3.6V Portable Vacuum Boost Up Easy

Today is the day 76 of quarantine in Argentina, I am so bored, so decide to bring alive my portable vacuum bought 20 years ago for my 1st car, it worked so poorly I forget it after a month...

Open it was easy, only 4 screws, a plastic case holds the 3 batt bodies.

I think I found why the original NiCd batts are so bad, the dummy charging circuit is a joke!

poor made 4.5V DC directly into batt pack! the only component (diode) to prevent batts reverse to the charger.

The batt pack is poor too, just 3 x 1.2v NiCds, no labels at all.

I tested the electric motor with my newly upgraded power bank (see here: https://www.instructables.com/id/ATX-POWER-BANK-Up... The motor needs about 8.1A at 3.6V, so I have to put 3 x 18650(model) Litio batts.

Each 18650 Batt holds about 2300mAh, I suppose it works in 2T, which means I can have max 4A in each one.

An easy job, grab a 3x batt case for 18650, and cut a "slot" for it.....

IMPORTANT:

!! DO NOT try to use the original charger, also Not a good idea to charge these batts in the case!

There are 18650 individual charges which have very advance charging protections. here's is a link for amazon:

https://www.amazon.com/s?k=18650+charger&ref=nb_sb...

The batt case I have in hand is for serial connection, needs to be modified to parallel, indeed simple for instructable guys.

The diode was taken off as I do not expect to charge it insde.

I made for extra security a metal band to hold the batt pack in place.

Now the "new" vacuum work at 3.7V / 6900mAh , so in theory, it can work 48 minutes none stop . would it be true?

Still unknown as the batts are not bran new.... however I found the significant increase of POWER!

Enjoy.