Whether or not the end user is satisfied with the design of their portable device largely depends on the performance of the battery.

  The key indicator of the battery is of course the life of the battery. On the surface, this is a simple specification, but it involves many factors, including: system load characteristics (time to operate at full load current, partial current, and microamps), power efficiency, system power management , battery type and charging method.

  In addition to the importance of the performance itself, the interaction of these characteristics can enhance or reduce the experience of the end user. In general, when users start noticing the presence of batteries, things get trickier! Good product design neither replaces the battery (such as a TV remote control) nor recharges the battery (such as an electric toothbrush) so frequently that the battery "disappears" from the user‘s eyes. Prevent users from focusing on the battery as much as the device‘s functionality.

  The mutual restriction between the battery and the system is a problem that is often overlooked in product design. It is very important to ensure that the capacity of the battery matches the needs of the system. The most common types of batteries used in portable electronic devices are alkaline, nickel-metal hydride (NiMH), and lithium-ion (Li+) batteries. They are not interchangeable, and most products have a best selection method.

  Alkaline batteries are non-rechargeable but offer certain advantages due to their extremely low self-discharge rate and cost (they do not require a charger or AC outlet). For lower power applications, alkaline batteries would be a good choice, but to be used sensibly, either quiescent or sleep current must be low.

  A common misunderstanding in design is: only focus on work efficiency, while ignoring the current consumption in the "off" or "sleep" state, even tens of microamps of current will consume battery power, so the product will not work even intermittently. lead to frequent replacement of batteries. Unfortunately, this design misunderstanding is more common than it was a few years ago, as many designs today replace mechanical switches with soft switches (which can completely disconnect the battery).

  Rechargeable batteries are a better choice when the load is too high for alkaline batteries or when batteries are to be replaced frequently, which has become standard for portable products such as notebook computers, PDAs, and cell phones. Rechargeable batteries should "disturb" the user as little as possible, and should be chosen that facilitate the use of the product (at least not affect the product‘s performance).

  NiMH batteries cost less than Li+ batteries and can be chosen if the normal use of the product is safe for the battery. This issue is even more important for low-cost products that lack sophisticated charging designs, since NiMH batteries are suitable for full charge and full discharge processes. This is more suitable for products that often use up power completely, such as power tools.

  Many portable products are different from the above, PDAs, cell phones are regularly charged, but they only consume power occasionally. It is best to use Li+ batteries for these products. In addition to a better power-to-weight ratio, Li+ batteries have two important advantages: low self-discharge rate and no limitation on short-term charge-discharge. Consumers do not need to consider the issue of "battery management", and seldom consider the battery in use, which simplifies the use of the product. Li+ batteries are especially useful when products have batteries that cannot be replaced by consumers.