ACID TEST

A bonanza of batter y info from tray restoration

SOME TECH ARTICLES take many months to plan and execute. Project cars, which can encompass years’ worth of tech, tweaking, testing, and road trips, can obviously take even longer.

There’s another category, though, which pops up occasionally: Tech that just sort of happens. What you’re about to delve into falls into that latter category.

Mopar Action’s first

conceals a moderately tweaked 451 stroker 400. With the massive RV2 “Thumper” cast iron Airtemp V-twin air conditioning compressor, and no attempt at weight reduction, it’s never going to be a serious track car. Still, down through the decades it has proven to be a reliable, fun, good handling cruiser. The paint, sprayed on nearly 25 years ago by our own Tony “Little Ant” Crecco, has held up well—with one somewhat annoying exception: battery acid has eaten away both paint and primer on a large portion of the battery tray, and the now-bare-and-exposed steel was pretty rusty and nasty looking. Butt-ugly, in fact.

The plan was to remove the tray, clean it up, and find some reasonable touch-up paint solution (after all, it’s a battery tray, not the middle of a door or hood.) Still, this would be an ideal way to test the validity of online claims from companies that purport to sell exact-match paint in pressure-packed shaker cans. Supposedly, if your car is a stock color, all you need to give them is the year and paint code, and a few weeks later, a package arrives in the mail with aerosol cans. Sounds too good to be true, but we’ll find out.

If you’re nervous about painting your battery tray, Ebooger will create a one-of-a kind signed painting of it and frame it in a Louvre Museum gallery quality heirloom frame to be enjoyed by you and future generations. Price on request (not cheap).

Like all 1972 Chrysler products, our car was Lynch-Road painted in single stage acrylic enamel, which is not very different from what Crec laid down when he repainted it circa late 1990s, with one exception from the factory process: not having a toaster oven quite large enough to fit a 1972 Road Runner, Tony added a chemical catalyst (“hardener”) to the brew to speed cure time.

We unbolted the tray—a 2-minute process if you are slow. Removed, and once the roofing felt was scraped off, its condition was way worse than it appeared at first blush—corrosion scars were deep and covered the inside almost totally. While it could have, no doubt, been repaired if there was no alternative (think: Bondo), reproduction trays are inexpensive, so we whipped out the gold card and had a new one in a short time.

We shaker-canned it, a process that was quite different than what we expected. Rather than repeating ourselves, we’ll let the process, shown in the nearby cell phone photos, be explained by way of the accompanying wordy captions.

Once reassembled, we then began to think about why this had happened. Despite our best-laid plans to line the tray with said roofing felt, the long-term outcome was less than desirable. Experience has shown that there’s only one reason why any lead-acid battery releases corrosive acid: overcharging. While our winter storage regimen has, for 20+ years, included a precise voltage-regulated charging regimen, designed specifically to prevent overcharging (and extending battery life by negating sulfating), somewhere down the line, this had clearly failed. Turns out that the fault lay with the Mopar Performance “reproduction” voltage regulator, which produced charging voltage which far exceeds FSM parameters, and, likely, is not temperature regulated, a real no-no for any street use. The fix also turned out to be quite different than what we expected and involved some literal twists and turns.

So, follow along, then, as we put the paint to the metal—and the amperes to the acid.

Held against the radiator yoke, it was a decent match—certainly good enough for a battery tray, but maybe not for an exterior panel touchup / blend job.

Corrosion on the battery tray, which had been painted with the car (correctly) ’bout 25 years ago. It smelled like lacquer. We tested it with daub of lacquer thinner. Lacquer it is, sad to say.

It didn’t look too much worse with the battery out, but then... Of course, it hadda be painted. We ordered an “exact match” (1972 paint code FE5) from AutomotiveTouchup. The first hint of trouble was the designation “basecoat” on the label. We had assumed, wrongly, that when you order paint for a 1972 car, it would be single stage.

We made an executive decision: proceed anyway. We peeled the labels off the repop tray and cleaned it up with solvent.

... we removed it and scraped up the roofing felt. The logical fix: A repro tray. Nothing to do but try it. We sprayed some on a piece of white cardboard and let it dry. The stuff did cover pretty well. But, as we feared, it dried to a virtually flat finish.

...the FSM’s chart.

We bolted it right back in. Lookin’ good.

...the only thing that can cause this: An out-of-spec voltage regulator. We jerry-rigged it (case must be grounded), and set it for...

We wire brushed the terminals, greased ’em up, and hooked it up. All good. We tried s slew of NOS regulators, and a few aftermarket cheapies. While they were within spec., they were all on the high end of the acceptable range (14.2–14.4 V.) ...13.9 volts. This will drastically increase battery life.

With the engine at fast idle, and an ambient temperateure around 75°, the voltage was over 14.9. There’s the trouble! Overcharging, as proved by... So, we found an adjustable regulator on eBay, from seller mcgworld_1. We added a piece of Scotch 88 electrical tape to weatherproof the potentiometer, then mounted it to the firewall. Done!

B AT T E R Y B A S I C S

ALL LEAD ACID CELLS, regardless of any other construction details (type, size, etc.), produce 2.1 volts fully charged. Link six of them together in series, and you AGM batteries (left) have numerous have a 12.6 volt advantages over “old school” liquid acid battery, exactly what batteries. The one shown here are all every Mopar built made by East Penn Mfg., who operates between 1956 and the world’s largest battery plant in—you 2022 came equipped guessed it—Pennsylvania—the small town of Lyon Station (pop. 478). I have with. The basics of had very good results from their prodlead-acid batteries ucts, what are also sold under various has not changed “store bands” (Diehard, Duracell, etc.) since French physicist Gaston Planté invented these in 1859.

Today, there are two basic subsets of lead-acid batteries available for our Mopars: First are the usual standard Most cellular phone towers use banks of liquid sulfuric acid AGM batteries for backup. batteries, most of which are semisealed, but all of which can spill acid in a collision, or explode due to overcharging. The second is known as AGM – absorbed glass mat. In this design, the acid is completely absorbed into the plate separators, which are made of fiberglass. I have used this type of battery with great success and longevity. The first brand I bought, in the 1980s, was Chloride. They had a full lifetime warranty, and, while they did not last my lifetime, they were amazingly reliable, and were replaced under the warranty when needed. These have been my go-to battery for the last half-decade. They are only, on average, maybe 50% more expensive than liquid acid types, and worth every penny. They can even be safely mounted in any position, and, even if punctured, produce near-zero safety risks.

Today, we now have a third choice, which we examined in last issue’s “lightweighting” tech series: Lithium Titanate. We tried one from XS Power, and it blew us away with cranking performance only dreamt about heretofore, and the weight reduction was incredible. The downside is cost, but you get what you pay for.

Lithium batteries are clearly the way forward. This XS Power Group 24 has performance almost beyond belief, and is super-safe, and super lightweight.

BUILD IT BET TER!

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