I was wondering if one can hack an LED light bulb to run on DC from a battery. It would require a power of about 15 Watts but I am not sure of the DC voltage inside the bulb after it is converted from AC. Does anyone know what it would involve and what kind of battery would be needed? Thanks.
A “simple” LED light bulb will full wave rectify the ~120VAC to ~170VDC, and then use that directly to power the LEDs. Most modern designs aren’t “simple” like this any more because of power efficiency and the proclivity of flicker as the unregulated DC bus sags.
Though the short answer is “no”. If you want to run it off low voltage DC, you’ll need to do a significant rewire and most likely a redesign of the onboard power supply for current regulation at the lower voltage. Have a look at Big Clive on youtube, he’s done a lot of tear downs and reverse engineering of modern LED bulbs and tends to draft up a schematic.
Thanks for the answer! I’ll check out the video’s. I was hoping to be able to supply light that looks like normal room lights when the power goes out. I suppose I could still use an small inverter to convert battery power to AC but I thought that might be too expensive.
If you are looking for a dc only bulb, you can buy A19 style bulbs in 12vdc for rv and boat usage.
Thanks. I’ll check that out. I am looking to retain the warm light color one can get from a modern LED bulb.
That simply pertains to the color output of the bulbs you are looking at. It has nothing to do with their power source.
I just did not know if they made different temperature light bulbs for DC yet. Since the do it appears my problem is solved and I can just use 12V LED bulbs. Thanks.
Anyone have thoughts on what type and rating of battery for a 10w 12V bulb? I’d rather not spend hundreds of dollars to power one lamp 10W, 12V lamp for a few hours.
A generic 12v seal lead-acid would do that.
10W at 12V is 0.8A, so a 8AH battery should last 10 hours.
Great. They are cheap enough I can get a handful to run a few lamps in different rooms. Thanks!
A possibility - 2700K soft white.
There are several others similar to this as well. ( I just picked one without any significant research - buyer beware, do your own research, etc, etc… )
Unless you switch to lithium iron phosphate batteries, I would either half that run time, or double that AH capacity. Lead acid batteries do not reliably recover from greater than 50% depth of discharge.
Aren’t they much more expensive?
In large sizes, the sticker shock can be prohibitive…
But here is a 6AH lithium iron phosphate for $33
Vs the cheapest 12AH lead acid I currently see at $26
So once you account for being able to use the full depth of charge vs the 50%, they can be surprisingly close at the small end.
Thanks! I’m leaning towards iron phosphate so I don’t have to worry about it.