Ok, was reading the thread about Arduino and 12v acid batteries and that got me concerned about my plans. Someone tell me if my logic here is bad.
I bought 4 3.7V 1050mAh 603450 lipo batteries. I have 2 pair joined in parallel and those joined in series to give me 7.4V. The plan is to hook 2 6-12v micro motors to the batteries via a controller. All of the 5v sensors and a g9 servo will be hooked to the batteries via a 5v buck converter on order from Adafruit. The Adruino vin will hook straight to the batteries and it will power the 3.5v for a logic level converter and ESP8266.
Since I haven't gotten the converter in yet I'm running all the sensors and the servo off the Arduino 5v and motors off of the batteries while plugged into USB and everything seems to work ok. Just wondering if I should be worried.
Here's a quick video before I added the ESP8266. This is running off the wall charger.
(Be kind pls. This is my first Arduino & 3d printing project and the first time I've picked up a soldering iron in oh... 40+ years.)
Fengist:
3.5v for a logic level converter and ESP8266 will come from the Arduino................Just wondering if I should be worried.
It's all hard to read, but perhaps you might worry more about about the bit that seems to worry you least. There is very little power available from most Arduino 3.3v pins and probably not enough for the ESP8266. And while you are pondering that, and since you intend to use ESP8266 WiFi, you might check that the Arduino isn't redundant anyway.
Nick_Pyner:
It's all hard to read, but perhaps you might worry more about about the bit that seems to worry you least. There is very little power available from most Arduino 3.3v pins and probably not enough for the ESP8266. And while you are pondering that, and since you intend to use ESP8266 WiFi, you might check that the Arduino isn't redundant anyway.
Thanks.
So, the master plan is for a robotics project. Since this is my first of many things, I'm stealing a lot of ideas. The idea is to use this guy's methods:
along with IR and ultrasound to give this robot some limited autonomy and obstacle avoidance. Since there's no way even a mega could keep track of all that data and since I've yet to venture into the raspberry pi realm I'm hoping to eventually have a web server and database it communicates with. So that's why the Arduino and the wifi.
I read that the servo draws a lot of current and that's why I decided on the buck converter for the 5v side. Are you suggesting I add another for the 3.5v?
I'm suggesting that is something you should definitely check.
You don't say which Arduino you propose to use, so I'm also suggesting you might question whether you should use one at all. I believe Uno, Mega and the like have about 20mA at the 3.3v pin. I don't know about 3.3v Arduinos. ESP8266 is not renowned for its frugality, or its wealth of i/o but it IS renowned for having far more speed and memory than your average Arduino - along with built-in WiFi. The NodeMCU has 11 i/o pins and may be quite suitable for your purpose. It is also dirt cheap. I'm not a WiFi expert but, if WiFi is what you want, I don't understand why you would get an Arduino and, if you really do need one, it would be a Mega - which has abundant i/o but not much power on the 3.3v pin!
Nick_Pyner:
I'm suggesting that is something you should definitely check.
You don't say which Arduino you propose to use, so I'm also suggesting you might question whether you should use one at all. I believe Uno, Mega and the like have about 20mA at the 3.3v pin. I don't know about 3.3v Arduinos. ESP8266 is not renowned for its frugality, or its wealth of i/o but it IS renowned for having far more speed and memory than your average Arduino - along with built-in WiFi. The NodeMCU has 11 i/o pins and may be quite suitable for your purpose. It is also dirt cheap. I'm not a WiFi expert but, if WiFi is what you want, I don't understand why you would get an Arduino and, if you really do need one, it would be a Mega - which has abundant i/o but not much power on the 3.3v pin!
Also worthy of investigation is the Heltec ESP 32 board.
Thanks again.
I do have a Mega clone (bought it on a friends suggestion. Buying a real one next time) but doesn't have wifi built in so that's why. And yes, I've seen the tests on the Mega's power consumption and yes I've also read the ESP is a power hog. What I have is what I have for now.
Wow, that heltec looks interesting, especially the price. Thanks! Bookmarked that.
Fengist:
The Adruino vin will hook straight to the batteries and it will power the 3.5v for a logic level converter and ESP8266.
Don't! Just don't!
Fengist:
Since I haven't gotten the converter in yet I'm running all the sensors and the servo off the Arduino 5v
You are asking for trouble.
"Vin" on the Arduino (all of the older ones) is simply useless. The on-board regulator has no useful heatsink, it cannot supply significant current without overheating and (hopefully reversibly) shutting down. Not to mention being inefficient. You need a proper switchmode "buck" converter to derive your 5 V from your chosen battery supply.
Fengist:
Here's a quick video before I added the ESP8266. This is running off the wall charger.
So you are powering it via the USB port. That is good for 500 mA so you have not encountered the "Vin" limitation yet.
If you want WiFi, you should really look at designing out the Arduino (Mega). The ESP can do all your processing and you use "port expanders" to interface many I/O lines, 16 at a time. Many sensors operate at 3.3 V anyway.
Fengist:
I do have a Mega clone (bought it on a friends suggestion. Buying a real one next time)
Arduino is open architecture, just like IBM, so this sounds like nonsense, and your friend's suggestion was sound. If you can tell the difference between the Mega you already have and a "real" one, you are a better man than I, Gunga Din. You will be better off casting about for something that does not necessarily even have Arduino written on it, but better suits your needs.
And yes, I've seen the tests on the Mega's power consumption and yes I've also read the ESP is a power hog.
Mega's consumption is not so much the problem as its ability to deliver through its own regulators and pins. These things are controllers, not drivers, Driving servos is a no-no. What you have being what you have is OK, just know its limitations.
Wow, that heltec looks interesting, especially the price.
Just don't!