Why are there so many types of batteries, while there are so many devices able to be powered by USB?

Are there market forces pushing products toward USB that didn’t push towards a single type of battery?

It’s easier to fit in a USB connection than design a battery (probably not possible) that can power anything from a small flashlight/bicycle light to a laptop.

It’s mostly due to runtime and size.
There are lots of different batteries, because they come in many voltages, capacities, and shapes. A designer of a battery-power product will try to use an off-the-shelf battery, but may end up needing to have one custom-made. There are many devices which can be powered from USB, but once you are away from a computer, you need a battery - and that means deciding what battery to choose based on how much space you have in your device, and how long it needs to run.

Think of the size of battery you can fit in a watch. Now imagine a heavy-duty flashlight, like the ones that can double as a club, powered entirely by watch batteries.

USB is new. compact internal rechargeable are relatively new.

primary and large rechargeable batteries are old.

batteries of different types and sizes are based on needs for lights, audio, calculators, watchs and phones and …

This reminds me of something I saw last weekend: a rechargeable AA battery that plugs into a USB port for charging. Quite a nice little product.

I still don’t know boo about electricity, but this answer knocked it out of the park.

Does anyone want to discuss why there aren’t more? Take the flashlight, holding 2 D size batteries. Why isn’t there one 3 volt battery used instead? In fact the majority of the battery operated devices I use contain 2, 3, or 4 batteries. Instead why aren’t a sufficient variety of batteries manufactured so the vast majority of devices would just contain one battery?

I have owned devices using a single 3 volt battery which was quite expensive and hard to find a stockist, why invent a new battery when ones available off the shelf, it’s just cheaper to use three existing batteries.

BTW the voltage of a battery depends on the type of chemistry used, if you want three volts from a single cell it has to be lithium based with all the advantages and disadvantages inherent in using lithium based chemistry.

Mainly the battery technology is different, but they all need recharging that that has to come from somewhere. The old ones were cylinders, and it is far easier to do a standard size. The new ones are IIRC printed and stack like pages, so far easier and cheaper to make a custom shape. Demand is for a compact product, so a custom design and rectangular shap work best here also.

To give a idea of cost, I got a aftermarket battery for my iPhone for $8 and that included the tool set to change it (it would ahve been under $5 w/o it). So the cost of these custom shapes is comparable or less then the old designs.

There is also the factor that manufacturers of products like camcorders etc want you to have to buy replacement or extra batteries from them at a large markup. They will sometimes include hardware that will try to make it impossible to use a non proprietary battery.

Cheaper to manufacture (mass produce) a zillion 1.5 Volt batteries that can be economically designed to fit in devices any number of ways and provide voltages at the following levels:
1.5
3.0
4.5
6.0
7.5
9.0
10.5
12.0
13.5
15.0
16.5
18.0

So instead of the consumer having to buy many different voltages of battery they could buy fewer sizes that might be combined to handle different voltages. Solves the voltage issue but then different size batteries are still needed to cover the capacity issue. Hence AAA,AA,C,D batteries.

Consider that some devices have the batteries side-by-side, while others have them end-to-end. By making individual-cell 1.5 volt AA batteries, you can use the same batteries for both of those devices, as well as for anything that only takes a single one. Make a custom battery for each of them, though, and you’d need to get different batteries for all of them.

When I buy batteries, I don’t think “Well, my TV remote is probably the next thing that’s going to need new batteries, followed by my flashlight and my wireless mouse, so I’ll buy the remote battery now”. I think “Hm, I’m running low on AAs, so I’ll buy some of those so I’ll have them for the next AA battery device I need, whatever it is”.

The OP’s question might be better targeted as “why haven’t watch/camera/hearing aid batteries become standardized into 3 or 4 options like batteries for flashlights/toys/larger items have?”

Let’s return to the USB issue, because I think there’s a big misconception there.

My current laptop has:
3 USB
1 VGA
1 HDMI
1 Ethernet
2 Audio jacks
1 Power socket

So… only 33% of them are USB. (And of the ones I’m using right now: 2/5 are USB). My USB are only 2.0 for the record… so there are multiple types of USB even though they use the same shape plug and are mostly backward-compatible.

Looking at it historically, USB was around for 5 years before it became popular. It only achieved so much market penetration when Apple decided to go 100% USB for serial devices. Until then, PCs were still coming with the old-style, PS/2, COM and serial ports, often with a USB or two for completeness. Once Apple made the switch entirely, peripheral manufacturers had no choice but to follow suit for the Apple market, but they also had an advantage because for the first time Apple and PC devices could use the same port. So the manufacturers had an incentive to encourage PC users to go USB. And one step further: USB was invented by Intel. Intel was very happy to see USB take over, and they did what they could to further penetration.

So my conclusion is that

  1. a plethora of connectors still exist and are still used. The OP’s original conclusion is incorrect.
  2. to the extent that USB is a common standard, we can explain that by seeing how two powerful manufacturers used their influence. Battery and device markets have never been dominated by such a small number of players to the same extent.