Retrofit module
The alternative was to design a retrofit module that can work with the existing meters and yet communicate with the outside world via a newer protocol. TWTG was tasked with the design and technical requirements for a small communications interface module that could retrofitted on to existing meters. “The first issue was the availability of power for the retrofit solution,” said Wesley Kerstens at TWTG. “It had to work with the latest communication protocols such as 4G/5G and LPWANs, which was straightforward enough, but it also required the means to store energy as most smart meters in the Netherlands are housed within the fuse box with no external power options. In addition to which, users would not be happy about their smart meters using their paid-for electricity.”
However, the TWTG design team knew that these meters have what is called a P1 access port, which can be used for various purposes from firmware upgrades to device monitoring. But it offers only a very small output – approximately 100Ma – which is enough to power an LED, but nowhere near enough to send a message via 4G, for example.
Wesley Kerstens continued: “It was clear to us that a small, yet powerful, energy storage device would be required to acquire energy from the port, store it and deliver enough power to the module to send data.”
This is when TWTG approached Avnet Abacus to help support the design and sourcing of the right components including the energy storage device. According to Patrick Kooijman at Avnet Abacus “Our challenge was to integrate a small battery into a self-contained module that could connect to the P1 port, together with logic board and antenna. One possibility we looked at was a supercapacitor, but its lower energy density would have meant it would have been too large.”
What was also important was that the battery could last for 10 to 15 years, meeting all the challenges of being charged and discharged without failure over for an extended period; and exceeding national government regulations, so the module could potentially be deployed across Europe.
Nichicon technology
And this was the eureka moment for the Avnet Abacus team. “One of our key suppliers was developing exactly the sort of technology required for this sort of demanding application,” said Patrick Kooijman. “Nichicon had developed a battery for use in a stylus pen for a mobile phone for the consumer market in Asia. The pen connected to the phone via Bluetooth and the battery could be charged quickly via wireless charging within a few minutes, plus it was built to last thousands of charge/discharge cycles. And if this battery could achieve enough charge from the 100Ma P1 output, then it could be enough to power a single data message per day.”
A speciality of the manufacturer’s battery technology was it provides high charge and discharge power. A medium-sized Nichicon battery – specifically the SLB08115L140 – appeared ideal for the purpose: offering an energy density of 58Wh/L, capacity of 14mAh, maximum discharge of 280mA and more than 10,000 cycles.
“We had one further key issue to address,” continued Patrick Kooijman. “We needed to source a suitable antenna for the new communications protocols, which we solved by bringing in a Kyocera-AVX device with an additional design modification to marginally increase the module housing for more space around the antenna.”
In addition to the battery, antenna and an advanced multi-mode LPWAN module supporting LTE Cat-M1, the Avnet prototype also integrated a SIM card and connectors from Molex.
“We were really impressed with the support from the Avnet Abacus team and their innovative solution,” commented Wesley Kerstens at TWTG. “Their help and the selection of the Nichicon battery technology in particular helped us meet all the necessary requirements in a simple and elegant package.”
Future possibilities
According to Marc Eichhorn at Avnet Abacus: “There is huge potential to deploy this type of solution using Nichicon’s advanced battery technology in a whole host of remote devices in IoT applications, or as a potential replacement for non-rechargeable batteries in next-generation product designs using energy harvesting from small solar cells, for example.”
“It can mean that the battery is no longer the life-limiting factor of products,” continued Marc Eichhorn, “This innovative technology can make products more sustainable and help save significant cost with field service engineers no longer having to replace disposable batteries.”
Find out more about how Nichicon’s SLB range of high-performance Li-Ion small rechargeable cells can provide that power, or if you want to discuss your requirements with one of our FAEs, get in touch in your local language
