The USB rechargeable batteries we sell are considered replaceable batteries in the sense that you can take them out of your device and replace them with new units. Replaceable batteries come in a variety of form factors including AAA, AA, and 9V. But as you know, some devices are powered by built-in batteries. These are hard wired batteries that cannot be replaced by the typical consumer.
Both types of batteries have their advantages and disadvantages. Needless to say, manufacturers and designers take stock of all their options before deciding which way to go. While there can be a case made for both types, manufacturers need to choose a path for every product they design.
Product Design Flexibility
A big concern for many manufacturers is design flexibility. The modern cell phone is a perfect illustration. Just think of your own phone and how thin the case is. It wouldn't be so thin if it were powered by a 9V or a set of AAAs. That is a problem for phone designers who want their units to be slim and compact.
Design flexibility is important in the electronic age. By choosing built-in batteries over replacement cells, manufacturers have the freedom to design their batteries in a variety of shapes and sizes. For products where design is more important than other considerations, built-in batteries offer undeniable design options.
The other side of the design flexibility coin is consumer choice. A good example here is a hand-held controller for a gaming console. Product design allows for both built-in and replaceable batteries. That's because game controllers don't have to be so small and thin.
In recent years, the trend has been toward built-in batteries that are recharged with a USB cable. But it is still possible to find third-party controllers powered by replaceable batteries. This gives consumers a choice in the types of batteries they use. To some manufacturers, leaving that choice available to their customers is important.
Another point in favor of built-in batteries is the ability to better deal with space constraints. Some of today's electronic devices have a ton of technology packed into them. Engineers want to keep the devices small in order to keep their weight down. That being the case, they need lithium-ion batteries capable of fitting into restricted spaces. Custom-designed built-in cells are often the best option.
One can make the case that replaceable batteries are superior because they allow multi-device interchangeability. In other words, you can take the AAA batteries out of your TV remote control and throw them in your headlamp for a morning hike.
Interchangeability makes life a little more convenient when you forget to recharge your lithium-ion batteries ahead of time. If you are using a device with a built-in battery, forgetting to charge it essentially means you're out of luck. But if you are using devices with replaceable batteries, you can swap or move them around as needed.
When it comes to manufacturing built-in and replaceable batteries, one always has to look at production costs. Common sense seems to dictate that mass-producing replaceable batteries is more cost-effective simply due to the economics of scale. However, the details come into play and it may not be so simple when one looks at the all-in costs of developing, manufacturing, shipping, warehousing, and servicing a product.
Manufacturers choose their batteries based on what is best for the design of a particular product, their market, and the expectations of their customers. We do hope that more product designers will lean toward the option of replaceable batteries when possible as this can make products easier to service and also recycle. This decision can ultimately be better for customers, manufacturers, and the planet alike.