At Moltech, we believe that there are nine key component areas in
a smart battery system which must be designed to function in harmony
if the most effective battery system is to be developed.
| Cells |
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work with the worlds leading cell manufacturers to provide a
full range of cylindrical and prismatic cells; and because Moltech
also manufacture cells, we know how to test them and we know
what the results mean to performance and safety. Our application
engineer professionals use this data to see through the manufacturers
data sheets to the real core performance data which is important
to each unique application. This "cell agnostic" approach is
the only one that ensures only the most suitable cells finds
their way into our custom battery products |
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| Insulation |
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safety of all of our battery pack designs is of the most importance - ensuring the battery continues to function safely through
extremes of temperature and mechanical stress. Moltech ensure
that insulation between cells, PCB's and other components is
not compromised by correct use of PTFE, Teflon, Kapton and Nomex
materials. |
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| Interconnection
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| Minimising
resistance between cells and other internal battery components
is important when designing batteries to power applications
with high current pulse discharges. - energy disipated within
the battery is energy wasted so Moltech strive to reduce internal
losses through use of pure nickel interconnection straps, correctly
gauged wiring and through the use of the latest low resistance
active and passive protection devices. |
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| Passive
Protection |
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Passive
protection devices include thermal fuses, thermostats and polyswitches - the use of each device is carefully considered to ensure the
correct level of protection is designed into each battery pack.
The characteristics of each unique customer application are
first examined and a safe operation 'envelope' is then established
around this characteristic using the correct current and thermal
devices. Careful selection and empirical testing remove the
possibility of nuisance tripping whilst allowing the battery
to be effectively protected if the battery is placed in an unsafe
situation. |
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| Fuel
Gauging |
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Moltech
Power Systems have years of experience in the design and application
of various battery fuel gauging systems. Whether a fully SMBus
SBS compliant system is required, or a more simple 1 wire interface,
Moltech can cater for every requirement.
Centre to all of these systems lies a deep understanding of
electronics and of cell performance; it is only by understanding
both of these that the complex correction algorithms can be
created which make accurate fuel gauging a reality.
Moltech Power Systems in-house intelligent electronics group
Inspired Energy design the hardware and firmware for each application
before prototyping the circuits and then bringing the solution
into full production - ready for integration into the battery
pack. |
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| Active
Protection |
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The
use of onboard integrated circuits which continually monitor
cell voltage levels and current activity and are capable of
independently removing the battery cells from the external circuit
are regarded as 'active' protection; such circuits Battery Protection
Modules (BPM's) are mandatory on all lithium Ion multi cell
battery packs.
A typical BPM monitors over charge (over-voltage) and over discharge
(under voltage) by monitoring the voltages across individual
cells and can switch the cells out of circuit by means of dual
MOSFETs if a preset limit is reached. An overload (over current)
condition can be determined by the monitoring the voltage drop
across the MOSFET(s).
Careful selection of the correct protection IC and support components
ensures that the battery functions within it's operational envelope
without nuisance tripping, but will be rendered safe if it is
over discharged, over charged or connected to an illegal load
or incorrectly operaitng equipment.
Where a fuel gauge is also required, the protection IC can be
designed onto the same PCB - however the fuel gauge and BPM
critical functions are kept separate to ensure that possible
erroneous fuel gauge operation can never compromise the operation
of the BPM. |
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| Termination |
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need for reliable, low resistance connection between battery
and host or charger demands is essential for a smart battery
system where the user many choose to use multiple batteries
and swap them in and out. Moltech offer a wide range of standard
or custom interconnect solutions to suit any design. |
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| Marking |
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| Clear
indication to the battery user, coupled with a moral and legislative
requirement to indicate warnings and recycling information make
battery marking something of a minefield. Moltechs considerable
experience in this field mean that this is one less area our
customers have to deal with when introducing their products. |
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| Casing |
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It
is important that a battery casing is light enough to retain
the high energy density of the internal cell technology whilst
being strong enough to protect the battery 'core pack' from
mechanical and thermal stress. although promoted by other battery
pack assemblers, the use of heat shrinkable inexpensive PVC
is not recommended for batteries containing lithium Ion cells
as this fails to offer either mechanical strength or an effective
thermal barrier. The use of injection moulded plastic casing
using a material which meets flammability requirements of UL94V-0
is strongly recommended by Moltech for these high value designs.
Moltech Power Systems engineers make use of the latest 3D modelling
software to expedite mechanical design. The data from this system
can be shared with customers to ensure host device / charger
compatibility before being used to develop sample cases through
rapid prototype techniques. Once approved, the same data can
be used for the manufacture of the injection moulding tool which
again reduces time to manufacture and market. |
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