There are two seperate power inputs on the Sumo11, one is specifically
for powering the logic and processor and is regulated through a 7805
voltage regulator. This power input is labeled 'MAIN pwr' and requires
at least 6.2 volts to function properly. I suspect that your 7.2v
battery is not fully charged. The other power input is specifically
for powering motors and servos, it's raw (unregulated) power directly
from the battery and is labeled 'MTR Servo pwr'. Both power inputs
share a common ground, but are designed so that there is no SAG or
interferance between the two. You have to be careful when choosing a
voltage for this input because it's NOT regulated. Most hobby servos
can only tolerate a 7.2v max. If you're not planning to use servos and
just want to give your motors full power, you can go as high as 14v
without any problems, just remember that the H-bridge is only designed
to tolerate 500mA per channel.

All this information is in the manual that comes on the disk, but
it's always better to be safe than sorry.

-Dan Gates


--- In Sumo11users@yahoogroups.com, "bxa1322003" <bxa1322003@...> wrote:
>
> Is there a ground-loop problem if I power the sumo with one source and
> the servos with another, especially if the sources are different?

>
> Also, what are the power requirements for the sumo? I have a 7.2V
> 2000mah battery. But when I power the thing up, I get the low tone
> buzzer sound from the sumo. I can't download any files. It just sets
> there. But when I power the thing up with a bigger source, the LCD is
> brite and begins accepting programs and functions properly.
>
> Has anyone experience this, espcially the 'low' buzzer sound?
>