In recent years, the use of lithium-ion batteries has been steadily growing. You find them in applications historically dominated by nickel metal hydride (NiMH) and nickel cadmium (NiCad) batteries. Is the lithium-ion battery so superior that it should replace NiMH batteries in all applications? When is NiMH a better solution? What attributes does it have that are better than lithium-ion? In this webinar, we answer those questions while reviewing the background and history of both battery chemistries and looking into the weight, risks, costs, and more in comparing lithium ion to nickel metal hydride. For more information on our custom battery pack solutions, visit https://www.epectec.com/batteries.

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Do You Really Need Lithium or Will
Nickel Metal Hydride Suffice?
05.29.2020

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Agenda
 Review of the two different chemistries
– Pros and Cons of Lithium based chemistries
– Pros and Cons of NiMH batteries
 Factors to consider when choosing to use NiMH batteries
– Weight, energy density, design simplicity, time to market, regulatory, cost
 Examples of ideal applications using NiMH
– Stationary applications, large batteries, large batteries requiring routine air
transportation, cost sensitive products
 NiMH Batteries can be as Smart as Li-Ion Batteries

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Review of the Two Different Chemistries

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Pros of Lithium Based Chemistries
 Light weight, more portable
 High Gravimetric energy density,
Wh/kg
 Higher cell voltage, 3.6V
– Less cells needed than NiMH
 Cycle life (Lithium Titanate)
 Some Li-Ion cells can better
withstand low temperatures and
warmer environments compared to
NiMH cells.
 Easy charge algorithm even when
powering load during charge
 Very low self discharge, ~1% month
– Ideal for low standby current
devices
 Large selection of Lithium
Chemistries to chose from
 Environmentally friendly
 Marketing views Li-Ion as “high-
tech” battery

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Cons of Lithium Based Chemistries
 Development and regulatory costs
 Cells lose permanent capacity when kept at an elevated charge state and
elevated temperatures
 Li-Ion batteries have active materials similar to lithium metal batteries. Ions
are a very active material. They can react easily and generate a lot of heat.
 Shipping restrictions
 Slower time to market
 Electronic safety circuits required
 More volatile chemistry if misused

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Pros of NiMH Batteries
 Lower Development and regulatory costs
 Can be left at 100% charge state with low cell degradation
 Faster time to market
 NiMH cells are safer. They have fewer active materials compared to Li-ion
 NiMH batteries can be completely discharged. They will still charge, just don't
let them go into reverse polarity or else they will be damaged.
 Customers can ship product back for servicing legally.
 Common sizes can be used in place of Alkaline cells
 Environmentally friendly
 Large batteries can ship by air

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Cons of NiMH Batteries
 High self discharge ~1% / day
 Heavier battery
– Less portable
 Low cell voltage, 1.2V
– More cells needed
 Complicated charging algorithm
– Difficult to power device while charging
 NiMH has a slight disadvantage at
extreme temperatures. Its voltage output
will drop
 NiMH generates more heat during
charge
 A very low the trickle charge is critical
 Marketing views NiMH batteries as old
“low-tech”

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Factors To Consider When Choosing To Use
NiMH Batteries

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Choosing To Use NiMH Batteries
 Factors to consider
– Weight / Energy Density
– Design Simplicity
– Time to Market
– Regulatory time and cost

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Weight / Energy Density
 NiMH weighs much more
than Li-Ion due to its Nickel
content.

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Design Simplicity
 Design Simplicity
– Minimal safeties required.
– Protection for charging and discharging outside
of allowable parameters.
• Current / Temperature

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Time to Market
 Time to Market
– Fast engineering development.
– Minimal to no regulatory testing required.

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Regulatory
 Unlike Li-Ion regulatory requirements
are much less stringent
 UN3496
 Special provision A199
– Protection of exposed terminals
– The words “Not Restricted” and A199
must be included

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Examples of Ideal Applications Using NiMH

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Examples of Ideal Applications Using NiMH
 NiMH batteries larger than 100Wh can be easily shipped by air
– Stationary large equipment batteries that needs to be shipped across the
world or country routinely.
• Large remote movie film sets camera lighting batteries.
• Large scientific suitcase size batteries requiring very long run times.
• Remote emergency UPS batteries for power backup.
 NiMH batteries can be used for ballast
– Top heavy medical cart batteries.
– Surface laptop keyboard or similar application.
– Any product where weight is needed to stabilize the product.

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NiMH Batteries Can Be As Smart As
Li-ion Batteries

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NiMH Smart Batteries
 A Smart Battery Pack is a battery capable of providing information
about its operating parameters to the outside world.
– These parameters can include:
• Charge level
• Battery voltage
• Charge and discharge currents
• Battery temperature
• State of health
• Remaining run time
• Remaining charge time
• And many more

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NiMH Smart Batteries
 The most common method of conveying the information to the host
system is through:
– I2C
– SMBus
– Single wire communication

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NiMH Smart Batteries
 A smart battery can also be a battery with additional circuitry added
that it controls:
– Built-in charger with various topologies
– Customer electronics
– Built-in fan
– Integrated Heater

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Summary

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Summary
 Pros and cons of the chemistries
– Each chemistry is different enough, making it easier to chose
 Factors to consider when choosing to use NiMH batteries
– Weight, energy density, design simplicity, time to market, regulatory, cost
 Stationary applications, large batteries, Large batteries requiring air
transportation, cost-sensitive products
 NiMH batteries can be as smart as Li-Ion batteries

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Our Products
Battery Packs Flex & Rigid-Flex PCBs Cable Assemblies Printed Circuit Boards
RF Products User Interfaces Flexible Heaters EC Fans & Motors

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Q&A
 Questions?
– Enter any questions you may have
in the control panel
– If we don’t have time to get to it, we
will reply via email

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Thank You
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