EXCESS 12v LOAD WHEN OFF - DRAINING 12 VOLT BATTERY

[smkettner]

Charged the battery and all seems fine today. I did check for lights to no avail.

Did notice an odd sequence in the charging. The 20 amp charger was soon up to 14.0 volts and rising slowly but I stepped away for a bit and it was at 13.2 and rising when I came back from the grocery. It was as if a 20+ amp load had been on the battery. All seemed normal again as I kept a close watch. I decided to disconnect a cable while the charger finished. Seems fine today.

Have turned off the auto headlights at this point.

 

[smkettner]

12v dead again today

Charging battery and hoping to get to work.

 

[fooljoe]

Could be that the new 12V is just defective. Otherwise maybe your DC/DC converter is bad, or you've got some kind of short that's drawing current from the battery even when the car's off (beyond the usual draw.) I think you gotta just take it in again, or take an ammeter to it to see if you can figure out where the power's going. If there is a short somewhere that could be a bit scary as that electricity's probably getting turned into heat somewhere...

 

[smkettner]

The 12v charges up just fine. Can't imagine it is intermittent.

It would seem to me something comes on and drains the 12v but hard to prove without a recording ammeter.

In the mean time I need my vehicle and it would seem the dealer would have little chance to actually find the issue.
Will be out of town for a week in August... might let the dealer have it to drive around.


One thing that bugs me is the charge level display such as the green bar(center display) when the vehicle is turned off shows green for an instant or two seconds and then shuts off. The display is there but the bar goes blank. Similar with the 16 bar charge level on display left only really works when the car is on. Seems like communication or memory of the battery level is getting lost or dropped. It works intermittently different. Rarely it actually works like it did when new but sometimes it does but only once or for a couple seconds. Dealer did not seem to care. Does not seem normal. Yes the 12v battery is well charged when this happens and measures 13 volts at time of shut down.

 

[smkettner]

Yes looks more like a defective battery. Got out the hydrometer today. SG is low even after charging last night and again this morning.

Now do I bother with the dealer or just go to Pep Boys for the Bosch AGM group 24 that I would prefer anyway.
I really don't need more grease stains on the upholstery.

 

[TonyWilliams]

Yes looks more like a defective battery. Got out the hydrometer today. SG is low even after charging last night and again this morning.

Now do I bother with the dealer or just go to Pep Boys for the Bosch AGM group 24 that I would prefer anyway.
I really don't need more grease stains on the upholstery.

I grew up fighting vehicle batteries... I hate 12 volt batteries. Just get a proper battery.

 

[smkettner]

Put the Bosch 24F in today. Time will tell if this resolves the issue.
Coupon in the weekly flyer for 35% off all batteries... made my day.

 

[smkettner]

Car did not want to charge this afternoon. Charged in the morning fine from 2 bars to 10 bars. Expected to finish this afternoon but no go. Started and drove fine so I parked it.

Measured 12v battery later this evening at 12.7 so it seems close to full and serviceable. This is a near new Bosch 24F AGM.

My question now is what should the 12v battery voltage be when the main battery is charging?
I measured 13.5 volts. That seems low to me as I was expecting 14.2+ same as in ready mode.

 

[TonyWilliams]

13.5v to 14.5v would be fine while charging.

 

[smkettner]

Thanks Tony.

Today again it failed to charge in the afternoon after interrupting the morning charge to go have lunch.
12v was fully charged last night with a portable so that cannot be the issue.

I could hear the contactor close then open after a split second.
Dread going back to the dealer to tell me nothing is wrong

 

[smkettner]

Today it failed to charge again so I headed to the dealer.
Of course the service writer and the EV technician then watched as it charged fine on the big Leviton while blaming my Schneider and the small Leviton and Clipper Creek at work are not compatible.
Just frustrating so back to work.

Did not charge again... pushed the extended setting and voila it starts charging. :|

Tonight I tried Entune app. Response 'battery too low to run pre-climate' Battery is 70+% when I pulled in. Start charge function just failed. Contactor just closes and opens and it fails to start.

It is a slow torture of intermittent failure. Eventually it has to get so dead Toyota will find something. Appointment for next Tuesday.
Good luck

Just measured the 12v draw when the car appears asleep. Close to 2 amps. Holy cow I had no idea.

 

[fooljoe]

Just measured the 12v draw when the car appears asleep. Close to 2 amps. Holy cow I had no idea.

Has anyone else checked whether that's a normal draw? I'll try to take an ammeter to mine tonight if I remember, and perhaps compare to the Leaf. However 24W doesn't really seem like that much...

 

[user 340]

However 24W doesn't really seem like that much...

Hmmm. If you leave your car off for 10 days, then that 24 W draw uses nearly 6 kWh of energy. That seems like a lot to me.

 

[miimura]

The 2 amps must be when the car is not completely sleeping. It takes a couple minutes for all the activity to die down. I suggest measuring it again, or even putting a data recorder on it to measure the current every second for an hour. If you don't have a data recorder, just make a video showing the multi-meter reading for 5 or 10 minutes.

 

[fooljoe]

Yeah, also it's worth noting that when you simply approach the car with the key in your pocket it "wakes up", and even without the key something similar happens if you're opening doors to pop the hood and such, so you'd need to set up some sort of remote or persistent monitoring and check in at multiple time points to get a sense of what the car's doing. And we still need some baseline data from others with normally functioning cars.

 

[smkettner]

Left the hood up last night in the garage. Keys are 30' away in the house.
12 volt draw was measured at just over 2 amps in the morning.
Measured with Fluke 325.

Is this normal?

 

[miimura]

Left the hood up last night in the garage. Keys are 30' away in the house.
12 volt draw was measured at just over 2 amps in the morning.
Measured with Fluke 325.

Is this normal?

That cannot be normal. There was another owner who was having troubles like yours and his dealer found that there was something defective in his car that was pulling more power than it should when the car was off. I think they changed the NAV head unit and the problem was gone. You could start pulling fuses one by one and see when the current goes down.

 

[smkettner]

More testing this morning after sitting overnight with the 12v battery charger.

In the morning the car was still pulling 2 amps continuous from the battery.
The two fuses that seem to reset the power draw to near zero are:

#9 G/W-B 10A Multiplex communication system
#10 RADIO 30A Audio system

as listed in the owners manual page 389.

When these fuses are replaced the draw stays near zero. Center screen reboots when the car is started. Car then continues to draw 2 amps again after settling down. Pulling the fuses again resets the draw to near zero. I need to take it in and explain this issue although I can see their eyes rolling already with another crazy customer that thinks they know something.

Any tips to tell the dealer please let me know.
I have in my mind there are more issues but one thing at a time.

 

[smkettner]

Dropped off at Carson today.

Dealer calls back my new 12v battery is bad. Does not pass load test.
Really? The car is killing the battery is the reason the car is in.
How about charge and retest?

Nooooo, Toyota must replace my three week old Bosch 24 at my cost. No more warranty.

We exchanged a few words.

 

[fromport]

Dropped off at Carson today.

Dealer calls back my new 12v battery is bad. Does not pass load test.
Really? The car is killing the battery is the reason the car is in.
How about charge and retest?

Nooooo, Toyota must replace my three week old Bosch 24 at my cost. No more warranty.

We exchanged a few words.

How do you stay polite in such events ?
I have such a hard time dealing with willingly not even trying to understand the situation.
Now you have to buy a new battery from them.
It will get killed within a month.
Your car will be stranded _again_
tell them you want to be reimbursed for all the time/trouble you will go through because of this unnecessary checking from their part.
argghh... i feel for you.