No power - no charging but seems fine?

[Emittim3]

I have a 1978 Excella 500 that we just purchased. Everything was working well, vintage diag panel showed AC power led lit, batteries were showing almost 100% and the other sensors for the tanks and propane tanks were are working. While the Mrs was using a carpet cleaning vacuum the electrical system seemed to shut off. The AC led is still lit. When I push the button under the AC led to look at the systems, the batteries now show only one led lit ("bad") and all others (tanks, propane) are still showing as they did before. There are no blown fuses, the AC LED goes on/off when disconnecting/reconnecting to my AC power source (our house). No lights work, water pump won't turn on, no AC plugs seem to work. The inverter in the front of the trailer hums (it was pretty hot after she was using the carpet cleaner but doesn't smell burned) and seems to look like there is no damage there. I left it plugged in with everything turned off inside over night thinking the batteries might charge. This morning it was all the same, just AC led lit, batteries still showing 'bad' and all other systems reading what they did before, inverter still humming. It's disconnected now, but what should I be looking into first? (since there are no blown fuses and everything seems to be in order otherwise)?

[DKB_SATX]

First off, assume that panel is a work of fiction until proven otherwise.

Get a multimeter. Measure what's really going on and go from there.

What you're calling an inverter is probably a CONverter/charger, and if it's humming (not fan noise but hum) it's probably ancient and ready for an upgrade. Unless your trailer has been radically modernized, the "household plugs" (the 120v plugs) don't really have anything to do with batteries or the converter/charger. They're directly energized from the shore-power cord via a 30A breaker box (it should have 1 30A main and a couple of 20A house breakers) This may be in the back of a closet or under a bed. It's possible that the vacuum cleaner caused one of the house breakers to trip.

[Belegedhel]

I would start by getting a decent multi-meter and a wiring diagram for you year of trailer. The wiring diagrams are in the shop manuals, but maybe a forums member could shoot you a scan or pdf.

Next, get familiar with the theory of electrical distribution in your trailer. You (should) have two systems, a 110 V AC system that delivers power directly to your outlets, the converter (univolt battery charger), and the air conditioner, and also a DC system that sends 12V DC to things like your overhead lights, vent fans, water pump, etc.

Next, disconnect that univolt converter and replace it with something modern. Call BestConverter.com if you need guidance.

Now, figure out where your fuse panels are. The 110v AC breakers will look something like a typical household breaker and will be in a small household style metal box. The DC fuses might be built into the end of the univolt. This is all assuming the previous owner didn't change them out with something else. You may also have automatically resetting breakers/fuses, which will only make trouble shooting more difficult. I would start by unplugging everything from every outlet (including the converter), getting your meter out, and start at the AC fuse box to figure out where you have power and where you don't.

good luck!

[uncle_bob]

Hi

You are talking about a 40 year old trailer here. It may have had a number of owners. Each may have had their own ideas about what should go where. The stock wiring diagrams are a great start, but "trust but verify" applies here. A systematic approach is the only way to stay sane in the long run. Multimeter and patience is a good combination in this case.This is not the last "surprise" you will have. Take notes as trace things out.

One of the first questions on any "new to you" trailer should be - how old are the batteries? Right after that would be - how old are the tires? Following that one - how long since the brakes were checked? Batteries over 5 years old are worth swapping out. If you have the original Univolt charger / converter, change it out at the same time. Tires over 6 years old deserve a really close look anything much past that needs to be swapped out. Both tires and batteries have codes on them showing when they left the factory.

None of this is intended to stop your fun. Just plan to work stuff in as you go along. Accept that some things will need to be done. Do some research on the options so you don't make a "repair" that you then re-do a year or three from now. It's something you can fill the evenings with rather than watching that BluRay disk for the eighth ( or is it nine on this one ) time.

Have fun !!!

Bob

[Emittim3]

Thanks. I'll post what I find. There is a fuse box in the front, seemingly original, but I'll check for any later additions. And I'll heed the recommendations for the converter modernization. The existing one seems newer than 78, but old in its own right. Seeing as it isn't bolted down to anything within the original storage box up front under the couch seems to mean that it isn't original, but is in the original placement. The two Optima deep cycle batteries are good ones, but I've yet to check the age on them. I do have a battery tester and will see if they're worth anything any more. The previous owner (second owner) just let it sit for two years after he bought it, so I'm doubting they were every charged/cycled so may not be worth anything any more.

[A W Warn]

Originally Posted by Emittim3

Thanks. I'll post what I find. There is a fuse box in the front, seemingly original, but I'll check for any later additions. And I'll heed the recommendations for the converter modernization. The existing one seems newer than 78, but old in its own right. Seeing as it isn't bolted down to anything within the original storage box up front under the couch seems to mean that it isn't original, but is in the original placement. The two Optima deep cycle batteries are good ones, but I've yet to check the age on them. I do have a battery tester and will see if they're worth anything any more. The previous owner (second owner) just let it sit for two years after he bought it, so I'm doubting they were every charged/cycled so may not be worth anything any more.

There is also a breaker box for the 120v system. In the 1978 31' I owned it was in the nightstand beside the bed. (mine was a rear bedroom double bed)

This is a link to a copy of the Owners Manual, you can download if you do not have one.
https://www.airstream.com/wp-content...xcella-500.pdf

Google "Best Converter" and find a phone number for Randy. He is a member on this forum. He is very knowledgeable and helpful in selecting the appropriate converter for an Airstream.

[uncle_bob]

Hi

There are a number of places you can buy a new converter.....

Bob

[68 Overlander]

That is likely either a Litton or Traid-Ultra Univolt (converter) and the humming is coming from the transformer. New converters are switch mode type and completely silent except for the fan when it runs for cooling. Back then, Airstream even installed an optional switch to turn that Univolt off at night on the transformer style converters.

[Emittim3]

Yep, it's a Triad TU-750-6 converter charger. I have a feeling that's the issue. All fuses are good on all DC circuits. Not sure if the batteries are good or not under load (testing them today) but if things were working, I should at least have something on the DC circuits, but they're completely dead. AC circuits all work as expected (tested all plugs and appliances that are on the AC circuit) when plugged into shore power.

I've already pulled the converter out, and could take it to see if anyone could test it, but it's old enough where I don't think it's worth bothering with. I need to completely rebuild the battery boxes and converter box up front anyhow. Previous owners really did a shotty job at patching the boxes as they became brittle over time and cracked/broke - covering them with household foam board, duct tape and fiberglass insulation. Inside the converter box was full of dust/debri so hardly any of the bottom screen was open to allow air flow from bottom to the top of the box that is vented to the outside/front.

With a new converter and re-built housing box, I'm thinking of putting in some DC fans in to mechanically move air through the box instead of relying on just having hot air rise out of the box to pull cooler air from underneath.Thoughts on that idea?

So - with the TU-750-6, what brand/model would you all recommend replacement with? I've read a post or few about Progressive Dynamics. But would like to hear experiences and recommendations from those that have been there and done that.

Thanks much!

[fwjumper]

You've checked the 120V breakers in the trailer?

[uncle_bob]

Hi

Unless you are trying very hard to keep everything "original" there is no reason at all to keep a converter from 1978. If it has not failed yet, that's doing very well. Don't continue to press your luck.

A modern fully solid state / switching based unit is a much better way to go ... even if they do occasionally blow up . I would stay away from the sub $100 stuff. You can go up above $1,000 for an inverter / converter combo. There are *lots* of choices in between.

Bob

[DKB_SATX]

It might be a useful test just to plug the converter in on the bench and test its outputs to see if it was actually putting out any voltage at all. If the converter *IS* outputting something north of 13V, then you have a wiring issue in the trailer and you can say "Hey this thing worked when I yanked it out of my trailer" as you toss it into the water to anchor your boat.

[68 Overlander]

Originally Posted by Emittim3

So - with the TU-750-6, what brand/model would you all recommend replacement with? I've read a post or few about Progressive Dynamics. But would like to hear experiences and recommendations from those that have been there and done that.

Thanks much!

The Boonbdocker and the Progressive are the most popular. Both are 4 stage with the Boondocker less expensive and has a better warranty.

[uncle_bob]

Hi

One thing to look at are the physical aspects of the converters. Wire goes in here / comes out there. It's this tall and that wide. When you go to fit it in somewhere it's a good bet that one or the other will fit a bit better ( unless you have a *lot* of room in your trailer ...).

Bob

[Emittim3]

Haven't tested the converter - but as one previously said, it probably makes for a better boat anchor than a reliable converter.

Had the Optima yellow top batteries tested. One was from 2013 and had very little charge, was showing barely 12v and tested "good" on the load tester. The other was from 2011 and was completely dead and the top of the battery showed signs of warping above two of the circular cells. Came to find out that an Optima yellow top is going for $324 these days. Insane! Maybe going with a 'house brand' deep cycle marine battery that is 1/4th the price might be worth it? I can buy 8 of them for the same price of just two Optimas and if I can still get 5 years of life out of them, WTF? Why would I buy an Optima then?

I'll test the converter this evening. But seeing as one battery was completely shot and the other had no charge (although it had been on the charging end of the converter for several days while plugged into shore power) I'm doubting it works - and even if it did I'll still replace it for sanity's sake and see if the local electronics recycling place will take it (lots of copper in there).

[DKB_SATX]

Optima batteries are a marketing gimmick. There are good AGM batteries that don't have expensive marketing campaign and are much more reasonable. Flooded lead-acid Group24s and Group27s are under $100 at places like Costco. As you move up the food chain to AGM prices go up, but you should be able to get 2 new Group27 AGMs for less than that one Optima yellow-top.

[uncle_bob]

Hi

In a lot of cases, you *do* pay for marketing when you buy a battery. That makes figuring out what is what pretty tough. It's also true that none of them are 100% perfect. The manufacturing / distribution process simply isn't good enough for anybody to get there. That said, 80% good is a long way from 98% good ....

Bob