Progressive Dynamics PD-6911 12V Capacity

[thrifty bill]

Still working on the 1977 Trillium 1300, time for some electrical improvements. Fuse holder on my converter was stuck in place, so reluctantly, I had to encourage it out. Usually when I encourage stuff out I will hear that distinct snapping sound when something breaks.... (Encourage = prying it out). But leaving the old stuck fuse in place was not an option. Either it comes out without breaking, or I start shopping for a replacement converter.

Well I got it out, 5 amp fuse was basically melted and one end was broken off! Amazing any of the 12 V was working.

I decided to compare the stock interior lighting load to the capacity of the converter.


Lets see, each incandescent 1141 bulb uses 18.4 watts. So then count the bulbs: 3 above the sink, 1 above the gaucho, 3 above the dinette, and 1 on the side of the closet (vertical, facing the dinette). That's 8 bulbs, for a total of 147 watts. 147 watts divided by 12 Volts = ~ 12.25 amps. The outside door light runs off the same system, if you turn it on, thats another 18.4 watts which brings us up to 166 watts ~ 13.8 amps.

Now running all the lights at once might be unrealistic, but very possible, Certainly running all 8 inside is very possible!

With the 5 amp fuse, my available capacity is 60 watts, quite a shortcoming. If you could find a 6 amp fuse (the rating of the converter), capacity is 72 watts. A 10 amp fuse doesn't really increase the capacity if the converter puts out 72 watts but eliminates blowing the fuse with capacity left.


Seems like a problem here: the converter's capacity of 6 amps, or 72 watts, means only four bulbs can be on at once. That means the sink light and one more light. Or the three dinette lights and the single gaucho light. Don't leave the outside light on or one light will have to be off.


How/why they designed a system where they had over double the demand in lighting versus the capacity of the converter beyond me. Maybe my math is wrong! If my math is OK, then the solution is LED lighting. Instead of 18.4 watts per bulb, the LEDs use about 3 watts per bulb. That means you can run up to 24 bulbs at once.

So I ordered LED lights on Amazon, including several doubles, a reading light, and a single. Two doubles will go over the sink and stove (four bulbs), one double over the gaucho (two bulbs), two doubles over the dinette (one per side, four bulbs total), a single above the rear window (one bulb) and a reading light on the vertical closet wall (one bulb). So 12 bulbs total versus a capacity of 24. I'll leave the outside light alone for now, as even if it is turned on, I'll be below the 72 watt limit.

The doubles all allow for turning on just one light or both (or none). So the additional lighting gives me the option of having more light in an area (like the dark to me gaucho with its current single bulb). And no current light over the stove at all. I'll be positioning the two doubles so one is towards the sink and one is towards the stove.

[thrifty bill]

Fuse out!

1977 Trillium Electrical by wrk101, on Flickr

[mizterwizard]

I went to all LEDs right off the bat when I got the trailer. One thing I found though was that some LEDs get really hot. You wouldn't expect it since they are so much more efficient but it turns out that rather than having a control circuit to limit the current a lot of them just use a resistor in the base. Of course if it is only using 5 watts or less in a fixture that is designed for 20 watts it shouldn't hurt but the resistor is in the base of the 1147 bulbs so the heat goes to a place where it isn't designed to be.

I did my shopping on Amazon and so I looked for reviews that talked about cool running or hot running. It took two rounds of LEDs but I finally got bright white high powered cool running LEDs. Now I just have to figure out what to do with the hot bulbs because it is past time to return them.

[gordon2]

Originally Posted by thrifty bill

...
How/why they designed a system where they had over double the demand in lighting versus the capacity of the converter beyond me. ...

Sounds like things were meant to run primarily off the battery, with the converter only for recharging the battery when things were off (or mostly off). Agree that this system does not seem to be designed to work without a battery installed.

[thrifty bill]

Originally Posted by mizterwizard

I went to all LEDs right off the bat when I got the trailer. One thing I found though was that some LEDs get really hot. You wouldn't expect it since they are so much more efficient but it turns out that rather than having a control circuit to limit the current a lot of them just use a resistor in the base. Of course if it is only using 5 watts or less in a fixture that is designed for 20 watts it shouldn't hurt but the resistor is in the base of the 1147 bulbs so the heat goes to a place where it isn't designed to be.

.

I had similar experience with the LED bulb replacements I used on my Casita. Much hotter than I had expected. This time I am replacing the light fixtures as well. Hopefully the result will be better.

All of the reviews I have read on the LED dome lights commented on the lens creating a weird pattern on the light. Nothing was perfect. None mentioned heat at least.

[wvorih]

Huh

[pedalmike]

Your math is correct. Assuming Trillium spec'd the PD-6911 from the factory, they must have assumed pretty minimal bulb use at any one time.

Output of the PD-6911 is 6 amps as you point out. Spec sheet here

https://www.progressivedyn.com/wp-co.../04/pd69xx.pdf

I'd suggest it's time to get a new converter/charger, even if you switch your fixtures over to LED.

You don't mention whether your trailer has it's own house battery. As you can see from the spec sheet, Progressive Dynamics assumed no trailer battery in the wiring diagram, just a tow vehicle battery.

A newer converter charger allows you to connect to shore power and charge your trailer battery at the same time. The newer ones also offer Multi-stage charging which supports long service life of flooded lead acid or AGM batteries.

[thrifty bill]

No house battery, doesn’t look like it ever had one. Right now I’m sticking with the old converter. My LED lights will draw less than 35 watts if I have them all turned on at once, so it’s well under the capacity of 72 watts.

[pedalmike]

Bill: I understand you wanting to keep the old converter. I'd just recommend you be careful and have good connections with the output fuse holder and the replacement fuse. Sometimes a bad connection creates excess heat/arcing and results in parts that look like the ones you removed from your Trillium.

Mike

[thrifty bill]

Yes I would really like to replace the fuse holder. Not sure how involved it is. Might do like another forum member and put a replacement converter behind the unit.

[mizterwizard]

Originally Posted by wvorih

Huh

I guess a further explanation is asked for?

The diode of an Light Emitting Diode is very efficient at converting electrical energy to light so it doesn't heat up much. It has a stability problem though. The diode, like all diodes, has a negative current-temperature slope. That is, as it warms up it passes more current. The more current it passes the hotter it gets. It's a runaway situation. At some point as the diode heats up it passes so much current that it gets so hot it is destroyed.

There are two general ways to fix this.

The cheap way is to put a resistor in the circuit with the diode that will only pass a certain amount of current, regardless of what the diode is doing.

There are problems with this method though. The LED is probably a 3-5 volt device and is connected to 12-15 volts. That excess voltage has to go somewhere other than the LED. If it goes to a resistor, most of the energy used winds up in the resistor, not making light. The resistor gets hot. It doesn't get as hot as an incandescent bulb though.

Overall it is still more efficient than an incandescent but the heat it does make is in the base, where the resistor is located. Most light fixtures for incandescent bulbs are not designed to have that much heat in the base. They will get hot in the wrong place and in the case of the overhead lights in my RV the fixtures melted.

The better way to control an LED uses an integrated chip mounted in the base of the bulb instead of the resistor. It senses the current passing through the diode and when it gets too high it turns off for an instant. This happens rapidly so you don't notice it. Much less energy is wasted so the light is more efficient overall and it doesn't get hot.

There are two further advantages to this method. Our eyes are sensitive to the maximum light output, not the average light output. We don't notice that there are dark periods because we only sense to the bright flashes. That means the bulb can be dimmer on average but still appear fully bright as though it was running all of the time.

The second advantage is that the LED can be made to put out much more light than it normal would. It would normally overheat if it did this. By flashing it there is less heat build up so the LED can be run brighter if pulsed than it could if it ran continuously.

I know these two things sound like the same thing but they are not. Putting them together, if the light is pulsed at a current flow that would normally burn it out if it was used continuously but the pulses are short so that they average out to be no more than normal, the light will appear brighter but use the same amount of power. That amount of power will be less than a resistor controlled LED because it is all going into the LED, not being wasted in the resistor.

Maybe you don't need that much light but then you can put in a dimmer bulb and have the light you want for even power used.

When selecting LED replacement bulbs it is important to be sure that the ones you get are controlled by a chip, not just a resistor. The best way to sort that out, since the resistor people try to talk like they have a control circuit, is to read the reviews and pay attention to any mention of heat.

I typically shop by price but this is a case where paying a bit more is essential because a chip cost more than a resistor.

I might point out that it isn't always possible to use the peak light sensitivity of our eyes. Most white LEDs are actually blue or UV and they get white light because they have phosphors that absorb some of the light and re-emit the energy as light of other colors to fill out the rainbow. These phosphors are not very fast to respond and tend to average out any pulses which means no bright peaks to fool our eyes.

[thrifty bill]

I guess this needs some pictures:


Double light over curb side dinette, along with reading light on the closet vertical wall:

1977 Trillium LED lights by wrk101, on Flickr


Double light over front gaucho:

1977 Trillium LED lights by wrk101, on Flickr


Two sets of double lights over the kitchen. I replaced the single three bulb unit that was centered over the sink, with a pair of two bulb LED units centered on the upper cabinet:

1977 Trillium LED lights by wrk101, on Flickr

[mizterwizard]

I remember as a child I would sit in a dark corner and read for hours. My mother would say that I shouldn't do that because it would ruin my eyes. Well, she was right. It has taken 60 years but now my sight is dimming. The more lights the better in most cases as far as I'm concerned. What you have done looks good to me.