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Discussion Starter · #1 ·
Hi folks,

I have a 2012 RAV4, V6, 4WD, just over 58,000 miles. I'm in California. First battery replaced after 3 years, second battery (Toyota) replaced 3.5 years later, just replaced third battery (Toyota) with Interstate MTP-24F after a little over 3 years on the Toyota battery.

I recently purchased an OBDLinkMX+ monitor for my other vehicle, and thought I’d connect it to my RAV4 to monitor the battery voltage reading, knowing time-wise it could be due for a new battery. Reading consistently about 13.5V while driving.

After sitting for a few days, the battery voltage (measured with multimeter) was 12.35V. Dropped to about 9.5V when started, then up to 14.1V idling. Not much of a change in voltage reading when turned on high beams and fan. Dropped to 13.5V while driving. Seemed to be pointing towards a battery issue from what I read online about what the voltage should be.

It chugged a few times when starting this morning, so I picked up a new Interstate battery and installed it this afternoon. It was fully charged (12.6V) when I installed it.

However, and this is what is concerning me, the OBD monitor is still reading 13.5V while driving.

(For comparison, on my other vehicle, which is a 4Runner, the OBDLinkMX+ reads 14.2V consistently while driving, and it also has an Interstate MTP battery.)

I was hoping folks here might be able to weigh in with experience: Is my RAV4’s alternator likely failing? Or am I worried over nothing?

Thank you in advance for any experience/insight on this!

Kauri
 

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Hi folks,

I have a 2012 RAV4, V6, 4WD, just over 58,000 miles. I'm in California. First battery replaced after 3 years, second battery (Toyota) replaced 3.5 years later, just replaced third battery (Toyota) with Interstate MTP-24F after a little over 3 years on the Toyota battery.

I recently purchased an OBDLinkMX+ monitor for my other vehicle, and thought I’d connect it to my RAV4 to monitor the battery voltage reading, knowing time-wise it could be due for a new battery. Reading consistently about 13.5V while driving.

After sitting for a few days, the battery voltage (measured with multimeter) was 12.35V. Dropped to about 9.5V when started, then up to 14.1V idling. Not much of a change in voltage reading when turned on high beams and fan. Dropped to 13.5V while driving. Seemed to be pointing towards a battery issue from what I read online about what the voltage should be.

It chugged a few times when starting this morning, so I picked up a new Interstate battery and installed it this afternoon. It was fully charged (12.6V) when I installed it.

However, and this is what is concerning me, the OBD monitor is still reading 13.5V while driving.

(For comparison, on my other vehicle, which is a 4Runner, the OBDLinkMX+ reads 14.2V consistently while driving, and it also has an Interstate MTP battery.)

I was hoping folks here might be able to weigh in with experience: Is my RAV4’s alternator likely failing? Or am I worried over nothing?

Thank you in advance for any experience/insight on this!

Kauri
Sounds like the alternator could still be Ok. Remember that the battery only provides juice to start, once running the alternator essentially takes over. Dropping from 14.1 at idle to 13.5 running could be normal considering the alternator provides power for the spark and ECU to manage the transmission and AWD controller, among other things.

From what we’ve seen with others, a V6 battery will last up to three-ish years in a hot climate. RTexasF and JuneBug have both reported numerous batteries over the life of their RAV, whereas I near Detroit with a 4-cyl had my first one last 7 years. Best thing is to monitor it a bit more, but it sounds OK from what you describe. They key detail is that the system voltage didn’t drop while running when you added load (high beams and fan).


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Discussion Starter · #3 ·
Good to know, thank you!!
I'll load test it again soon, and turn everything I can on (high beams, fan, radio).
 

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IMO 13.5 is low. I'd like to see 14.0-14.4V. One definitive test you can run if the battery has cell caps is a hydrometer test. That way you can see if the cells are actually getting fully charged or not.
 
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my Alternator (4 Cyl Engine) completely failed after about 70-80 000 miles if I converted correctly between miles and km so it might just be the end of life of the alternator, those aren't too expensive to change. But the Voltages sound still within reasonable.

Battery life depends highly on climate as well as battery and car use. If you let your car sit for months and the battery gets super low, that hurts the battery. There are huge quality differences between the "bigger" battery brands - here in Peru I once made the error to buy a cheap chinese battery that was recommended to me and it lasted only like 2 1/2 years.
 

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Agree with Dr. Dyno about the voltage being low. With sealed batteries it generally reduces battery life to open it to test individual cells since the introduction of ambient air disrupts the recombination process regarding vaporised electrolyte components. The reported 12.6V fully charged condition with the Interstate battery in Post #1 is low for a new, supposedly fully charged battery.
 

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Discussion Starter · #7 ·
Agree with Dr. Dyno about the voltage being low. With sealed batteries it generally reduces battery life to open it to test individual cells since the introduction of ambient air disrupts the recombination process regarding vaporised electrolyte components. The reported 12.6V fully charged condition with the Interstate battery in Post #1 is low for a new, supposedly fully charged battery.
Good to know, thank you!
What should the fully charged voltage have been on the new Interstate battery? I was of the impression 12.6V was max battery charge, but I'm still learning about all this :)
I bought the battery from a local reputable shop, but they could have had it on the shelf for a while.
The hydrometer test looks like it's beyond my comfort level, unfortunately, since I'm not good with chemicals.
I'll check the voltage and repeat the load test again soon (I work from home so will do it after work).
 

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The reported 12.6V fully charged condition with the Interstate battery in Post #1 is low for a new, supposedly fully charged battery.
Not sure about that since I see many flooded lead-acid battery state-of-charge charts online that call 12.6V fully charged. Of course that's a "resting" voltage not measured just after shutting the car or charger off. So that would apply to a new fully charged battery off the shelf like the one the OP bought.
My fancy battery condition tester reads % of life (based on the CCA you enter for the battery), % of charge based on voltage and internal resistance. It reads 12.6V as 100% charged.
 
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Discussion Starter · #9 ·
My fancy battery condition tester reads % of life (based on the CCA you enter for the battery), % of charge based on voltage and internal resistance. It reads 12.6V as 100% charged.
A little off-topic, but can I ask which battery tester you have? I've been considering purchasing one if it can tell me more than the info I can get with my multimeter and OBD monitor. Thanks!
 

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The hydrometer test looks like it's beyond my comfort level, unfortunately, since I'm not good with chemicals.
I just did one the other day to check for a weak cell in an Interstate battery in a van I helped a friend from church buy.
And you do have to be very careful with the acid. Don't get it on ANYTHING. After I tested the cells I realized I didn't have a way ready to rinse it with water and couldn't carry it dripping to the garage sink. So I set it on the ground and went and got a cup of water to do a first rinse then rinsed it several more times in the sink before putting it back on the shelf.
So with a little care and forethought it's a safe and easy test.
 
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A little off-topic, but can I ask which battery tester you have? I've been considering purchasing one if it can tell me more than the info I can get with my multimeter and OBD monitor. Thanks!
I have this one: Ancel BST100 12V Automotive Car Battery Tester 220Ah Charging Analyzer 2000CCA | eBay
Here's the manual for it but the test result they show in 5-1-6 is totally stupid since it must've been on a totally dead junk battery:
Besides showing realistic test results he's getting with a similar tester, at the 6 minute this presenter discusses 12.6V being a full change.


My tester shows Health, Charge %, Voltage and Internal Resistance on the first screen whereas he has to go to page 2 for IR.
 
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Just to reply to the post above, 12.6V is the maximum theoretical charge of a battery (6 cells at 2.1V per cell), but after a fresh charge you can get surface charge I believe which can show higher than 12.6V - A quick blast of headlights will sort that out.

I agree as above too, unless it is a smart charge system (not on these gen Ravs) I would expect to see north of 14V when running charging. Could be a bad alternator as above, but also be a bad cable or connectors with resistance - I have seen both cases. Also with Dr Dyno on the hydro tests too
 

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Thank you! I'm going to order one of these; it looks like it'd be a great addition to my toolkit especially since I've been helping maintain my mom's Toyotas as well as my own.
One operational thing it took me awhile to figure out is that each clamp, both positive and negative actually has two jaws, a "normal" one on one side and an inner one on the other side. It's easily seem in the video and works correctly by default when testing a battery with nothing attached to the terminals. But with a battery in a vehicle you have to make sure just the inner one makes contact on its side otherwise you may get a false or no reading. I make it contact the end of the bolt on the battery cable.
 
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Running voltage sounds low. I'm guessing bad alternator. Do the RPMs drop a bit at idle when turning on the headlights? Or do they dim whole driving and coming to a stop?

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Discussion Starter · #16 ·
Could be a bad alternator as above, but also be a bad cable or connectors with resistance - I have seen both cases.
Cable or connector issues could be it---I'll look things over under the hood. Thanks for pointing this out! We've had mouse issues in the past, nothing recently since I made a "mouse moat" from aluminum flashing that so far has successfully kept them out. But I'm thinking there could be a partially chewed wire somewhere that I haven't yet caught.

One operational thing it took me awhile to figure out is that each clamp, both positive and negative actually has two jaws, a "normal" one on one side and an inner one on the other side. It's easily seem in the video and works correctly by default when testing a battery with nothing attached to the terminals. But with a battery in a vehicle you have to make sure just the inner one makes contact on its side otherwise you may get a false or no reading. I make it contact the end of the bolt on the battery cable.
Good to know, thank you! I'll test the old Toyota one I took out as well as run the available tests on the new battery that's currently in the car as soon as I receive the Ancel BST100.

Running voltage sounds low. I'm guessing bad alternator. Do the RPMs drop a bit at idle when turning on the headlights? Or do they dim whole driving and coming to a stop?
I admittedly don't drive at night much, if at all (I work from home), so I don't use the headlights much and haven't noticed this happening, but I will definitely try to check this soon! I didn't see a noticeable drop in voltage when I turned on the headlights and fan right after starting it to load test the alternator, but I will also test this again to make sure I didn't miss something. Thank you for the advice!
 

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Also note that the BST100 and many similar units (I bought this one for my son to use on the 6V batteries on his solar system on Maui) also perform other tests such as charging system and starting tests. I haven't used mine for those tests but certainly will in the future. I've never checked alternator ripple either but am now wondering if high ripple might be an early indication of problems.

Here's a good video that shows some of the other tests. (Looks like we save $100 by not needing the printer or a 24V test.)

 
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On my tester, it does look at alternator ripple and gives a result of the test. As you say @Dr Dyno, it is another indication of a pending problem if the ripple it out of spec.
 

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Discussion Starter · #19 ·
To add to the puzzle…

The scanner is consistently reading the voltage to be around 13.4-13.6V in an around town situation (which is where I’d previously been testing it; sorry, I probably should have mentioned this in my original post!). However, on higher speed roads and freeways, it goes up to 14.1-14.3V and stays there until getting back into town. (The 14.1-14.3V is the voltage I’d expected to see all the time, based on comparing readings from my 4Runner; but my 4Runner is a 1999 manual transmission so perhaps it may not really be a good comparison since it has way less electronics than my 2012 RAV4.)

I do think the Toyota battery was getting old, because when I started my RAV4 this morning with the new Interstate battery, the voltmeter reading only dropped to about 10.5V (previously it was dropping to 9.5V), then went up to 14.2V or thereabouts. And, with high beam headlights, fan on highest setting, and radio on, the reading didn’t drop much more than 0.05V (and anything in that range I think is subject to error in my voltmeter). (Again comparing with readings from my 4Runner, this is what I’d expected to see.)

I’m very curious what the Ancel tester’s alternator ripple test will say about the alternator (it should arrive late next week, and I’ll follow up here will the results). I’m still mystified whether this is just normal RAV4 behavior, or if the alternator is starting to weaken, or if there’s something else going on.
 

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Maybe the old battery terminals had a little crud on them causing a small voltage drop - fitting the new one may have sorted the problem.

Let us know what the tester reports
 
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