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.
Bench (Tailgate) Testing
Before we hooked the batteries up for our torture tests, we used AutoMeter’s sophisticated hand-held BVA-260 battery tester. We chose it because it has built-in features that to date were only available in either many separate units or in large rolling-cart style testers. In addition to the CA, CCA, and AH testing we performed, it is capable of testing starters and alternators as well.
We tested both of the batteries from each manufacturer, and while the actual measured ratings between individual batteries were very close, we took the mean of the measured rating for the numbers we’ve included here.
The idea behind the winch test was to drag Trasborg’s 6,500-pound M-715 up a steep sand hill and measure just how far we were able to do so.
As the motor temperature goes up, so does the amperage required to do the same amount of work, so it was important to keep everything at the same temperature across the board. After speaking to a major winch manufacturer, we were advised that the internal resistance of a winch could do unpredictable things over 150 degrees. That is, it can increase at different rates over many different pulls. Not that a winch will stop working over that temperature, we’ve all done it before. Since we were engine-off how well batteries did, we opted to make sure the winch stayed below that temp and in the same range for every battery. To do that, we used a Ryobi Tek 4 digital infrared thermometer and tested the temperature of the winch during every pull. Between pulls, we tested the voltage of the batteries with a Ryobi Tek 4 digital multimeter.
We weren’t sure how big of a hill we’d be able to pull the M-715 up, nor were we sure what size winch we’d need. So, we got both a 9,500-pound (Seal 9.5 rsi) and a 12,000-pound winch (DV-12 Light) from ComeUp Industries. We then used a receiver mount (PN 881084) and attached it to the front of Feature Editor Verne Simons’ flatfender. Of course, a 3,000-pound flatfender doesn’t have much chance of pulling a 6,500-pound M-715 up a hill, so we parked the flattie on the back side of the dune and dug it in until it didn’t move when winching. The 9,500-pound winch didn’t quite get the job done, so we switched over to the 12,000-pound winch. Over the course of 3 days we did about 50 pulls, about 40 of which lasted for just over 4 minutes each.
The idea behind leaving the lights and stereo on in the Jeep was a good one, but none of us have a Jeep with much of a stereo. A quick at-home test showed that even cranked all the way up, a factory stereo would last somewhere between 10 and 30 hours. We did the quick math and that had us out in the desert listening to music for 100 to 300 hours (anywhere from 4 to 12 days). That just wasn’t happening.
So, Trasborg decided to get fancy and build a boombox that would draw more power. Using a 20-year-old Soundstream Reference amplifier helped things along. Older amplifiers are much less efficient than today’s amplifiers. Since it was a five-channel amplifier, he hooked up five Kicker speakers. The box needed to be somewhat man-portable, so it got a pair of 5 ¼-inch speakers, a pair of 6x9 speakers, and an 8-inch subwoofer. It was all fed by an old Sony head unit and whatever CDs Simons could scrounge up on short notice.
But that alone didn’t draw enough power so Trasborg added 620 watts of old-school halogen lights. All told, with the lights and music cranking, we were able to draw a fairly consistent 40 amps as measured with an AutoMeter DM-40 inductive AC/DC clamp meter. We then ran the lights and stereo until it shut off which happened right around 9 volts. Much too low to start many Jeeps, but when hanging out around the fire, it isn’t all that uncommon to just let the stereo run until it shuts off.
Since we were dealing with many batteries and we wanted to make sure that every battery was topped off and as ready to go as possible between rounds of testing, we used the BusPro-660 from AutoMeter. It is optimized for AGM batteries but also has no problems with regular wet batteries. It is capable of charging and maintaining up to six batteries at a time. It has six leads and each one is independently computer-controlled. It can then decide if a battery is good or bad as well as if it requires charging or just maintaining. Once the light goes solid green, the battery is fully charged and ready to go.
Some of the batteries came back with errors as according to the BusPro-660. When that happened, and it did happen from time to time, we put the offending battery on the Optima Digital 1200 charger. While it is optimized for Optima batteries, it is perfectly capable of charging even wet cell batteries. It has advanced computer-controlled programming that is capable of analyzing a battery and then determining the best way to proceed with charging it. Using this, by the end of the test any battery put back on the BusPro would eventually show green for good.
Since we were in the middle of the desert, we needed 120 VAC power, so all the chargers were run off of a generator to bring the batteries back to life before testing them again.