This is just a PSA for my fellow 350h owners. Waiting for wife while she went into a store to pick us some things, I had the car on "Accessory" mode, engine not running. Only was waiting for about 20 minutes. When she got out, the car would not "start" or enter the ready mode. Many icons showed up intermittently on the dash, the Infotainment screen would start and go off. Crazy antics and no real warning what was wrong. Guessing I depleted the 12v battery I was able to use my "jump start" battery pack to get the car going again. If this had happened without me knowing I was using the battery, you would have no clue what was going on. Too many messages and conflicts. One prominent message was "Parking Brake Not Available". Warning, the rear hatch will not open, the doors will not open electrically but under the hood in the fuse box there is a jump start port.

So, after successfully starting the car (not a lot of power required) I had a ton of messages from "Low Battery Voltage" to "System Malfunction" with instructions to go to the dealer. This being a Saturday afternoon, I took a chance, went to the dealership and the tech could not take the car in but told me the messages would go away eventually once the battery was charged again. He mentioned this could take a day or so. While this message was active, no driver assist functions are available. No cruise control and messages that braking is reduced.

Got home, removed the battery and charged overnight. Re-installed the battery, all the messages were still there. After driving around the area for about 25 minutes and restarting the vehicle all the messages are cleared and all functions back to normal. Apparently removing the battery for charging only resulted in losing the seat memory settings. All other settings and radio settings appear to be fine.

Sorry for the long post, but I could not find anything online regarding low 12v battery conditions and Message Resets. A post like this would have helped me relax and get through this situation. Bottom line, do not use the Accessory mode in your hybrid. Start the car if you will be sitting for a while with the radio on. Hope this helps someone down the road.

UPDATE: Just took a 900 mile road trip with no issues at all. So once the 12v battery is charged again everything goes back to normal. Lost my seat settings and MPG History as far as I know. Everything else is A-OK

 

I had something similar in my 350h a while
back. The battery died while I was playing with the vehicle settings in the garage. I got the same parking brake error and then the it died and refused to start up. The headlight flickered for a while. I had to manually open the door from underneath the handle and jump started the vehicle.

i noticed that even in acc mode, the head and taillights would come on. It probably drained the 12v faster with them on.

Because I don’t drive the vehicle much and it’s just taking the kids to from school, I plug in a battery tender over night every 3-4 weeks.

 

I've read similar accounts from RAV4 owners. ACC mode can certainly become a trap for people that don't know better. I keep it in Ready mode with climate control off if I'm sitting for a while. I too put mine on a BatteryMinder once a month, though that's true of all my vehicles. Vehicle charging systems rarely fully charge a lead-acid battery, so an occasional top-off can extend battery longevity quite a bit.

 

I had thought in general all ICE cars will kill the 12V battery in accessory mode?!

 

Thank you so much for the helpful information you provided.

 

Is your accessory mode enabled?

On my Rx 350h the accessory mode is disabled in the touch screen. The dealers usually disable it due to some issue with profiles not loading properly.

If ACC is disabled then pushing the start button without brake will put the car in ON mode, Engine not ready. This supplies power to everything.

I miss the simplicity of RX4..... But then again the world moves on and I have no choice to learn to adapt.

 

My understanding is that On and Not Ready means that the 12v battery is providing power and is not being charged. My understanding is that the 12v battery only charges when On and Ready, or when the traction battery is plugged in and actively charging, but not when plugged in and not charging.

I have verified that On and Not Ready draws heavily on the 12v battery, pulling it down to 11.1 v in short order on a cold morning, and then the battery immediately jumps above 13 v once On and Ready is initiated.

 

Yes, ACC is available on my car. I pushed the start button without holding the brake. Never again LOL.

 

Sure, they will all kill the battery but ICE cars have a much higher capacity 12v battery and with a normally healthy battery you should be able to sit in ACC mode for over and hour or much more with only the radio on. Not so on the tiny capacity Hybrid 12v battery. Lesson learned.

 

I feel like it's more than just the smaller battery. The replacement RX350 batteries have a reserve capacity of 120 vs the 350h batteries that have a reserve capacity of 100 or 105.

If 20 minutes kills a 100 rc battery, then 24 minutes would kill a 120 rc battery.

 

Another factor in battery drain these days is the high-powered sound system.

It draws a LOT more current than an old AM radio with a single speaker. I made that mistake a few years ago, detailing a daughter's lease car prior to turn-in.

 

Regardless of whethet it's ICE or hybrid, it's probably just best to not run accessories without either the engine runninng or the hybrid system active. Takes all the guesswork out of worrying about the size of battery and whether it will last.

 

Agreed but normally not a problem to run the radio for 20 minutes in and ICE car, but the point here is that if you run this battery down in a Hybrid, you are in a whole different world of recovery. ICE car that you inadvertently ran down the battery, jump it and you're good in most cases unless the battery is already old and compromised. Do it in a brand new Hybrid, and you may have no idea what's going on and how to recover. Hoping this will help should this happen to someone else.

 

There is a setting for accessories that you can set, where you turn off the engine and Hybrid system but the radio stays on till you open the driver door. I have used this for listening to radio while I am waiting in the car and that has not have much effect on the battery. Radio alone does not consume that much battery but the screen brightness probably consumes more so be careful at night.

 

I have mine set to leave the radio on until the door is opened. I haven't had any issues using just the radio like that.