Battery

[RXGOLD]

I recently purchased a certified used 2006 RX400h. I rarely see a green battery in the navigation screen. It is usually blue. Is this normal? The mileage in the city is about 19 mpg. I'm wondering if there is something wrong with the battery :(

[katzjamr]

it is normal to see mostly blue down to two bars that turn rose color, you will see green from time to time usually after a cruise down some hills. the main battery is never charged 100% or depleted all the way to keep it in a sweet spot for longevity. it is the extreme cycling that shortens battery life. the next time you are in for service at the dealer you can have them make sure your ISC is set correctly, it can get out of whack if the starter battery is changed or disconnected, that might be affecting your mileage. i dont see where u are posting from, a warmer climate will also improve mpg, i.e. there is a winter mileage penalty and about three mpg increase in warmer weather. it also helps to drive in a hybrid style that increases mpg, you can read about that here. even tho some dont agree, premium fuel will also increase power and mpg usually enough to offset the increased cost. also we like to inflate the tires to 34 up to 36 psi, its better for mileage too.

[Better Luck]

I recently purchased a certified used 2006 RX400h. I rarely see a green battery in the navigation screen. It is usually blue. Is this normal? The mileage in the city is about 19 mpg. I'm wondering if there is something wrong with the battery :(

I get no less than 24 MPG on a tank and I use regular grade gas. I drive combined hwy city pron=bably 70% hwy. I get green bars almost anytime I drive my car down my street which is down hill. I have a 2008.

[skyfish400h]

I recently purchased a certified used 2006 RX400h. I rarely see a green battery in the navigation screen. It is usually blue. Is this normal? The mileage in the city is about 19 mpg. I'm wondering if there is something wrong with the battery :(

This is normal. The system tries to keep the battery at around the 80% mark to prolong the life of the battery. They don't like to be fully discharged or "topped off" because it puts stress on the inards.

19 mpg is a bit low but if you are new to driving a hybrid, that can happen. The single most effective trick I've learned is to briskly accererate up to your crusing speed and then take your foot off the gas pedel just long enough for the engine to shut off and the battery motors to kick in (less than a second). then gently re-apply gas pressure until you can just barely mantain your speed. Using the cruise control once you are up to speed will do the same thing.

This behavior tends to set you appart from ordinary traffic, so its not always practical... but I do it when I can.

Also using the "B" mode in heavy, slow and go traffic can help you not only control your position and speed in traffic that is constantly changing, but makes the most of regenerative breaking. But when traffic evens out you should swich back to "D" because that way you can take advantage of the coasting. These cars are REALLY good a coasting

Coasting also tends to make you stand out in traffic too (in an obsticle sort way :chairshot: ).

[richard4u]

i have a 2007 RX400h i can get 36-37 mpg if i really try - it is called " feathering " taking advantage of coasting and running on battery only - like the guy said - get up to speed then engage cruise control - set it then - go a litte faster with the gas pedal and let up so the cruse can maintain your speed- you will see the ICE = internal combustion engine , will then shut off and you will be running on battery only- this can happen at any speed - here is a disclaimer - in the city i like to really get on it - then i usually get 20-21 mpg - but look at the fun i am having - i think it's worth it - i run reg. gas as far as i can figure the hi test is iffy depending on the season . i think when it is hot out the premimum gets a little better mpg . i run regular year round - this is a great car and lots of fun to drive - richard

[RX400h]

...very good points here. I would like to emphasize that although the door sticker lists 30 psi as the recommended tire pressure, this is much too low. As was mentioned, keep the pressure at 34-37 psi. I set the pressure to 35 psi and average 24.3 MPG. That's about the same as a Camry 4 cylinder that weighs 1000 lbs less and has 100 horsepower less than the Rx400h.

[SOMEONE ELSE'S GOT MY NAME]

rxgold, welcome!

Don't worry about the little green / blue / pink battery screen(s) as the system will take care of itself. Even when it's completely full/green, it's STILL not really full (btw, all this is in your manual if you got one with your ride) ... rather 80% or less ... similarly when/if it appears completely empty (it can go that low), your car still has about 20% traction battery reserve remaining. That's why the batteries will last easily over 100K miles ... because by not going into the high/low extreames, their life is increased. As for low mpg's ... as stated above, it can be tire pressure (I keep our AWD 400h at 40psi and get over 30mpg) and/or driving habbits, and/or extra hot/cold temps ... hilly driving ... short trips ... or combonations of any/all of the above. Give it time! If high mpg's are your goal ... practice practice practice. My experience here is that most Lexus drivers aren't so concerned about hypermiling, rather power/handling/looks :P . I'm the odd ball, and get off on seeing how far I can stretch a tank of fuel ... to the shagrin of my wife.

[katzjamr]

congrats on keeping your mpg high even when fuel costs went lower, i was prettygood but found myself slipping as gas got cheaper, now i am back on track. i just want to note that obviously as you increase tire psi the ride becomes harsher, and for me 40 is too uncomfortable. also i wonder if that high a figure puts you too high in the range when the tires heat up on the highway. i am told nitrogen negates this as it is not as sensitive to heating and cooling. just commenting

[riwyle]

i am told nitrogen negates this as it is not as sensitive to heating and cooling. just commenting

Without gong into gas laws. perfect gas, etc., the short answer is you will see no difference in this regard between air (79% Nitrogen and 21% Oxygen) and 100% Nitrogen. Some may disagree, but I know I am correct.

[RXGOLD]

Thanks for all the responses :)

I will try your suggestions and see if the mileage improves...once again, thanks!

[skyfish400h]

i just want to note that obviously as you increase tire psi the ride becomes harsher, and for me 40 is too uncomfortable. also i wonder if that high a figure puts you too high in the range when the tires heat up on the highway.

The other negative to high tire pressure is uneven tire wear. I started out my new set of tires at 40 and quickly lowered it to 38 due to harshness as you point out. Then the uneven wear started to become noticalbe so I droped to 36 then to 34 and now the center is so much more worn than the edges I've dropped all way down to 30. The ride is nice and soft, but the handling suffers and milage should be worse, but I haven't see it yet.

As for tires heating up, as long as you don't go over the MAX COLD printed on the side of the tire you are in no danger of over pressure at hot temperatures. But to get this right you have to measure and adjust the pressure when the tires are COLD. The best way is to overfill them at a nearby service station just before you get home and then bleed them down to the desired pressure the next morning when everythign is cold. Even if you try to measure the pressure as you are filling them at home with a 12V air pump you will still not be getting the correct reading because the air is heated by the compressor as its going in.

[katzjamr]

btw i was told the small 12v air pump, and the small air compressor stations, put more moisture with the air in the tires than a large commercial compressor. also most station pump gages are not accurate so use an individual tire gage when filling. i am not experiencing uneven tire wear from 36 psi, however when the steering recall was done the dealer showed me the results of their four wheel alignment, and my rear tires were off by the most amount they had seen. this helps to explain part of the reason the oem goodyears wore so quickly on the outside edge. i didnt catch it the first 12000 miles, and at 15K when i asked the dealer for an alignment at no charge, it is the only time they ever said no.

[Gryphon]

btw i was told the small 12v air pump, and the small air compressor stations, put more moisture with the air in the tires than a large commercial compressor. also most station pump gages are not accurate so use an individual tire gage when filling. i am not experiencing uneven tire wear from 36 psi, however when the steering recall was done the dealer showed me the results of their four wheel alignment, and my rear tires were off by the most amount they had seen. this helps to explain part of the reason the oem goodyears wore so quickly on the outside edge. i didnt catch it the first 12000 miles, and at 15K when i asked the dealer for an alignment at no charge, it is the only time they ever said no.

Your comment about 12v air pumps adding additional moisture is interesting. I have both a 12v rechargeable Craftsman inflator pump and an air hose reel on my garage ceiling that is constantly pressurized. Generally I find that the small pump is less trouble to use than dragging around an air hose making sure not to scuff the paint.

Do you have any references to support your statement about the moisture difference? I would like to read more.

Tom

[katzjamr]

it was a comment made from my friend an auto body shop owner who is a block away from my store, i will ask him where he got his information on monday. we used to have a local chevron that had a free air supply for tires from their large shop compressor. they have replaced it with one of those little compressor pay stations so i dropped by his body shop for free air, (not my lexus, my 21 yo employees altima that had about 15 lbs in each tire) that is when Jerry commented not only was i saving 75 cents but the moisture the little compressors add to the air.

[Gryphon]

it was a comment made from my friend an auto body shop owner who is a block away from my store, i will ask him where he got his information on monday. we used to have a local chevron that had a free air supply for tires from their large shop compressor. they have replaced it with one of those little compressor pay stations so i dropped by his body shop for free air, (not my lexus, my 21 yo employees altima that had about 15 lbs in each tire) that is when Jerry commented not only was i saving 75 cents but the moisture the little compressors add to the air.

Thanks, I will await you response. I do think your friend may be correct after thinking a bit. My large air compressor has filters to catch moisture and impurities whereas the little battery powered thingy does not. So I suppose that the small one could introduce more moisture into a tire although the amount may or may not be significant.

Tom

[RX400h]

Large compressors on large tanks have a water drain for good reason - hot air hits a cool tank and moisture in it condenses on the tank's inner wall. A small compressor's air won't condense as easily and since many have no tanks at all, the moisture has no where to go but into your tires. Regardless, until recently, I have always used a small Coleman compressor to top off my tires and I have never had a tire degrade to a point where it failed before its tread wore out.

I now have a Craftsman Professional compressor, but really, the only way to ensure that the air is moisture-free would be to mount a particulate and coalescing filter combo right at the fitting that you press into the tire valve stem. Even having the filters mounted to the tank would not be enough to prevent air running through a fairly long hose to cool off and condense.

By the way, speaking of topping off tire pressure, here's an interesting device:

http://www.tireright.com/ezair.htm

[Gryphon]

Large compressors on large tanks have a water drain for good reason - hot air hits a cool tank and moisture in it condenses on the tank's inner wall. A small compressor's air won't condense as easily and since many have no tanks at all, the moisture has no where to go but into your tires. Regardless, until recently, I have always used a small Coleman compressor to top off my tires and I have never had a tire degrade to a point where it failed before its tread wore out.

I now have a Craftsman Professional compressor, but really, the only way to ensure that the air is moisture-free would be to mount a particulate and coalescing filter combo right at the fitting that you press into the tire valve stem. Even having the filters mounted to the tank would not be enough to prevent air running through a fairly long hose to cool off and condense.

By the way, speaking of topping off tire pressure, here's an interesting device:

http://www.tireright.com/ezair.htm

That's an interesting device but no price on the site and the phone number is disconnected.

Tom

[skyfish400h]

The small 12V pumps DO introduce more moisture because the tire serves the same funcion as the tank does at the service station. After the air is compressed its hot and can hold more water. As it cools the water condences out and collects on the inside of the "tank". In this case your tires. This is why you constantly need to drain these tanks at the service station because they will collect water in the bottom. Even the little compressor/tank combo's at Lowe's have a drain on the bottom.

One way to combat this is to use a 12 compressor that has a tank attached. Even a small tank should allow enough heat transfer to cool the compressed air and squeeze out the water before it goes into the tire. Failing that, you could run the output from the compressor thru a long vertical coil of copper tubing (like a still) and then run the bottom of the tubing into a small trap where you can drain out the condensate.

There is a price to be paid for everything... 2nd law of thermodyanmics.

[RX400h]

That's an interesting device but no price on the site and the phone number is disconnected.

Tom

It's too late for me to call, but did you try this number as well?

(407) 855 5213

The small 12V pumps DO introduce more moisture because the tire serves the same funcion as the tank does at the service station. After the air is compressed its hot and can hold more water. As it cools the water condences out and collects on the inside of the "tank". In this case your tires. This is why you constantly need to drain these tanks at the service station because they will collect water in the bottom. Even the little compressor/tank combo's at Lowe's have a drain on the bottom.

One way to combat this is to use a 12 compressor that has a tank attached. Even a small tank should allow enough heat transfer to cool the compressed air and squeeze out the water before it goes into the tire. Failing that, you could run the output from the compressor thru a long vertical coil of copper tubing (like a still) and then run the bottom of the tubing into a small trap where you can drain out the condensate.

There is a price to be paid for everything... 2nd law of thermodyanmics.

I agree, but as I mentioned, I've been using a small tankless air compressor for 20 years and have never had a problem with tires. If you can get 6 years of life out of any pair of tires, you are doing well. After that and even if the tread depth is okay, you should still replace that pair of tires.