Why are power tool batteries a bundle of multiple cylindrical cells rather than a brick like phone or laptop batteries? Are there advantages other than cost?
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Laptop batteries are also multiple cells, simply encased.
Lithium Ion batteries have a cell voltage of around 3.7 V, that is driven by the chemical potential of the materials used.
It’s not possible to change that, **any** Li-Ion battery cell ALWAYS has 3.7V. Any device that wants more than 3.7 V to run, like Laptops or power tools, need to use multiple cells.
Power tools often used a pack of 18650 cells because these are a commonly available standardised size, so they’re comperatively easy and cheap to get as off the shelf components and integrate, and size isn’t a big constraint for power tools (unlike laptops, who don’t really want cylindrical cells cause they take up to much space)
Laptop batteries are also multiple cells, simply encased.
Lithium Ion batteries have a cell voltage of around 3.7 V, that is driven by the chemical potential of the materials used.
It’s not possible to change that, **any** Li-Ion battery cell ALWAYS has 3.7V. Any device that wants more than 3.7 V to run, like Laptops or power tools, need to use multiple cells.
Power tools often used a pack of 18650 cells because these are a commonly available standardised size, so they’re comperatively easy and cheap to get as off the shelf components and integrate, and size isn’t a big constraint for power tools (unlike laptops, who don’t really want cylindrical cells cause they take up to much space)
Laptop batteries are also multiple cells, simply encased.
Lithium Ion batteries have a cell voltage of around 3.7 V, that is driven by the chemical potential of the materials used.
It’s not possible to change that, **any** Li-Ion battery cell ALWAYS has 3.7V. Any device that wants more than 3.7 V to run, like Laptops or power tools, need to use multiple cells.
Power tools often used a pack of 18650 cells because these are a commonly available standardised size, so they’re comperatively easy and cheap to get as off the shelf components and integrate, and size isn’t a big constraint for power tools (unlike laptops, who don’t really want cylindrical cells cause they take up to much space)
My calculated speculation is that it has to do with the manufacturing volume of the tool in question and safety (to some extent). The cylindrical cells (Li-Ion cells) come in standard sizes whereas the pack kind (Li-polymer) is somewhat a custom fit taylored to the application.
If the number of units that you produce and the overall product size doesn’t justify the customization costs, it’d make sense to go with a standard cell.
The only other reason I can think of is that the Li-Ion cans being metal offer some more resistance to impact punctures. A squishy Li-Po cell is protected only by the outer case. These kind of batteries explode or at least go up in flames when punctured.
My calculated speculation is that it has to do with the manufacturing volume of the tool in question and safety (to some extent). The cylindrical cells (Li-Ion cells) come in standard sizes whereas the pack kind (Li-polymer) is somewhat a custom fit taylored to the application.
If the number of units that you produce and the overall product size doesn’t justify the customization costs, it’d make sense to go with a standard cell.
The only other reason I can think of is that the Li-Ion cans being metal offer some more resistance to impact punctures. A squishy Li-Po cell is protected only by the outer case. These kind of batteries explode or at least go up in flames when punctured.
My calculated speculation is that it has to do with the manufacturing volume of the tool in question and safety (to some extent). The cylindrical cells (Li-Ion cells) come in standard sizes whereas the pack kind (Li-polymer) is somewhat a custom fit taylored to the application.
If the number of units that you produce and the overall product size doesn’t justify the customization costs, it’d make sense to go with a standard cell.
The only other reason I can think of is that the Li-Ion cans being metal offer some more resistance to impact punctures. A squishy Li-Po cell is protected only by the outer case. These kind of batteries explode or at least go up in flames when punctured.
Those square batteries aren’t allowed to have vents and are less durable and more prone to swelling or exploding than the cylindrical ones. The high power ones for drones and the like are usually charged in a fireproof bag with a bucket of sand nearby.
Also multiple batteries in series gives you higher voltage, which allows for more power, which is more important than battery capacity on a lot of power tools.
Those square batteries aren’t allowed to have vents and are less durable and more prone to swelling or exploding than the cylindrical ones. The high power ones for drones and the like are usually charged in a fireproof bag with a bucket of sand nearby.
Also multiple batteries in series gives you higher voltage, which allows for more power, which is more important than battery capacity on a lot of power tools.
Those square batteries aren’t allowed to have vents and are less durable and more prone to swelling or exploding than the cylindrical ones. The high power ones for drones and the like are usually charged in a fireproof bag with a bucket of sand nearby.
Also multiple batteries in series gives you higher voltage, which allows for more power, which is more important than battery capacity on a lot of power tools.
Convenience. A phone needs a special flat battery to fit in its confined body. Whereas, with a laptop or power tool, bulk is not as much of an issue.
A lot of power tools *and laptops* use cylindrical cells like the 18650 in their battery packs, just arranged in different ways: In power tools, it’s most convenient to stack them in a box that snaps into the tool handle, whereas in laptops they’re best lined up end-to-end along the back of the laptop where they won’t get in the way of the laptop’s other components or in the way of the user’s typing.
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