I recently created a 12v battery consisting of 10 sub-C nimh batteries. I'm gonna power my motor controller with it. But I want to know if is safe to power the arduino directly from it. I've attempted it with no smoke or anything. But I feel like the board heats up a little to fast and more than I'm used too. Also the actual batter voltage measures around 12.9v so I alittle concerned. I was considering adding a linear or switching reg. before my arduino but I'm worry that I'm just gonna be wasting electricity with the linear or money with the switching.
So should I need a regulator or not? If my arduino continues to heat up, but at a a steady pace what will happen?
Yes you can, but the regulatoar may get warm.
Why not pick off the voltage after 4 batteries, ~4.8V, and power the arduino from there? Connect to the 5V pin on the power header.
Hmm... The on-board voltage regulator would likely survive because it's within 10% of the rating. However, I wouldn't recommend it because this will cause a lot of extra heat and almost certainly shorten the working life of the regulator IC. Instead, you should either get voltage regulator with a higher input range, or perhaps if you don't mind spending the extra money an Arduino-compatible board designed to work with higher input voltages. An example of the latter would be the Ruggedino, which can be powered with upto 24 VDC.
I considered that pick and chose method CrossRoads mentioned. But the problem I see is discharging in an imbalanced way. I especially don't want that when I'm charging my bat pack.
So I'm thinking of using a regulator just for some safety but like I said, I don't want to be horribly in efficient.
So then my needs would be 12vin to 7/9vout.
And max current out 1A. Does this sound correct? What would I need as the possible lowest? 500mA? 800mA?
Also I cannot grasp what the voltage drop out means. (2v @500mA). How does that apply to wasted current and/or required vin?
Or with these specs and current would switching reg vs a linear be overkill?
How much current are you taking from the Arduino 5v line for external devices? If you are taking very little, then powering the Arduino from 12V will be fine, because the regulator will only be dissipating around 300mW. However, if you are also powering relays, lots of LEDs, LCD backlights etc. from the Arduino 5v line then this will increase power dissipation in the regulator. You could consider whether any of the devices you are powering from 5V could be powered from 12V instead. For example, in designs using an LCD display, I never power the backlight from 5V, I power it from whatever I am feeding the Arduino Vin pin or barrel jack (with a suitable series resistor of course).
Haha not sure what my demand is cuz my reciever is running off the 3.3v and it's wave bird reciever. Other than that sometimes I have a piezo. And a couple LEDs but I plan to add a couple more. And the logic for my driver
I see well given that the5v is properly regulated are the any risks plugging 5v from the regulator into the +5v rail?
Does that regulator mentioned by crossroads require anything else? Or is that pretty broken out?
The price seems decent enough at 4 bucks. But still I could get a Lin reg for .50.
Well one more question. What's the max current limit draw through the arduino from USB? Cuz that has always been sufficient.
"I see well given that the5v is properly regulated are the any risks plugging 5v from the regulator into the +5v rail?"
No.
"Does that regulator mentioned by crossroads require anything else? Or is that pretty broken out?"
Pretty broken out. Add 10uF aluminum electrolytic cap to input & output.
"The price seems decent enough at 4 bucks. But still I could get a Lin reg for .50."
Depends what kind of battery life you want. You want to use a bunch of your battery capacity heating up a 5V regulator? That's your call.
"What's the max current limit draw through the arduino from USB?"
500mA, then you blow your PC's USB fuse.
I see. And well I believe I'll try both since shipping is gonna cost more. But 500mA hmm? And thats not arduino regulated. So how much current would the entire unit draw if I wanted the 5v to produce 500mA?
If you put in >7.5 to the barrel jack & use the onboard regulator, you could get close to 800mA, and how much above 7.5V will determine how hot the regulator gets, up to the point where the regulator goes into thermal shutdown.
Ah dooly noted. But you mis the point of my question. How many amps pass though the whole assembly but are not part of the 800mah being produced my the 5v reg?
Greenbean209:
Haha not sure what my demand is cuz my reciever is running off the 3.3v and it's wave bird reciever. Other than that sometimes I have a piezo. And a couple LEDs but I plan to add a couple more. And the logic for my driver
Look up the datasheet for your receiver to see how much current it takes. LEDs are typically 20mA each depending on what series resistor you are using. Logic chips draw very little current if they are CMOS such as 74HC series.
Yes, but: the regulator may run real warm depending on how much current is being drawn.
Also, car power may be really noisy, especially at engine start. You may want to use a mobile phone charger kind of adapter to take advantage of its power filtering.
An example:
i am going to plug it only when the car is already running and not at the start up.arduino will only supply 5 volts to two servo motors . I found this: http://arduino.cc/playground/Learning/LeadAcidBatteryAdapter
will it be ok if i use to the positive pole one fuse 1A?
CrossRoads:
Power in = power out.
12V, 800ma = 7V, 800 ma heating the regulator, 5V, 800mA dissipated elsewhere.
Powered from USB:
5V,500mA not going thru the regulator at all, bypasses it.
5V, 500mA dissipated by everything else.
Ok so there's no confusion. Im basing my theoretical current draw off of the arduino maximum capacity. And my question is if using the 800mA max for the arduino. Then all my power source needs to be capable of is 800mA?