Smooth2o

Some users report that the 12V battery dies after using the EV mode only for frequent short trips due to drains on the battery from lights and other devices and bc ir doesn't get charged. So they recommend a trickle charger.

1. Does the 450H+ have an alternator similar to gas powered vehicles and charges the 12V battery?
2. Does it have a DC to DC converter that uses the traction battery to convert 300+ volts to 12+volts to charge the 12V battery?
3. Does this converter operate only on hybrid mode while driving the car?
4. Does this converter also work when the vehicle is plugged in such that the plugged in voltage is used via the traction battery to charge the 12V battery. If not, why not?

lsft

1. No there is no alternator - the 12V is charged by the DC to DC converter.
2. Answered #1
3. The convertor works in EV mode as well.
4. My understanding is that when charging, the 12V battery is being charged and used at the same time. I don't have understanding and how to monitor the situation. Maybe @CdO have better answer.

CdO

Yes (during charging; but, not before or after)... but, slowly*. When I looked while charging, the voltage was ~12.6V.

Basically, if the traction battery is charging or discharging (READY) the 12V battery is charging (or at least not draining).
All other times, the 12V battery is discharging (~0.2 Watts minimum).

*Edit: I just checked again... seems to target ~12.6V which in my case was taking up to ~1A. So, it is charging somewhat like a 1 amp trickle charger (while charging the HV battery).

lsft

Thanks for checking on that. Are you charging on the 120V or a level 2 charger? Just want to see if there is any difference. If you are using 120V charger you can charge for 12 hours. If you use level 2 with 6.6kW, then it's 2.5-3 hrs max.

drox

How long can the NX450h+ sit idle before draining the 12V battery?

I am going on vacation for 2.5 weeks soon and was going to leave the car unplugged at 50% HV battery. Just wondering if I need to worry about a dead 12V when I get home...

Also, would doing a remote start using the Lexus app and leaving the car on for 20 minutes charge up the 12V battery? I am not sure if the car is in the READY state when remote starting using the app.

nx450plus

This likely works. My service department suggested it to me this winter---Remote start using the Lexus app and leaving the car on for 20 minutes charge up the 12V battery

mbezzo

We were just gone for 2 weeks - didn't even think about the 12v battery and had no problems on return.

shiftD7

I was away this past Christmas for 3 weeks and had no issues (car is condo underground garage)

Before leaving for an extended period I always charge up the car fully and the run it down until around ~70% left in the battery since it will still start up in EV mode as long as you have a charge and then I can at least start driving it before turning on HV. So far, that has worked for me.

Smooth2o

OK, second time I didn’t get this comment. Not sure why you have to run the battery down to 70% full. The car would start up in EV if it was at 100% too, no?

shiftD7

Sorry I left that part out. I I run it down to 70% since a fully charged battery accelerates degradation (as does a fully empty battery)

CdO

In case you didn't see this in the other thread...
The manual says:
Observing the following can help suppress battery capacity decline...
Leave a low level of charge in the hybrid battery (traction battery) when leaving the vehicle undriven for a long period of time.

When the car is off (and not charging) the HV battery is completely disconnected from everything... zero drain... only self discharge.

You really can't fully empty this battery. When in HV mode the battery bounces back and forth between ~12-14% actual state of charge (25-30% "App" SoC). Given this fact, it must be safe to assume that this level of charge does very, very little to degrade the battery.

CdO

I mostly use the stock EVSE at 240V... ~3kW. (I think any time you use 240V is it considered "Level 2".)

Well the Mrs has a long drive today; so, I was going to check the current draw when plugged in after a charge. I wanted to get everything hooked up and ready before it finished so I didn't waking anything up. Right about the time I was doing this I guess it stopped charging (even though it said I had an hour to go... smh). Apparently, the current spiked (>10A) and blew the fuse in my meter; so, still no definitive answer. I had to use my meter to check the fuse in my meter?

Edit: consolation... I got to see 53 miles EV range for the first time. (~85.3 km)

lsft

I wonder if level 1 - 120V charging would give less charge to the 12V while charging since it's plugged in for 12 hours for a complete charge and for 240V 12 Amps using the stock EVSE would most likely give more charge to the 12V. I don't know.

Greatly appreciate you doing the measurements and causing the fuse blow on your meter.

That is great you got 85.3km/53 miles. The best I did last year was 84.1km.

SgtLip

You guys are all talking above my comprehension level. I'm relatively new at this EV stuff. And I stay away from anything electric, especially 240V. Anyway, I have been plugging in after driving and today it charged the EV to 40 Miles. That is what I don't understand. I thought it was designed to charge for 37 Miles? How does it get to 40 Miles (in my case) and 53 Miles for LSFT?

Does it get better the more you drive it and charge it? I currently have 1,428 miles on the car.

Smooth2o

Don't quite see how you got so high a milage. Is this due to the 240V charge? I charge @ 120V with a 6KW charger. Not sure how long it takes bc I have never been below 20 miles before charging. I usually get 33 miles. So if a 240V charge would give 50% more milage, I would install 240V but I only have had the car for a week or so. Is it due to 240V??