oldguy44

Put a new battery in the Lexus Saturday, seems to be a three year cycle. Started fine so I shut it off. It is my wifes car and does not get driven much. We went out to dinner last night and before we got out of the driveway I had the dreaded hybrid warning. The restaurant is only about two miles away so I ignored it figured I would look at it today. Got out of the restaurant and the da...thing would not start. As is generally the case I forgot my cell phone, there was a time when I had 20+ phone numbers in my head but with the cell they are all in the phone and I do not need to remember them. Could not call my daughter because I did not remember her number and could not call AAA because I did not have my cell phone. So I walked the two miles home Got my '63 Pontiac hot rod and came back to get the wife. Had the Lexus towed home this morning and the new battery seemed to be quite low judging by the interior lights. Put the battery charger on it for a couple of hours still no start. Amazingly enough my cheapy scan tool will not read the hybrid codes but it did cancel them. Car started fine and seems to be OK.

My two questions are it it possible that the new battery has enough starting voltage to ignite some of the on board computers but not all and that is what triggered the hybrid system? Second question, does anyone know how much amperage the parasitic computer draw should be? I am wondering if there is too much draw on the battery causing it to go down rapidly. As soon as the battery shows fully charged I will pull the negative cable and measure the amperage draw with everything off and see what it is. One of my meters will measure light amperage draw so I should be able to get a fairly accurate reading.

LeX2K

Was the battery fully charged when you put it in? What is the battery voltage now? I don't know what the normal parasitic draw is on a hybrid but can't be much different than a normal petrol car which is 50 milliamps or less after the car has been sitting off for at least 30 minutes.

But instead of worrying about that make sure the battery is charged up if you still have issues get the battery load tested.

oldguy44

The parasitic draw on this hybrid is considerably more than on a conventional, it tells you in the owners manual that if the car has not been started in three weeks it probably won't start and if it does do not shut it off for at least a half hour. My pickup can sit for a couple of months and start with no problem. Apparently starting VOLTAGE is extremely critical on a hybrid, something like 12.6 minimum to boot up all the computers
That being said I did charge the battery and I will check it in a couple of days to see how it is. My guess is that I may have gotten a bad one, not the only new part I have ever put on that did not work. If it proves to be bad I will take it back and get an OPTIMA what I should have done in the first place.

salimshah

To clarify, the hybrids must [should] be run once a week minimum. This is not important for the 12v battery, but more so for the traction battery. One can jump or replace the 12v battery but if the voltage level drops on the traction battery, it needs to be charged by a qualified shop. [you will have to flat-bed your RX]

The 12v battery once manufactured needs to be charged regularly even when it sits on the shelf of the retailer. For safety reasons these shops only run the chargers during the day time while shop persons are there to monitor [unlike overnight charging at home]. There is a reasonable chance that a new battery picked up form shop has not been in the charging loop and once installed it is not robust enough for sustained use. One should have the new battery load tested as it is picked up. I generally shop at Costco for batteries and never had a problem but I still charge the new battery at home for 12+ hours.

If you can, have the newly purchased battery tested in circuit [I need to study some more on inverter technology of hybrid as it may not be charging the 12v at "ALL" times .. with non-hybrids the 12v battery is charged when ever the engine is running].


Salim

oldguy44

I did charge the new 12V battery and it seems to be fine now. Pardon my ignorance but by traction battery are you referring to the large battery under the car? If so I once ran it completely dry trying to get home after an engine malfunction. Once I got the engine running it charged up and has been fine since.

That notwithstanding I may need to trade it in on a conventional car. My wife drives very little any more and every couple of months I need to charge the battery because I never think to drive it.

Originally I loved the drivability of the hybrid especially in the mountains (no constant upshift and downshift just feed the motors more electrons), but now that It has become a seldom driven second vehicle in many ways it is becoming a PITA.

salimshah

Exactly, the high voltage battery. In RX hybrid, that battery [not the 12v] battery is used to start the engine, so a minimum charge must be maintained or else it goes off line.

The thing you enjoyed ... continues stream of power ... comes from the CVT [there are no discrete gears that one steps through as the vehicle gains speed]. Some enthusiasts hate it.

Salim

Clutchless

If you purchased a battery maintainer for about $30 it would keep your 12-volt battery in a peak operating fully charged state indefinitely. Of course you need somewhere to plug it in to a wall socket.

If plugging into a wall socket is not an option because you keep it outside, there are solar battery maintainers that connect to your battery (about $30 - $50) and sit on the dash top to collect the sun and maintain your battery charge. I have one and it works great for stored vehicles. The thin wire from the engine area to the solar panel inside the car is hard to see. You cannot use the power outlet in the car for this as it does not work when the car is off.

I assume the 450h has the 12v battery under the hood same as the 350. I know some hybrids have them in the trunk area or behind the rear seat (like my HS250h).

oldguy44

I have been thinking about a battery tender just trying to work out the logistics so it is never plugged in when I am gone otherwise my wife will just pull out and drag it along when she backs out. I don't need another thing clogging up my already overcrowded mind and failing memory. I have an outlet about three feet away from the battery where the car is parked in the garage. Just need to figure a foolproof signal to remind me to unplug it. Just dawned on me that if I do not put a plug on the front of the car but open the hood and connect it directly to the battery that will be an obvious reminder. Thanks, at my age I can sometimes be a little slow on the uptake.

Thanks for the quicky lessons on the ins and outs of the hybrid. My experience pretty much pre-dates computers. My daily driver is a 63 Pontiac convertible with an engine and trans out of a 2015 Silverado in it. Modified just enough to run RIGHT. The car has one computer and I carry a programmed spare in the trunk just in case.

salimshah

For 450H there are two small posts in the engine compartment and the 12v battery is in the trunk. These posts are too small for big clamps of jumper cable. Charger clamps are about the largest clamps that can connect to the posts.

EVs and Hybrids have some common things but the Lexus hybrids basically act as a sponge to absorb energy while braking and puts out useful energy for low speed. Perfect for stop and go and reverse. At higher speeds the electric motor kicks in for assist but mostly it is the ICE that does the lifting. The beauty of Lexus hybrid is in the transmission where power from electric and/or ICE is transferred to the wheels and in regen phase the wheels transfer power to the generator(motor).

Salim

oldguy44

Not on mine the 12v battery sits behind the left headlight.

salimshah

Which yr? Mine is 2011

Salim
[learning never ends]

oldguy44

2006, the first year.

salimshah

That figures. This thread is in 3rd gen 450H. Would you like this thread moved to 2nd Gen? We can leave it here if you like.

Salim

oldguy44

Do with it what you want. My wifes car is doing fine and I understand a little more of the intricacies of the hybrid system so I am a happy camper.