Final Thoughts.
Servos and DC motors have been used a lot in this tutorial, as most robots will have servos, motors, or both installed. There may be times that using many servos or very heavy duty ones directly off the EZ-B may not be feasible due to power requirements.
So putting a lot of what has been talked about in this tutorial together, such as "current", "voltage", "power supplies", and "series/parallel", we can find a more efficient of powering them. A good way to power these servos and DC motors, is to power them directly from the "power source". That could be the same source that's powering the EZ-B (parallel) providing the motors and devices connected to the EZ-B use the same "voltage". This way, depending on the power supply specifications, they will get all the "current" they need to operate at optimum efficiency. You could also use a separate power source and power the motors or servos from that.
So, we started with amps then voltage, then everything else that which these power variables are used with...
EZ-B pins that deliver the power,
Batteries and mains supplies that deliver the power,
Series/Parallel which is how this power is distributed,
Multi-meters to measure the power,
Regulation to reduce or increase the power,
and the Wire that transports the power.
Lots of subjects that all interconnect. Hopefully from reading through this tutorial, you will see that there is a lot information to take in for getting the right power requirements for your robotic projects. But if you take each of the above steps one at a time, you will soon be able to understand what is needed, and hopefully avoid any mishaps.
Isn't electricity a weird and wonderful thing!
Happy building.
Tutorial created on 11th October 2015.
Thanks for this info. Still not sure why everything says it will handle 20plus servos because power wise, they cant. also a 20amp fuse will probably to blow before ez-b blows. this would be great in the specs!!
Thanks again
Scott
I'm not an expert, but there is common sense too.
Not all servos are equal: there are small torque and high torque servos, there are cheap servos (bad electronics, counterfeiter etc) and good servos (good engineering) and smart servos (with micro-controller e.g. Dynamixel with temperature, load, torque control).
Servos/motors have different current rates e.g. idle, torque stall, peak, inrush.
Some setups don't accommodate the Inrush/Peak current. Inrush Current is commonly used to describe the current that is required to energize an AC powered device when first applying voltage and power to it. If you have all your servos moving at same time you have a Inrush current during a brief period.
Some batteries have high discharges rates for example a lipo battery with 1000 mAh and a C=20 can handle 20 amps, but a niMH (AA) can't handle 20 Amps so the battery plays an important role.
And last not all fuses are equal there are quick-acting and time-lag (slow) a slow fuse can handle as much as 10 times the current for a brief period before blowing up...
Without knowing all details we can't make assumptions.
I recommend using EZ-Robot HDD digital servos for prototyping you product development, because they're the highest efficiency that you'll find. PTP is correct, in that your post may be assuming a specific servo experience, which is impossible to generalize. The EZ-B can provide power to entire InMoov large servo configurations. Even the EZ-Robot JD humanoid uses an EZ-B v4 and has 14 hdd servos and powers off a single 7.4v battery. This conversation of power requires explicit details of the hardware selected for your product development - as it cannot be generalized.
If you have questions regarding the EZ-B v4 manufactured by EZ-Robot, then you can visit their website at www.ez-robot.com to contact them directly. Otherwise, the opensource hardware and software for the EZ-B v4 design is available in the Synthian GitHub link at the footer of this website. Lastly, there's a number of supported hardware platforms for ARC in the Getting Started link on this website. Many options to ensure you experience positive results with your product development.