My Creation! His name is DR-6

[bonmot]

Why do you say.. drop down to somewhere near 8.2v? To take in account the voltage of the battery under load? From my understanding Lipo's should easily hold above 3.2v/cell under load, especially in robotics applications which require much less continuous and surge current compared to typical RC applications.

I agree with Billyzelsnack. I use LIPO's for my helicopters. Current is 10A to 30A for my small size chopper. 3.2v/cell is already heavily heavily loaded.

If talking about 10A for the robot walking, we should be able to easily see >3.5v/cell before using up to 70% capacity of the batteries.

[mic2]

Why do you say.. drop down to somewhere near 8.2v? To take in account the voltage of the battery under load? From my understanding Lipo's should easily hold above 3.2v/cell under load, especially in robotics applications which require much less continuous and surge current compared to typical RC applications.

I agree with Billyzelsnack. I use LIPO's for my helicopters. Current is 10A to 30A for my small size chopper. 3.2v/cell is already heavily heavily loaded.

If talking about 10A for the robot walking, we should be able to easily see >3.5v/cell before using up to 70% capacity of the batteries.

Guys,
8.2v is the power cut-off voltage NOT the load voltage! 3cell li-po is 11.1v when fully charged you will get a bit more. When using li-po battery you’ll have to use a battery monitor board to prevent it over discharging, I would recommend not to setting the threshold too low and damage the battery.

For a safety zone each cell shouldn’t drop more than 1v to be trigger the power cut-off point e.g. 3 cell =3v 11.1-3= 8.1v however you can set the voltage higher to achieve a longer battery life.

Anyway I have corrected my bad English.

[bonmot]

Hi MIC2

You are right about the over discharging issue. Yes, all my airplanes, helis and cars has a low voltage monitor to monitor each cell, and stop it going below 3.2V. Basically it has 2 stage of warning: warning and cut off.
Of course I don't do cut off on my airplanes and helicopters for the obvious reasons

But to be clear to other people reading this thread, 3s LIPO WILL at least give you 10.8V power when running a robot when current is less than 10C.

[mic2]

But to be clear to other people reading this thread, 3s LIPO WILL at least give you 10.8V power when running a robot when current is less than 10C.

This looks OK to me.

By the way what kind of controller board you're planning to use for the HV300 servo?

[bonmot]

Hi Mic2

I am going to use whatever is avaible for me in my lab.
I do microcontrollers for living.

[Rick_swarty]

hi i'm back, after long time, last i can return to join robosavvy again. this is my simple work.
this is robot where i create. thr robot used intel atom, controlled uses modified atmega 8535. intel atom with OS windows XP for detection colour and instruction to controller with serial communication. thanks for the mic2 for any advice
http://imageshack.us/photo/my-images/196/photo382q.jpg

[billyzelsnack]

Very cool. Vids please!

[Rick_swarty]

Very cool. Vids p

Sorry i don't have vids. But anytime i will post vids. because i'm busy right now....