Designing an IoT application involves a lot of choices. You’re looking for performance and quality, but balancing that alongside a low Total Cost of Ownership (TCO).

When it comes to your battery choice, it’s no difference. You will likely have made decisions about the type of cell you need and explored the datasheets – and more often than not the declared performance of the battery options you have are broadly similar. It’s natural then, to go for the cheapest option that’ll ‘get the job done’.

However, not all batteries are the same. Datasheet performance isn’t always an indicator of how batteries will perform in a year’s time, or in extreme conditions. If you have to replace batteries in all of your devices sooner than expected – any short-term cost savings are soon lost.

While price doesn’t always indicate quality, there are times when it can be a useful guide.

So, what’s behind the price of a battery? What are the elements that make a difference in a battery, and how do these elements impact the success of your project, the customer’s return on investment (ROI), and the satisfaction of the end user?

Batteries are made up of several components that react chemically to provide energy. Although the main chemistry used in a cell might bear the same name from one manufacturer to the next (Lithium-Thionyl chloride, for example), each manufacturer develops its own proprietary recipe.

Various ingredients will be added to the chemistry to offer a more stable voltage, deliver more energy density, limit voltage delays, etc., which explains why performances vary from one cell to another.

The construction of the cell may also differ from one manufacturer to the next: various materials can be used for the anode and cathode, the separators or the sealing. Their composition and physical properties also vary depending on the quality or the metal grade that is being used.

The sealing is a good example: the glass-to-metal seal that is often used is quite a complex component for which the manufacturing process is key to provide a qualitative sealing performance of the cell. A leaking cell could provoke irreversible damages to your IoT device. To protect it, it is therefore crucial to ensure that the mechanical components used in the battery are carefully selected and controlled.

Same for the casing: if you want your connected object to be resistant in harsh environments, you may want to make sure that the can of the cell is made of high-grade stainless steel.

Impurities or low-quality active materials and mechanical components can lead to lower performances or safety risks, impacting the reliability of the battery and the repeatability of performance. And when your solution is being deployed in the field, safety, performance and repeatability of the performances are equally important.

As a final point on quality - the manufacturing process should also be taken into account. Does the manufacturer control the products at all stages of the manufacturing process? Are the connections soldered manually or automatically? Automated lines combined with process control at all stages of manufacturing are a guarantee of the repeatability of the results and performance. It also ensures less scrap and easier integration of the batteries in your connected object.

Batteries are hazardous goods and as such, they are to be handled with care. The price of a battery can reflect the additional safety features included and the number of relevant certifications.

Battery manufacturers can include additional safety features on their cells to add to their security. Saft, for example, have Li-SOCl₂ spiral cells that feature a fuse that can be triggered in case of an external short circuit. These particular cells also feature safety vents that can release the pressure instead of exploding if the cell is subjected to an incident in the field.

Whatever the features chosen, batteries need to pass a number of safety tests and certifications, which are not easy to get. Batteries are tested and re-tested in order to get the right certifications. This is especially important if your device is deployed in explosive (ATEX) or other risky environments or if you need to ship your devices.

The manufacturer must provide technical reports committing them to the lifespan of their products. A few examples of such certifications are:

• the IEC 60086-4 that specifies tests and requirements for primary lithium batteries to ensure their safe operation under their intended use and anticipated misuse.
• the UL1642 that aims to reduce the risk of fire or explosion when lithium batteries are used in products.
• the UN38.3 transport regulation which also requires a number of tests to guarantee high safety standards of the cells so they conform to IATA regulations and can be shipped.

The list of the raw materials needs to be certified too and the EU in particular has a very strict policy on this matter. All applicable batteries in the EU market must pass RoHS compliance that specifies maximum levels of phthalates for some restricted substances. The REACH certification (Registration, Evaluation, Authorisation and Restriction of Chemicals) addresses the production and use of chemical substances, and their potential impacts on both human health and the environment.

And a battery’s end of life isn’t the end of the story. As an end-user of the battery and in some specific supply chain schemes you might be held responsible for the disposal and the recycling of the batteries, which is not cheap.

The EU battery directive (2006/66/EC) specifies an obligation from manufacturers, distributors or even users, to organize the collection and recovery of wasted industrial batteries to ensure proper recycling.

In these above instances, the price is not only a guarantee of safety, but a token of the manufacturer’s responsibility.

The final piece of the ‘price’ jigsaw is in the additional services.

Batteries can be complex to understand with various factors to consider. You might benefit from the help of a technical expert to help you choose the right solution for your device will ensure the success of your project. Ideally, this expert can provide you with a lifetime calculation of your battery whilst taking all the parameters into account.

Once you’ve selected a battery, there are other things you might need some help with. You might have to navigate the challenges of transporting lithium batteries, get additional certifications for your device, or, once your device is deployed in the field, you may come across new issues that you didn’t foresee. In these cases, having an expert to turn to, to evaluate the situation and determine a plan of action can be of great help.

This service is often included as an added benefit with higher price batteries. Having the right support at hand can save you time and money.

There’s a lot that goes into the price of a battery.

While the cheaper option might seem sensible to maintain a lower TCO – that’s not always the case because of the hidden costs. A poor quality battery that requires replacement will send costs soaring. Not having the right support or certification can expose you and your end user to additional costs that eat into the ROI.

That’s why Saft use first class components, ethically sourced, to ensure the stability and the reliability of our cells, which are controlled at all steps of the production.

Our selected suppliers are using only high-grade raw material of our cells, ensuring a high resistance in harsh environments. Our batteries are amongst the best performers on the market, and we are not afraid of committing over their lifespan.

The production lines we use allow us to integrate the elements in an automatic, repeatable way, without scrap on the customer or integrator side.

Our batteries have received all the necessary certifications, which makes them a favorite choice for many IoT developers conceiving products for the industry.

We support our customers to help them comply with the European Directive regulations and we take care of our batteries’ disposal and recycling.

And last, but not least, we offer an array of support and services throughout our products’ entire lifetime, including lifetime calculation based on proprietary mathematical models, and aftersales management.

*This is an updated version of an article first published in December 2020.