Auto Battery Test

[Z3Dreamer]

Local auto repair shop tested DW's car battery. Battery is 6 years old so I replaced it, but I want to understand the battery test. Battery is rated at 700 CCA, but is only at 475 CCA.

I could not find the manufacturers specs. But my logic says that if it still generates 475 CCA and the engine requires 400 CCA, we should still be good to go. Let me give you a ridiculous example. If I had a 5,000 CCA battery that only generated 2,500 CCA I would still be good because DW's car starts fine with the 475 CCA that her battery now generates.

Car is a 2011 Toyota Rav4 Limited with 120k miles. 4 cylinder engine.

Again, I am not interested in confirmation that we should have replaced the battery, I am looking for help in interpreting the test results. If you know the minimum specs on this vehicle, that would be helpful.

 

[njhowie]

So I don't have the guaranteed correct answer, but will give my view.

All of the Rav4 batteries I've searched for indicate 650CCA to 850CCA, so 700 is in there. Although 475 may be enough to start yours, will it be sufficient in all situations over the longer term? Probably not. I ask myself, why in the world would Toyota deliver it with a 700CCA battery if 475 were sufficient? They wouldn't. Obviously the 475CCA battery would cost less and reduce the cost to manufacture the vehicle, so if it were "good enough", don't you think that's what Toyota would have included?

Of course, lots is going to depend on your use of the vehicle and normal temperatures where you live. This is likely why Toyota included a battery which is more than "you" need. They are providing what's best for all conditions. If you get sub-zero temperatures in the winter, 475CCA might not work. However, if you're in Florida, 475CCA may be just fine. The fact that you now only have 475CCA from the rated 700CCA after 6 years may be indicative that the hotter weather is taking a toll, and may continue to deteriorate the battery over time.

Getting 6 years out of a battery isn't terrible. I can normally go much longer than that, but our temperatures are not at extremes throughout the year.

 

[ERD50]

How do you determine that " the engine requires 400 CCA,"?

Sure, the 700 CC may be for bad/worst case, so if you aren't trying to crank in cold weather, you *might* get by with that marginal 475 CCA. But, it also indicates the battery has degraded, and that might/probably means you are on a steep slope to even lower CCA, insufficient to crank your engine, or complete failure.

-ERD50

 

[Ian S]

I agree with njhowie: you need a significant cushion of CCA's to start a car engine in all foreseeable conditions. Battery output is quite dependent on temperature since it involves a chemical reaction that proceeds slower with colder temperatures. Couple that with the fact that it is much harder to turn over an engine at colder temperatures and that cushion has to be even higher. FWIW, I lived in Phoenix for over thirty years and virtually every car battery in every car, OEM or aftermarket, I had lasted just a tad over three years. They simply could not take the heat.

 

[OldShooter]

Interesting. I have never, ever, considered CCA as a criterion for evaluating battery condition. In my experience a failing battery shows up when it does not reliably hold a charge. That's when I replace them. I wonder how CCA correlates with actual battery condition and ability to hold a charge.

 

[CRLLS]

According to https://www.rav4world.com/d1/attachments/pdf/Toyota_Batteries2011.pdf

The factory battery was a Group 35 and had 550 CCA.

That said, your current battery is at 68% of it's original rating. It maybe has another 1 year left IMO.

I used to just wait until the battery does not start the car, then replace it. Today, I have a device that measures battery impedance and report the % of cranking amps available. All this without having to start the car. I would replace a battery around 60% of its rated capacity regardless of the car it is going into. BTW, I would hazard a guess that the car only needs may be 200 amps capacity to start the engine.

I'm not certain but I think that a battery's ability to "hold a charge" is mostly unrelated to CA. Either way, a battery that has either problem is time for a change.

 

[Sunset]

According to https://www.rav4world.com/d1/attachments/pdf/Toyota_Batteries2011.pdf

The factory battery was a Group 35 and had 550 CCA.

That said, your current battery is at 68% of it's original rating. It maybe has another 1 year left IMO.

I used to just wait until the battery does not start the car, then replace it. Today, I have a device that measures battery impedance and report the % of cranking amps available. All this without having to start the car. I would replace a battery around 60% of its rated capacity regardless of the car it is going into. BTW, I would hazard a guess that the car only needs may be 200 amps capacity to start the engine.

I'm not certain but I think that a battery's ability to "hold a charge" is mostly unrelated to CA. Either way, a battery that has either problem is time for a change.

That is kinda my criteria, if the car won't start without charging the battery first, it's time to go.
However, this is on our spare car.
On the main vehicle we depend upon, I'll replace the battery when I notice it's getting weak, based on how slow the starter sounds or if the lights dim a lot when driving, etc..

What device do you use to test batteries ?

 

[Z3Dreamer]

How do you determine that " the engine requires 400 CCA,"?

Sure, the 700 CC may be for bad/worst case, so if you aren't trying to crank in cold weather, you *might* get by with that marginal 475 CCA. But, it also indicates the battery has degraded, and that might/probably means you are on a steep slope to even lower CCA, insufficient to crank your engine, or complete failure.

-ERD50

Thanks for replying. I said "if". I am trying to find out what the car needs. IF it needs 400 and the battery is down to 475, I am good.

 

[Z3Dreamer]

OP here. I was not clear. The battery was not the original. The battery was having no problems. The auto shop just did a courtesy. I replaced it so DW wouldn't worry, but wondered how you tell if it is generating such power to meet Toyota specs. Hence my example of a 5,000 CCA that was at 2,500 CCA would still be great.

Replacing a battery that is still doing its job is inconsistent with the FIRE code of ethics.

 

[Z3Dreamer]

According to https://www.rav4world.com/d1/attachments/pdf/Toyota_Batteries2011.pdf

The factory battery was a Group 35 and had 550 CCA.

That said, your current battery is at 68% of it's original rating. It maybe has another 1 year left IMO.

I used to just wait until the battery does not start the car, then replace it. Today, I have a device that measures battery impedance and report the % of cranking amps available. All this without having to start the car. I would replace a battery around 60% of its rated capacity regardless of the car it is going into. BTW, I would hazard a guess that the car only needs may be 200 amps capacity to start the engine.

I'm not certain but I think that a battery's ability to "hold a charge" is mostly unrelated to CA. Either way, a battery that has either problem is time for a change.

This is good info. The old battery was at 475 CCA and the OEM was at 550 CCA, so the old batter had 86% of the new OEM charge. That sounds like a good battery, right?

 

[CRLLS]

That is kinda my criteria, if the car won't start without charging the battery first, it's time to go.
However, this is on our spare car.
On the main vehicle we depend upon, I'll replace the battery when I notice it's getting weak, based on how slow the starter sounds or if the lights dim a lot when driving, etc..

What device do you use to test batteries ?

I do not have this exact device, but it is basically the same.

https://www.amazon.com/TOPDON-100-2...70784879&sprefix=auto+batter+,aps,585&sr=8-67

I bought mine on eBay a few years back. It uses a phone app. There are other similar devices that don't use an app and have their own display and buttons. I chose the App based device, so I never have to worry about broken switches and displays or possibly a dead battery (if they have an internal one. I like it but don't use it often.

 

[ERD50]

Thanks for replying. I said "if". I am trying to find out what the car needs. IF it needs 400 and the battery is down to 475, I am good.

OK, but you really have no idea what the car requires - it varies under different conditions. So I don't see what kind fo determination you can make.

And I'd guess that a battery rated at 700 that's down to 475 is showing problems. In many cases with batteries, the drop off is not linear at all. 475 might drop to 400, 350, 300 in a short while. As I said in my earlier reply, this could be a very steep slope.

-ERD50

 

[Koolau]

According to https://www.rav4world.com/d1/attachments/pdf/Toyota_Batteries2011.pdf

The factory battery was a Group 35 and had 550 CCA.

That said, your current battery is at 68% of it's original rating. It maybe has another 1 year left IMO.

I used to just wait until the battery does not start the car, then replace it. Today, I have a device that measures battery impedance and report the % of cranking amps available. All this without having to start the car. I would replace a battery around 60% of its rated capacity regardless of the car it is going into. BTW, I would hazard a guess that the car only needs may be 200 amps capacity to start the engine.

I'm not certain but I think that a battery's ability to "hold a charge" is mostly unrelated to CA. Either way, a battery that has either problem is time for a change.

I too have usually waited for a battery to go "bad" until I replace it. Now that we're down to one car, I found out the hard way that doesn't work very well. I had to have someone bring me a battery this last time as I couldn't even jump the car. The phrase "dead as a door nail" comes to mind but YMMV.

 

[ncbill]

Most of my batteries have died gradually so I now keep one of those compact lithium battery-based jump starters in them.

 

[CRLLS]

I too have usually waited for a battery to go "bad" until I replace it. Now that we're down to one car, I found out the hard way that doesn't work very well. I had to have someone bring me a battery this last time as I couldn't even jump the car. The phrase "dead as a door nail" comes to mind but YMMV.

Having that happen is rather inconvenient, not to mention can be very dangerous. I had one car battery die on me (actually DW) in the middle of the road on a rainy night rush hour. DEAD! No lights- no power anywhere! And she was in the middle lane. She called 911 to have the police come to run interference on the traffic. We had it towed home where I got ready to check out the electrical system. It turned out that the 11 year old battery terminal had rotted away from the rest of the battery. If I held the cable with half of the actual terminal still in it to the stub of a terminal remaining, it started up just fine. The battery still had the power to crank and run. That night the battery was replaced. It had showed no indication of any diminished capacity.

The cost of a new battery compared to the inconvenience or danger of having it fail is not worth trying to get the last 10% of life out before replacing it. I'm not a teenager working for minimum wage anymore. BTD

 

[Koolau]

Most of my batteries have died gradually so I now keep one of those compact lithium battery-based jump starters in them.

Yes, I've depended on this strategy myself. I have two (count them, 2) of the Li battery jumpers AND a lead acid unit that has lights, air pump and 200 watt inverter. No go when that battery died. It was just gone. No previous warning. With only one car, I was stuck - thankfully at home - not in the street or dark parking lot, bad neighborhood, etc. YMMV

 

[njhowie]

This is good info. The old battery was at 475 CCA and the OEM was at 550 CCA, so the old batter had 86% of the new OEM charge. That sounds like a good battery, right?

Respectfully, I think that's the wrong way to look at it. You have a 700 that is not the original and it has degraded to 475. How many years ago did you install it? How many years did you get out of the original 550 CCA battery? I assume you put the 700 in because the original had died, correct?

I believe it's clear that you are running them down over time, for one reason or another, and having 86% of the new shouldn't give you comfort...maybe it was just a year from needing to be replaced? Or heaven forbid, even sooner, possibly at a very inconvenient time/place.

An ounce of prevention...

 

[Graybeard]

I agree with njhowie: you need a significant cushion of CCA's to start a car engine in all foreseeable conditions. Battery output is quite dependent on temperature since it involves a chemical reaction that proceeds slower with colder temperatures. Couple that with the fact that it is much harder to turn over an engine at colder temperatures and that cushion has to be even higher. FWIW, I lived in Phoenix for over thirty years and virtually every car battery in every car, OEM or aftermarket, I had lasted just a tad over three years. They simply could not take the heat.

People find this hard to believe but heat in summer kills more batteries than cold in winter.

 

[JoeWras]

People find this hard to believe but heat in summer kills more batteries than cold in winter.

Heat kills, cold tests.

When I lived in Florida, I couldn't believe how cars ate batteries. At work, we all seemed to be giving each other rides to get batteries. 3 years was the magic number.

 

[isisdave]

CCA stands for Cold Cranking Amps. If you didn't test the battery at the lowest temperature you experience, and on an engine that hasn't run since last night, your tester's assertion that your battery "is" 475 CCA doesn't mean much. At 10 degrees and a cold engine, it might need 600, if only for three seconds.

BTW, my experience in California was that batteries died on the first cold night in fall. Or at least that's when we discovered that they weren't adequate when it stopped being warm.

 

[Z3Dreamer]

OP here. Y'all are lecturing me that I need to replace that battery. My second sentence said I already replaced it. That is not what I am asking. I am trying to figure out how to match CCA with my car. Does it need 400? 800? 650? If I buy a 5,000 and it goes down to 2,500, is that still a good battery?

If I replaced my tires after 5,000 miles, would you say: "Why take a chance. I replace after 3,000 miles." Of course you wouldn't recommend something that silly.

Back to batteries. I think the answer is that none of you replace batteries based on technical readings. You replace based on how long you have had it, how bad your weather has been and, finally, whether or not there are any issues. Correct?

 

[Z3Dreamer]

Respectfully, I think that's the wrong way to look at it. You have a 700 that is not the original and it has degraded to 475. How many years ago did you install it? How many years did you get out of the original 550 CCA battery? I assume you put the 700 in because the original had died, correct?

I believe it's clear that you are running them down over time, for one reason or another, and having 86% of the new shouldn't give you comfort...maybe it was just a year from needing to be replaced? Or heaven forbid, even sooner, possibly at a very inconvenient time/place.

An ounce of prevention...

There were no issues but I replaced anyhow. I got 6 years out of the battery, but it was garage kept. Overall, I am not unhappy with the battery, just trying to find out how to match stated CCA with car's needs.

 

[CRLLS]

OP here. Y'all are lecturing me that I need to replace that battery. My second sentence said I already replaced it. That is not what I am asking. I am trying to figure out how to match CCA with my car. Does it need 400? 800? 650? If I buy a 5,000 and it goes down to 2,500, is that still a good battery?

If I replaced my tires after 5,000 miles, would you say: "Why take a chance. I replace after 3,000 miles." Of course you wouldn't recommend something that silly.

Back to batteries. I think the answer is that none of you replace batteries based on technical readings. You replace based on how long you have had it, how bad your weather has been and, finally, whether or not there are any issues. Correct?

Incorrect. Go back and read #6. I answered what battery your car came with and when I change my battery based on testing.

 

[Z3Dreamer]

Incorrect. Go back and read #6. I answered what battery your car came with and when I change my battery based on testing.

I did not ask what it came with. I asked what CCA it needed. It obviously needs less than 550.

You also use a tester but then decide on 60%. Would you still replace if you had a larger capacity battery to begin with? An 850 CCA battery at 60% would still have more power than is necessary.

I think it is to the point of arguing and I will stop. I am sorry that I am not making my question clear.

 

[Jerry1]

I think your question is clear. Given your example, I’d change out the battery. I’m assuming that when the battery was installed, someone decided they wanted 850cca to give them some cushion. So, that is my starting point. If I lost 40%, then I’ve likely given up most of my cushion and I would replace it. Your other example is out of the range of possibilities. In your example of 5000 going down to 2500 goes out of range. There’s no standard car battery that would give you that much initial cushion.

As has been mentioned, there are a few factors that may impact your comfort with any particular level of cushion. Things like temperature and dependability will be major factors. If I lived in a mild climate, had a second car, and only used that car for local trips, I’d be comfortable eating into my cushion and put off the expense of a new battery for awhile. If it was my only car and my spouse had health issues, I might feel uncomfortable eating into my cushion by even 20%.

Kind of like when to take SS. It depends.