Reviving a 10-year old cordless vacuum. Li-ion battery upgrade. It's alive!

Parts

• 10 x high-drain 18650 Li-ion cells
• 5s Li-ion protection board
• Soft start circuit
• MOSFET (STP80NF55)
• 2 x 100k ohm resistor
• 4.7uF capacitor
• 2 ohm 5W resistor
• 1N5820

I have used a Shark cordless vacuum for 10+ years. After the first few years of intense use. it didn't hold charge any more, so I replaced the battery pack once. The original battery pack is 18v, 12 Ni-MH cells in serial. It costed around $60 or $70.

After another few years of use, I found it needs another battery replacement. But, I didn't feel to spend more money on the old machine, and just put it into the storage for a few years. Actually, while clearing up my storage room recently, I thought I would throw away the vacuum, but I changed my mind and decided to give it another life.

As I said, because I didn't want to spend too much money for the vacuum, I decided not to buy an original replacement battery pack. Instead, I decided to upgrade it to a Li-ion battery pack. However, for a high wattage device like the vacuum cleaner, I needed high-drain Li-ion cells, which usually cost over $5 per cell. Fortunately, I could find cheap Chinese high-drain Li-ion cells for $20 for 10 pack on ebay.

Build a pack: 

Soft start circuit

Pack everything in the shell 

Replaced charger with a 5s Li-ion charger - BTW, the original integrated charging circuit was bypassed, so the charging indicator LED on the handle does not work any more.

Precision Temperature Controller

1. Front panel

- Input: RTD or K-type thermocouple

 2. Rear panel

- Output SSR max. 40A

3. Current temperature

4. Maintanance of contant-temp

Test equipment - impacting device

It's already 10 years ago. I built a test equipment at my friend's request. He was a material engineering PhD candidate and needed an equipment that could apply repeated and consistent impact on a sample surface. He also asked that the intensity and rate of the impact should be adjustable.

So I devised this device:

1. The electromagnet (EM) header first picks up a steel bearing at a time, and drops it onto the surface of the test sample. The impact intensity can be adjusted by changing the height of the EM header and the period is programmable at the host PC.
2. The steel bearings are reclaimed after the impact and raised to the upper repository to get ready for the next drop.
3. Experimental data is collected by the sensor module and analyzed at the host PC.

The EM header is an air core electromagnet, which has minimum effect of residual magnetism and housed within a PTFE case.

Copper plating on a stainless steel pot

(Re-posted: originally posted in Sep., 2012)

Wanna get a nice copper-clad stainless steel cookware? Just buy one from a reliable brand, though it may cost over $200. Never try this at home - failed.

Titanium barcode dog tag

(Re-posted: originally posted in Nov., 2012)

Laser engraved on a titanium dog tag. Works greatly at shops (Ralphs and CVS)