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Discussion Starter · #1 ·
... at least for me.

I had the dead battery problem last December. I had the DCM firmware update (T-SB-0095-20) applied in December. The problem happened again in January, so I took it in again and had the revised DCM firmware update applied (it had just been revised earlier that day), and the battery changed (due to bad cells).

No problems after that, until yesterday evening. Car was totally dead again (fortunately, it was at home in my garage). I jumped it this morning and drove it for 1/2 hour to charge up the 12V battery.

I am not sure what I am going to do about it. If I take it in, they will likely not find a problem. I am not sure if the cells are now damaged in the battery.

The car is no longer reliable to me (and I would get rid of it if I could). I will be carrying the jump box with me now everywhere. Oye!
 

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2021 Rav 4 XLE gas engine
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... at least for me.

I had the dead battery problem last December. I had the DCM firmware update (T-SB-0095-20) applied in December. The problem happened again in January, so I took it in again and had the revised DCM firmware update applied (it had just been revised earlier that day), and the battery changed (due to bad cells).

No problems after that, until yesterday evening. Car was totally dead again (fortunately, it was at home in my garage). I jumped it this morning and drove it for 1/2 hour to charge up the 12V battery.

I am not sure what I am going to do about it. If I take it in, they will likely not find a problem. I am not sure if the cells are now damaged in the battery.

The car is no longer reliable to me (and I would get rid of it if I could). I will be carrying the jump box with me now everywhere. Oye!
Even though you are under warranty and could get new OEM 12v free you might consider shelling out some bucks and getting a good quality AGM.
 

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Discussion Starter · #3 ·
Yeah, maybe. It is just over $200 for a battery at Advanced Auto. They will do a free battery test too, IIRC.
 

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The 12 volt battery will not be charged in 30 minutes. Its just a question of time in READY mode. At best power will be transferred from the traction battery at about 10 amps so not allowing for any efficiency losses that would get you 5 amp.hours of charge. If you do not use the car enough to keep the battery charged you should use a separate charger once a month. Typically mine requires 10 hours on an intelligent charger to restore full charge. The live systems on modern cars drain the battery, particularly if connection are maintained via phone apps/gps and the anti-theft systems too.
 

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2021 Rav 4 XLE gas engine
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If you do not use the car enough to keep the battery charged you should use a separate charger once a month. Typically mine requires 10 hours on an intelligent charger to restore full charge.
Another reason to get an AGM --they are "deep cycle" and can be re-charged repeatedly without degradation. If you do monthly charges to a flooded lead/acid 12V it shortens it usable life span.
 

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2021 RAV4 XLE Premium Hybrid
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The 12 volt battery will not be charged in 30 minutes. Its just a question of time in READY mode. At best power will be transferred from the traction battery at about 10 amps so not allowing for any efficiency losses that would get you 5 amp.hours of charge. If you do not use the car enough to keep the battery charged you should use a separate charger once a month. Typically mine requires 10 hours on an intelligent charger to restore full charge. The live systems on modern cars drain the battery, particularly if connection are maintained via phone apps/gps and the anti-theft systems too.
I use an intelligent charger every couple of weeks on my RAV4 hybrid. Easy to do with the connects in the engine compartment fuse box, as shown in the owners manual.
 

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I believe any decent new car has AGM battery these days including the Rav4 hybrid. Never had a problem with my 2019 Rav4 hybrid limited. Something changed in 2020 model. I know my 2019 will turn off interior lights if doors are left open, something the dealers tried to write off the dead battery problem at first.
I would have called the Toyota service... let them jump it and figure it out. But with it happening months apart... that's difficult to identify.
 

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I believe any decent new car has AGM battery these days including the Rav4 hybrid.
The gas model 5th generation RAVs all have an OEM plain, old flooded lead/acid battery and not a very good quality one at that. I do not know whether hybrids have an AGM 12v. Easy enough for hybrid owners to check--see if it has the two large cell plates on top. If so, its not AGM.
 

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... at least for me.

I had the dead battery problem last December. I had the DCM firmware update (T-SB-0095-20) applied in December. The problem happened again in January, so I took it in again and had the revised DCM firmware update applied (it had just been revised earlier that day), and the battery changed (due to bad cells)...
Note.
T-SB-0089-21 said:
SUPERSESSION NOTICE. The information contained in this bulletin supersedes Service Bulletin No. T-SB-0095-20.
- The Introduction and DCM Reset and Firmware Update Procedure sections have been modified. Service Bulletin No. T-SB-0095-20 is obsolete and any printed versions should be discarded.
 

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2021 Rav 4 XLE gas engine
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Most cars have EFB batteries these days to enable stop-start systems.
The gas XLE and other gas models DO have the auto stop/start. They have what is known as an EFB (enhanced flooded battery). This is merely a flooded lead/acid battery with a completely sealed top so you do not need to add distilled water and indeed you can't open them to do so. They are not that different from earlier batteries and are pretty cheap. The AGM is completely different and superior to an EFB of the same size -- they have many more CCA (cold cranking amps) and are shock and vibration resistant. That's why they are used for racing and off road. Probably the hybrids have EFBs like the gas models. I do not know. Can someone confirm?
 

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Probably the hybrids have EFBs like the gas models. I do not know. Can someone confirm?
It does appear to be the case that this gen of Rav4 hybrid takes an EFB battery. That's what Autozone shows as a replacement. For the first gen Rav4 hybrid (2016-8) and for my 2010 Prius they show AGM replacement batteries. My Prius does indeed have an AGM. I'm not sure what the reason for the change is.
 

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Discussion Starter · #15 · (Edited)
My previous Toyota hybrids all had AGM batteries, so it looks like Toyota is going cheap on them now by putting in these EFP batteries.

Edit: I wonder if this is really the case, if I have a Limited. It might be an LN2 battery, which I think is an AGM size H5???

Thanks everyone for the feedback / info.

The AGM that Advance Auto recommends is this: https://shop.advanceautoparts.com/p...ttery-group-size-h5-680-cca-h5-agm/10700670-p which is currently about $232.

I am thinking either I may possibly get this T-SB-0089-21 applied, and may also get an AGM battery put in. Still thinking it through.
 

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... at least for me.

I had the dead battery problem last December. I had the DCM firmware update (T-SB-0095-20) applied in December. The problem happened again in January, so I took it in again and had the revised DCM firmware update applied (it had just been revised earlier that day), and the battery changed (due to bad cells).

No problems after that, until yesterday evening. Car was totally dead again (fortunately, it was at home in my garage). I jumped it this morning and drove it for 1/2 hour to charge up the 12V battery.

I am not sure what I am going to do about it. If I take it in, they will likely not find a problem. I am not sure if the cells are now damaged in the battery.

The car is no longer reliable to me (and I would get rid of it if I could). I will be carrying the jump box with me now everywhere. Oye!
At first when I read your post, I thought you had a RAV4 Hybrid (because you posted it in the "4.5 Rav4 Electric Hybrid" section). But I'm now assuming you do not have the hybrid version.

Basically, if your battery is going dead after a short period of time (a couple of days) of not being used, then your problem is in one of three areas: 1) You have a defective battery that cannot hold a full charge, 2) Your alternator/charger system is not fully charging the battery, or 3) your electrical system is is slowly draining the battery when the vehicle is not in use.

Any service shop should be able to determine if your battery is defective as well as checking your alternator/charge system. (1 & 2 above).

There might be something draining your battery when the vehicle is not in use. To check this out, you need to disconnect the battery (Positive terminal) when the vehicle is Off and insert an ammeter between the positive lug on the battery and the positive cable which normally connects to the positive battery terminal. Do Not Try to Start the Vehicle - you will blow the ammeter!!!!! When a door is open and the interior lights go on, you will see current being drawn to power the interior lights. With all doors closed and no interior (or exterior parking) lights, you should see a very low current draw. (Unfortunately, I can't tell you what is the average current draw with the RAV4 off, and all lights out. I'm assuming it should be less than 0.1 amps.) If your vehicle is drawing excessive current with everything off, then it is time to look for something that is drawing current when the vehicle is off........
 

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Discussion Starter · #17 ·
^^^ I have a 2020 RAV4 Hybrid Limited.

I would think the amperage drawn would not be negligible since the 12V battery keeps the computer running, but I don't know any more about this.
 

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At first when I read your post, I thought you had a RAV4 Hybrid (because you posted it in the "4.5 Rav4 Electric Hybrid" section). But I'm now assuming you do not have the hybrid version.

Basically, if your battery is going dead after a short period of time (a couple of days) of not being used, then your problem is in one of three areas: 1) You have a defective battery that cannot hold a full charge, 2) Your alternator/charger system is not fully charging the battery, or 3) your electrical system is is slowly draining the battery when the vehicle is not in use.

Any service shop should be able to determine if your battery is defective as well as checking your alternator/charge system. (1 & 2 above).

There might be something draining your battery when the vehicle is not in use. To check this out, you need to disconnect the battery (Positive terminal) when the vehicle is Off and insert an ammeter between the positive lug on the battery and the positive cable which normally connects to the positive battery terminal. Do Not Try to Start the Vehicle - you will blow the ammeter!!!!! When a door is open and the interior lights go on, you will see current being drawn to power the interior lights. With all doors closed and no interior (or exterior parking) lights, you should see a very low current draw. (Unfortunately, I can't tell you what is the average current draw with the RAV4 off, and all lights out. I'm assuming it should be less than 0.1 amps.) If your vehicle is drawing excessive current with everything off, then it is time to look for something that is drawing current when the vehicle is off........
Using the diagnostic mode, each RAV4 [model code AXAA52(4)L- or AXAH52(4)L-] user can determine the state of the 12V battery without leaving his car.
 

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The Hybrid RAV4 is a totally different animal than the "normal" RAV4 as there is no separate Alternator to power the 12 volt system, and the 12 volt battery isn't used to start the gas engine. You're correct that "the 12 volt battery keeps the computer running" - (just one of several "computers" in the vehicle). To my knowledge, the 12 volt system is powered by an inverter connected to the high voltage battery. I'd suspect that when the vehicle is off and all lights are off, that something else is drawing power from the 12 volt battery. (When turned off, the USB ports are turned off as well as the 12 volt accessory port.)

A small amount of current is required (from the 12volt battery) to maintain at least one computer/processor in the standby mode. I've owned a RAV4 Hybrid since Jan. 2020 and haven't used it much (I've only have 11,000 miles on the odometer). It is fairly common for me not to use the RAV4 Hybrid for a few days or a week and I've never had a dead 12 volt battery issue. (Before I had a Prius, and after 7 1/2 years the 12 volt battery died - not unusual, (I've never had a lead-acid vehicle battery last more than 8 years.)
 
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