I read that a battery should be replaced when the voltage drops to 12.4v on a fully charged battery.
Is this true?
Is this true?
When to Replace Battery?
- Thread starter TheLoneRanger
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There are many battery state of charge charts out there like this one:
https://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/
The temperature of the battery is also important as the voltage will be lower when it's colder.
Basically you replace a battery when it fails a load test. Most auto parts stores will do a free load test for you. It's possible to get a 12+ voltage reading but once you put a load on it, you get no current.
I suppose you could just buy one too. Maybe one of these two?
https://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0
https://www.amazon.com/Bastex-Battery-Insulated-Carrying-Automotive/dp/B01N75BLH5
https://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/
The temperature of the battery is also important as the voltage will be lower when it's colder.
Basically you replace a battery when it fails a load test. Most auto parts stores will do a free load test for you. It's possible to get a 12+ voltage reading but once you put a load on it, you get no current.
I suppose you could just buy one too. Maybe one of these two?
https://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0
https://www.amazon.com/Bastex-Battery-Insulated-Carrying-Automotive/dp/B01N75BLH5
It depends on your tolerance to your vehicle not starting or leaving you stranded someday. A "Good" battery will hold 12.6 volt over night when fully charged and still connected to your vehicle. A 12 volt battery is considered flat or dead at 12 volts. Fully charged and connected to your vehicle should hold no less than 12.4/12.3 if you have a little 4cyl motor. A diesel pick up truck will be close to S.O.L. at 12.3 volt overnight, and that's with 2- 12 volt batteries.
I start looking for replacement and testing the battery when i hear the engine start to crank slower and charging seems to do nothing. I know the end is near. I don't want to be stranded somewhere. Thats a pain.Its also better to replace before absolutely necessary so you can decide what battery you want and maybe even get in on sale. When you're stuck somewhere, you usually get the closest or easiest to get battery. I don't know if it helps but I like to periodically put my batteries on the maintenance charger. I haven't driven a whole lot lately and I just charged the mazda and f150 batteries and it took all day for both, even though they both started the vehicles without issue. I like to think I am helping them last longer but who knows.
Nick1994
$100 site donor 2024
Is it your car charging it to 12.4V or a high quality battery charger?
Could be the car not charging it enough.
Could be the car not charging it enough.
The battery in my car right now showed 12.6 volts fully charged the day I have purchased it open circuit. After about 3 years it showed 12.2 volts after standing for a night in my car.6 and a half years later, it still works.I maintain it now and then using a ctek charger. Batteries are quite mysterious sometimes.
Originally Posted By: E150GT
I start looking for replacement and testing the battery when i hear the engine start to crank slower and charging seems to do nothing. I know the end is near. I don't want to be stranded somewhere.
While that all sounds good, in the Arizona heat most of the time you are not afforded that luxury. Batteries will go dead all but instantly, and without warning. I've been lucky. All of mine have managed to die at home in the garage.... Except one. I got in my truck one morning, and the engine spun like a top, and fired right up. The volt meter showed nothing out of the ordinary. I then drove 3 miles to the store, got out and went inside. When I returned 10 minutes later NOTHING. The dome light wouldn't even go on. I thought someone stole the battery.
I was able to walk home, get my other car, and jump start it..... Barely. I got it back home, and parked it in the driveway, and went and got another battery. It tested dead at the store. They gave me a new one for no charge under warranty. It was 2 years old. Typical for a Arizona battery. 2 Summers and that's it.
Out here batteries don't give you signals or warnings. They just drop dead. Like a retiree on a golf course.
I start looking for replacement and testing the battery when i hear the engine start to crank slower and charging seems to do nothing. I know the end is near. I don't want to be stranded somewhere.
While that all sounds good, in the Arizona heat most of the time you are not afforded that luxury. Batteries will go dead all but instantly, and without warning. I've been lucky. All of mine have managed to die at home in the garage.... Except one. I got in my truck one morning, and the engine spun like a top, and fired right up. The volt meter showed nothing out of the ordinary. I then drove 3 miles to the store, got out and went inside. When I returned 10 minutes later NOTHING. The dome light wouldn't even go on. I thought someone stole the battery.
I was able to walk home, get my other car, and jump start it..... Barely. I got it back home, and parked it in the driveway, and went and got another battery. It tested dead at the store. They gave me a new one for no charge under warranty. It was 2 years old. Typical for a Arizona battery. 2 Summers and that's it.
Out here batteries don't give you signals or warnings. They just drop dead. Like a retiree on a golf course.
One slow crank and I'm looking for a problem. If the battery load tests marginal out it comes.
Average life is normally 4-5 years on a lead acid, but ive had some last much longer. I also have a 10 year old Interstate in my older Audi A4 that shows 11.8 but still cranks it over no problem. Its a lower compression turbo 4 cylinder so that might be aiding its longevity.
Originally Posted By: rooflessVW
One slow crank and I'm looking for a problem. If the battery load tests marginal out it comes.
If you have a gear reduction starter it really doesn't take much to kick things over, so a battery that cranks slow is pretty far along on its death curve.
I've read that if the voltage dips below 9 during cranking, a battery is toast. One would need a logging/ graphing meter to get this accurately, but watching the dash light bulbs dim a lot with an experienced eye can diagnose this.
One slow crank and I'm looking for a problem. If the battery load tests marginal out it comes.
If you have a gear reduction starter it really doesn't take much to kick things over, so a battery that cranks slow is pretty far along on its death curve.
I've read that if the voltage dips below 9 during cranking, a battery is toast. One would need a logging/ graphing meter to get this accurately, but watching the dash light bulbs dim a lot with an experienced eye can diagnose this.
Sis' battery was on month #35 of a 36 month free replacement period when she called.
Turn the key and it'd drop to 3 volts.
"Go get a battery" was all the AutoZone man said to the employee.
Turn the key and it'd drop to 3 volts.
"Go get a battery" was all the AutoZone man said to the employee.
If you think it's time just change it. Not worth getting stuck somewhere. I had a 3.5 year old O'Reilly Super start that just quit on me a week ago. Replaced it with a Korean made Centennial from Battery Systems for $97. I had a Centannial in my Dodge that went 6 years, I think I paid $52 for that one years ago. O'Reilly, AZ, Napa are around $140 now. Overpriced money makers for the chain stores. They can keep them.
I bought my WRX new in March 2016. Battery has already died a few times on me.
Apparently Subaru puts some notoriously bad batteries in their cars, and possibly the alternators don't charge the batteries well enough.
Apparently Subaru puts some notoriously bad batteries in their cars, and possibly the alternators don't charge the batteries well enough.
Originally Posted By: Wolf359
There are many battery state of charge charts out there like this one:
https://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/
The temperature of the battery is also important as the voltage will be lower when it's colder.
Basically you replace a battery when it fails a load test. Most auto parts stores will do a free load test for you. It's possible to get a 12+ voltage reading but once you put a load on it, you get no current.
I suppose you could just buy one too. Maybe one of these two?
https://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0
https://www.amazon.com/Bastex-Battery-Insulated-Carrying-Automotive/dp/B01N75BLH5
Be cautious using those types of testers, I have seen lots of batteries did shortly after using them, of course the battery was on the edge anyway but those thing will put the final nail in the coffin.
Use a tester for CCA if its down around 60% of its original capacity you probably should start looking for a battery.
https://www.amazon.com/Clore-Automotive-...76C0A1089EF5HAM
There are many battery state of charge charts out there like this one:
https://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/
The temperature of the battery is also important as the voltage will be lower when it's colder.
Basically you replace a battery when it fails a load test. Most auto parts stores will do a free load test for you. It's possible to get a 12+ voltage reading but once you put a load on it, you get no current.
I suppose you could just buy one too. Maybe one of these two?
https://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0
https://www.amazon.com/Bastex-Battery-Insulated-Carrying-Automotive/dp/B01N75BLH5
Be cautious using those types of testers, I have seen lots of batteries did shortly after using them, of course the battery was on the edge anyway but those thing will put the final nail in the coffin.
Use a tester for CCA if its down around 60% of its original capacity you probably should start looking for a battery.
https://www.amazon.com/Clore-Automotive-...76C0A1089EF5HAM
https://www.harborfreight.com/digital-automotive-battery-analyzer-66892.html
Is the one I have. it is not perfect but it definitely helps find issues.
Is the one I have. it is not perfect but it definitely helps find issues.
So far my original battery in my 15 Tacoma has been great. Every six months I check the fluid level and top off as necessary.
Originally Posted By: billt460
Originally Posted By: E150GT
I start looking for replacement and testing the battery when i hear the engine start to crank slower and charging seems to do nothing. I know the end is near. I don't want to be stranded somewhere.
While that all sounds good, in the Arizona heat most of the time you are not afforded that luxury. Batteries will go dead all but instantly, and without warning. I've been lucky. All of mine have managed to die at home in the garage.... Except one. I got in my truck one morning, and the engine spun like a top, and fired right up. The volt meter showed nothing out of the ordinary. I then drove 3 miles to the store, got out and went inside. When I returned 10 minutes later NOTHING. The dome light wouldn't even go on. I thought someone stole the battery.
I was able to walk home, get my other car, and jump start it..... Barely. I got it back home, and parked it in the driveway, and went and got another battery. It tested dead at the store. They gave me a new one for no charge under warranty. It was 2 years old. Typical for a Arizona battery. 2 Summers and that's it.
Out here batteries don't give you signals or warnings. They just drop dead. Like a retiree on a golf course.
It gets hot here too but I wouldn’t last long in Arizona heat either. I suppose carrying a jump pack would do no good as those probably get discharged in the heat too just as the starting battery. AAA probably does a good business there.
Originally Posted By: E150GT
I start looking for replacement and testing the battery when i hear the engine start to crank slower and charging seems to do nothing. I know the end is near. I don't want to be stranded somewhere.
While that all sounds good, in the Arizona heat most of the time you are not afforded that luxury. Batteries will go dead all but instantly, and without warning. I've been lucky. All of mine have managed to die at home in the garage.... Except one. I got in my truck one morning, and the engine spun like a top, and fired right up. The volt meter showed nothing out of the ordinary. I then drove 3 miles to the store, got out and went inside. When I returned 10 minutes later NOTHING. The dome light wouldn't even go on. I thought someone stole the battery.
I was able to walk home, get my other car, and jump start it..... Barely. I got it back home, and parked it in the driveway, and went and got another battery. It tested dead at the store. They gave me a new one for no charge under warranty. It was 2 years old. Typical for a Arizona battery. 2 Summers and that's it.
Out here batteries don't give you signals or warnings. They just drop dead. Like a retiree on a golf course.
It gets hot here too but I wouldn’t last long in Arizona heat either. I suppose carrying a jump pack would do no good as those probably get discharged in the heat too just as the starting battery. AAA probably does a good business there.
Originally Posted By: ARB1977
So far my original battery in my 15 Tacoma has been great. Every six months I check the fluid level and top off as necessary.
It’s those Panasonic batteries. Wish we could get those as replacements.
So far my original battery in my 15 Tacoma has been great. Every six months I check the fluid level and top off as necessary.
It’s those Panasonic batteries. Wish we could get those as replacements.
Looking at both a Centech battery analyzer and a multimeter that has a min peak hold, such as an Agilent U1251A, gives you a good idea. That mix is similar to having both an analyzer and a carbon load tester.
I've had a battery test adequate with the Centech yet not start a car after sitting overnight.
I don't like buying single-use test equipment. A used Agilent DMM can be had for a few hundred from EBay and it has many uses. A carbon pile tester has only one use. That said, the pros have to buy a battery analyzer with a printer (such as a Midtronics) and send back a report with a battery in order to get warranty credit.
I've had a battery test adequate with the Centech yet not start a car after sitting overnight.
I don't like buying single-use test equipment. A used Agilent DMM can be had for a few hundred from EBay and it has many uses. A carbon pile tester has only one use. That said, the pros have to buy a battery analyzer with a printer (such as a Midtronics) and send back a report with a battery in order to get warranty credit.
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