Hello,
At this time, I make a humanoid robot. This one: https://www.robotshop.com/letsmakerobots/node/27414 and now it's time to use battery power.
I have a battery 7.4v Li-ion 3200mah (2 x 3.7v), the type is PL-5545135! My question is: When the battery is full supply, the voltage is 8.2v. May the servos have trouble or destroy?
The servo will probably be
The servo will probably be able to operate, but at those voltages will operate faster and thus will wear out much faster. Also, I am unsure as to if the circuitry will be able to handle such voltages. A 5V regulator will be the best route to go.
Re: 5v regulator
What is the highest current 5v regulator one can find? If he runs more than a few servos on even a 2A version he may run into current issues. Would a pair of properly sized diodes in series not be a better call in the case of servo power?
Yes, diodes would work great
Yes, diodes would work great too, but won’t give you a linear power output when the battery drops. There’s the LM2679T-5 which is a 5A 5V regulator, but would require a bit of work to get it working. Diodes would be quick and easy.
I have been working on those
I have been working on those multiservo robots and the best works for me is using 15A 6V switch regulate UBEC. In my experience I run up to 24 servos with no problem. If you don’t use regulator you might burn your servo easily with fully charged 2S Li-XX batteries. I learned that by hard lesson and burn 3 expensive servos in a day.
Good luck to your red dragon. 
Winner!
Winner!
I would measure current draw
I would measure current draw for each servo, then determine the greatest load in each system. Worse case, is that you’ll need two of those UBEC’s hardmouse posted.
f
yes i need ubec 6v 8A, thank you
I have been working on those
My robot,has got 20 metal standard servos,2 plastic and 4 micro metal.They have many Amp…The ubec http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=6233 is perfect for my robot