12v LED Puck Lights Wired 2S2P on a 24v System

[ATXist]

Hey All,

I bought these puck lights: https://www.amazon.com/gp/product/B012ZOI3ZW/ref=ppx_od_dt_b_asin_title_s01?ie=UTF8&th=1

They're 12v puck lights, and I have a 24v battery, so I wired them in 2S 2P, thinking that should convert the 12v lights into 24v. They're all wired up, installed in my ceiling, and a test run showed they work fine with a dimmer switch I installed, though it was a quick test. I just want to do a sanity/safety check, and make sure this is an appropriate way to have these lights wired.

Are there any concerns with the way I've done this?

Thanks,

 

[chrisski]

I’m interested in what happens to the LEDs.

I bought12/24 volt lights for a conversion I went to. Wanted 12/24 volt puck lights, but could not find them. I have a new DC circuit I added that I installed accessories that are dual voltage for when I do my RV 24 volt conversion. For RVs, I did need to keep a 12 volt circuit to run 12 volt items like high powered leveling jacks, the carbon monoxide detectors and other 12 volt items that came with the RV.

 

[rmaddy]

I have those exact lights (from the OP's Amazon link) also wired in 2S2P connected to 24V. They do work though I haven't had a chance to run them too long yet myself. I have another set of very similar puck lights wired in 2S5P that I have run for a total of about 2 hours so far. The only issue I've had so far is that those lights get really warm. But I don't know if it's just those lights or if it's due to being wired 2S5P and hooked up to 26ish volts.

 

[chrisski]

I’m curious what gauge you’re running?

I tapped a USB charger into a 12 volt puck light, and the wire was only 16 gauge. The USB charger had a built in voltmeter, and I was surprised to see the voltage drop by .5 volts when I turned the lights on. I could lose and additional .5 volts by using both ports on the charger. I do Wish the wire gauge was thicker Than 16.

 

[rmaddy]

I’m curious what gauge you’re running?

I don't know if you are asking me or the OP but all of my LED light runs are with 16AWG wire. Though the leads on the lights are only 18 or maybe even 20AWG. I cut all of those leads down to about 3 inches when connecting my own wire. I haven't made the effort to check the actual voltage at the lights. I should do that. But it would actually be good if I had a full volt or two drop since my 24V system is really in the 25-28V range.

 

[Steve_S]

There is a GOTCHA here ! Pending if you are powering direct from the battery or going through some form of Buck converter. If you are running 24V, remember that when charging you can tickle you to 29V, some devices & even buck converters will not handle that. For Buck Converters / Transformers and such running from a 24V battery should always be rated for 30V input (when charging is occurring).

Buck Converters WILL FAIL if they are only 24V input rated, when they fail they allow full voltage through. I roasted a couple learning an Expensive lesson by burning up a motor due to buck-converter failure. Picture a 12V motor getting 28V which happened to be my RV Furnace - NOT a Happy Camper with -30C temp outside that day. (Murphy's Laws applied "on spec").

SIDE NOTE that affects your goodies, few mention.
IF you are charging your battery bank via a Genset (non Pure Sine) whatever sinewave the genset outputs is passed through the Inverter/Charger or Charger "AS IS". Pure Sine (via Inverter Genset is cleanest) but most "construction" grade Gennies are MOD Sine and the real cheapo's - don't go there. MOD Sine is OK but it is crude and are subject to fluctuating to Fluctuating Frequencies which can vary from 55Hz to 65Hz (just within rough tolerances) and that can have a deleterious effect on your gear (motors & fine electronics like a computer, LED Lights, etc)

IF using a Non Pure Sine Genset, a Conditioning Converter from 24V or 48V to 12V circuit is strongly suggested. For 12V, a simple conditioner only between bank & 12Vdc sub-panel is suggested. Ideally Isolated Converters are the Best & Safest Solution all around.

High Quality Reliable KNOWN GOOD Converters/Condtioners here: (not cheap but you get what you pay for including peace of mind).

DC-DC Converter | Isolated, Step Up, Step Down | Samlex America

Samlex high-efficiency DC-DC converters regulate the DC voltage that is input to the converter. Available in isolated, step up or step down options.

samlexamerica.com

Who wants to use a $10 Buck that could fail & cause a fire in their expensive RV or residential Powerbank systems ? Is saving a few pesos worth the potential of havoc ?

 

[12VoltInstalls]

I’m curious what gauge you’re running?

I tapped a USB charger into a 12 volt puck light, and the wire was only 16 gauge. The USB charger had a built in voltmeter, and I was surprised to see the voltage drop by .5 volts when I turned the lights on. I could lose and additional .5 volts by using both ports on the charger. I do Wish the wire gauge was thicker Than 16.

Two things. Actually three.
For one, depending where/how the usb voltmeter gets it’s data inside the scary little plastic device (I have one like that too LOL) it may be ‘seeing’ a sag due to its own internals.
im weird: I most always way over-gage stuff. With a clean homerun from a decent fuse box most LEDs are fine on 16ga
In your case, I think there may be pixie wranglers inside the lights enabling the dual voltage use - not so much of a ‘tolerance’ as inefficient (but cheap!) internal engineering. And that’s probably a heat loss equal or more to the LED mA draw.

I have some dim/bright 12V RV ceiling lights that are pretty stinkin bright on high but they basically have no power control circuitry: just an A/B/off switch. They get warm if on for some time. A friend’s new camper has fancy ones that apparently dim by voltage and all the LEDs stay on, just dimmer or brighter. Those lights are warm to quite hot all the time.
I don’t think the 24V market has matured yet imho. At least with most cheap 12V lights they achieve 12V use voltage by series/parallel arrangements on the devices with no cheap poorly designed circuit boards doing anything. I think that nearly any cheap straight up “12v” LEDs are either arranged series to be 12V or just have resisters in them.

Thirdly, I think most usb cables have nearly imaginary wire gauges in them