Following on from my previous post where I looked inside a cheapo battery charger from eBay – I have since gutted the charger. All that I kept was the case and the battery contacts.
Gutting the unit eliminates a potential fire hazard. I replaced the circuitry with a dedicated lithium ion battery charger IC instead.
I’m using a MAX1555 and it is a single chip solution which requires a minimal number of external components. It is a single cell charger and has a maximum charge current of 280mA.
The chip has dual inputs, allowing you charge a battery from either a USB port or a DC plug pack. When charging from a USB port, the charge current is limited to 100mA. Whereas, the DC plug pack input allows for a charging current of 280mA. Also, this version of chip has a charge status indicator which can be used to drive an LED.
I’m not going to use the 240VAC socket anymore, and I’ve replaced it with a micro USB socket. This change lets me use a USB wall socket adapter which can deliver 1500mA at 5VDC. However, my new circuit will only require 280mA. (I’m already thinking about a 2nd iteration of this project which will use an IC with a higher charger current to charge faster.)
Its amazing how cheap some stuff is on eBay these days.
For example, I picked up 3x lithium ion batteries and a charger to suit my Olympus TG-4 camera for $25 Aussie dollars, including free delivery.
I have an upcoming camping trip and I wanted to get some spare batteries for the camera.
I didn’t want to buy just 1 battery in case it was dead on arrival so I got 3. The battery charger was a bonus. Olympus don’t supply a proper battery charger when you buy a TG-4, you have to charge the battery in the camera with a USB charger and charge times are pretty slow. Olympus sells an AC powered charger but its about $70 and doesn’t include extra batteries. I was hoping that the new charger would be faster or reasonably good, but I didn’t have high hopes on the quality of the battery charger.
Two screws at the back of the charger were removed, but the plastic halves are ultrasonic welded together. Splitting the ultrasonic weld was very easy though. A bare minimum of plastic has been used and it isn’t very rugged.