Fluorescent bulb to LED - Page 3

Viva · 04-06-2015, 11:05 PM

Okay, well this is something I haven't done before. I borrowed a friend's meter (because it's a decent one - maybe a Fluke? I'll have to check - mine is only a cheapie). I set it on AC voltage as directed by Marine Beam, then turned on the light, then removed the bulb, then stuck the probes into the tombstones on either end. Meter stayed at 0. (Actually, it My solar charger was "on" as the sun was out (but this is just a 50-watt panel at the moment). So.... not accurate?

I guess I don't really understand how I could have "AC ripple" when my rig isn't plugged in, the generator isn't on, and I have no inverter, but apparently it's possible (?). Really right now there isn't much of anything to do anything, since I'm in "hard tent" mode. The lights are one two different circuits, and nothing else on either circuit is "on." I also took out all the other fuses (just to be sure), but that didn't change anything.

So, I wasn't able to measure any "AC ripple" using Marine Beam's instructions. OTOH, the bulb wasn't "squealing" when I took the measurement either (it only does it about 60% of the time). I have the meter at the ready for next time it squeals though.

As I mentioned, they are going to send me two new bulbs. That may take care of it.

Bit of a mystery!

JWA · 04-07-2015, 04:02 AM

Quote:

Originally Posted by Viva

I guess I don't really understand how I could have "AC ripple" when my rig isn't plugged in, the generator isn't on, and I have no inverter, but apparently it's possible (?).
S

The so-called "AC ripple" super imposed on DC current would be a function of the electrical components in the circuits being measured. SCR's, diodes and many other solid state parts will rapidly "switch" on and off which can induce a voltage reading that resembles alternating current.

It would take somewhat specialized voltage/current measuring such as an oscilloscope---the typical DMM not usually able to accurately read microvolts of the nature you'd be looking for in this situation.

Slightly off topic but hopefully maybe a partial explanation.............

boywonder · 04-07-2015, 08:22 AM

...If you are not plugged into shore power, generator offf and do not have an inverter then your voltage should be flat as a pancake...ie ripple free.......

Viva · 04-07-2015, 12:04 PM

Well it does look ripple free from what I can tell, and my current system could hardly be more basic (I can't think what would be causing anything, because there really isn't much here - although that will change as I wire up my new system - still just basic DC though, no inverter planned and probably won't plug in too often).

I could imagine how the original "converter" (i.e. primitive charger) in the rig could damage something (and I was plugged in when I did the bulb conversion). The fellow at Marine Beam felt that a dried up/damaged/old capacitor in an older converter/charger could cause a problem with their chipset/power supply in the bulbs. But that makes me wonder why they don't always squeal now - just maybe 75% of the time. I'd expect it to be 100% of the time (not that I really know). At any rate, the old converter is soon to be history - can't wait to toss that ugly thing out!

The really interesting part, to me, was that first the bulb over the sink started doing it (I put in two, one over the sink and one by the door). So I moved that bulb to the door fixture, at which point the door bulb started squealing and the sink one was quiet (in other words, the problem moved with the bulb). The two fixtures are on different circuits (albeit they are both lighting circuits). After a couple of weeks, the non-squealing bulb in the kitchen also started doing it though, so now they are both noisy.

I'll have to report back after I get the new bulbs. I won't be plugged in at all (and by the time I am next plugged in, it will be with a new charger, etc.). They said they typically don't hear of this problem, and that ripple or bad converters usually make the bulb burn out, not squeal. OTOH, most people apparently can't hear the squeal, so who knows if it's just mine, or if it's more common but just many people can't hear it (~12,500 hz).

I'm also considering either making my own with an LED roll (such as you can buy on Amazon), although I have heard they may not work well due to our rigs not really being "12 volt" all the time, but rather ranging from ~14.4 to ~12.0. On the other hand I know folks who have gone this route and are happy. I also looked at the Cabin Bright strips. I called and the owner of the company is very customer service oriented. I'm still not sure I understand exactly what makes them different than the typical LED's on a roll (I mean, besides that you don't have to cut/terminate them yourself), but apparently they are better at handling the voltage range of an RV or boat due to something (?) about their design.

I have a few more fixtures to either convert or buy different ones (to go LED), but am waiting to see how it goes before going all out.

Sorry if this took over too much of the thread. It started "innocently," just because I wondered if the other poster who mentioned the Marine Beam bulbs had heard any high-pitched sound.

Scalf77 · 04-07-2015, 02:48 PM

Viva,

The fact that he was telling you to use the AC function to look for noise on the DC line does not mean that the noise has to be coming from 120 or AC, so you don't have to be plugged in. Your solar controller would also be a good source for possible switching noise. Also, remembering that you have a Smartgauge. If I remember correct it possibly does some interesting things that could also induce some noise. It would be at least worth disabling to see if noise went away. The noise is most likely coming from the their own DC to DC converter, they look like a good company so hopefully they just had a manufacturing escape.I would say make sure your ground and power connections are good, but knowing your attention to detail, I expect you already checked that,

-greg

Viva · 04-07-2015, 05:07 PM

Greg,

Okay, I see what you mean. So just using that AC voltage setting to look for the ripple. I checked during the day on purpose, so the solar controller would be "on" (although the lights whistle at night, too).

On the Scangauge II: Do you mean it could do something even when the rig is parked and no keys in the ignition? If so, I'll unplug it from the OBD port and test again. I think the rest of my connections/grounds are in good shape (but hey, grounds are often a culprit, so I hear you).

One of their guesses was that the noise was coming from the.... erm... don't have my notes on me to remember their exact words, but something like a capacitor in a constantly switching power supply that is in the bulbs (which enables them to deal with a wide range of DC voltages) (will look at notes in case that sounds like nonsense). Essentially something in the light vibrates against something else in it.

I should get the new bulbs early next week, which means that if I put them in and test, I won't have changed any other variables. So we'll see. They're also including a prepaid return slip so that they can check out the noisy bulbs. Will be interesting to see what we find out.

I may also change one of my other (same) fixtures with the cheapo LED stick-on strips, since I have a roll of those on hand. Just for comparison. Sounds like they are not as robust, but it's always interesting to see how something works.

As I mentioned before, I have other bulbs of theirs (festoon style) and have been very happy with them.

Thanks for your input!

boywonder · 04-07-2015, 05:21 PM

Quote:

Originally Posted by Viva

One of their guesses was that the noise was coming from the.... erm... don't have my notes on me to remember their exact words, but something like a capacitor in a constantly switching power supply that is in the bulbs (which enables them to deal with a wide range of DC voltages) (will look at notes in case that sounds like nonsense). Essentially something in the light vibrates against something else in it.

Switching power supplies can be noisy....especially low cost supplies...

Scalf77 · 04-07-2015, 06:14 PM

Quote:

Originally Posted by Viva

Greg,

On the Scangauge II: Do you mean it could do something even when the rig is parked and no keys in the ignition? If so, I'll unplug it from the OBD port and test again. I think the rest of my connections/grounds are in good shape (but hey, grounds are often a culprit, so I hear you).

I was thinking more about the Smartgauge Battery monitor, reading on some of the possible implementations of how that might work, it is anything but a voltmeter.

-greg

Viva · 04-07-2015, 11:00 PM

Oh sorry, you did say Smartgauge. I need to learn to read! I have a Smartgauge but it's still in the box - part of my "it's going to be installed any day now, honest" electrical system upgrade

I looked at my notes on the bulbs. They have a "switch mode power supply" with capacitor(s). I wouldn't think that Marine Beam would use a particularly cheap one (at least they strike me as "the real deal" electrical quality nerds), but there is one in the bulb, as I understand it. IIRC, this is what makes it able to easily handle dimmers and/or the 11 volt to 15 volt range of DC power in boats/RV's. <--- Keep in mind that I may have a detail wrong here - just going by my notes from my phone conversation with Marine Beam.