Asked — Edited

Powering Your Servos With Ez-B4

Unfortunately I was runing in to a problem. I have a humanoid robot with 18 servos (probably she will get 2 more). So I was happy to receive my new EZ-B4. First I found a 10A fuse in the "power adaptor" I did not want the whole plastic staff on to my robot. (Less weight and I did not have space for it as well.) So I got the board naked. eyeroll I did not want to use the power plug aswell. So I got rid of it. I was soldering cable straight to the board. I used a bench powersupply for the tests. I have noticed a diode in the power input (D1). The diode marked for A7 p39. Is it 1n4007?
Because that is an 1A diode? confused

Any way My servos 6-7.4V

2S lipo straight off the charger 8.4V (nominal 7.4) mad So I should use UBEC. (Castle Creations BEC-PRO 20Amp) But I do not want to use it. (More weight, and the effiency of the BEC in not 100% so I do not want to waste the battery power for heating the air) But instead of that I will use 2s LiFePo4 straight off the charger 7.2v (nominal 6.6V):) I will power it not from the power input pins of the board. Instead i will connect the negativ for the input pin. But the positive straight for the top board servo pins (3 pins where is the smilie on the top board) Oh yeah with an 15A fuse. And I will set the voltage monitor for 5.6V

And the other thing. Because the speaker left in the plastic. Is there any one tried an 1w 8Ohm speaker on it externally?

If you have any toughts please share with me. Thanks.

(How you can recognize stupid people? ........... They never ask.)


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oaba, you will find over 10,000 robots powered with the EZ-B v4 and nearly all have 12 or more servos - however, those are ez-robot servos and we designed the robots and servos so the current draw is a known variable. Thank you for the information, however some important information is missing.

The number of servos is not entirely relevant unless you know the amperage draw. The EZ-B v4 specifications can be found in the datasheet, which is available in this course:

You will not want to exceed the specifications of amperage draw. However, currently you do not know what your requirements are. That will require either trying it out and seeing if the poly fuse blows, or use a meter to measure the current.

There are thousands of servo manufacturers and models. Each servo draws a different amount of current, and therefore have different amperage requirements. A large servo, powerful servo, or poor quality smaller servo may draw equally high amperage. The number of servos is not a valid unit of measurement to calculate amperage requirements.

I'm having trouble understanding the part about the charger and power supply? I believe that you're asking if you can power the robot with a power supply? Or are you asking what power supply to use for charging the battery?

If you're going the battery route, which makes sense for a robot - the LifePo batteries or LiPo are both great. There is a lot to know about batteries, if you're asking for additional detail. There's some great tutorials on this website that can help understand to further detail - but not necessary to get up and running right away. The amperage of a battery is not the only value to consider, as there is also a discharge rate. For example, a 1 amp battery will have a discharge rate value which defines how quickly that 1 camp can be used. Meaning, are you discharging the battery at 100 ma per hour? Or 1 amp per hour? or 2 amps in 30 minutes? or 4 amps in 15 minutes? etc... etc... The discharge rate value will tell you how quickly you can discharge the full current potential of the battery.

To start, i would recommend connecting the servos to the EZ-B v4 and providing power from a sufficient battery or power source. See how your robot works and how long it lasts. Once you've at least tried it, you will be able to measure the current and tweak the power source accordingly.

Regarding the EZ-B v4 and any diodes or components that you've recognized - remember the ez-b v4 is a very high-tech and complicated electrical computer. Every part on the ez-b v4 was selected by engineers to meet the product spec requirements. If you find components on the ez-b v4 pcb, they may be part of one of the many functions that the ez-b v4 performs. Such as streaming audio, video, wifi, digital switching powersupply, and more.


@oaba So what exactly is your problem? I read through your entire post but you didn't mention what problem you were having... The ezb4 has a 20amp fuse in the power shell...

If it is a power issue, I have built 2 inMoovs pretty much powered via a single ezb4 and operating without issues... That is to say the ezb4 is powering 12 giant scale Hitec HS805bbs servos without a problem.... You can pull 5amps continuous and 20amp in spikes through the ezb4 board. JD has 16 servos and one rgb led and does quite well using a 7.4V 1300mA Lipo battery....


I have read and see all of the related tutorials. I have RC experience aswell and electrinic enginiering aswell. I am new in robots. I am just discovering it. So I like to ask others to get more knowledge. I like Ez-b a lot. Very nice PCB design aswell. But the software part what I like most. That is amazing job. Congrat. (I think you could make a market for projects to encoridge people to coding.) What I have asked in the earlier comment make sense. Might it does not come across because english is not my native language.

Servos: In the RC we always use BEC to power servo (Usually that inside the ESC). Because the brushless motor need 4-6s voltage. I use one or two servos in cars.

Voltage of the servos: I do not want to use BEC in my robot. My servos rated 6-7.4v. I just want to know. Am I right not to get the fully charged 8.2V on to my servos hooked up? I do not wish to damage my servos.

 That is why I would use lifepo. (There is no mention in the tutorial lifepo)
 (There is some advantage of lifepo I like. Life time double than lipo,
 cheaper, voltage good for most  the servos} (Disatvatage only 20C max.)

Hitec HS805bbs is an 6V servo (Operating Voltage: 4.8-6.0 Volts). 
So is it no problem to over volt servos? 
(probably over heating and more current usage?)

Amperage: I had to use external BEC on my RC car because it use more current
than the ESC can supply. In normal mode OK maybe 0.5 Amp. But on load. On carpet or in a sharp turn it can go higher. Example Hitec HS805bbs. on 6V 8.7mA/idle and 830mA no load operating. 12 x 830ma=9.96A without load. I am probably just too carefull. I do not want to fry EZ-B :) And that D1 diode just made me think. What SMD diode can withstand to 10 amps. But in case of richard it did. But Dj if you could tell me type of the diode I would be pleased.

Thanks. Sorry might it hard to get the knowlage in my head. stress


I found in the Ez-b manual 5 amp continous 20 Amp spikes. (That is the D1 diode spec) So why is 10 amp fuse? Why not 5 amp in the power base?

Other thing My servo timing for the full extend 0.55ms-2.45ms -95 - +95 Ez-b does 1-2ms. Can I do something?

User-inserted image

What the electronics powerd with? Software? Current? .............. The answer no. The right answer is: The electronics woks by smoke. If the smoke comes out. Electronics stop works.


@oaba What fuse are you talking about? The fuse in the ezb4 base is a 20 amp fuse not 10... I am not sure about the rating of the poly fuse, however...

It is 20 amp because it has to handle 20 amp spikes... Makes sense to me.... Dude, I think you are really way over thinking things.... Put your clipboard and calculator down and start playing with your ezb4. You won't hurt it unless of course you are @Nomad...:P



are you borred.i never broke any off my ezbv.also the batts where not my, fault.but i got 6 new ones.:)


Yes.... I am bored.... Waiting for my pizza to arrive... :) Don't worry, we all still love ya' @nomad...:D



i hope so haha:) injoy your pizza


Nomad, You're such a good sport. RR! However you still love him..... like the rest of us. :D


Hi Alan. Yes I have the software actually the whole cd. If you want I can upload it. No bother. But I think he should change for ez-b. And not playing with some robo basic stuff.

I am not bored just not a rich guy. I think and ask before doing any damage.

Is there something information about the Hitec servos? With standard 1-2ms it turns only +-60 degree. Any chance to squeze out 0.55ms-2.45ms from ez-b?

Richard you where right it is an yellow 20 Amp fuse.


Thanks, if you check the post I linked, the robot belongs to his University, so he needs to prove that the motherboard is bad before he can replace with an EZ-B, which was also my suggestion.

I have no idea about your servo question. Jeremie could probably answer it.



@ Richard R

Do you supply more than 6V via EZB4 to your HS-805BB servo?

If so , how much?


@Aerius No, I use a 6V 12a SLA battery in my inMoov