RMCA

Greetings,
I’m a new poster here. I have a 2010 RX450h that we purchased in 2013. At that time we were getting mid-24 to low-25 mpg. The mpg has been steadily dropping over the last year to hi-21s. There has been no real change in our driving habits or patterns. Is it possible that as the hybrid battery ages the mpg goes down? I’m at a loss to explain or understand what’s happening here.
thanks in advance for info.

ukrkoz

The first indication of decreased battery performance is a reduction on fuel economy and diminished vehicle performance. The vehicle does not get the same fuel mileage that it used to and it feels sluggish - lacking in power during acceleration.

https://hybridautomotive.com/pages/faq#fail

RMCA

Thanks for the confirmation. We will keep an eye out for further deterioration.

tempestv8

Does the built in systems in the Lexus tell you when to replace the battery pack at all?

RMCA

Droid13

I read the linked page. While some of the information on it is modestly useful, in my opinion the information is way too hyped marketing oriented and suggests the owner should be fearful of some normal operations. I was particularly annoyed with the reference to the "third warning". Yes, if stuck in heavy slow/stopped traffic the hybrid battery is going to discharge (especially in the referenced warm weather when A/C is typically in use) fairly quickly, and yes, the engine will start to charge the battery, and yes it will idle higher to run the generator.

But when this happens, no... No evil demons have taken control of your vehicle. You have not lost control of your vehicle because the battery is "forced" recharging. No driver inputs are ignored (unless you consider yourself Jedi material and are trying to use The Force). No need to flee from the vehicle and hide in a nearby ditching clutching your cherished religious symbol wondering if you'll see your family again.

The before and after photos of the battery charge. That's quite a drop. It is common to lose a bar or two, maybe even three if the car has been sitting for a while (NiMH batteries are not known for having great shelf life). A full drop from top to purple would be unusual, but it's also common for the vehicle to tend to heavily rely on electric power after startup while the engine gently idles to warm up, which can drive the battery meter lower, even into purple during the first 2 or 3 minutes of driving.

MellonC00

In CA, "The battery pack in any hybrid Toyota is warranted either for 10 years or 150,000 miles.

Now, I'm not sure when this policy started but I'd think you'd qualify.

takeshi74

Wow, OP is old but in response: It's certainly possible. However, it's also possible that you're not aware of or accounting for other factors. 24/25 to 21 isn't a significant delta IMO. Are you relying on what the vehicle is reporting or are you actually calculating MPG?

ukrkoz

OP already has crappy mpg to start with. That's moderate driver conventional RX350 mpg. We have one, she does 21-22mpg.
On the other hand, my 2012 Highlander Hybrid with identical to OP power train does 32 summer and 28plus winter in VERY challenging terrain.
Hence, 24 to start with dropping to 21 - either hybrid battery goes down or driver got led foot and does not know how to hypermile a hybrid. Or, lives in Alaska and drives mostly in 40-50 below zero.

tus

Have to agree with this. The article does ignore quite a few things that were engineered into the system that would prevent you from getting to the states it mentions.

The problems with NiMH happen when you are at either full capacity and charging or completely drained and still trying to pull current. What will happen is the negative or positive electrode will get deteriorated when when over charged or drained. Since the system never fully charges or discharges the battery pack this really isn't an issue. I actually have some 20 year old RC NiMH battery packs that are still fine since I never charge them over 85% or let them run flat.

Getting back to the OP's question, I have to ask, what's the mileage on the car and what maintenance have you been doing? Since the RX is a hybrid, not an EV, and get's all of it's power from the ICE, I would suspect the drop in mileage is from the engine and/or drive train deterioration and not the battery.

Might be time for new plugs, wires, fluids, and whatever else the thing needs to get it back up to where it was.