire propagation
throught casing/
packaging flames and
batteries flames
Risk of run-away
propagation to the whole
stock, risk of large flames
No specific need for batteries.
A flame extinguisher system is
recommended
No specific need for batteries.
A flame extinguisher system is
recommended
No specific need for batteries.
A flame extinguisher system is
recommended
Specific battery fire
extinguishing systems: large
amount of water (or similar),
or flame extinguisher and
cooling systems.
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Test rationale for the power tools batteries
This test intends to prove
 batteries can be classified according the table in case 2F. (the most
hazardous among all cases except 3)
100 Wh and 300 Wh are similar.
 In worst case conditions:
-
Using cells with a reactive chemistry (NMC or LCO type, no LFP type).
Using high energy cells: as for the large majority of this type of batteries, it is
proposed to use high energy cells of the same standard size (“18650”). The case of
larger cells is not tested here: it is propose to limit the demonstration to batteries
made of cells of less than 20Wh.
Using a maximum energy density: batteries in their packaging (instead of
batteries in equipment), closely over-packed, in a representative number.
In a first step the cells will be at the standard SOC ( 50%, reference state,
and 100% TBC)
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Test description
Test practical organisation
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