Li-Ion Quality Considerations
Occasionally I meet someone who understands the
characteristics of battery cell chemicals equally
to myself. In almost all instances
they have better written communication skills than
myself. Even though I see my articles plagiarized
and modified on other web sites I believe if the
article is correct and well written to just give
credit to the original author. This is a
reproduction of an article written by David Hardy of
PAG ltd., with important information and points
about the safety of lithium ion battery packs.
FYI-- PAG lithium ion battery packs and other
comparable quality brands are available through
Rathbone Energy, Inc., at discounted pricing.
Call for more information.
Rathbone Energy, Inc.
as used in rechargeable cells, possesses a fantastic
power-to-weight ratio, and this makes it
particularly attractive to our industry. It is for
this reason that it is especially well suited to the
latest portable broadcast equipment, because, while
cameras have become more compact, the current
required to power them has steadily increased. The
expectations of the user to access this reserve of
power safely, is behind many of the problems being
In the 1970s and 1980s, cell
manufacturers introduced commercial rechargeable
cells based on metallic Lithium. Unfortunately, some
of these batteries quickly earned a dubious
reputation for safety.
Metallic Lithium in
rechargeable batteries was replaced by Lithium kept
in its ionic state. In this way most of the
electrochemical benefits of Lithium-based cells can
be reaped without the safety issues associated with
the volatile pure metal.
In order to maintain safety,
the present Lithium-Ion technology must still be
treated responsibly and with respect. It appears
that many users of this “safe” technology are being
lulled into a false sense of security, for it is
perfectly possible to implement this technology
poorly, resulting in a potentially dangerous
To this effect, and with past
history behind it, the International Civil Aviation
Organisation (ICAO) has introduced stringent
regulations that preclude the transportation of
Lithium-Ion batteries without a Manufacturer’s Air
Transportation Certificate. The certificate attests
that the product being transported meets those
regulations (false declarations incur severe
Despite the aforementioned advances in
electrochemical structure, Lithium-Ion batteries
remain inherently intolerant of overcharge,
over-discharge and high current abuse, and all
reputable batteries contain electronic protection
circuits that are designed to protect both the
battery and the user if these conditions are brought
The target charging voltage of a Lithium-Ion cell is
4.2V +/- 0.05V per cell, and the protection circuits
should prevent charging above the specified safe
voltage. Consistent overcharging can cause the
plating of metallic Lithium within the cell.
Bringing metallic Lithium back into the equation
will cause instability, especially if the cell is of
lower manufactured quality, and especially if any
moisture has been introduced inadvertently during
the production stage.
Over discharging can cause copper plating that leads
to internal shorting within the cell. The protection
circuits should stop discharge well before the
battery gets below 2.5V per cell. A well-designed
battery would permanently disconnect if a voltage
below 1.5V is observed by the protection circuit.
If the battery is discharged at an excessive rate,
the excessive transition of Ions can bring about a
breakdown in the crystalline-layered structure of
the plates of a cobalt oxide Lithium-Ion cell. This
can lead to a sudden rise in temperature that could
possibly ignite the organic solvent of the
electrolyte (which will not self extinguish).
Quality, branded cells are a vital prerequisite to
the creation of a safe Lithium-Ion battery. Poor
quality cells may develop internal shorts, or their
electrolyte may be contaminated, giving rise to
further problems. We are disappointed to note that
such products are being imported to our market and
branded as professional products.
A quality product, such as the
PAG Lithium-Ion battery, is designed around safety
protection at every level. As the electronic
protection circuits are vital for the safe operation
of a battery, it is essential that they, in turn,
should be protected, as in fact they are in the PAG
battery. The electrolyte is a highly corrosive and
conductive organic solvent. If the electrolyte were
to be liberated for whatever reason - perhaps as the
result of impact or a manufacturing defect - it
could easily prevent a poorly designed or uncoated
protection circuit from operating properly, or
indeed from operating at all.
This in turn would leave a
faulty or damaged Lithium-Ion battery in an
unprotected and therefore extremely hazardous state.
It should also be noted that electrolyte seepage
between circuit areas that have an electrical
potential between them can then result in a
conductive path being built-up through the
electrolyte, this can then lead to ignition.
The PAG battery is fitted with
two protection circuits, each independent and each
capable of disconnecting the battery. Each circuit
protects the battery from over- or under-voltage,
over-current and excessive temperature. Other
manufacturers rely on a single protection circuit.
Using semiconductor devices
that are rated up to 100V, the PAG battery is fitted
with protection against charging from an unsuitable
and inappropriate charger. Other manufacturers rely
on their single protection circuit, usually with
devices rated to only 25V or 30V.
The PAG battery will reject
charge in temperature extremes. Other manufacturers
have no such protection at all.
The PAG battery has its
protection circuits coated with Parylene, the
premier conformal coating, as proof against
electrolyte leakage. Other manufacturers boards are
not protected in this way.
Considering all the above, the
PAG Lithium-Ion battery range is the safest and most
reliable on the market.
It is essential that a
Lithium-Ion battery is never opened or tampered
with, and to prevent this, all PAG batteries are
sealed and electronically tamper-protected.
If a Lithium-Ion battery cuts out, consider why this
may have happened. Check the state of charge and the
load applied. It is not good practice to draw high
current over extended periods routinely.
Consider using more than one
battery at a time to share the load. Most
manufacturers provide some method or product to
facilitate this. PAG produces the Power PlateTM
which enables two batteries to be connected in
parallel in order to extend run-time or share a
Operating a Lithium-Ion battery
within its correct rating will enable the battery to
achieve its expected cycle life and capacity.
If one manufacturer’s battery
will run a heavy load above its rating where another
will not, this does not mean it is a “better
product”. Under these circumstances a battery that
does not cut out may be poorly protected and this
can be dangerous.
Whatever the subtleties of
chemistry employed, all Lithium-Ion batteries remain
similar in that they can be potentially dangerous or
designed and manufactured to be safe. Our philosophy
is to produce quality products with safety foremost,
and in this respect we will not cut corners.
PAG batteries are protected
PAG batteries are protected
PAG batteries automatically
revert to sleep mode during extended storage periods
thereby protecting against deep discharge abuse.
Many batteries that we have tested do not do this.
PAG batteries are protected
against excessive discharge rates and automatically
PAG batteries are automatically
protected to inhibit operation when the active core
is beyond the safe upper and lower temperature
The PAG battery protection
circuits are themselves protected against
inadvertent cell electrolyte leakage by means of
Parylene conformal coating.
PAG batteries are protected
within a polycarbonate case that combines high
structural strength and chemical resistance.
PAG batteries are sealed and
tamper-protected against unauthorised interference
with their original quality build standard and
PAG products are supported by a
Worldwide Authorised Dealer Network.
PAG batteries are manufactured
within the coveted International Standards
ISO 9001: 2000 quality standard, a procedure that
assures strict quality control at every level.
PAG Ltd. is an ISO
9001:2000 Registered Firm.
Quality & Technical Director
PAG Ltd., London.
The Negatives of Lithium Ion Batteries
Lithium Ion for Broadcast
Sunday, September 04, 2011 11:45:20 AM