Dumb Charger Design

[Supernam]

Many rechargeable electronics such as shavers, cordless phones, vacuums, etc. use dumb chargers. They are simple wall worts producing a particular voltage and current.

I was curious as to how they choose the voltage and current for a particular battery pack. For example, the MagCharger uses a 14V 220mA wall wart to charge a 6V 2500mAh battery pack. What if I had a 7.2v battery pack, how many volts would I need from a wall wart?

 

[65535]

Most Dumb chargers, use a simple wallwart, and just trickle charge as the voltage reaches the pack voltage, less current is drawn. I imagine though that with the MagCharger there is a voltage cutoff circuit, and with electronic devices the charger is built in to the device.

 

[Mr Happy]

I don't think 14V 220mA tells the whole story. There is most likely more to it than that, a maximum current regulating circuit at the least.