Running Mini-Itx from battery

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Hi,


I am currently building a robot which has onboard Mini-Itx motherboard. Apart from this it has two 12v motors which draw about 500 ma each. I am powering this bot using a 12v 7.5 AH battery.Everything seems to be running fine except that sometimes when the load increases the motor draw excess current which ultimately results in voltage drop.Because of this my motherboard shuts down as it requires correct 12 volts to function. What could be the solution. I don't want to use two batteries.

 

[(*steve*)]

you need to isolate the 2 power supplies, the one to the motor, and the one to the mini-itx board.

You only have a single battery, so what you'll need to do is connect the mini-itx board to the battery via a diode and place a large capacitor from the diode to earth. Short high current bursts to the motors which causes the battery voltage to sag will be "filled in" by the capacitor so the ITX board will not see such a dramatic voltage drop.

The size of the capacitor depends on how long the battery voltage is depressed and the current draw of the mini-itx board.

 

[Resqueline]

Use a schottky diode for minimum voltage drop.
Alternatively, if that doesn't work good enough, you'll have to insert a buck/boost switchmode inverter between the battery and the MB.

 

[davenn]

Would a mini DC-DC ATX PSU be ok for you ?

I use them for powering all sorts of thigs other than computers. They have awesome curent capabilities considering their small size.
I dont know where you are from but I know several different brands are available in the UK, Australia or the USA

This one I got here in Australia is powering a piece of amateur radio gear of mine in the field from the car battery.....
http://www.sydneystormcity.com/IMGP6596.jpg

quick specs are.... outputs are +12V @ 12A, -12V @ 100mA, +5V @ 6A and +3.3V @ 6A.

cheers
Dave