Three times you need the right 9V battery
20 October 2017
We know batteries are important, but we continue to buy cheap, subpar batteries that run out too quickly and simply cannot handle the heat. This piece explores the demands that three essential applications place on the humble 9V battery.
This piece originally appeared in the September 2017 issue of Electronic Product Design & Test; to view the digital edition, click here – and to register to receive your own printed copy, click here.
The 9V battery was originally invented for transistor radios in the 1950s, and at the time, it was expected to deliver 22.5V. As the power demands of transistor radios came down, so did the power output of the battery – until its size and power was eventually standardised into the 1604 international ANSI standards.
Nowadays, 9V batteries are used in everything from speakers and smoke alarms to walkie-talkies and industrial meters. But most 9V batteries simply aren’t built to handle the wide and diverse applications they are now used in. Let’s take a look at three areas, and in particular, what engineers should consider before choosing the right 9V battery:
Even though electronic devices have become much smaller in the last few years, they’ve also been packed with a growing list of features. Handheld radios, test and instrumentation devices, portable speakers and wearable devices, for example, often feature backlit LCD displays, radio antennas for cellular GSM, CDMA or Wi-Fi communication, and powerful speaker drivers, as well as a host of sensors.
When selecting a battery for handheld devices, one must consider three things: size, weight and energy density. Size and weight go without saying; after all, you don’t want to design a product that is larger than necessary, just to accommodate the battery. What most people forget, however, is that as you make the battery smaller you’re also reducing the runtime. To compensate, choose a battery with a higher energy density, so that it will offer the same runtime as a larger battery.
According to the US National Fire Protection Association (NFPA), dead batteries caused 24 per cent of all smoke alarm failures in 2015. Since the sole purpose of a smoke alarm is to alert the user to a fire, it is absolutely critical that battery performance is reliable.
Similarly, safety devices, such as security sensors, emergency beacons, telematics and metering equipment, usually lie dormant for long periods of time – often in extreme environments and only calling on their batteries infrequently.
For safety and security applications, consider a battery with a long storage life and wide temperature range. For example, Ultralife’s U9VLJP lithium-manganese dioxide 9V battery has been shown to offer a shelf life in excess of ten years, with little loss in performance. The battery can also be used in temperatures from –40 to +60°C.
Probably the biggest challenge for the 9V battery is in medical applications. Devices in medical and healthcare environments usually see more frequent use, and the equipment is usually more sensitive to electromagnetic interference (EMI). Devices typically range from medical instruments and patient monitors, to data recorders and surgical lighting.
When choosing a 9V battery for medical use, consider a high pulse capability and a non-magnetic design. A high pulse rate will deliver consistent power to even the most demanding devices – something that Ultralife has achieved in its 9V battery, by designing it with low internal impedance so that it can supply a high power output with a stable voltage. The U9VLJP also has a low magnetic signature because it is constructed with a stainless steel outer container.
Taking these small steps in choosing a 9V battery will result in significantly higher long term performance suited precisely to each sector’s needs – so we can stop replacing our batteries out of habit, and do so when we actually need to.
Contact Details and Archive...