My altinator stopped working so I went to a pick and pull and got a replacement a couple days later after having the altinator replaced the car wouldn’t start so I took the altinator back off and to it to advance auto so they could check it but it turned out it was good. So I had my battery checked and they said it had to charge. So I charged and it still won’t hold charge. I started to mess with the plug that goes into the altinator and realized when I did that the battery light came on so I replaced the plug and still won’t hold charge.
If the alternator tested fine, but the battery required a recharge, it could be that battery isn’t capable of holding a charge.
If you don’t know how old the battery is, replace it.
Battery’s don’t last forever.
Tester
Could that still be the problem if the battery is 6-8 months old .
Yes.
I’ve purchased bad brand new battery’s.
It depends on how long a battery sat on the shelf prior to being purchased.
That’s why I look at the date code before purchasing a new battery.
Just go on the web and look up battery sulfation while sitting on the shelf.
Tester
Charge your 8 month old battery with a battery charger after disconnecting it from the car, then wait a couple days, then have it load tested. If it tests ok then, your replacement alternator may have a faulty diode and is draining the battery. That’s something a shop can easily diagnose by doing a parasitic current test.
George.
We keep telling you, NOBODY does load testing on battery’s anymore!
It’s 2016!
We do CONDUCTANCE testing!
Tester
That tester has no meaningful specifications at all. None. I have no idea what it’s testing.
@Tester Looks like a neat tool. Reading through the manual I found it interesting rather than testing cranking amps, it measures the voltage while cranking, and if less than 9.6 v the battery fails the test. Easy way at home to test a battery with a voltmerer? Will try mine today, see what I get.
There is a manual? I’ll take a look. But it sounds like something any voltmeter could do.
I don’t like conductance tests simply because I’ve found on a number of occasions that the conductance test would declare a known bad battery was good. This has happened once with my daughter last year (AutoZone) and twice with me (once last year at Wal Mart).
In one case involving me the battery had 2 known bad cells (both 1.8 volts after a 4 hour charge) and would go dead within hours while on the bench. Wal Mart’s conductance tester and printout kept saying it was good and they kept saying the starter was bad, the ignition switch was bad, the battery cables are no good, or the alternator had failed.
What part of going dead within hours on the bench and out of the car is so hard to understand…
So unfortunately, this always led to deliberate sabotaging of the crummy battery to make them see the light.
Yes, you can test a battery with a voltmeter. Charge the battery, disable the engine so it will not start (pump relay out, etc), and crank it over for 10 seconds or so. The voltmeter should maintain a minimum reading of 10.2 volts. Anything less the battery is failing.
I suspect Tester is correct though. This video shows the use of all of them, voltage, load, hygrometer, and conductive, and is worth a look. Having replaced two batteries this week, I’ve been looking for something better than just the voltage test but I’m not willing to pay $200. Its cheaper to replace the batteries. One 3 1/2 year old OEM failed at the gas station just before heading out on a 200 mile trip. Glad it happened when I could still get a new battery from NAPA instead of in lonely South Dakota. The other one was a 3 year old Delco that I just decided to replace pre-emptively because it would be sitting at the airport for two weeks in the cold. So I’ve bought a couple of those plug in voltage testers which is better than nothing and also a cheap jump starter. I guess having to call for a jump once every 30 years isn’t bad but still not convenient.
Could someone tell me what this is it was left unplugged. And just realized that today?
That’s your cruise control module.
“Load test” vs. “conductance test”? I expect those are just two different methods for testing the same thing – the battery’s internal resistance. The l load tester I use as a driveway diy’er is a low resistance heating element with two heavy duty leads which I attach across the battery terminals. The resistance of the heating element is designed so the current is around 100 amps. Tthe battery voltage drops under this load of course, and after the voltage stabilizes, about 10-15 seconds, that’s how the battery internal resistance is judged.
There’s more than one way to measure the battery internal resistance of course. The conductance tester gadget is just one of those other ways. I can totally understand why a shop would prefer to do it with the conductance tester. It’s easier, and it’s somewhat dangerous the way I do it, as a defective battery could possibly rupture in that situation.
But for purposes of discussion here on Car Talk forums, I’ve always interpreted a battery “load test” or battery “conductance test” as the same thing. Just differing semantics is all. Two different ways to obtain an assessment of the internal resistance of the battery.
If you interpret a load test as the same as a conductance test, then you would have to interpret a compression as being the same as a leak-down test.
A compression test informs if there’s a loss of compression.
A leak-down test informs why there’s a loss of compression.
Tester
The so called conductance test, as far as I can see, just measures battery voltage with the starter running. That can be used to calculate internal resistance of the battery. And the load test will server the same purpose. The math is easy.
Conductance is 1/resistance.
George and Bill, did you watch the video? I thought he did a good job of showing the difference in them. Voltage was one part of the test but not the conductance part and the starter was never running that I saw.
I respectfully disagree with Tester to a point about compression and leakdown tests. What Tester says is true BUT…
A compression test can certainly tell someone if it’s a ring or cylinder head valve problem.
If it’s a ring problem it’s going to need major engine work.
If it’s a valve problem it doesn’t make any difference if it’s an intake or exhaust or whether it’s one cylinder or all of them. It’s going to need major engine work and that means one or both heads along with all valves get serviced.
Good video @Bing.
Yosemite
I replaced my battery and I’m still having the same problems. When I idle everything dims out all my lights etc…but when I move it brightens right up. One time while driving every thing shut off like my lights etc. But the car kept on driving at around 30mph but about a min later everything started acting normally.