Asked — Edited

Voltage Supply And Regulator Questions For Ez-B V4 Controller, Servos And Sabert

If the Voltage input (Vin) can be between 4.5 and 16 VDC (according to the published specs) to power the EZ-B v4 controller what is the optimal recommended voltage?

EZ-Bv4 datasheet v0.5

If I want to power the EZ-B controller using a 12 volt automotive battery, does that same voltage go out to the servos or is it internally reduced via a built-in voltage regulator? If I still want to power the EZ-B controller with a 12 volt battery, is it necessary to install a separate voltage regulator for the Vin, servos or other devices?

What is the ideal voltage for the servos?

If I use the Sabertooth motor controller, are there any other voltages to be concerned about for the input to the Sabertooth?

What are the pros and cons of operating the EZ-B at higher voltages?

What happens if the low battery warning is turned off and the voltage goes below 4.5 volts (other than probably hurting the battery)? In essence, if the Vin goes below the minimum, will it harm the EZ-B controller, servos, camera or distance sensor, or will it simply stop functioning until a proper Vin voltage is present?


Upgrade to ARC Pro

Your robot can be more than a simple automated machine with the power of ARC Pro!


Hi @Jimwest,

As I was mentioning in another thread, we recommend 2S (7.4V) LiPo batteries (ours are rated for 1300mAh). These batteries give our servos a great amount of power without going over their limits. Our 3 Robots all have this type of battery built-in.

The EZ-Bv4 on-board 3.3V voltage regulator is only used for the Analog sensors, I2C peripherals, Camera and the EZ-B main board, it is not used for the servos. The voltage you input into Vin is what arrives at the servos as well. Try not to feed your servos 12V.

Operating the EZ-B at higher voltages doesn't have any huge advantages unless you have servos that can handle the higher voltages, one downside is that you would have to use in-line voltage regulators on the EZ-B servos that are in our development kit.

Operating the EZ-B at lower voltages (let's say 5V) can allow you to use almost any servo on the market without any kind of voltage regulation.

As for the Sabertooth, have a look around these forums and the Sabertooth Datasheet of the exact controller you are after and you should get a good idea about their limits. I believe a common input to a Sabertooth is 12VDC.

Running the EZ-Bv4 lower than 4.5V won't cause any damage you will just see the 3.3V voltage regulator start to drop it's regulated voltage and we can't really guarantee what kind of results you will start to see after that. As you are probably already aware, if you have a 7.4V LiPo battery and you drop under 6.6VDC you will risk damaging the battery. LiPo batteries do not like to go under 3.3VDC per cell, hence why the low battery warning exists ;)


Further to what Jeremie said... The sabertooth 2 x 5 recommended input voltage is 6v to 18V and the 2 x 12 recommended input voltage is 6v to 24v... Sometimes I use a 12v battery with my projects.... If they require servos, I made myself some 6V inline regulators using LM7806 Voltage regulators and just spliced them into some servo extension cables.... I also made some 5V inline regulators too for powering sensors like the ping.... DJ has pointed out that a better 5V reg is the LM1084 non variable 5v voltage regulator....


I'm using the same regulated 12vdc power supply to feed both my V4 EZB and my Sabertooth 2x12 (but on separate feed lines). However I have an adjustable voltage regulator before the EZB V4 that drops the input (Vin) from 12vdc to about 7vdc. This gives full regulated 12vdc power to the Sabertooth and any adjustable Vin power I want to the EZB. I've chosen 7vdc because that's the voltage the servos and sensors I have plugged into the EZB's I/O pins of the digital ports are mostly compatible with. Works great and I don't have to listen to that annoying "My batteries are low" warning.

As an added note if you're not already aware; the Sabertooth has it's own outstanding 5vdc onboard regulator. The 5v port on the control side is an "output" port. You can power other components in your robot needing 5vdc from here if needed.

User-inserted image



Will the ez-robot servos work reliably at 5 volts? Are there any drawbacks with not operating them at 6.5-7.2 volts DC? Thanks Much ! Rick Bonari


Less voltage is less strength