EXCESS 12v LOAD WHEN OFF - DRAINING 12 VOLT BATTERY

Today my RAV would not charge as it normally does. Seems to turn on but thinks the battery is too low to go anywhere. Had about 23 miles when I parked it. Was plugged in maybe 30 minutes later as another employee finished and swapped the cord to mine. Car did refuse to turn off while I tried several times to cycle it on-off to get charging to start. Would tun off after sitting for a bit.

Periodically when I open the door lately the GOM says LO and once I start all becomes normal with the miles displayed. Must have been my warning.

Tech is supposed to look at it in the morning. Any guesses?

Bad 12v battery? It's a common failure and can cause seemingly non-sensical behavior.

davewill said:

Bad 12v battery? It's a common failure and can cause seemingly non-sensical behavior.

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Yep... the full battery / LO indication on the GOM is your clue.

Get a new 12 volt battery.

I had ONE occurrence of seeing LO when I got into the car and it immediately switched to normal. This was about a month ago. It has not happened again.

Are you saying this is a sign of a 12V battery problem??

Why would the 12V battery last only 2.5 years in an EV vs. what seems like ages in an ICE vehicle?

eplantz said:

I had ONE occurrence of seeing LO when I got into the car and it immediately switched to normal. This was about a month ago. It has not happened again.

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Interesting... I just had my first occurrence of seeing LO momentarily while getting into the car before it reverted to showing the expected three quarters charge.

http://www.myrav4ev.com/forum/viewtopic.php?p=22290#p22290

I did have a complete breakdown ONCE about a year ago, but it was something going haywire with the DC/DC charger for the regular 12V battery. I had to have it towed to the dealer under warranty because it was totally undriveable after that one happened. They replaced the 12V battery and the problem went away. My conclusion? The 12V batteries in these cars - even new - will not last much more than about 2 years before they will croak, i.e. premature EOL failure, and I believe some of the Model S Tesla 12V batteries will do exactly the same, so Tesla recommends their replacement every 18 months to prevent bricking those cars. I believe RAV4EVs inherited the same issue.

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12 volt battery thread:

http://www.myrav4ev.com/forum/viewtopic.php?f=8&t=1738

What to reset with 12 volt power loss / battery replacement:

http://www.myrav4ev.com/forum/viewtopic.php?p=20859#p20859

eplantz said:

Why would the 12V battery last only 2.5 years in an EV vs. what seems like ages in an ICE vehicle?

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Because it is a common start battery not a deep cycle. RAV4-EV tends to deep cycle the battery too much due to drawing down when the car is off.

Of course my #2501 starts working when the tech takes a look at it. I suggested the 12v should be tested but that went no where.

And they noticed the gear noise.... Maybe something will come of this anyway.

I plan to get that G35 yellow top Optima once the car is out of the shop.

#2501 is back from the dealer. Dealer found nothing wrong. Charged last night just fine on the timer.

12v battery seems to hold 12.9 volts fairly steady so I will hold off on replacement for now. Will be monitoring this closely.

Dealer told me a new drive unit will be ordered. Could take 4 days to 4 months to get delivered.

On Tuesday after an opportunity charge at work using a AeroVironment Turbo Cord at 240VAC, I received the LO reading on the mileage when I turned it on. Wouldn't go to Ready, so turned it off and on again. This time LO switched back to normal mileage remaining and turned on the car as normal. Next month will be 3 years of ownership, so I planned to replace the tired 12V lead acid this weekend.

Of course, on Friday my wife and I swapped cars so that I could have her windshield crack fixed. While picking up my daughter from her elementary school, my wife hit the power button, but it did not provide the Ready light. Then of course, it would not turn off, even after lots of cycling. Needless to say, my wife was not happy about this. 12.2V was on the cigarette lighter meter and it continued to drop, finally down to 10.9V. She called a friend to come give her a jump start. I told them to not even bother turning on the other car, just provide the voltage to the battery to trigger the main contactor so the DC-DC could do the rest. After connecting the other vehicle's battery, the voltage rose to 13V. However the car will still not turn off or on. I told her that she needed to disconnect the 12V negative terminal to reset the car's computer. Luckily, the JdeMO's installation added a butterfly nut on the negative terminal which allowed this to happen without the need of a 10mm wrench (even though I carry one in the armrest). After removing the 12V neg cable, reconnecting it, and having jumper cables attached to the other car, the system rebooted and powered up fine, with the Ready light on.

Last night I installed a new 12V battery and all is good.

Well, after reading these battery comments, and the other 12V battery thread, I decided it was too risky to not change my 12V battery. The original was 2.5 years old and one occurrence of LO. I did NOT have a problem (yet). With the really cold temps here in Chicago (1.5F this morning), it did not seem safe to "let it ride". My radar detector was showing 11.5V in accessory mode.

So, Friday, I drove to Sears. They have a few deep cycle batteries but none that would fit.

I then drove to NTB (National Tire and Battery) and they have NO deep cycle batteries.

I then drove to Pepboys. They had a few deep cycle/marine batteries. None in Group 35 size. But they have a Group 24M size which was pretty close. BUT, during installation discovered the terminal posts are in the front top (vs. back top in the original). There is NO slack in one of the negative cables, so this was a no-go after 1.5 hours.

Enough for one day.

Today, I went to Sams Club to get the Optima Yellowtop Group 35 battery. They installed it. I was told the battery is smaller so the tie-down bracket was not as snug as the original but probably OK. So, I have the new deep cycle battery.

(Interestingly, the radar detector still shows 11.5V in accessory mode, so apparently you should not use this as a diagnostic tool).

Car seemed OK after the dealer found nothing. Drove and acted fine over the weekend.

Now it shows LO again as the door is opened. When shutting down the green charge bar in the center console appears for a split second then goes blank.
Will check the 12v battery when I get home.... hope I make it.

Going to try reboot by disconnecting the 12v battery.

smkettner said:

Going to try reboot by disconnecting the 12v battery.

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It sounds like the battery is doing a great job of disconnecting itself !!!

Definitely sounds like a bad 12 volt battery. I just replaced mine. Had a similar issue. Car wouldn't turn off. Went with the standard Group 24 battery instead of the smaller Group 35.

Get home tonight and it sits for an hour. Display now reads normal. Battery 12.93 volts.

Tomorrow I carry the voltmeter with me.

So a few times randomly and infrequent the display is showing the same trouble but the car starts, runs and charges fine.

Today when turning the vehicle off at my charging spot the green bar in center display went blank when it s/b about 75%.
Car did not initially start charging. Timer display times were odd but I don't recall details. Hit charge immediately and car charges normal.

Tonight I disconnected the 12v battery for about two hours for a reboot. Will see if this helps.

I did find it interesting with some latent voltage on the cable of 1.1 volts steadily declining over the two hours to .06 volt.
I guess this is why Tony recommends disconnected overnight to get a full reset.
Did cause the navigation to reboot.

So far so good with the reboot. No more issues yet. Did see 145 on the GOM today

Today again similar situation as the OP with car failed to charge and failed to run.

It would turn on fine but would not charge or engage to drive. The main contactor seemed to close and then open with a thunk. Changed timer to immediate charge and same result. Battery was 30% but vehicle said LO please plug in to charge. All charge level bars were blank. Climate message said only defrost available. I suppose all that is normal when the vehicle will not keep the main battery connected.

Found a wrench and removed the 12v battery cable for about one minute. Car was able to charge after reconnecting. Drove home fine a couple hours later.

Anyway does this seem normal or is something failing and eventually needs an actual repair?
Does an event like this stay in the trouble codes for later or does the reboot erase the info?


Toyota put in a new 12v battery a couple weeks ago.

12 volt battery is dead again today

Well, you sound the issue (dead 12 volt).

Check to see what light your are leaving on (like the rear door light).