Puzzling car battery question

[1lieutenant]

My Lexus GS 350 is going on 8 years with the original battery. The car has never had a problem starting and all the electronics work properly. Regardless, I decided to purchase a battery tester. Here are the results. I am planning on replacing the battery asap. your thoughts.

 

[walterjay]

I would replace the battery. Don't get stuck.

 

[Nukeman7]

The readings look consistent with an 8 year old battery nearing the end of life stage. As walterjay said, go ahead and replace it soon unless you carry an on-board battery jump pack.

 

[SC Maintenance]

You can't use CCA unless its 0F or colder. You need to change to just CA. If there is no CA spec on the battery just increase CCA by 15%.

Having said all that, its likely done. Almost 15 ohms resistance is pretty high. 10 m. ohms is OK, 5 m. ohms is very good.

I would charge it, then let it sit overnight, and test again using CA. My guess is its still done, but that would be the proper process.

Also, have you tried your tester on any other batteries? If its new, just to make sure it does in fact work.

 

[1lieutenant]

I did check it on my wife’s 3 year old MB GLC 300. Forgot to change the CCA to 770.

 

[supton]

I think some cars are more sensitive than others to weak batteries. Honda seems to like to undercharge, which surely can't help... At any rate, 8 years, it's lived a good life.

I could question the tester, how do we know it's good? but in this case, 8 years? It can't be long for this world.

 

[1lieutenant]

I think some cars are more sensitive than others to weak batteries. Honda seems to like to undercharge, which surely can't help... At any rate, 8 years, it's lived a good life.

I could question the tester, how do we know it's good? but in this case, 8 years? It can't be long for this world.

Despite no apparent problems, the battery is being replaced this Monday.

 

[DuckRyder]

I bet a charge with a good quality charger capable of reconditioning would significantly improve the results.

But yeah, 8 years is a good run.

 

[bobdoo]

I bet a charge with a good quality charger capable of reconditioning would significantly improve the results.

But yeah, 8 years is a good run.

My Cteks have this as an option. It pushes higher than normal charging voltage into the battery, to 'stir' the acid up. I've used it for more than 5 years, and it only seems to boil more acid out of the batteries. (I've used it on 6 batteries that are in constant use -2 car, 2 sump pump, and 2 boat (the last four are deep cycle)).

I have a Solar battery tester, similar to OP's, and have a spreadsheet where I save ambient temp, volts, and 'CCA', so it's not just my recollection RE: the state of the batteries.

I keep a close eye on the state of charge, so my mileage is probably much different than others...

 

[SC Maintenance]

I did check it on my wife’s 3 year old MB GLC 300. Forgot to change the CCA to 770.

The big "tell" on this one, vs your older one, is the internal resistance is under 5 milliohms. Your older one is like 15 milliohms - which shows that the battery is slowly failing inernally.

I would just replace if it were mine.