Is 21.6V Cordless Vacuum Cleaner Stronger Than 12V Cordless?

Probably! Answer is not that simple…

Nominal voltage of lead acid battery cell (today rarely used in cordless vacuums, but these are still present in cars, UPS devices, boats etc) is 2V, NiCd and NiMh cell voltage is 1.2V and lithium battery cells have around 3.6V – keep this ‘around’ in mind for lithium batteries, since they come in various versions and chemistry that vary slightly and their cell voltage can vary a little bit.

For example:
– 6V SLA (Sealed Lead Acid) battery has 3 cells,
– 12V SLA battery has 6 cells,
– 12V NiCd or NiMh battery has 10 cells,
– 14.4V NiCd or NiMh battery has 12 cells,
– 7.2V lithium battery has 2 cells,
– 14.4V lithium battery has 4 cells,
– 18V lithium battery has ONLY 5 cells.

We say ‘only’, since power of cordless vacuum cleaners is (actually, it is the same for both cordless and corded vacuums):

Power (W) = current (A) x voltage (V)

So, for the same power, if voltage is increased, current can be decreased. Weaker current means lower power loses in cables, but also less stress to the Dyson 912433-04 battery.

Newer batteries do cost more, especially lithium batteries, but they come with increased both voltage and capacity and with reduced weight. So, newer models come with motors optimized for higher voltages, draining the same or even stronger currents. Therefore, if newer cordless vacuum cleaner has increased voltage from 12V to 18V and capacity from 3.5Ah to 7Ah, with the doubled current than before, then:

– power is increased 3 times, for example from 100W to 300W,

– operating time is increased since newer Dyson 917083-01 battery with 7Ah capacity can be drained little bit longer with 2x stronger current than older 3.5Ah battery due to lower capacity loses when battery is drained with stronger current, for example, if older vacuum operated 15 minutes at full power, then new model will probably operate at least 20 or even 25 minutes.

Physics, Chemistry, Math … Who doesn’t love them?!

Anyway, as this examples clearly demonstrates, newer battery types is the way to go when performance is required – meaning lithium Dyson 17083-2811 batteries.

For cheaper cordless vacuums, NiMh batteries are still great power source that will still be around for years.

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