I have an old Diecimila and I was wondering if I can run it with a 12v car battery. Also I was wondering about when the car is running the voltage goes up to 14.5v. Can I still run the arduino?
Tx,,
Check the documentation first:
It would suggest that that would be OK. However, it depends on what else is hanging off the Arduino and drawing on the regulator.
Its only a linear regulator so it would be best to feel the regulator to make sure that it is not getting too hot as the higher the current that is drawn, the more heat it has to dissipate.
Good thing is, the Diecimila has a relatively large voltage regulator [DPAK, and not tiny
SOT223], so even with 12V for Vin, the regulator may not get too hot, but you will need to
check it, given whatever loads you are drawing from the 5V pin on the board.
Roughly speaking the power dissipation in the v.reg will be Pd = (12V - 5V) * Iload [load
current], and this value should ideally be kept below 0.5W or so for the DPAK. You can
figure the current.
The bad thing is, automobile battery busses are very noisy, due to contraptions like
alternators, spark plugs, and air conditioner compressors in the system. You should:
a) use extra noise filtering on the power in wire to the Arduino board.
b) use your old cheap Arduino board [Diecimila good] rather than an expensive board
like a Mega, Netduino, etc.
For extra filtering, I might try something like a 10 ohm, 2-watt series resistor followed by
a large electrolytic capacitor, eg, 680-uF at 100WV, and a husky Transzorb, maybe 18V at
1500 Watt rating, with both wired directly to the Vin lead on the Arduino board.
They have cheap adapters that plug into the cigarette lighter plugs that convert the 12V to 5v via USB. That would be the easiest/safest option.