Hey guys,
Quick question. The Arduino Nano (v2.3 to be specific) has a voltage regulator. And can be powered externally through pin 27 (+5V input/output) and ground. The power source for the Nano is said to be able between 6 and 20V, but recommended between 7 and 12V.
Could I simply hook up the battery to the Arduino pins, would the chip be ok and perform properly and because it's a battery, it would only draw as much current as it needs. Or would it just fry in a split second.
Thanks 
car batteries are really noisy (electrically due to the alternator & ignition) and the regulator is up to 20V, but with how much load and how much heat can it stand, plus some other crap I cant think of right now
I would use a automotive transformer (ie cigarette lighter phone charger) and maybe some additional filtering depending on what you use to drop that hostile environment into something safe and low (or roll your own)
Thanks Osgeld,
I plan on only using the car battery as a source when the car is completely turned off and the circuit will be completely disconnected through a switch when the doors are unlocked.
The arduino is to power my car alarm, and a switch connects the power when my door is deadlocked. I think that should solve the noise issue. But i understand what you meant.
This is also another reason why I cannot use the cigarette lighter, as it only has power when the car's ignition is on.
I plan on running a lead directly from the battery terminal. So back to my original question, would it fry or fly?
Yeah, I have a few large diodes that I have salvaged, I'll test them first. But I'm sure they would help.
The idea of using a cell phone, etc, charger that plugs into a cigarette lighter isn't dead, I trust? I understand that it can't be plugged in "normally", but it could be wired to the car battery directly, and would take care of some of the issues of drawing power from car electrics.
"Frying" circuits is a function of voltage. The 12v car battery is perfectly safe.
However, if you turned the ingnition key with the Arduino attached, you might smoke it. The starter motor causes significant surges.
I'm working on better power conditioning for my Mega board but I've not
finished all the research. There is some good info on the thread if
you did not see it.
car batteries are really noisy (electrically due to the alternator & ignition) and the regulator is up to 20V, but with how much load and how much heat can it stand, plus some other crap I cant think of right now
Huh? If the battery's dead or the connections corroded you might have problems but a constant voltage source in the range 12--14V with internal resistance in the milliohm range is fine for driving a voltage regulator with 20V max Vin. And noise is not an issue in the input to a regulator!
My arduino nano is no more... In other words, it didn't like the car battery and is no longer of sound mind. >:(
You have not made clear your connection arrangement. The Arduino built in regulators can tolerate 12 volts. I've used a lead acid 12v battery with no problems. How did you connect it? Did you start the vehicle?
Back to the cell phone charger idea...
I would quess that GOOD instances such devices have significant circuitry to filter the noise and over-voltages present in cars when the engines are running.
Of course, distinguishing the good ones from the not good ones might be difficult...
Yes, I did see that the poster only intended to use the device when the car was NOT running, but...
a) Other people with other needs will probably read this thread
b) Can he really be sure he'll never forget to disconnect Arduino before starting the car? (Well, maybe after frying one...)
Yes, a car battery can be used to power a nano, but not if it still has a car attached to it ;D
joe mcd:
Well, with the car completely turned off, and having nothing currently powering the car. I tested the voltage of my car battery - it was 12.XX. So knowing the Arduino can supposedly support 20V, I thought it was safe. The way I connected, was directly to the battery terminals with alligator clips (polarity was correct just if you wanted to know).
tkbyd:
I might explain my powering of the nano more in depth. My car features a deadlock available via the central locking. One lock press locks the buttons to the down position, and the second button press removes the functionality of the knob from the locking mechanism. I have purchased a 'microswitch' which I am placing on the deadlock actuator. This switch supplies all power to the Arduino.
The car cannot be started when it is deadlocked, and nor can you deadlock it when the car is running. Under this idea, I think the Arduino should be safe.
Any ideas to what may have happened?
On a related note (I am a total noob), does anybody have advice for connecting a solar panel to a 12v lead acid car battery? I have little experience, and in my garden I am planning to have a 12v car battery power both my arduino as well as some 12v lights (for minutes at a time, a couple times a week), and some 24v solenoids to control water flow (and maybe a 12v water pump if I need more water pressure than gravity provides). I also wanted to put in a solar charger (as having a charged 12v battery around is a handy thing).
Having not smoked any electronics yet, my neanderthal first thought is to clip everything 12v directly to the battery terminals. I read that I needed something to prevent overcharging of the battery.
I also saw an article about protecting the arduino from excessive voltage/amperage
http://www.arduino.cc/playground/Learning/LeadAcidBatteryAdapter
so I assume I need an inline fuse just in case...
I also plan to have a 12v->24v voltage converter power the solenoids as needed. I still don't know if it's easier/cost effective to build a voltage converter or to buy one. I also don't know what kind of relay I need to turn the solenoids off/on... [I have a related post on a water solenoid thread:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1229955902/24