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Quadrupede bluetooth Spider


After printing pieces to Prusa I3 is the new 4-legged spider with bluetooth comm :)


Powering SG90 servos with lipo and BEC

Hi there,

I'm building a robot with 15+ SG90 micro servo's.

To power it, I've bought a 2C lipo battery, and a 5/6 volt BEC.

I've hooked up the BEC's 5v (red) to all the servo's red, and the BEC's ground to the servo's ground, as well as some arduino grounds (that control the servo).

The BEC has an on/off switch.  When the BEC is switched to off, and I plug the battery into the BEC, a surge of current flows through to the motors.  They all "twitch" very rapidly, and I've had some wires melt/smoke.

My questions are:

Servo powering problem

Hi guys, me and my friend have built an arduino controlled Quadruped "mantis" robot.

Solar charger for multiple batteries

Hi everyone,

I couldn't decide which forum topic to use for my post so I'll post right here in the "Absolute beginners" because I'm actually a programmer and I'm quite new to electronics so I don't want to put expectations too high. I may do or say something that looks pretty stupid for an experienced robot builder so forgive me and don't hesitate to mention it if it happen, I'm here to learn.

Now that I'm done with the presentation part, here is my multipart question.

I managed to build some kind of Solar Li-Po charger using a tutorial and stuff I bought at Adafruit.

Royal AP8000 8000mAh USB battery for $12 !!!

I just visited one of Costco's Clearance Outlet stores nearby, and found this LiPo battery pack for $12!  Just because it was out of it's packaging!

5v 2.1A out, wich charge level meter on front panel.  Weighs about 12oz...

Had to buy two of them  IMMEDIATELY before someone came to their senses!

It retails at Costco for $40, which is still a great price for LiPo  8000mAh here in Canada. 

Soldering Wire to Battery Holder

I am told there are no stupid questions, but this one may change your minds.

I am working on my second robot, he is going to use 5 D-cells and has 4 motors each with 5 amps draw at stall.

A little math implies 20 amps, if I stalled all four motors.  While I am hoping to never see 20 amps draw, (yes I am putting in a fuse), I am not very impressed with the wires coming off the battery holders.  They are 24 gage, and I was thinking about using 16 gauge wire for the wires coming off the battery holders and the leads of the motors.

Smart Phone Portable Battery Pack


Just curious if anyone has built a robot before that used one of those external smart phone battery packs.  Seems like an easy way to provide a rechargeable source.

Something like this: http://www.amazon.com/Photive-2600mAh-Portable-Battery-Charger/dp/B00BFY59BA/


powering PMDC .75HP motor with 12V 56AH battery

motor specifications:

power      =  .75HP

rpm         = 1500

voltage    =  12V

current    =  46.6 amps

torque     =  36kgcm

BATTERY specification:

type      =  lead gel battery (used in e-bike)

voltage    =  12V

current    =  28Ah (amph)

no. of batteries using  = 2 connected in parallel

Walk forword,back.left,right,balance one leg, up-down 1 or 2 leg,Turn right-left,Control With Bluetooth
Using a
My new Biped Robot "Red-Dragon V3"   what's new -Remove the camera Read more

Just a quick question regarding battery use on a hack RC car.

Would it be a bad idea to power my robot with one battery. I would be using 5 rechargerable batteries which will give me 6-7volts or should I just power my atmega328 and maybe ultrasonic ping sensor with a 9volt batteries and the rest with the rechargerable.

Standalone atmega328

1 dc motor with L293D

1 micro servo

1 ultrasonic ping sensor

6 leds (3 sets each)

what battery would you recommend for powering 10 servos at 6v ?

I am currently working on a humanoid robot and am trying to ruduce the weight and increase the opperateing time I am useing 4 AA batterys to power the top half 12  servos and another 4AA batterys to power the bottom half 10 servos  22 servos in total . The AA batterys tend to go flat quite quickly and haveing 8 AA batterys make the robot heavyer also if i could recharge the battery it would be a great help. the servos are rated at 6v maximum and 4.5v minium what would you recommend ?

Any help is greatly appreciated.  

Arduino servo


I tried to build a photovore using and arduino and tested it via usb cable,so far so good the system worked as intended as soon as i plug my battery via the dc connector the servo worked but extremly slow why?

website about batteries

Here is an excellent website about batteries and charging process :


Battery has 3 wires??!!!


Sorry if I'm being naive but I just got a lithium -Ion rechargeable battery pack (8.4V 2000mAh(2C)) and guess what..Yeah it has got 3 wires (a red one,a yellowish creamy one and a black one).Now could u please tell me what each one means and also the need for doing this.Btw what does 2C mean ?

Thanks in advance.


test own power

i have seen it done before and looked around but the only things i can find are voltage dividers and op amps. i am thoroughly confused and just want to make a picaxe monitor its own battery

any help would be appreciated


Palocell - 8 x 1100mAh AAA NiMH for under 6 quid!

Just come across these very cheap, high capacity AA and AAA NiMH cells on Amazon - 8 x 1100mAH AAA for under 6 quid delivered.  UK company - Worcester based, but I can't get much sense from their website ( http://www.palo.co.uk/ ).  I can't find any independent test data on them - The only promising link is a 404. Anybody had any experience with these? 


In circuit charging of NIMH pack

I'll be putting together a 14.4v 5ah battery pack out of 12 solder tabbed C cells.  The raw voltage will be fed into a 100w step up DC-DC converter to supply 18v to a single board computer, and also to two

Which power supply setup do you prefer?

So I want to buy some AA's and power up my Tamiya twin motor gearbox.

I would go for B, because A will discharge uneven. But B will discharge equal. The only problem is, that ONE DC motor uses max 3V. So when only ONE is active, it will take a punch of 7,2V instead of max 3V


So which of these do you prefer? A or B?


Arduino tamiya twin motor gear power supply and stuff


Hello thereI am building a simple Arduino tank but the problem is that after running it for 20? seconds it starts to run slower and slower. Then after turning it off, and on it does not run anymore. After letting it stay off for almost 5 minutes, it runs really slow. Looks like the 9v battery can't handle it?

navigate in various ways, teach me about robotics
Using a
Hi! MAEP 2.0 is the second version of MAEP (please check it out if you haven't already). I won't go into all the details about things that are the same as the … Read more

Battery Question

I have a laptop battery that is still very good these are its ratings:

Critique my power system--Please!

Edit.  I got into a discussion with Chris the Carpenter about pricing and alternate parts sources, and found an interesting item on Ebay that should work out.  See the bottom of my post for more.

I'm in the planning and parts procurement stage of a relatively (for me at least) complicated robot project.

The heart lights up when you hug him
Hi, this project was my christmas present to my girlfriend this year. What it does is that every time the bear is hugged, the heart fades in, pauses, and then fades … Read more

LiPo batteries and chargers question


I'm going to make an hexapod robot and I need a LiPo battery. The 20 servos (SG-5010), when moving, needs 12 A.

I've already bought some servos in the past from Hobby king, and now I was wondering if you can suggest me a LiPo which works with my configuration: http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=86&v=&sortlist=P

I want to buy from Europe to avoid custom duties. Also I'll need a charger. http://www.hobbyking.com/hobbyking/store/__216__408__-Battery_Chargers.html

Power Screwdriver Motor

So I bought a few power screwdrivers for the main drive motors for my new robot project. I have started creating a rocker bogie suspension system out of PVC pipe. This suspension will require 6 drive motors. The power screwdrivers run on 4 AA batteries. So the motors are 6 volt. By browsing the interwebs I figured out that one AA battery supplies about 2.4A. So I figured that each motor would require 9.6A. But since I have 6 motors I would need 57.6A. This would require a huge SLA which would weigh about 20lbs and cost around $100.

Li-ion 7.4v and servos

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.

What batteries to power my Arduino robot.

I would like to know what type of battery setup I should use for my robot. I have 6 AA batteries powering my motors so it's just everything else... which currently consists of...

Arduino UNO

SN7...etc.   H bridge motor driver chip

Mini Servo

Sharp IR sensor

How big/mAh of a battery do I need? And how many?

I going to begin building a robot and I would like to know how many mAh to I need for it. The robot will have two motors (drawing about 1-1.5 A each) and the other components use much less current (all of the components draw about 30 mA).

And do I also need two batteries? One for the motors and one for the microcontroller+low draw components?

P.S.: Any suggestions on a charger too?