How much capacity loss is OK?

[Elkins45]

My 2017 Titan still has the factory battery. It’s rated at 720 CCA. I put the load tester on it yesterday and it tested at 600. So far the battery is performing fine and hasn’t shown any loss of ability somI’m sure it’s good for at least another year, but at what point do you decide it’s lost too much capacity? 20%? 30%? Half?

 

[Lubener]

I would believe you are still OK for now but I would retest in the fall. Your battery is getting old to support a retest before winter. Back in the days of the big V8's, the batteries had 550 CCA's.

 

[John Galt]

My advice is replace it now. This was your warning, heed it, you may not like where the next warning occurs at. New batteries can work one minute and fail the next. They don’t slowly discharge like the old lead acid batteries used years ago. I drove over to vote and when I came out 15 minutes later the battery that had started the car was now dead. Could not even jump start it. Newish ~6 y/o NAPA battery.

 

[carviewsonic]

It’s six years old, so not much time left in it anyway. I would replace it soon, before it leaves you stranded somewhere.

 

[SC Maintenance]

The cheap ancel tester I have tells me to replace at 60% capacity.

I bought the cheapest walmart 24F battery and it was only 82% of rated capacity when brand new. I presume the ratings are optimistic because its holding fine after 1.5 years.

I think internal resistance is a better measure. Below 5 mili ohms I think it is - is good. Anything approaching 10 is bad - so I have been lead to believe.

 

[paulo57509]

FWIW - The battery in the seldom driven Lumina is +5 years old. The abused Ever-Start Maxx is rated at 725 CCA.

After years of self-discharge/charging cycles and then connected to a BatteryMinder, fully charged it only tests (w/Foxwell tester) at 95 CCA. It's enough to start the engine.

No, I would not drive farther than out of town.

 

[mr_boring]

if you have a drop cord and can do it without your neighbors stealing (not all of us have a garage or even a private driveway) put a battery tender on it a few times over the course of a couple of weeks and test it again. You might be pleasantly surprised. I put a tender on mine at least every few months (more often if I remember to do it) and my 2018 Motorcraft tests fine so far. When it's really cold (rarely) or really hot (often) I try to do it every couple of weeks when I get home from work. You can always snake the cord up though the bay and close the hood even if you don't have a private drive.

Batteries do not last long in modern vehicles because modern vehicles do not charge properly. Remember 10-20-30 years ago when you could get 4-6 years out of a battery on just about any vehicle? Why is it that many batteries fail now in less than 5? A huge proportion at much less than 5 even?

Has battery quality REALLY gone down that much? Maybe a little. You be the judge.

No. It's the way vehicles charge batteries now, especially with vehicles that mainly see trips that take less than 10 minutes. They draw insane amounts of juice AFTER you shut many of them off AND they pull insane amounts of juice at start up. And manufacturers (some) DESIGN charging systems to charge LESS to get better economy. Your vehicle may only charge your battery for 8 of those 10 minutes - which is absolutely ridiculous. Even after a long trip, I drive 60+ miles one way to see my girl and I do that several times a week, my tender will take hours to charge up my battery to 100%, even though it's only had 2 starts in 120ish miles.

 

[zzyzzx]

I would not be worried about that amount of capacity loss unless you are letting it sit for at least several weeks between starts. If it were a daily driver you could go a lot below 600 and you wouldn't even notice.

 

[John105]

The cheap ancel tester I have tells me to replace at 60% capacity.

I bought the cheapest walmart 24F battery and it was only 82% of rated capacity when brand new. I presume the ratings are optimistic because its holding fine after 1.5 years.

I think internal resistance is a better measure. Below 5 mili ohms I think it is - is good. Anything approaching 10 is bad - so I have been lead to believe.

V=ir and I’ve noticed what you said. R gets worse over time and measuring V alone isn’t a good way to judge.

All the costco batteries I’ve bought when tested new they exceeded the ratings, because it’s never been cold when I bought them. More like 60F to 80F. So I’d see high 800s on a 710’ish CCA battery

 

[fantastic]

Has battery quality REALLY gone down that much? Maybe a little. You be the judge.

They got 6yrs out of this battery so I don't think battery quality has gone down.

OP: 6 yrs on a standard lead acid battery your on borrowed time. Go replace before winter temperatures.

 

[John105]

They got 6yrs out of this battery so I don't think battery quality has gone down.

OP: 6 yrs on a standard lead acid battery your on borrowed time. Go replace before winter temperatures.

How come BMW batteries last 12+ years? I played the borrowed time game in 2011 and replaced my 5 yo battery when the dealer said not necessary. The battery is still in the car 2023. Shouldn’t we believe in science (load test) over “feelings”.

 

[fantastic]

How come BMW batteries last 12+ years? I played the borrowed time game in 2011 and replaced my 5 yo battery when the dealer said not necessary. The battery is still in the car 2023. Shouldn’t we believe in science (load test) over “feelings”.

If you've gotten that long then great but that would be an outlier. I guarantee that is not the majority though. Where you live plays a big part on how long they last. Battery manufacturers build them with those climates in mind. Getting a battery to last longer is going to be most likely in cooler climates than a hotter one.

Regardless, they are showing a good chunk of degradation and overnight batteries can start your car to get you down the road or short out leaving you stranded. 6 yrs is excellent service out of a battery. An older degraded battery may start and run your radio etc but why risk putting extra stress on running it all at potentially lower voltagesand over working the alternator.

Of course I recommend getting any battery load tested but we must disagree on when a battery is on borrowed time. If there is hardly any degradation then keep going if you're like but my trucks electronics are quite expensive and will damage parts if the batteries are not in good shape so I change mine every 3-4 years.

 

[John105]

If you've gotten that long then great but that would be an outlier. I guarantee that is not the majority though. Where you live plays a big part on how long they last. Battery manufacturers build them with those climates in mind. Getting a battery to last longer is going to be most likely in cooler climates than a hotter one.
Regardless, they are showing a good chunk of degradation and overnight batteries can start your car to get you down the road or short out leaving you stranded. 6 yrs is excellent service out of a battery. Whole a degraded battery may start and run your radio etc why risk putting extra stress on running it all at potentially lower voltages.

I don’t know the science behind it but BMW has an IBS (sensor) and an algorithm whereby as the battery ages, it is charged less. When the battery is replaced like for like (say lead acid 90 Ah, it is “registered” so the car knows it was replaced and can charge it aggressively. If the type changes to AGM, or a different Ah is installed, it needs to be coded. My suspicion is that’s why they last. My wife’s aunt has a 2006 330i, she decided to proactively replace her battery during the pandemic in 2020.

 

[willbur]

The cheap ancel tester I have tells me to replace at 60% capacity.

I bought the cheapest walmart 24F battery and it was only 82% of rated capacity when brand new. I presume the ratings are optimistic because its holding fine after 1.5 years.

I think internal resistance is a better measure. Below 5 mili ohms I think it is - is good. Anything approaching 10 is bad - so I have been lead to believe.

Good info- source (or opinion)?

 

[fantastic]

I don’t know the science behind it but BMW has an IBS (sensor) and an algorithm whereby as the battery ages, it is charged less. When the battery is replaced like for like (say lead acid 90 Ah, it is “registered” so the car knows it was replaced and can charge it aggressively. If the type changes to AGM, or a different Ah is installed, it needs to be coded. My suspicion is that’s why they last. My wife’s aunt has a 2006 330i, she decided to proactively replace her battery during the pandemic in 2020.

Ah, the over-engineered German auto's. I would like to own a MB one of these days but probably never will b/c there is 0 service support for that type of auto in my neck of the woods. It would fit well with my German last name though.

 

[John105]

Ah, the over-engineered German auto's. I would like to own a MB one of these days but probably never will b/c there is 0 service support for that type of auto in my neck of the woods. It would fit well with my German last name though.

My car can provide heat for up to 45 min or an hour with the engine off. In 17 years, I tried it 1x

Another time I sat in my car at lunch and came back into the office.

Sam: Hey John, do you know your parking lamps are on, on half your car?

Me: they are? So that’s what that symbol meant on my dash. Looked like triangular rabbit ears.

It took me 1/2 hour to figure out how to turn them off. Could not tell you today how to turn on left or right parking lamps and I’ve had the car 16.5 years

 

[f355spider]

My car can provide heat for up to 45 min or an hour with the engine off. In 17 years, I tried it 1x

Another time I sat in my car at lunch and came back into the office.

Sam: Hey John, do you know your parking lamps are on, on half your car?

Me: they are? So that’s what that symbol meant on my dash. Looked like triangular rabbit ears.

It took me 1/2 hour to figure out how to turn them off. Could not tell you today how to turn on left or right parking lamps and I’ve had the car 16.5 years

Both of those features have been on most BMWs since the late 1990s. My 2001 E39 540 M-Sport has them.