The catch
Shark Clean & Empty Cordless
The stated runtime tops out at 40 minutes.
Side by side
Shark BU3521 vs PowerDetect Speed IA3246IV: For low furniture, IA3246 adds a folding wand
Quick verdict
If you want a simpler automatic-emptying setup, choose BU3521. Homes with awkward low furniture get more from IA3246IV, which adds a folding wand and a larger base.
Before you buy
Why, and what it costs you
Speed's base holds about half again as much debris
At 2 L, the IA3246IV base is about 54% larger than BU3521 at 1.3 L.
Where this comes from
(2 / 1.3 - 1) × 100 = 53.8%. How often you empty it depends on debris volume and household use.
The catch
Shark PowerDetect Speed Clean & Empty Luxe
Pickup on high-pile and in crevices was weak, per RTINGS.
Shark Clean & Empty Cordless
- Why pick it
- Have automatic emptying without added reach features
- Work with a compact bagless base
- The catch
- The stated runtime tops out at 40 minutes.
Shark PowerDetect Speed Clean & Empty Luxe
- Why pick it
- Clean under low furniture
- Hold more debris between base emptyings
- The catch
- Pickup on high-pile and in crevices was weak, per RTINGS.
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What this page compares
BU3521 is the pick for a simpler automatic-emptying setup. IA3246IV adds a folding wand and a larger base for homes where low furniture is awkward.
Pay for the extra reach only if you will use it
Which one fits
Pick the situations that sound like you
Have automatic emptying without added reach features
The base on either machine already takes care of daily bin disposal. The Speed upgrade is more convincing when the wand hinge lets you clean places the straight wand makes awkward.
- Shark Clean & Empty Cordless
- Better fit
- Shark PowerDetect Speed Clean & Empty Luxe
- Depends
Go beneath low furniture with a folding wand
BU3521 uses a straight wand, but IA3246 has MultiFLEX. When low furniture makes repeated bending awkward, the hinge is the relevant upgrade.
- Shark Clean & Empty Cordless
- Not suitable
- Shark PowerDetect Speed Clean & Empty Luxe
- Better fit
Work with a compact bagless base
Both models empty automatically, and only the compared IA3246IV adds MultiFLEX. Low furniture is a clearer reason to buy Speed than auto-emptying alone.
- Shark Clean & Empty Cordless
- Better fit
- Shark PowerDetect Speed Clean & Empty Luxe
- Depends
Hold more debris between base emptyings
From 40 to 60 minutes is how far the listed maxima rise. Speed explicitly uses a non-powered attachment for its claim, so powered-head use has to be checked separately.
- Shark Clean & Empty Cordless
- Depends
- Shark PowerDetect Speed Clean & Empty Luxe
- Better fit
In practice
Differences you will notice
Speed's base holds about half again as much debris
At 2 L, the IA3246IV base is about 54% larger than BU3521 at 1.3 L.
How we worked this out
(2 / 1.3 - 1) × 100 = 53.8%. How often you empty it depends on debris volume and household use.
The dock has nothing to do with the reach upgrade
Both models empty automatically, and only the compared IA3246IV adds MultiFLEX. Low furniture is a clearer reason to buy Speed than auto-emptying alone.
How we worked this out
A charging and emptying base comes with BU3521. IA3246IV also documents a folding MultiFLEX wand.
A higher runtime ceiling does not prove a longer carpet session
From 40 to 60 minutes is how far the listed maxima rise. Speed explicitly uses a non-powered attachment for its claim, so powered-head use has to be checked separately.
How we worked this out
60 - 40 = 20 minutes separate the published ceilings. Because the operating conditions differ, no floor-runtime percentage claim can be made.
Option A
Shark, BU3521
Clean & Empty Cordless
Straightforward and lower in cost, this Shark detects the floor and sits on a compact bagless auto-empty base.
- Best for
- Quick daily cleaning, if a convenient dock counts for more to you than maximum power or runtime
Facts we checked
- Shark specifies a runtime of up to 40 minutes.
- The 1.3-liter bagless base handles charging and emptying the onboard bin.
- It has HEPA filtration and automatic floor detection.
Option B
Shark, IA3246IV
PowerDetect Speed Clean & Empty Luxe
A Shark dock system at seven pounds, with bidirectional cleaning, automatic sensing and a flexible wand.
- Best for
- Quick pet-hair and stair cleaning, backed by a compact auto-empty dock
Facts we checked
- Shark lists the stick at seven pounds, with up to 60 minutes in Eco mode when a non-motorized tool is used.
- The two-liter bagless dock charges the vacuum and empties it, and it is rated to hold up to 45 days of debris.
- In the package are the MultiFLEX wand, crevice tool and Pet Multi Tool.
- Shark's listing gives an 8.3-inch cleaning path, a 0.5-quart onboard bin and a 14.2-pound complete system.
Spec by spec
Where they really differ
| Spec | Shark Clean & Empty Cordless | Shark PowerDetect Speed Clean & Empty Luxe | In practice |
|---|---|---|---|
| Base capacity | 1.3 L | 2 L | Neither base uses bags. |
| Low reach | Straight wand | MultiFLEX folding wand | On furniture, the Speed hinge is the difference that helps. |
| Maximum runtime | Up to 40 minutes | Up to 60 minutes, non-powered Eco | Maxima are not powered-floor endurance. |
| Floor response | Automatic floor detection | PowerDetect Speed sensing | A sensor brand name alone does not establish pickup. |
| Filtration | HEPA system | Sealed HEPA system | Care is still needed for filters and seals. |
Trade-offs
What each pick costs you
With Shark Clean & Empty Cordless
- The base holds less debris than IP3251 does, and you still dispose of the dust by hand.
With Shark PowerDetect Speed Clean & Empty Luxe
- Despite the HEPA label, it did poorly in testing at containing fine particles.
Decision guide
How to decide
Pick BU3521 for a simpler automatic-emptying setup. IA3246IV brings a folding wand and a larger base, which helps in homes with awkward low furniture.
Pay for the extra reach only if you will use it
The base on either machine already takes care of daily bin disposal. The Speed upgrade is more convincing when the wand hinge lets you clean places the straight wand makes awkward.
Base capacity counts most with bulky debris
With pet fur, a larger container can be useful. Neither base becomes maintenance-free because of it, and it does not guarantee a fixed number of days between emptyings.
Check the tools before you call either package complete
Included crevice and pet attachments can differ between Shark retailers and suffixes. Rely on the exact BU3521 or IA3246IV listing and not on an accessory photo for the whole family.
What this page can’t tell you
- We have not run a matched pickup or endurance test. What you see here rests on manufacturer ratings and published dimensions.
- Different parts of a vacuum system are described by bag capacity, cup volume and carrying weight.
By the numbers
What the data shows
What we found across the cordless vacuums we compare, plus the checked facts behind each finding.
How many fit
This guide keeps all 66 models in play. The pick rests on the facts and trade-offs on this page.
66 models fit, out of 66 checkedThe gap in numbers
Shark PowerDetect Speed Clean & Empty Luxe lists 60 min for listed maximum runtime, 50% more than the 40 min on Shark Clean & Empty Cordless.
- Shark Clean & Empty Cordless
- 40 min
- Shark PowerDetect Speed Clean & Empty Luxe
- 60 min
- Models with this figure
- 41 of 66
Show the facts and the math
How we countedNo needs are preselected here. Open the matcher and add the ones that apply to your home, room or setup.
How we calculatedThe top runtime figure usually comes from a low-power mode or an unpowered tool. Use it to gauge scale. Other attachments and modes give different runtimes. For context, 41 of 66 models publish comparable figures.
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| Shark Clean & Empty Cordless | None of these needs is a documented match |
| |
| Shark PowerDetect Speed Clean & Empty Luxe | None of these needs is a documented match |
|
Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
Shark Clean & Empty Cordless
Have automatic emptying without added reach features
See price & reviews on AmazonShark PowerDetect Speed Clean & Empty Luxe
Clean under low furniture
See price & reviews on AmazonEach link opens in a new tab.
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