12vdc CFL Bulb Max input voltage? (urgent Hurricane Ian)

Thread Starter


Joined Feb 1, 2019
Hey my fellow Diy'ers,

I'm preparing for Hurricane Ian that should be to me in a couple of hours!!!

I've got a few of these 12v DC CFL bulbs (Model HY-2U 12v)


I have a ton of 4s Lipo batteries for my R/C hobby which are 16.8v fully charged.

If you took a educated guess, do you think these bulbs would be able to handle it? My thoughts are YES... Since a 12v "Lead Acid" car battery would normally have 14.5v +/-

Just wanted another opinion before I blow up 1 of the 3 I have...



Joined Sep 24, 2015
Couple things here, a car battery's nominal voltage is 12 volts. It's full charge resting voltage is (when new) 12.6V. When in operation in an automobile, the standard float charge is 13.8V. Just after start-up the voltage can go as high as 14.5V but with a new battery it seldom goes up that high. However, after a heavy starting cycle, a motor that is hard to start, it could go up into the 14V range.

I don't think the intent was to have that light operate at 14V, but rather its true intention may be that of use in a camper or trailer that operates from a 12 volt battery, not one that is connected to a running car engine. But it may be possible the light can withstand short excursions into the 14V range. But to operate it on 16.8V for longer than a second may prove fatal.

Since by now you've probably faced the hurricane, and likely knocked off the internet for now - this may be a moot point. So I hope you've weathered the storm successfully.


Joined Jan 23, 2014
But 12V things are often designed to survive lead-acid battery "12V" which varies from 11V to as much as 16V if the battery is equalizing. Some devices are even OK for 24V vehicles (read the very fine print on USB/phone chargers). CFL are arguably obsolete, so it's not a tragedy if they let smoke out.

You can make a nice 12V lamp by wiring three COB LED panels from dollar store "switch lights" in series. Just make sure they include a resistor on the COB board. If you want dimming, get a PWM dimmer/speed control module from ebay.

Another option are MR16 bipin LED reflector lamps (as sometimes used in track and garden lights). They are intended for 12V AC, and have regulated buck converters, so can handle a wide range of DC voltage. The ones with a single LED will often run from as little as 6V. Not dimmable, as far as I know, unless you open them up; the buck driver chip often has an adjustment pin that can vary current with a voltage or PWM signal.
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