@oblivion
With those conductance/capacitance testers, you must enter the battery’s size, in cold cranking amps
The cheapos will tell you pass or fail, and the voltage
The more expensive ones will tell you all that, plus the measured cca of the battery, percentage of rated capacity, and a few more things
Back in the “good ole days” it was SOP to use a VAT 40 or similar piece of equipment to test batteries by replicating the current demands for starting a car 3 times in a row and if while doing so the voltage never dropped below 11v and returned to 12v+ aftereward the battery was good to go. A normal start for a Chevrolet 350 engine pulled a momentary 550+/- amp draw and 350+/- amps for a few seconds until the engine started. Of course cold weather would increase the amps and drop the voltage. But if a battery’s voltage was not quite up to expectations after the 3d loading I would crank the engine and if the starter would ‘eagerly’ spin the engine without the voltage dropping below 10 under load it was considered OK.
Of course there’s more than one way to skin a cat. And a hydrometer and anode/cathode cell tester were great for verifying a bad cell. But if a fully charged battery is unable to provide starting current for 3 repeated efforts it isn’t reliable.
When I was young there was a battery shop in town that would not install a battery in a car with a radio. The shop owner had seen too many batteries fail prematurely due to radios running them dead. Back then radios had tubes and used more current than the headlights and batteries were somewhat weak.
My how times have changed.
@oblivion: based on what you’re saying, it sounds like the printout for my new battery may indicate a problem. Since the battery was warmer than 0 degrees, it should have tested above it’s rated capacity, and it didn’t. However… what @db4690 is saying about what the tester requires is quite accurate. I pulled the model number from the receipt and googled it. There is an option on the tester’s menu to enter the battery capacity.
So, I’m still a little unclear on whether this indicates a problem or not. A lot of the info here is saying that based on the temperature, the battery should have no problem testing at the advertised CCA capacity. But, I’m not certain if the tester produced a skewed result because it thought it was testing a 650CCA battery and not an 800CCA. If the tester is basing it on an algorithm or something and is not able to actually test the true CCA, than that would explain the result. However, the ~400CCA rating of the old battery is what prompted them to recommend replacement, so the test results must be accurate to some extent.
CCA results aside, I hear you guys on the spark plugs. I agree that it needs to be done, however it’s just not something I’m going to run out and have done tomorrow. The battery was already unexpected, considering I had my car in for suspension service 3 weeks ago and I was told they had checked the charging system like I asked. I need to plan for the expenditure, and also explore the option of possibly having my brother do it if he’s willing.
Answer me this… if you received that printout after having the battery replaced, would you go back and question them on it? The car is fine now, it starts quicker than it ever has before. It’s moreso just making sure I got what I paid for. I paid $35 for install when I could have had it done for free with my suspension, and I paid an extra $25 to get the “Gold” style battery. I felt good about the purchase, but then felt kinda let down when faced with the possibility that the battery isn’t testing the way it should.
In case you’re curious, here’s a transcript of the printout.
MIDTRONICS
MDX-P300
BATTERY TEST
GOOD BATTERY
Volts 12.63V
Measured 718CCA
Rating 650CCA
Bat. Type Regular
Bat. Location In Vehicle
STARTER TEST
NORMAL
Volts 11.02V
CHARGING TEST
OK
Volts 13.87V
Differences on the old battery being that it measured for 12.71V / 402CCA. Old battery had starter test of 10.35V and charging test of 14.15V.
That simply means that the tester found that the battery has 718CCA at the time of the test. The rating CCA is entered by the user of the test equipment and isn’t particularly relevant unless you want to express available CCA as a fraction of rated CCA. Sometimes a battery tests above rated CCA, sometimes below. I’ll bet if you tested that battery 3 times with the same tester you’d get 3 different results.
The starter test and charging test are almost meaningless to me because they lack actual amperage readings of the systems at work.