I have a NOCO Genius 5 and a Genius 1 and use both of them sporadically if the SOC drops below 12.4v. I have battery monitors affixed to both of my 450h+ PHEV's and keep an eye on them every other day or so, using their app on my iPhone. I never use ACC mode and every few days I simply let the cars sit for 30 to 45 minutes in READY mode to keep the batteries at a healthy SOC. The battery on the RX has only croaked one time which led me to be a little more pro-active with these vehicles until Lexus gets their act together and does something to improve their charging algorithm. Since I have started this, I have not had any battery failures in either the NX nor the RX. I also have a NOCO jump starter under the seat of both cars, in the event of a battery failure. I also have a NOCO Liion battery in my Vespa. I suppose that you could say that I am somewhat invested in their products. They all seem to work fine. All of my key fobs are either kept in a Faraday box or I just turn them off to prevent the seemingly common issue of the fobs connecting with the cars. All in all it seems to work well. Yes, it is a bit of a PITA but, other than this issue, they are both great cars.

 

I went ahead with the Noco 5 and also a battery monitor. Charged overnight, unplugged the charger the next day to check the battery discharge rate. It doesn't seem normal that charge went down from 99% to 47% within ~ 2 hours?

 

If your battery's resting SOC does not go above 12.4v when fully charged, I would think that your battery is sulfated. Since you have the NOCO Genius 5 charger, you may want to try putting it thru the repair (desulfation) mode to see if you can improve things. Since this mode will boost the charging voltage, it would be best to disconnect the battery leads to your car prior to performing this procedure. Follow the instructions in your NOCO charger manual.

 

Can I leave the Noco plugged in? While it's a giant stress test for me to have to watch my wife's car battery slowly die, and I've done everything I can do to fix the issue (deleted the app, faraday box, etc) If I get this slow charger, can I just leave it connected to the terminals and plug in daily?

Or is there a similar trickle charger similar to what folks use in extreme cold environments that will keep the battery charged.

Next week we are out of town for 8 days, and I guarantee it will be dead when we get back, which will make my third time in the four months we've owned it. I am prepared to just sell it and move on from Lexus. This was our first (we've owned Toyota's for 10yrs) and never experienced these problems with any other vehicle.

 

I made a trip to the east coast last month and left one of my NOCO chargers plugged in the entire 11 day trip. Once the battery is fully charged, the NOCO charger will go into float mode, cycling on and off as necessary. For my other car, I did nothing and the battery only dropped about 12%. All of the fobs were either deactivated on placed in a Faraday box. Both of our cell phones were with us on the trip so, there was no interaction between the cars and the Lexus app. I assumed that the 12% loss was due to the cycling of the EVAP system's leak detection pump.

 

At least the Noco Genius 5 is explicitly also a "maintainer", suitable to be left connected (It automatically goes to maintenance mode when it senses the battery is topped off). From another site, at least one person's Genius5 when in maintenance starts charging again when it sees about 12.4V on the battery (they were using a bluetooth battery voltage monitor, to see when it started charging again).

The Genius5 operating temperature is listed as: -4°F to 104°F (-20°C to 40°C)

If you expect to use it regularly on a specific car Noco has accessories, including ring-terminal leads/. For a non-hybrid vehicle you can put the ring terminals on the two battery clamp bolts so you aren't mucking around with the alligator clips.(leave the cable in place, it has an integrated cap for when it isn't in use, then connect/disconnect the Noco using the quick-connect clip that is on the lead coming out of the charger)

 

I would definitely encourage you to get the problem documented with the dealer (by letting the car die and calling roadside to haul it to the dealer 3 or 4 times), and then go the route of lemon buyback with Lexus corporate. With the severity of problems you are having, its not a drain issue, and likely a (more) defective car than others and you won't lose any money. Quite a few folks reported started lemon process with Lexus corporate and few have reported successfully completed it for these battery issues - although many obviously don't stay long enough in the forum to report the "moving on from Lexus" part (as they move on from clublexus as well).

 

Aside from proactively charging the 12v battery with my Nico genius 5 every 2-3 months and keeping a battery jump box with me, I have never had a dead battery on my 350h. I keep the Lexus app closed unless I need it, I deleted my digital key, my wife's fob is in her purse 10 feet from the car, no faraday boxes are used and still never any issues. I think aside from parasitic drain form various sources the biggest problem with the 450h+ is its lack of quality 12 volt charge time. If you use the 450h+ the way a PHEV is intended, you should try the drive in EV mode as much as possible. The 12volt battery gets its charge from the traction battery which gets its power from either an external wall charger(450h+) or the ICE. Since the engine is not running most of that time (unlike the 350h), it doesn't get the power from the ICE as much as in the 350h. Could that be another reason for the higher 12v failure rate? Just a theory, I may be totally wrong. Maybe the charging algorithm on the 450h+ is different than the 350h? Also the 450h has more electronic drains from its extra tech? Because of this and if I had to do it over, I would still favor the 350h over the 450h+ at least until Lexus figures out this battery mess.

 

The charging algorithm is the problem.

Charging algorithm is a software/firmware function with (flawed) math behind its design, and not dependent on EV mode or HV mode, that's been firmly established if you review this thread, with hard data from multiple folks with RX450H+, including NX450H+ owners (for benefit of new people joining the thread after a dead battery, and reading this thread - let's not speculate and confuse them, so I crossed out the speculations I believe aren't supported by data). Aside from an inadequate charging algorithm, the higher drains due to vanity frills that can't be avoided in the 450H+ because Lexus only sells them with those frills, are quite likely increasing the risk of failure.

If I had to do it over, I wouldn't buy a Lexus Not because of the 450H+, but the larger lack of customer focus, and a highly lethargic/reactive attitude to problems by the company.

 

The first time, Roadside jumped it and we just let it run in the garage for a bit to get the battery juiced up. The 2nd time it died, Roadside jumped it and I drove it directly to the dealer, which is when they pulled the battery to test it, and told me that it was fine.

So... next week, when we are out of town for 8 days, it will likely be a paper weight when we come back. I'll call Roadside, jump it again and just drive to the Dealer and tell them to leave it sitting for 3 days.

If that fails, then I will start the process with my NJ state Lemon Law program and go from there.

If you leave it permanently connected, do you use the points under the hood, or connect it to the battery? Depending on those, how do you run the cable outside of the car? leave a window slightly cracked?

If buying a Noco5 works, then I am all for it, I like the RX 450h+ and my wife loves it, it's the damn drain issue that's killing it for us.

I also noticed that in addition to the battery connection accessory wire, they also sell a 12v cigarette lighter adapter as well. Maybe less fussing with the battery leads going that route.

 

I initially had cables connect to the battery direct and then opted for an installed option allowing for direct connect to the front of the RX.

First set up, as I have to back my RX into my garage it was not a convenient set up for me due to the location of the electric outlet. With careful placement the back door closed on the cable without any noticeable pinching.

Current set up with a installed OEM trickle charger, super convenient, but over priced should be part of the factory build.
Cheers

 

I'm curious as to how widespread this issue is on the 350h and if it's still occurring on the current production models as I'm picking one up on Friday. It's my first Hybrid vehicle so the battery does have me a bit concerned, especially with things like the electronic door handles and whatnot.

 

By chance do you have a part number for that? My wife pulls in because our 240v car charger is mounted on the right side, same side as the charge port. I'd much rather "hard wire" using your method

 

I now longer have the receipt, and the part number is not listed on the Lexus Canada site only the product image and description. Just check with your parts dept. Cheers

 

CCGS has a much more exotic setup. I have an optional eyelet ($15-20) permanently attached to my battery. When I want to charge, I just connect the charger wire to this eyelet and run the wire out my right rear window.

NOCO GC008 X-Connect M10 XL Eyelet Terminal Accessory Genius Smart Battery Chargers