I guess it's different for everyone apparently. My wife's car acted up yesterday with an apparent battery issue. It tested out ok this morning but after it sat overnight inside at about 48* in the annex bay. It acted up outside when it was *9 with a negative wind chill. It was a top line 3 yr (36 month) battery that just started its 51st month. I just went ahead and got her a new battery because I love her and don't want her to have any problems while she's driving all over 3 counties and especially when it's bitter cold out. The battery passed every test in the not freezing shop. If a battery is going to fail, or most any other car parts for that matter, it will be when the weather is at extremes.
Just to clear it up, a proper load test is using a carbon pile to pull half the cold cranking amps out of a battery for 15 seconds, battery should stay above 9.6v Sent from my iPhone using The H.A.M.B. mobile app
It takes a while but it's measured in days, not weeks. Sulfation is just the stuff on the plates, that is converted back and forth into electrolyte as part of the normal discharge and charging process. Supposedly, anytime a battery sits below about an 80% charge for more than a few days, some permanent sulfation sets in. Higher temperatures increase the rate of chemical reactions. This is why lead-acid batteries don't last as long as they otherwise might in places like Arizona. Automotive starting batteries should avoid deep discharging whenever possible, they can be ruined in just a half dozen or so cycles. "Deep cycle" or marine type batteries are designed for repeated deep discharge and charge cycles. Basically for best performance charge them whenever practical and they should give best service. One thing to keep in mind. A dead battery will freeze solid at around +25° F and may explode if charging is attempted, and is scrap in any event. A fully charged battery is good to about -60° F below zero. In that sense a trickle charger is sort of like a battery warmer. Something to think about before leaving a dead battery out in the cold snap in much of the country.
I have used many different testers over the years with varied results. The most consistent readings I have gotten has been by using an old style VAT 40 unit. With a battery at full charge , 12.5 or so. Apply a 15 amp load for 15 seconds. Average starter draw is 175 amps. If the battery reads 9.6 volts or more after the 15 second load, it will be acceptable for use. Anything lower and the battery is bad. I went around with a college boy Ford service rep. one time on a warranty battery. He checked it with an arbst tester and it passed. I had used a VAT 40 and it failed. He wanted to charge us back because the battery was "good". I said okay, let's put that battery in your demo for a week and if it lasts, then back charge us. He thought about it for a while and decided to okay the claim. The VAT 40 is low tech and accurate if you know how to use. I have very little faith in the new 20+ push button gadgets for their accuracy. A 175 amp load for 15 seconds and battery above 9.6 volts is highly accurate and fast to do.
The VAT 40 was, and still is, the gold standard for battery/charging system testing, but it won’t fit in any drawer of my tool box........ Sent from my iPhone using H.A.M.B.
I think the handheld conductance testers are accurate but they require a little judgment. If it comes back and sez a battery is defective it is. If it comes back and sez a battery is OK, well ... it might be. Might not. A 15 second load test is definitive, but it takes time and is only accurate if the battery has a good charge. If it was charged up in the first place the customer probably wouldn't be in the fix they are in to begin with. Then it will need charging again after the mini-torture test. The conductance type testers use the battery's own voltage to power them, they don't need to be charged up all the way for testing. The feed a pulsed high frequency AC signal back through and can determine battery health that way. Supposedly. For warranty service you can kinda see why they are favored over labor intensive methods, it's real quick and no other equipment needed.
I have this model, pictured. No manual, so not clear on some of it. Model CB. Is it a load tester as well? It does have a carbon rheo inside but it doesn't seem to be the full monte. Works great for testing generator output and regulators.
Guess I should get a carbon pile tester. Not familiar with them, this is for sale near me, is it carbon pile? Either that or swap meet season's coming up..
I used to meet a bunch of older guys at the scrap yard and we used to help each other forage for what ever; including batterys...The guys would take the caps off and with a healthy chunk of steel connect the Pos and Neg posts while peering down the acid fill holes observe the amount of bubbles the acid made! The more profuse the bubbles the better the chance of the battery being usable...I would walk away during the test..
To be absolutely accurate use half the cold cranking amps for the load, a battery must be 3/4 charged or better to test Sent from my iPhone using The H.A.M.B. mobile app
To be absolutely positively super-duper accurate nominal battery voltages have a correction factor applied for ambient air temperatures other than 77° F. The minimum acceptable voltage is a little less than 9.6 volts as temperatures go down. http://www.batteryfaq.org/
I realize you're kidding, but this is actually a fair way to test the battery if a carbon pile load is not available. Disable the ignition system first, so it won't start, connect a good voltmeter to the battery, and then crank the engine over with the starter for 15 seconds while observing the volt meter. If the voltage drops below 9 volts the battery fails the test. There are 2 problem with this test though: 1. it's hard on the starter; and 2. a bad starter will put an extra heavy load on the system and draw the voltage down. This can give you a false impression that the battery is at fault when really it is the starter, and you may spend the money on a new battery only to find that the car still won't start. But, if you know the starter is good, you can use it to test the battery. Testing the starter is a little trickier, you need an inductive amp gauge with a high enough amperage capacity you can clamp around the battery cable to the starter, then check for current draw while you are cranking it over.
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