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.
