Running DC motor from battery pack

[ady_mech]

Hello all

As a part of a larger application/product, I have a few brushless DC fans that I need to run from four 1.5V duracell C-batteries (connected in series, so total of 6V). All the fans are 12VDC rated. They differ in their flow output and the current they draw (ranging from 0.2A to 0.6A).

However, some of those fans (larger ones) don't run when I connect them to the battery pack. I believe the reason for this is that a DC motor draws a much larger current during startup and the battery pack is not capable of providing that large startup current.

Now I have the option of having a PCB (that does other things in the product) that I can use to operate the fan. But I don't know what I should advise the PCB designer to incorporate. What would I need to do in the PCB so that I can run these fans from this 4-pack? I just need to be able to startup the fan (by providing whatever voltage/current it requires) from these batteries. Once the fan is running normally, I would supply the power to these fans from a different source (thermoeletric chip).

Your suggestions would be appreciated.

Thanks

[ante]

The problem isn