My battery was fine one day, then down to about 11.7 volts the next. This happened during our first couple of 90 degree days this year. It’s a “five-year” battery that is just shy of four years old. It took 16 hours with a battery tender to get the battery back up to charge.
I removed the battery from the charger and took it to a battery store where it passed the load test. I then read that a battery fresh off a charger will have what is called a “surface charge” that can skew load tester results. There are several ways to dissipate the surface charge, turn on the headlights, or just let the battery rest for several hours. I am going to let the battery sit overnight, then take it to be tested again. It is a nearly four-year-old battery. I am on the fence about doing the test vs just replacing the battery. Are the load tests accurate in estimating battery health? The alternator on this vehicle is under the engine and is no fun to replace, so I don’t want to stress the alternator with a weak battery.
For what it is worth, the battery is used in a vehicle that is driven only during the summer months, and even then it is driven pretty infrequently.
The car was driven for three hours on Friday. It was started and stopped several times with no issues. On Sunday it just clicked instead of turning over, and the battery was at 11.7 volts. To rule out the alternator, tonight I reinstalled the battery and got 14.66 volts at the battery with the engine idling.
A parasitic draw from an interior light is possible. The car is a two-door with long doors. With two vehicles in the garage, there is not a lot of room to open such a long door and conversely to swing it fast enough to latch completely. This can cause an interior light to remain lit. Others in the family have not fully closed the door and I have reminded them to make sure the door is completely closed. Of course, I was the last person to drive the car before the battery died, so I could have made the mistake I remind everyone else to avoid.
I will get the load test again just to be sure. If it is time to replace the battery, so be it. If it is still good for this summer, I will replace it next year since it has been in service since August 2017.
My wife drained the battery (3 years old) in our 1999 Honda by leaving an interior light on. After a long slow charge it tests out OK now, resting voltage and running voltage. It does not have removable caps, so I can’t test its state of charge by directly measuring the specific gravity of the fluid.
So I tested the 4 year old battery in our 2007 Chrysler van. It had removable caps. Every cell was undercharged, and would not take a higher charge! That’s the least life I’ve ever had from a battery. New battery - no caps. I’ll miss 'em.
Not a classic. It is a 1995 Oldsmobile Cutlass Supreme convertible (factory coupe conversion). From 1990 to 1995 GM hired a customizing firm called Cars and Customs to set up shop at the Olds factory to take Cutlass coupes off the assembly line and turn them into convertibles.
Four year old batteries have caused me to call for jump before. When they get four years old or even three, I’m watching them pretty close for replacement. I’ve got a 4 1/2 year old one now that is barely at it’s rated CCA so it’ll be gone pretty quick. I’ve had one fail in a year that wasn’t used much.
A co worker of mine had a part time job @ a McParts store. He said based on their warranty returns, any battery over three years was on borrowed time. Basically the warranty past three years was a financial gamble not a technical issue relating to the life or capacity of the battery. Many lasted 5 years but enough came back in the 3/4/5 year time frame to give them that impression. Qualitative data not quantitative but certainly note worthy.
My experience is years ago a battery would show signs of failing, usually harder/sluggish to crank. More recent seems to be sudden failure. Normal crank one day, no crank the next.
VERY likely there is a parasitic draw and not the interior light. Cars this old can develop small shorts in an electronic device… ecu, radio, abs ect… that can start to pull more than the 20 - 40 milliamps this car would pull pull from the battery when off.
Since I assume you have a multi-meter you can do this test.
Charge the battery. It should get into the 12.6 to 12.7 volts range.
Remove the fuel pump relay or disable the ignition.
Crank the engine over for 10 to 15 seconds.
The meter should not go lower than 10.2 volts at a minimum.
If it does the battery is failing.
What you are doing there is essentially load testing the battery with the actual load it is exposed to daily.
@kcac_1_157641 what’s your climate like?
In the south US 4 years is a long life for a battery, in the north or Canada batteries can last 10+ years.
Heat kills a battery, cold buries it.
Also, if a battery is chronically undercharged by short, infrequent trips, common in the COVID era, its life is shortened.
At any rate get the electrical system checked to avoid possibly sentencing a new battery to a short, unhappy life.
For what it is worth, I ran the car briefly last night to measure the alternator output (14.66 volts).
This morning I checked the battery voltage. It was 12.85 volts.
I am in Wisconsin. but the car is a convertible that is driven May through October. The other months it is stored in an unheated garage.
I used to always remove the battery during the six months of storage and stow it in the basement on a battery tender. The past two winters I have left the battery in the car and just disconnected the negative terminal. The car fires right up when I pull it out of storage. I drive it 5 minutes to my home, put the battery on a trickle charger, then start driving the car once the battery is fully charged. Is letting the battery slowly discharge for those six months damaging the battery?
I never worried about my boat battery, but it does not take much to start a 90 horse. I think the battery lasted at least 11 years. I would do the battery maintainer and it would charge up OK. We turn the electric off Sept. to June, but a maintainer would be a better idea.
Perhaps a little.
Lead acid batteries really “like” to be kept full all the time.
It’s better to fully charge before sitting 6 months, and safer than leaving on a tender unattended.
Sitting without a charge being applied by a battery charger or alternator is the worst thing in the world for a battery.
As it sits idle the sulfuric acid in the electrolyte sticks to the lead plates. When charging occurs acid is driven off of the plates. Each time the amount being driven off dwindles a bit more until the battery gives up. The longer the acid remains on the plates the more difficult it is to drive it off.