Archives for December 2014

Dec 29 2014

How my Airstream lost its mojo in the carport

Next week I’m going to camp in the desert in California, and so I’m getting the Safari ready now. I’ve learned that anytime the Airstream has been sitting for a while, it’s best to start checking all the systems at least two weeks in advance. That way the little problems that sometimes crop up during storage can be resolved without a last-minute panic.

I figured I’d find something that needing doing, but was completely surprised by what turned up. The Tri-Metric battery monitor was reporting the batteries were at 73%. Since the Airstream has been continuously plugged into power since late August, this was clearly suspicious. The batteries should have been at 100%.

The Tri-Metric 2020 (by Bogart Engineering) is one of several amp-hour meters you can install in place of the existing battery monitor that came with your travel trailer. I recommend this upgrade to everyone, for reasons I’ve outlined previously. It’s about $200 plus installation, and well worth it for anyone who ever camps off-grid, has solar panels, or just wants to know what’s really going on with their batteries.

The Tri-Metric is highly accurate. It “counts” every bit of power (in amps) that goes in or out of the batteries, so when it reports 73% charge, it’s pretty darned close, like within 1-2%. We’ve had that Tri-Metric running in the Airstream for nine years and it has always been reliable.

So the first thing I checked was that the Airstream was in fact receiving power. That was simply a matter of looking at another meter in my case, but if you didn’t have one, turning on an AC-powered appliance would verify power as well. Just plug in a lamp or something.

The second thing I checked was that the power converter/charger was doing its job. You might recall that earlier this year I switched from the factory-installed converter/charger to an Intellipower 9260 with Charge Wizard. This was in order to get better battery charging when we were plugged in. The factory put in a 2-stage charger, and the Intellipower has three stages, plus somewhat more “brain” so it doesn’t overcharge the battery, and the option of manual overrides using the Charge Wizard.

The Tri-Metric answered this question too. It was showing that the batteries had a tiny rate of discharge, about -0.05 amps. Turning on additional DC power consumers (lights, fans, water pump) revealed that the rate of discharge never changed. That’s because the Intellipower was doing at least part of its job, stepping up the power input as needed to compensate for DC power draws. If the Intellipower wasn’t working at all, the Tri-Metric would have shown a dramatic increase of discharge.

Now, to understand what’s coming next, you need know something about the way batteries charge. A fully charged “12 volt” battery really runs about 12.7 volts. (This varies by the type of battery chemistry used, but here I’m referring to the typical “wet cell” lead-acid batteries that come with your Airstream.)

Think of volts as electrical pressure. In order to get 12.7 volts into the battery, you have to “push” power into the battery a little harder than 12.7 volts. The harder you push, the faster the power goes in. But there’s a limit to how hard you can safely push, so for this typical sort of battery the manufacturers usually recommend about 13.6 volt for a normal charge. When the battery is really empty you can push a little harder (meaning more volts), and when it is nearly full you have to back off and push more gently (less volts).

The Intellipower, like many other RV converter/chargers, has pre-set levels at which it charges the batteries. If the battery is full or nearly full, it charges at “storage mode” rate of 13.2 volts. This keeps the battery topped off, compensating for a little “self-discharge” that naturally occurs with lead-acid batteries.

If the battery is somewhat discharged, the Intellipower steps up to 13.6 volts. This is the “normal mode” of charging.

If the battery is really discharged and needs a bulk charge quickly, the Intellipower goes for broke and pushes hard at 14.4 volts. It will only do this for a little while before returning to the normal mode of 13.6 volts.

Those are the “three stages” that I was referring to earlier, and it works just great for conventional batteries.

With the trailer plugged in, the Tri-Metric was telling me that the battery voltage was steady at 13.2 volts. That’s not the actual voltage of the battery, because it was receiving some input from the Intellipower. To get the true voltage, I disconnected the AC power and waited for the battery to have a chance to “settle”.

Ideally I should have let it settle for 24 hours with no charge or discharge (e.g., disconnected), and then measured at 77 degrees, but I was impatient and didn’t want to disconnect the battery at that time, plus it was cold outside. So I waited six hours with a very small load on the battery (from the refrigerator’s circuit board and a few other small “parasitic” drains), and checked the voltage again. It was 12.7 volts, which in a conventional battery would indicate that it was about full.

If this had been the end of the story I would have concluded that the Tri-Metric had somehow lost calibration and wasn’t counting the amps correctly. But that just didn’t sit well with me. The Tri-Metric seemed to be acting normally. After six hours of the trailer being unplugged, the Tri-Metric was reporting a 70% charge, which seemed about right. Something else had to be wrong … but what?

The answer surprised me. Long ago we replaced the original Airstream batteries with an Absorbed Glass Mat (AGM) battery. These are sold under various brand names, such as Optima. Ours happens to be a Lifeline 4D model. I looked up the charging requirements for this battery and discovered that it has entirely different voltage requirements, as follows:

Absorption Charge voltages (“normal mode”): 14.2- 14.6
Float Charge voltages (“storage mode”) 13.1 – 13.4

Although the Intellipower charger was supplying power to the battery, it just wasn’t enough. When the battery wanted 14.2 to 14.6 volts, the charger gave it 13.6 volts. Sitting in storage, the charger gave it only 13.2 volts, which was fine for a while, but not enough to maintain the AGM’s rated “full” level of 12.9 volts. The battery gradually lost power.

The upshot for you is that there’s a dirty little secret about most power converters: they aren’t optimized for charging AGMs, at least not the Lifeline ones. In our case, the Intellipower documentation doesn’t address this, and factory voltage output settings can’t be changed. I checked a few other popular brands and found they are exactly the same. Only a few brands, like Xantrex, have the built-in capability to push the correct voltages needed for AGM batteries. If you have switched to AGMs and haven’t upgraded your converter/charger to the right brand, your battery is going to have reduced capacity as well.

The really peculiar thing about this is that it took eight months for my problem to crop up. Why didn’t I notice a charging problem before?

Because we have solar panels, and a separate solar charge controller (a Blue Sky Solar Boost 2000e). The Blue Sky charger can be programmed to output a range of voltage, so you can optimize it for your batteries. The factory default on that device is 14.0 volts (compared to 13.6 volts on the Intellipower), and that makes a huge difference. So when we were parked outside, our batteries were getting their last 27% of capacity courtesy of the sun and the Blue Sky—and I didn’t realize it until now.

At home, our Airstream lives under a carport, so the solar panels don’t produce any power. And, in colder temperatures, it takes a little more power to charge the batteries—about 0.5 volts more. (This is just a weird battery chemistry thing.) So after four months of sitting in the carport with slowly declining temperatures and inadequate voltage from the Intellipower, the battery slowly lost power and the solar panels weren’t there to save the day.

It’s possible the battery still is underperforming. I’m going to test it this next week when I take the trailer out of the carport and go camping for a week. If I’m right, a full charge should be possible in the sunshine, and then I can “equalize” the battery using the solar charge controller (which goes to 15.2 volts in equalization mode), and exercise it through a few charge/discharge cycles.

I may also adjust the BlueSky charger for slightly more output voltage. I’ll have to do that after the battery has reached full charge. It may already be at an optimal setting, but since I don’t know, it will be a good exercise to check it once we have full sun.

If the battery is fine and it comes to a full charge next week using solar power, I’ll have to start looking for a better converter/charger. It’s a bummer to have to replace that unit again, but with the right unit in place the battery should charge faster when plugged into AC power—and most importantly maintain its state of charge all winter long.

Dec 22 2014

Things polishing taught me

For years I’ve seen the amazing mirror shines that people have put on their vintage Airstreams, and I’ve thought, “I’ll never do that on my ’68 Caravel.” My impression of polishing was that it was an exercise for (a) people who are trying to pump up the re-sale value of a trailer. i.e., flippers; (b) people who think a day spent detailing a car for a show is a day well spent, i.e., (to my point of view) masochists.

Well, there I was on Friday and Saturday of this past weekend, in the driveway spending most of the daylight hours with a rotary buffer in my hands … and so I have to admit that my assessment was far too harsh. There are good reasons to polish a vintage Airstream that go beyond financial profit or masochism.

As I said in the previous blog entry, the impetus for this project was Patrick’s offer to come down with a batch of Nuvite polishes and tools, and show me how to do it. It was impossible to say no to that. So despite my earlier prejudices, I’m now one of those guys who has polished his Airstream—and you know, it’s kind of cool.

In the course of the two days, I learned many things, such as:

Polishing isn’t as hard as I thought. I had imagined severe muscle strain from holding a heavy rotary buffer, and excruciating effort to reach every little crack and seam. Actually, the buffer did all the work and even the edging work wasn’t that bad.
It’s not as messy as I thought. I suited up with a long-sleeved shirt, vinyl gloves, and a baseball cap, so my skin was barely exposed. I thought I’d end up covered in black aluminum oxide, but it wasn’t much at all and it washed off easily. Even the driveway cleanup was easy: just a push broom to sweep up all the little black fuzzies that came off the buffing pads. However, I’m glad I chose to wear my cheap sneakers.
Polishing actually “repaired” the surface of the Caravel’s metal body, at least at a microscopic level. After nearly fifty years, the skin had a lot of pitting and scratches. The polish moves the metal around so that pits and scratches get filled. I was amazed to see lots of little scratches disappear.
The neighbors love it. I was concerned that two days of buffer noise, flecks of black polish getting flung around, and the sight of us working on a vehicle in the driveway in defiance of our neighborhood’s antiquated deed restrictions, might cause some of the neighbors to get a little upset.Far from it—people who were passing by paused to wave or give us a thumbs-up. Yesterday a neighbor dropped by to say how amazed she was with the shine. Turns out that polishing a vintage Airstream is kind of like having a baby. Everyone praises you, even though it’s noisy and messy. Now my Airstream has been transformed from a kind-of-cool “old trailer” to a showpiece.

The only unfortunate part of this is that we ran out of time. Patrick came down from Phoenix on Friday so we didn’t get started until noon, and both Friday and Saturday we had to stop around 5:30 because we ran out of daylight. It’s hard to get big outdoor projects done near the Winter Solstice. (I suppose I shouldn’t complain—many of you are buried in snow right now.) On Sunday we both had other things to do.

We got as far as polishing every section of the trailer two or three times in Nuvite F7 (with F9, a more aggressive grade for a few heavily pitted areas). We also managed to do about 90% of the trailer with the next grade, Nuvite C. Realizing we would run out of time, we finished just one panel with the final grade (Nuvite S) using the Cyclo polisher and some towels, just to see how it would look. That’s what Patrick is doing in the photo above.

It’s fantastic. The shine is definitely mirror grade. The metal still has lots of blemishes (deep scratches, minor dings, and pits) but from more than five feet away all you see is a reflection of the world around the Airstream. Click on the photo for a larger version and notice how well you can see the palm tree in the reflection. You can even me taking a photo.

Compare that section to the panels above, which have been done up through Nuvite C but haven’t had the final step yet. The blackish smudging on the upper panels is just some leftover polish that we haven’t cleaned up with mineral spirits yet. It wipes right off.

Since we are both tied up with holiday and year-end stuff, and then I’ve got Alumafiesta prep to do, Patrick has offered to come down for a day sometime in January to do the final work on the Caravel. That should take him about 4-5 hours. If I can help, I will. In any case, the Caravel will be on display at Tucson/Lazydays KOA during Alumafiesta in late January 2015, so if you are coming to that event you can see for yourself what we did.

Dec 12 2014

The polishing project

Although the North has been dealing with winter storms and the usual inconveniences of winter, down here in the southern Arizona desert it’s the best time of year for outdoor work. For the past couple of years I’ve taken the opportunity to do major Airstream maintenance between mid October and January, taking advantage of the cool and generally dry weather we get at this time of year.

This time around it looked like I might get away with just chilling out, but then Patrick called and prodded me about getting the Caravel polished. He’s The Guy from Nuvite Chemical Corp., and if you have a vintage Airstream you probably know the name Nuvite. It’s the premiere polishing compound used to make Airstreams shine like mirrors.

Now, Airstreams never came out of the factory with “mirror shine.” They generally had a sort of matte shine, the color of factory-fresh aluminum (which of course is exactly what they were.) You could see yourself in it, but not very clearly. With time, the aluminum would gradually oxidize to a dull battleship gray color, not particularly attractive, which is why Airstream began applying a clearcoat in the 1960s. The clearcoat delayed the oxidization so the trailer looked new longer.

But eventually the aluminum oxidized anyway, and so vintage trailers owners have a choice: live with the dull patina, or get to work with some polish. Polishing is a labor-intensive job, so for my 1968 Airstream Caravel I chose the path of least resistance for many years. I had the clearcoat chemically stripped off back around 2005 when Colin Hyde was doing some sheet metal replacement on it, and then around 2010 my buddy Ken took it upon himself to do a polishing pass on the trailer, to even out the differences between new metal and old. But the Caravel has never really been super-shiny, and lately it has oxidized back to a patina that belies the trailer’s 46 years.

The photos below show what I’m talking about. The first photo is a 1953 Airstream Flying Cloud that we used to own. It is fully oxidized. Once a layer of oxidization forms on the trailer, it protects the rest of the aluminum and doesn’t deteriorate further. So there’s no harm in leaving it like this, but it’s not very pretty. (The streaks below the reflectors are from rusting steel trim around the reflectors. This trailer had been sitting for over twenty years when we bought it.)

The second photo shows another 1953 Airstream Flying Cloud, but nicely polished. (It belongs to Dicky Riegel, former president of Airstream and more recently the founder of Airstream2Go.) Hard to believe that the metal can go from one state to the other, but it’s absolutely true. This is what you can do with a few cans of Nuvite and some work.

Enter Patrick. He is The Guy who goes around the country demonstrating how Nuvite works. I can’t figure out how he does it, since polishing is a demanding task that involves holding a heavy power tool against the trailer body for hours. The black aluminum oxide stains your clothes and skin too. Yet Patrick is always smiling when I see him, and his fingernails always seem to be clean. He seems to think he has the greatest job in the country.

That must explain it, because he called me and reminded me that months ago we talked about polishing the Caravel. He certainly could have let it go, since I wasn’t chasing him, but instead he’s going to drive down from Phoenix on December 19 and spend a day or two in my driveway showing me how Nuvite can turn the Caravel into a mirror-like “jewel.”

I’m going to help him, or at least attempt to. I’m pretty sure he can finish the trailer before I figure out how to get my gloves on, but he’s a good sport and willing to give me lessons on technique. I’m also inviting some local friends to drop in and observe or help. With luck this might end up as a Tom Sawyer-esque episode where all my friends help do the work.

If you are in Tucson or willing to drive down on Dec 19, ping me and I’ll give you directions to the fun (email: my first name at airstreamlife.com). If you want to observe from afar and keep your clothes clean, I’ll post photos here of the process.

I also hope to learn more about the chemical process of polishing. It’s interesting in a geeky way. From what I know so far, we aren’t removing anything from the aluminum, but rather “turning over” the surface material chemically. I’ll ask Patrick for details. And if you want to see the trailer in person, drop by Alumafiesta in late January. I’ll have it on display in the campground or inside the Event Center.