DC powered devices

[solidstate]

Just curious if anybody knows what I am doing wrong. I am experimenting with running devices like a modem, dvd player, etc off of a 12 volt battery. I have tried a modem, external hard drive, and a dvd player, that all use a 120 ac to 12 volt dc power supply. It will blow a pico fuse in the circuit board, or burn the solder traces up on the board. I am making sure that it is polarity correct, the battery that I hook up is 12 volts, however it is 12.6 volts. I am thinking of trying a battery that is partially discharged, maybe just under 12 volts.

Any other suggestion?

 

[kellys_eye]

Assuming the polarity IS correct there is no reason why the devices shouldn't work correctly. If they are blowing fuses then you ARE doing something wrong. They should easily tolerate 12V +/- 10% (so 10.8V to 13.2V)

 

[dave9]

Try some inrush current limiting, low ohm resistor of suitable wattage or thermistor in series. I would not use a (presumably lead acid) battery in a discharged state due to wear/cycle-life, would sooner drop 0.7V with a silicon diode in series before doing that.