I had a general work up done on my car recently (say 2 weeks maximum). As part of this, the shop was supposed to do an AVR test to measure my battery strength. I ‘passed’, and was told the charge was good.
Over this past weekend, my battery died while on a road trip, causing me to be towed and an out-of-town shop charge to replace it.
My question is, how far into the future are the results of an AVR test supposed to ‘clear’ the condition of my battery. Did this first shop just not do the test, or could the test have come out ‘OK’ and the battery totally die within 1 1/2 - 2 weeks?
There are several possibilties here.
An AVR test puts a varible load on a battery to assess it condition.
If for example your battery is rated at 600 Cold Cranking Amps, the test should load the battery to 300 Amps for 15 seconds and the voltage at the end of the test is read. It is generaly accepted that a good battery should hold 9.6V or above at this aperage. (assuming 70 degrees F)
[ul]
[li]Now the technician might have not loaded the battery to 300A. This would make the battery look better than it in fact was.[/li][li]The technician might not have run the test for the full 15 seconds. I have had batteries look good at 10 seocnds drop like a rock at 12 seconds.[/li][li]The battery might have just passed the test, and then failed, or the battery in fact failed, and the technician misread the results[/li][li]The battery might have had one failing cell and five good cells. This condition can give an apperance of a good test result, but end up with a tow bill later. (I even had this happen to me on my own car once.)[/li][li]The techncian might have not used a varible carbon pile tester, but rather a fixed load tester (which is way cheaper to buy) these tester hit the battery with a fixed load, which probably isn’t enough to properly load the battery. Result, if this type of tester says the battery is bad, it is. If this type of tester says the battery is good, it might not be.[/li][li]Scumbag did not do the test, and charged you for it.[/li][/ul]
I would suggest that you discuss this with the shop owner. An honest reputable shop will be willing to discuss this with you, and they might wish to make some adjustment on your bill. Be nice but firm, ask them for what voltage the battery held at the end of the test.
Oh and a full electrical test should also include a starter draw test, an alternator output test, and voltage drop tests for both the positive and negative cables.
So, I’m right in thinking it’s about 85% that the technician either F*ked up the test, or didn’t bother doing it.
I should add the following ot my original story:
A) I was told the shop was ‘unexpectedly busy’ and they would try their best to fit me in at my booked time. When I came back, I was ready with no word of the rush mentioned before.
B) I have CAA (Our AAA here in Canada), so I didn’t actually pay for the tow. It could have been far worse, but I’m not happy if this was avoidable.
C) The place that was supposed to have done the work was one of those quickie in & out places (I should know better). I won’t mention the name, but suffice it to say, it doesn’t look like everything they touched turned to GOLD.
D) I don’t seem to have any sort of readout of my test in my papers.
Basically, I probably got screwed like a cheerleader on prom night, right?
Batteries fail in different ways. Sometimes, as with any electrical or electronic item, a battery can go out suddenly with no warning and no detectable signs of imminent failure.
AVR, if memory serves, originally meant “alternator/voltage regulator,” from back in the days when voltage regulators were totally separate from alternators. But in practice, it was–and still is–a combination testing of battery condition, charging system performance, and starting operation. New testing technology is making the procedure described by Rick obsolete, and many shops now use sophisticated electronic battery testers. These generally give a pass or fail readout–“voltage at the end of the test” is not applicable.
The real answer to your question–how far into the future are the results of an AVR test supposed to ‘clear’ the condition of my battery?–is “not at all.” The tests are not predictive. They show the status of things at the moment of testing. Alternators, starters, batteries, etc., sometimes (not always) die suddenly in ways that nothing short of x-ray vision or a crystal ball could foresee.
The shop might have botched the test–there’s no way they can prove that they did it right. But it’s easily as likely that the testing was done properly, and there’s no way to prove that they did it wrong.
Seriously??
I mean, (no offense intended) but that sounds pretty dumb. Why bother ever doing the test then? Obviously, the bloody battery is good enough to start the car when they ran the test…I didn’t need a test to tell me that; just a turn of the freakin’ key!
What I’m driving at here is, if they could start my car to do the test, then my battery is, in essence, good enough to pass…so doesn’t the simple act of turning over the engine become the actual test?
There HAS to be a little more degree of forcasting with this type of test. Obviously, things can happen that no test will ever find and ‘predict’, but this seems so fishy to me. I pick up my car, and no later than 2 weeks later the battery is suddenly dead. And I mean DEAD! A jump start got me maybe 50 feet (luckily to street-level from the 6’4" max clearance underground parking) before it died again. That’s a dead-as-dead-can-be battery is it not? I couldn’t even roll up the power windows! (I was orginally thinking Alternator, but the new batt is running fine now).
Is there no possible way this type of failure withing 10 days could have shown in a shop test.
Also, I had a cracked battery terminal that needed replacing, but I imagine the valet did that when he tried to jumpstart me the first time.
PS: Upon further thinking…(though admittedly, I have been drinking) could someone have stolen the good battery out of my car and swapped it with a near dead one? Nah…why would a thief bother to install a bad battery? He’d just steal it if he wanted it, right?
Let me try to clarify. The helpfulness of the testing is that often there is evidence of a failing battery even though there are no symptoms obvious to the driver. If the battery fails the test (or, in certain cases, one or more of the several tests) undertaken, that is predictive–you know it’s going to fail soon, even if it’s currently working well. So when a battery goes bad in a way that can be tested for, the testing is very beneficial in giving advance warning.
The problem is that not every battery failure can be tested for. In those instances, the testing gives no clue to imminent trouble.
Another way to put it is that if the battery fails a (properly done) test, you know it’s bad and likely to give out soon. If the battery passes all appropriate tests, although you know it won’t fail soon in some of the ways it can fail, you don’t know whether or not it might fail soon in other ways it can fail.
It’s perhaps a bit like our ability to assign risk probability to having a heart attack or stroke by measuring blood flow, arterial deposits, blood pressure, etc. But we have no way (usually) of predicting if there will be a stroke or death due to an aneurysm. It still makes sense to be tested, but the tests cannot prove that there won’t be a sudden and unforeseen failure.