• Question: How can you make battery powered electronics last longer?

    Asked by Holly on 2 Jun 2020.
    • Photo: Henry Lancashire

      Henry Lancashire answered on 2 Jun 2020:


      To make battery powered electronics last longer you can: make the battery bigger; increase the energy density in the battery; or reduce the amount of power the electronics use.

      Modern rechargeable batteries have an energy density of over 100 Wh/kg (Watt hours per kilogram). So 1 kg of battery could power an old style light bulb (60 W incandescent) for about 1 1/2 hours, and a larger battery could power this for longer.

      We can use more efficient electronics. Modern LED light bulbs are much more efficient, and use about 5× to 10× less power than old style light bulbs for the same light output. Therefore 1 kg of battery could power a modern LED light bulb for about 10 hours.

      Storing more energy in a smaller space allows us to make smaller batteries which can power electronics for the same length of time as larger batteries. Lithium Ion batteries, like the battery in most mobile phones have a much higher energy density than the Lead Acid batteries used to power the starter motor in most petrol cars. Storing lots of energy in a small volume is risky, materials such as those used in Lithium Ion batteries can catch fire if they are damaged or not used correctly.

      Modern ways of making batteries keep the risks very low, and scientist and engineers are researching ways to make batteries smaller, safer, and to use fewer environmentally damaging materials.

    • Photo: Tom Rooney

      Tom Rooney answered on 2 Jun 2020: last edited 2 Jun 2020 11:13 am


      This is a very good question and one that engineers are looking at all the time!

      Essentially there are three ways to look at the problem – Improved Electronics, Improved Batteries and Alternative/Supplementary Power Sources:

      1) Make the electronics more efficient – This can be broken down into further approaches:
      a) The electronic components themselves – select or design components that run on lower voltages and draw fewer microamps.
      b) Work rate – Whatever your system or device is doing, design into its processes and coding a more efficient work rate. To do this identify the tasks that require the most power and reduce the time it needs to do this or the frequency of this action.

      In the field of underwater transponders Sonardyne have spent a great deal of effort on working on this as our hardware is at the bottom of the ocean running on its internal batteries for its lifetime, In order to maximise the time the unit is operational for (between 1 and 6 years!) we have designed the electronics to work very efficiently. The most power demanding elements for our transponders is communicating with other transponders and taking environmental measurements (as the sensors need to be powered up); therefore we have programmed in a greater element of autonomy and AI into the processor functions to keep both of these actions to a minimum.

      2) Make the batteries more efficient. There is a huge worldwide effort in this regard:
      a) Rechargeable batteries – Lithium alloy batteries are improving all the time to reduce size, increase power density, maximise duration and minimize charging time. However this is a complicated issue with many problems:
      i) Lithium is a highly volatile element and these batteries have a significant risk of fire in the event of battery failure. As Lithium reacts with water, even the moisture in the air can fuel the fire and attempts to extinguish using water can make the situation far worse.
      ii) Lithium and the other rare metals used in the battery design are sourced through open cast mining and large scale industrial manufacturing processes that produce large quantities of carbon and other toxic waste products – Electric powered cars for this reason are not as eco-friendly as you may think.
      iii) Rechargeable batteries have a limited life – you only have so many charges and re-charges before the power density begins to fade. Smart chargers and battery telemetry data help monitor and manage this die-off but before long your electronic system will begin to last less time on each charge.
      iv) Toxic waste – when it does die you have to dispose of it somehow and it contains some pretty toxic compounds and chemicals that need to be processed correctly to recycle them or render them harmless to the environment.

      b) Replaceable batteries – Chemical batteries have been around for a long time and these too are being improved. Again, they have issues though:
      i) They have a finite life. When you use up the power in a chemical battery you have to replace it (like the Alkaline Batteries in a toy) when its gone its gone.
      ii) Toxic waste! A traditional power cell you’d use in a toy also contains some pretty toxic compounds and chemicals that need to be processed correctly to recycle them or render them harmless to the environment.
      iii) Greater power density! However they do have one advantage over rechargeable batteries. For their size they have a greater power density than Lithium based rechargeable cells, and that power is sustained for longer during its life. A rechargeable battery’s voltage drops off gradually in the last 20% of its charge which can affect the electronics’ performance; a replaceable battery’s voltage dies off in the last 5% of its life (which is longer anyway) so you get a more reliable performance for longer.
      v) New chemical batteries coming on to the market. People are looking at molten salt batteries and other forms of sustainable replaceable battery designs. There is a UK company (metaletrique) that have designed an exciting battery that uses an inert (non-toxic) electrolyte liquid, aluminium anodes and air – the battery is a quarter of the size of a comparable Lithium unit and produces four times the power density. Once the anodes are depleted they can be replaced four times using the same electrolyte, and after that the liquid can be recycled to have the aluminium extracted, purified and turned back into anodes. They recently drove an electric powered delivery van 1500Km on a single battery charge! So perhaps a smaller version of this type of battery might be the answer to your question.

      3) Supplement the batteries with another source of power – depending on the environment or application your electronics are operating you could consider having a supplementary power source built in to your device. Things to consider are:
      a) Photovoltaic Cell (Solar panel) – If your device has access to sunlight this is an easy addition to make that will keep your device running for much longer. If designed correctly you could run on solar alone and only need the battery as a “keep alive” supply.
      b) Wind Turbine – If your device is going to be used outside or in a place where there may be sufficient airflow (like inside a ventilation system or on a vehicle) you could consider a turbine. There are some small efficient on the market or you could design your own!
      c) Water turbine – as above but for water or other fluid flow.
      d) Motion generator – If your device is in a dynamic setting then fitting a small generator that creates power when it’s moved is worth looking at. High quality wrist watches have been using these devices for decades and, depending on the scale of your device, there are many types that could be used to supplement your battery power and make the system more efficient. One form of motion generator is a dynamo, a small generator that converts rotational energy into electricity.
      e) Electromagnetic induction – if your device is to be used in a setting that has an electromagnetic field (such as near power cables) you may be able to tap off some of this energy right out of the air and use it to power your device!
      f) Permanent Magnet motors – Look on YouTube for many demonstrations of these at work. A motor driven by permanent magnets and a small exciter voltage can drive a much bigger generator to give impressive outputs. Maybe a smaller scale version (maybe using nano technology) is the future of sustainable power for electronic devices!

      I hope this has been a useful answer – Like I said it is a huge subject so a very good question to ask.

      In essence the solution to most problems in this area will lie in a combination of ALL of the answers above.

      Tom

    • Photo: Isabel Vidal

      Isabel Vidal answered on 2 Jun 2020:


      Well, regarding the design or the manufacturing I have no idea as it is not my field of expertise

      But for example, with a mobile phone or a tablet, you could make your battery last longer if you reduce the brightness of the screen and turn off Bluetooth and location.

      Usually there are ways to save energy when using the devices, or even to recharge. Electric cars batteries can be recharged using the energy generated when the car brakes.

    • Photo: Owen Jeffreys

      Owen Jeffreys answered on 3 Jun 2020:


      This depends whether you are the consumer or the designer of the electronic product.

      If you are the consumer:
      1. For example you have bought a battery-powered mobile phone. You have fewer options to save the battery power because the electronic and software engineers have designed the product to work the way it does. However, there are sometimes little things you can do to conserve the battery power. For example the WiFi module uses a lot of power – if you turn off WiFi that would save some battery power. The same goes for the Bluetooth and camera and screen.

      2. Toy UAV/drones are becoming popular. Again, this is a consumer product (i.e. you’ve bought it fully designed and built), so you are limited in options to conserve battery power. However, the heavier the drone, the faster the motors have to spin; the more work involved, the more battery power is consumed. So if you could make it lighter (e.g. by removing the camera) it would fly for longer. However, if you are interested in making it fly for longer without removing anything, then another approach is to increase the battery capacity. This is not conserving battery power, just giving it more power in the first place. Battery capacity is measured in mAh (milli-amp hours). If the battery is 2000mAh (2000mA = 2 amps) that means that the battery will last for an hour if the product is using 2 amps (electronic engineers call this “drawing 2 amps”). So you can see, the bigger that capacity value, the longer the battery will last. NOTE: if you have a drone, Holly, I’m not suggesting you try either of these ideas 🙂 it might permanently damage it.

      Now if you are the designer of the product, then you have lots of freedom to make an energy-efficient product which uses as little battery power as possible. This is a very important part in the design of a product and many, many hours are spent trying to produce efficient designs.
      1. From an electronics side, this can using low power electronic components in the product (e.g LEDs instead of normal bulbs), using more efficient circuits (e.g. low voltage integrated circuits), only enabling features which are required (e.g. turning off transmitters when not being used), switching to a low power mode if little resource is being used, making use of a standby feature if the product is not used continuously, adding solar panels if the product is outdoors (although this doesn’t conserve power as such, it just recharges the battery)
      2. From a software side, writing more efficient software so the program runs quicker saves battery power, even AI can be used to detect the most efficient times to enable product features and turn off standby etc, the list goes on and on…

      Thank you for your excellent question! It is such an important question in today’s modern world where natural resources are being used up and we always need to find new ways to conserve power and produce cleaner power. I hope this was a helpful answer.

    • Photo: Tom Stewart-Brackenridge

      Tom Stewart-Brackenridge answered on 14 Jun 2020:


      Modern battery-powered products use Lithium-Ion batteries. These types of batteries do not like to be drained completely and then fully charged again. They typically like to be drain half way or 50% and charged back up to about 80%. I am unsure why, but the life of the battery can be extended because of this charging pattern.

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