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The climate control in my car needs to have some backing lighting bulbs replaced. Can I use a 14V 65mA bulb instead of the 12V 60mA bulb that is suggested by other people who have replaced these bulbs? Not sure but I believe the orginal burnt out bulb is a 12V 70mA. Anyone forsee any problems using the 14V bulb. Thanks!

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  • \$\begingroup\$ tried applying ohms law to solve that question? \$\endgroup\$ – PlasmaHH Jan 27 '16 at 20:23
  • \$\begingroup\$ A neat solution would be to wire in some LEDs \$\endgroup\$ – user1582568 Jan 27 '16 at 20:26
  • \$\begingroup\$ Yes it should be fine. They will be a bit dimmer when the car is off, that's it. \$\endgroup\$ – Passerby Jan 27 '16 at 20:38
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I don't see a problem in using that 14V bulb just so long as its current rating is about the same as the one to be replaced. It may not be quite so bright but I doubt if you will notice.

But consider this: an automotive bulb may be rated at 12V but it is designed to work across the range of voltages present on the car electrical system. With the engine running fast the alternator will output at least 14V. With the engine stopped the battery provides a voltage between 11V and 13V depending on its state of charge. Your 12V bulb is designed to work across this range of voltages. You could even call a 12V bulb "14V" because for most of the time it is working at 14V. An automotive grade bulb should also be sufficiently robust to withstand the shocks and vibration in a car. A 14V bulb probably isn't automotive grade and may not be quite so robust. Personally I do not see any advantage in using a 14V bulb. Get a good quality 12V bulb and as an instrumentation backlight it should last the life of the car.

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There are three concerns when replacing components like bulbs

  1. Exceeding the power rating (Watts = Volts*Amps, the voltage and current going through the bulb) which could be a thermal problem and heat things up to much. If you use a lower wattage bulb, you should be fine.
  2. Exceeding current, The driving circuit in most cases should be fine, but its a good idea to stay below the current of the original part, you'll want to stay in the same range.
  3. A bulb that is built for 14V says that because of the lifetime and/or brightness rating, that's what it was tested for. Since it draws about the same amount of current you should be fine. The bulb might be dimmer but it should be about the same or higher resistance.
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  • \$\begingroup\$ For your item 1 it needs to be made clear that the (Volts*Amps) relates to the volts applied to the bulb and the actual amps that is drawn through the bulb. That will be the actual power (watts) consumed by the bulb. The ratings stamped on the bulb may not represent actual in usage wattage unless the applied voltage is the same as the voltage stamped on the bulb. \$\endgroup\$ – Michael Karas Jan 27 '16 at 21:30

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