Investigating Black & Decker Dustbuster (vacuum cleaners) Battery Degradation

[Kiriakos GR]

The long story in sort, this is that Black & Decker Dustbuster (vacuum cleaners) they do cause battery degradation mostly due their selected operating voltage.

The Black & Decker Dustbuster design this changed over time several times, the changes influenced aesthetics, improvements’ at the suction storage tank and use of different technology of battery cells.
First Dustbuster came with NI-CD then this was replaced by Ni-mh and now latest Dustbuster using Lithium.

The unchanged part at the Dustbuster this is it DC electric motor which is there to deliver performance no matter what.

While I am still having one first revision Dustbuster of 1999 this has two cells 1.5V x2 and relative charger (transformer), I did found this week as dead gift one more modern Dustbuster which I did repair and I am now testing it.

The modern Dustbuster this is 7.2V version with six NI-CD cells.
By removing the battery pack I did direct test of the DC motor and at 7.0V this was requiring 10.5 Ampere, my professional DC power supply came at it limits.

When I downgraded the voltage at 5.8V this is equal to four NI-CD cells, the current were lower down to 5.5A and this value it is something that most NI-CD or NI-mh cells they can tolerate with out damage.
But wait this 5.8Volts brings us down to the specification of 4.8V Dustbuster.

The first conclusion here this is that Dustbuster classified as 7.2V this is a battery distraction device, when a Dustbuster classified as 4.8V this is more electrically friendly to it batteries.
And the oldest Dustbuster classified as 2.4V this is batteries best friend and poor performer too.

Black & Decker China, somewhere in the way they lost the balance regarding electrical engineering correctness, and they did small and huge mistakes which a customer wallet will have to pay.

Black & Decker China, at some models of Dustbuster classified as 9.6V was forced to add high-low switch step instead of simple on and off switch,  they where forced to do that because  eight NI-CD cells they will deliver approximately 11.2 volts and current consumption will eject as high as more than 14 Ampere when cells are fully charged.

Now the charger (basically a regular transformer) this is not the source of battery degradation.
The charging circuit can be blamed only due it fundamental electrical design simplicity, one transformer capable to deliver 150 or 200 mA this works as constant current source.
When the cells can not store more incoming energy, then additional energy this simply converted to heat and all battery cells get warm just a few Celsius above the room temperature.   

As practical example I will mention statistics from a 4.8V classified Dustbuster.
The compatible transformer should have the specification 6~7 Volts at 200mA.
The AC voltage of this transformer with out load this is at 10.4Volts.
Now under load the same transformer at 200mA consumption will deliver no more than 8.3V AC and actual DC voltage at the batteries will be no higher than six volts.


My investigation ended by me taking in consideration all facts above, and the solution is to downgrade my Dustbuster V7210 from 7.2V version to 4.8V version and be very happy with this improved model, which is also capable to trap the dirt inside due a rubber guard at the end of it sucking tube.
4.8V version this now seems as electrically a wiser choice too, makes the motor spinning faster and the electrical energy this now used in a productive way.

Dustbuster V7210 at 7.2V default version, it seemed to me as be a car this burning it tires so to impress it viewers at the cost of it own owner.

[Kiriakos GR]

And now the goods news !! 

I was using Black & Decker classic for several years, but while this is still working I decided to retire it in favor of few decades Newer V7210

The newer design of dust collector canister, this is better one which actually it does trap everything inside it due a special rubber valve.
And even the dust filter design this has significantly improved.
 
The life of one Dustbuster in a workshop this is easy,  it will not be used to capture regular dust but particles, plastic - metal - wood so to name a few.
Another application for it, this could be the collection of electronic spare parts or screws which fallen at the workshop floor, due the usual accident of small plastic rack type storage box this fall down from our workbench.

I seem to be not a talented advertiser of Dustbuster products, and I will stop here my speech.