Battery Tester Lies?

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Or does the machine knows the battery is under warranty so it fudges the results? :-) The background:- 99 Camry; I noticed little bit weak cranking. Doing some testing showed it had no load voltage of 12.2V (should be 12.6 or above) and dipped down to 8.9V (should have stayed over 9.6V). The alternator is fine (13.7V - 14.4V)and car runs mostly on the highway (30 miles one way). This is OEM Toyota battery replaced in 1/2012, so it has still some warranty left. Just for the grins, I took it back to the dealer. His machine tests it and it passes the battery! The printout given to me shows RESULTS: - GOOD - RECHARGE RATED CCA 575 MEASURED CCA 612 MEASURED VOLTS 12.32 DEGREES F 62 STATE OF CHARGE (SOC) 75% STATE OF HEALTH (SOH) HIGH Anybody wants to bet that if I were to take this battery to Autozone or Advance, they *will* fail it and sell me a new one?
 
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Really need to check with a battery hydrometer. I have seen batteries test out fine on the electonic tester but still show bad on the hydrometer.
 
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Do you own a battery charger? If you can fully charge it the Advance auto tester can give you a good reading. Your voltage should be at 12.60 plus when resting over 6 hours to get a good reading. You can always grab one of the basic Noco chargers off Amazon if you need a new one.
 
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Originally Posted By: Vikas
STATE OF CHARGE (SOC) 75% STATE OF HEALTH (SOH) HIGH
If state-of-charge is 75%, then state-of-health of something is most definitely NOT "high". 75% is DEAD. Either your charging system is not working properly, or the battery is dead. You report running voltage as 13.7 to 14.4. Why the huge range? Surely they didn't observe that whole range in a single test? How did they measure the running voltage?
 

Nick1994

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I had my 97' Camry's battery tested in December of last year and it read as a bad battery. It still started it everyday for 8 more months and 12,000 more miles I put on the car by the time I sold it. It was an Interstate.
 

Vikas

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I was talking about the alternator output based upon the engine rpm, vehicle speed, electrical load etc. I have digital gizmo plugged in to cigarette lighter. The printout provided by the dealer did not give any charging system data. If the car is being driven daily 60 miles and the alternator is working, I really don't believe an external charger is going to make difference. Is somebody saying that my alternator is overcharging the battery at 13.7V? I do not believe so. The alternator output follows correct pattern. After the car is started the voltage is little higher and as the car runs, it drops down as the battery recharges. I will rip off the sticker and see if can pop up the place where I can check/add water. May be it needs water.
 
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Originally Posted By: Vikas
I will rip off the sticker and see if can pop up the place where I can check/add water. May be it needs water.
Maybe it needs something stronger if you want it to fail that test. hide
 
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I was shocked that my OEM battery on my 07 is still good, 130k miles and still testing as "good". Have it tested at a couple other car stores and see how their results compare..a battery from 2012 should be testing as excellent as far as im concerned..
 
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Originally Posted By: Vikas
I was talking about the alternator output based upon the engine rpm, vehicle speed, electrical load etc. I have digital gizmo plugged in to cigarette lighter. The printout provided by the dealer did not give any charging system data. If the car is being driven daily 60 miles and the alternator is working, I really don't believe an external charger is going to make difference. Is somebody saying that my alternator is overcharging the battery at 13.7V? I do not believe so. The alternator output follows correct pattern. After the car is started the voltage is little higher and as the car runs, it drops down as the battery recharges. I will rip off the sticker and see if can pop up the place where I can check/add water. May be it needs water.
I don't believe this to be true, sometimes the battery needs to be topped off with a real charger and all is well. If you are tight on money you can buy a charger at Walmart and return it if you are un satisfied with the results.
 

Vikas

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Quote:
I don't believe this to be true, sometimes the battery needs to be topped off with a real charger and all is well.
Can you provide some supporting material for this? If the car was a short tripper, I would have agreed with you. I already ran the numbers at the dealer; he would have given me $15 in credit and I would have to pay for new battery and the installation charges and the new battery would have no warranty going further! So, collecting on the pro-rated warranty is out of the question. Do I do the right thing and swap the battery myself and don't worry about it for next few years or do I want to take this as a challenge on myself to see if I can squeeze extra life out of this one? Logically the answer is obvious but sometimes emotional side steers one to the wrong side. One thing is for sure. If the battery comes out this car, it is NOT going back in again. Can I use the external charger while the battery is still hooked up to the car?
 
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Try this first before you do anything else: Engine COLD, key OUT, engine OFF: 1) turn your headlights ON and wait ten minutes 2) turn the lights OFF again and wait 10 minutes 3) using an ordinary digital voltmeter (DVOM) set to VDC, touch the terminals of the meter to the terminals of the battery and read the voltage 4) go look at the thermometer outside your kitchen window and find out what the air temperature was at the time you took the reading. What are the numbers, including the air temperature? (It is important that you give the entire decimal portion of the voltage!) Then, START the engine, and 1) engine COLD, touch the DVOM to the battery terminals and note the reading 2) drive the car until fully-warm and park again 3) engine still running, read the battery voltage once more. What are those numbers?
 
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I am curious to see the results of the test Tegger recommends. Also would like the source so we can interpret the numbers ourselves. But I warn you, last fall I had the battery on my Ranger tested including the CCA output etc. It tested good. One February morning of -20F it would not start and I ended up changing out the battery that evening in -15 in my driveway. To make matters worse the bolt was very rusty and spinning at the bottom. It was behind the battery so I had to use a hacksaw blade holder (mini handle clamps to blade) to saw it off. After getting the battery out, I still had to remove the bolt and worked on it for quite a while before I figured out I could still thread a nut on it if I cut down the center part of the plastic hold down block. All this time, I would be working for about 5-10 minutes at a time, then run in the house to warm my hands. Ironically I have a furnace in the garage, but for some reason it would not start that day, and with a dead battery it would not have been simple to move the truck into the garage anyway. That was the morning my battery was dead, my wife's van's doors were frozen shut, and my son's truck started but the parking brake was stuck. I freed the parking brake and made my way to work. If we have another winter like that I may start looking for a job down south!
 
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Having a charger on the battery shouldn't hurt the car, it will be seeing the same voltage (14) as the alternator puts out. This is kind of a hard call.... you probably don't want to be stranded in the coming winter months. Driving 60 miles should charge the battery pretty good, unless there is something draining power. Do you think you could have a drain while shut off?
 
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Yes you can hook a battery to the car while the it's in the car. If the state of charge is low, the state of charge is low, there's no way around it, it needs to be topped up! The reason why it's low might be hard to track down, but that's always harder to find. If the battery won't hold a charge immediately after you charge it then you probably have a bad battery.
 
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I've seen a few almost new batteries which checks out fine with battery tester cca readings. But they would not start an engine after sitting for a few days. After I've charged those batteries, I check the electrolyte with a hydrometer, and they had poor readings. That's why they would not hold a charge for long.
 
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1. Charge battery and test for current capacity under load. You are testing how well the battery charges. 2. Charge battery and let battery sit a week then test for current capacity under load. You are testing how well the battery holds a charge.
 

Vikas

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Serious question regarding the following
Quote:
Engine COLD, key OUT, engine OFF: 1) turn your headlights ON and wait ten minutes 2) turn the lights OFF again and wait 10 minutes
Is there even a chance that the observed voltage before start of step one will be *lower* than at the end of step 2? To ask it differently, do you believe voltage will actually rise at the end of step 2 as compared to beginning of step 1?
 
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Originally Posted By: Vikas
Serious question regarding the following
Quote:
Engine COLD, key OUT, engine OFF: 1) turn your headlights ON and wait ten minutes 2) turn the lights OFF again and wait 10 minutes
Is there even a chance that the observed voltage before start of step one will be *lower* than at the end of step 2? To ask it differently, do you believe voltage will actually rise at the end of step 2 as compared to beginning of step 1?
Performing the above procedure ensures that any "surface charge" is eliminated. My understanding is that the second number can indeed be lower than the first, under certain conditions.
 
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<span style="font-family: 'Verdana'">You guys that live in the rust belt should probably be spraying all your starter circuit connections down with penetrating oil on a regular basis. We're spoiled out here in California; we never have to worry about rust. </span>
 

Vikas

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Does eliminating surface charge, raises the voltage? If not, what is the point of that exercise if the resting voltage is already too low? I am not trying to be a jerk but trying to understand how that is going to give us better diagnostics. If I was seeing resting voltage of 13V, then yes, I can understand the rationale for it but it it is already at 12.2V, why would I want to turn the lights on for 10 minutes which might make the resting voltage to 11.9 and then I might not even be able to start the car!
 
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