Real-world battery testing, Jp-style
Like so many of our hare-brained schemes, this one started around the campfire after long day of wheeling. The question was pretty simple: “Is it possible to test batteries head-to-head to see which one is the best?” The general consensus was that it should be possible. We immediately thought of an engine-off winch test. You get your Jeep stuck somewhere and the engine dies (whether you are on your side, or facing possible hydrolock)…can your battery get your Jeep out? We had to know, but we also wanted to keep it as fair as possible from battery to battery.
Trasborg took the ball and ran with it. He spent months on the phone with battery, tool, and winch companies to devise a series of tests that would fairly and accurately test batteries against each other. Once that was done, it was time to actually get batteries on hand for testing. Many companies, once told what the testing was to consist of, bowed out. The batteries we actually got to test represent companies that are confident in their offerings and were OK with us printing whatever the results were. In the end, we got to test five different batteries: The Optima Yellow Top, NorthStar, Odyssey, Die Hard Gold, and Die Hard Platinum were the victims.
The testing was to take three main forms: The first test was a bench test of new batteries to see how they hold up against their advertised ratings. The second was to be a winch test which consisted of towing a heavy Jeep up a loose sand hill until the winch stopped pulling. And the final test was designed to simulate how long a battery might last if you ran your stereo and lights when you got back to camp. We weren’t sure if the batteries would come back to life after running them all the way flat during the tests, so we got two of each.
As it turns out, each battery could be brought back to life and showed very similar bench testing marks after the abusive testing. We will be running these batteries in our Jeeps for at least the next year, if not more, and we are open to retesting the batteries after a period of time if enough of you are interested.
A physically larger battery will often outperform a smaller one, so we limited the testing to the most common size battery found in Jeeps: the Group 34. Most of the testing happened out in the California desert over a four-day period.
The letters are all well and good and a good indicator of what a battery is capable of, but most people just don’t get what all the letters mean. Here’s how it breaks down.
AH: Ampere Hours or Amp Hours is the amount of time a battery can put out a number of amps. For example, if your headlights take 5 amps to run, and after 20 hours your battery is dead, it would have a 100AH rating. Not all manufacturers use the same amperage to come up with this rating, which is why we didn’t include it in the “ratings” category. However, we were able to measure each battery for a true apples-to-apples comparison.
CA: Cranking Amps is a rating of just how many amps the battery can put out for 30 seconds at 32 degrees F. It is usually a higher number than CCA and unless you live where it never freezes, kind of useless. If a manufacturer is sneaky, they will sometimes just rate a battery’s “cranking amps” without using the abbreviation in hopes that you might compare their “cranking amps” to another’s CCA.
CCA: Cold Cranking Amps is a rating of just how many amps the battery can put out for 30 seconds at 0 degrees F. If you are shopping for a battery to start your Jeep, this is the key one to pay attention to. The old rule of thumb was that you need 2 CCA per cubic inch to start an engine. So for a 4.0L (242ci) you would need only 484 CCA. However today’s higher compression engines sometimes require more we tend to suggest no less than 650 CCA with more always being better.
RC: Reserve Capacity is the amount of time a battery can maintain a useful voltage under a 25 amp discharge. That could mean your stereo and a few pairs of halogen or incandescent driving lights. It is expressed in minutes and is a good number to look at if you will be doing a lot of engine-off things such as partying at camp.