Finally, Batteries You Can Believe

By Brian Condell & Alessandro Vinco

Data Capture within large warehouses would not be possible without having fast, safe reliable battery management to allow all these handheld devices to operate. Following on from the previous blog, this blog considers the various aspects of battery use within Data Capture from battery management, charging to battery safety, and secure authentication to the importance of a reliable battery fuel gauge.

Battery Management – Charging Solutions

With the growth of battery-powered devices within the industry comes the need to charge batteries as fast and as safely as possible. USB-C is becoming the more commonplace charging method and as such USB Type-C chargers are required. Figure 1 below shows how a single-cell battery can be charged using the MAX77860 USB charger. This charger features a single input, which works for both USB and high-voltage adapters. It supports USB Type-C CC detection under BC 1.2 specification. This switched-mode battery charger with two integrated switches, provides small inductor and capacitor sizes, programmable battery charging current, and is ideally suited for portable devices such as smartphones, IoT devices, and other Li-ion battery-powered electronics.

Figure 1- 1-Cell Battery Management

For two or more battery cells, there is the MAX77958 USB-C PD controller and the MAX77961 charger. The USB-C PD controller can not only be used for 2+ cell architectures but also when required charging power needs to exceed 15 Watts (legacy 1-chip USB solution mentioned only support <15 Watts: if more power is required you will need to implement USB PD with the MAX77958).

Figure 2 - 2+ Call Battery Management

Battery Safety and Secure Authentication

As many of us have experienced there are lots of counterfeit products in the world today. While some of them may be safe to use, a counterfeit battery is not one of them! We have all heard stories of items going on fire due to the use of faulty or counterfeit batteries.

Many different battery manufacturers throughout the world claim to have the same quality and safety levels as the original OEM batteries, but that is not the case. Ideally, you want battery packs to be safe to use, high-performance, and accurate. Therefore, ensuring to only use genuine batteries is imperative for any business.

For high-volume applications, a system designer must mitigate the risk of unsafe aftermarket clone batteries. To prevent battery pack cloning, an IC like the MAX173xx integrates SHA-256 authentication with a 160-bit secret key. Each IC incorporates a unique 64-bit ID.

See Figure 3 below.

Figure 3 - Secure Authentication and Battery Safety with MAX173xx

A way to achieve this is by integrating SHA-256 authentication within the battery during manufacture. This involves coding a hashing key (private key) at the factory into the fuel gauge chip that goes into the battery pack. See Figure 4 below. When the battery is connected to the system, the host processor shares a random message to the battery gauge IC and reads the coded message back. If it corresponds to the hash computed internally that means the fuel gauge had a correct private key and is considered genuine. In turn, if the battery fails the authentication test it will not be allowed to connect to the inner circuitry of the system.

Figure 4 - Procedure to Verify a Battery

Authentic batteries are safer and provide the best power performance.

Integrated Fuel Gauge

Everyone is familiar with the battery ‘fuel gauge’ on their phone. And some people no doubt get frustrated when one minute the gauge shows 10% battery capacity remaining and then suddenly find the phone dies shortly after! While this may be inconvenient for a person, imagine the impact within a logistics and data capture environment when the battery in the hand-held scanner unexpectedly dies when an operator is busy scanning parcels. This can lead to multiple parcel deliveries being delayed if not scanned in time! For large-scale logistics more accurate battery fuel gauges are required, allowing better management of these handheld devices and no delays to you in the long run.

As an example: In a warehouse that operates 24h/day, having a 10% error from the battery gauge means each battery is marked as discharged after 7.2 hours of operation instead of its real 8-hour capacity. This equates to over 120 additional battery swaps every year for each scanner - or two hours of downtime per operator.

If the correct battery charge can be reported in all temperature and load conditions, then there will be no unexpected shutdown with loss of data. The MAX1730x is one such IC that automatically compensates for cell aging, temperature, and discharge rate, while also providing accurate state-of-charge (SOC) in milliampere-hours (mAh) or percentage (%) over a wide range of operating conditions. This in turn makes it industry-leading when it comes to battery accuracy.

Figure 5 - General architecture of a fuel gauge device

Find the fourth blog in this series here.

Interested in learning more, check out Analog Devices’ battery management solutions.

References

• Battery chargers
• MAX77958 Standalone USB Type-C and USB Power Delivery Controller
• MAX77961 USB-C Buck-Boost Charger with Integrated FETs for 2S/3S Li-Ion Batteries
• MAX77860 USB Type-C, 3A Switch-Mode Buck Charger for 1S batteries
• MAX17303 1-Cell Fuel Gauge with Protector and SHA-256 Authentication
• MAX17320 2S-4S Fuel Gauge with Protector, Battery diagnostic, and Authentication