hexapod powering

[benji]

hey folks, i did baught a battery for my bot ,,6 volts 9amps ..sounds a lot but here is what i got to power

12 servos (500ma * 12==6 amps)
1 stepper(500ma)
a sharp ir (nearly 500ma)
RF transmitter/reciever( ??)
and the atmega128

my question is about consideration for capasitors at the input,,for such big current drag whats the best cap tp use at the in?
all the stuff above are feeding from the battery directly exept the atmega128 which is having 5 v after a 7805

now i have a 0.33uF at the input and a 0.1uF at the 7805 out (micro in)

[BANE]

where did you get that battery

Bane

[Tsukubadaisei]

That is fine, just follow what the datasheet says.

[benji]

so no need other than this little 0.33 uf cap for all that stuff?   

[benji]

where did you get that battery

top secret 

to be honest with ya i didnt try it yet , its just written 9 amps and i doubt it can give 5 or 6 which i would be glad with

[Admin]

Guess the cap value, no other way. 100uF and a 1uF as a minimum.

The cap removes sudden drains/spikes in the voltage, but to know what that spike is, you'd have to test it after everything is already hooked up and running.

You can use an oscope to see how caps affect the spikes.

[benji]

should i expect too many spikes from batteries?

[Admin]

The batteries don't cause the spikes, the devices that use the battery power does. Motors are the worst offenders . . .

[izua]

servos won't suck 500mA all the time. depending on the stepper motor function, you can also power it down after it does its job, since the detent torque might be enough, or at least lower the current through it.

anyway, where did you get the battery? lead-acid?

[benji]

actually i didnt buy it yet but i saw it at a store,, it lookslike the AA batteries but way more thicker
and its written on it 9000 mA

[benji]

each cell provides 1.5 v so i have to ge 4 serially connected