spineman

I agree, I am already pulling my hair out. No one answered my previous question as to what I was pointing to in the picture. I ordered a used part on ebay. WTH only $35. I new decent multimeter/amp meter would cost much more than that.

My battery charger read 12.4 to start and takes overnight to charge. This is just after I went on another trip, 8 hrs total driving. The battery shouldn't be that low.

I didn't really want to start a new thread about this, but I guess I will have to as I don't think it is a battery issue at this point, unless the sensor, as I was asking, may keep the battery from charging. I don't know how these cars charge their batteries either. I know it is some sort of DC converter. Anyone know if it charges all the time, or when it has the extra juice? As for diagnostics, the service bulletin you pointed out, shows a typical alternator and does not mention the 450h.

bclexus

I had my 12 volt battery load tested at my Lexus dealership and here is the result:


However, it is common for a standing 12 volt battery to float around 11.6 volts to 11.9 volts - then when the car is started - and the ICE starts charging the 12 volt battery with its AC/DC converter - the battery will read 13.9 volts to 14.5 volts.

Below are pictures I took of my 12 volt battery's voltage before starting the car and right after starting the car. Within a minute of two the voltage will typically read 14.1 volts to 14.5 volts.









Get one of these from Amazon for your console cigarette lighter socket and you'll always know what voltage your 12 volt battery is providing.




Dual Ports 3.1A USB Car Cigarette Charger Lighter Digital LED Voltmeter 12V/24V

gripau1

A std 12v battery has 6 cells, each cells outputs 2.1v and internally connected in series. If one of the cell is dead or failing you will see a voltage less than 12.6v. So if you detect 12.0v or less, yep its time to change the battery. Even new battery can fail as a DOA as it could be sitting on the shelf for months at a time.

I usually change the 12v battery at 4-5 years of age as part of a maintenance schedule. I don't want my wife to be stranded and stressed out because I cheapen out on a couple of hundred bucks.

Concerning the picture its a plug to the thermistor / temp sensor. Usually the BMS wants to monitor if the battery is over heating. Putting the sensor on top of the plastic battery which is insulated is not ideal but its better than nothing.

I don't have access to Lexus service manual, so I don't know the exact values to check. However generally speaking, if you want to test the thermistor. Put the sensor on an ice cube and see if the resistance change. Put the sensor in warm / hot water and see if the resistance value change again.

If you disconnect the temp sensor I don't think the BMS will throw up an CEL but see what happens.

bclexus

Here is a picture of the embedded thermistor and its harness plug on the GS 450h 12 volt battery.


The part number of this particular thermistor is 202AT-2. This 202AT-2 thermistor is a NTC type with a value of 2k Ohm, rated at 1% tolerance.

This particular thermistor is a DigiKey Part Number 4316-202AT-2-ND manufactured by Semitec with a Product Number 202AT-2. Its description is a NTC THERMISTOR 2KOHM 1%

A NTC type thermistor is a 'Negative Temperature Coefficient' thermistor as opposed to a PTC. NTC thermistors are resistors with a negative temperature coefficient, which means
the resistance decreases with increasing temperature.

A 2k Ohm thermistor will read 2,000 Ohms @ 25°C (77°F) with a lower resistance at higher temperatures - and higher resistance at lower temperatures.

2k Ohm thermistors are not very commonly used. 10k ohm thermistors are more typically used.

► Note the hose connection for gas expansion on this battery.

Typical 12 volt vehicle batteries don't have embedded thermistors with an appropriate harness plug and a hose connection for gas expansion.


I typically use 10k ohm thermistors for my various projects. I'll always design or build around a NTC 10k ohm thermistor.

Here's a 10k ohm NTC thermistor I have on-hand that I'll be putting into use soon on a non-vehicle type project

bclexus

Here is a neat little device available from Amazon for $28 that reads the battery's voltage and ambient temperature via Bluetooth on a free app for your smart phone.

spineman

@bclexus Thank you for the information. and @gripau1 . I am certainly going to buy that monitor so I can track it from now on.

I did throw the baby out with the bath water when I traded in the battery (the thermosensor)...so...that may be the problem! No codes but it makes sense since the original battery lasted 10 years with no problems, and only the new one isn't charging correctly. I did have the battery load tested and it was good. So I need to purchase a new sensor and see if that helps

spineman

Actually, now that I pulled it out, mine is an air temp sensor. So I guess there is no resistor on the battery???

bclexus

A thermistor is a resistor of sorts! Yes, the 12 volt battery in a GS 450h uses a thermistor as a thermal sensor to measure the battery's case temperature or the nearby air temperature. The thermistor doesn't have to be physically attached to the battery to fulfil its purpose. But its circuit needs to have the correct thermistor resistance value to work correctly.

The picture (image above) of the device you posted actually has a built-in thermistor along with the female plug in a single unit. That self-contained unit actually eliminates the need for a specially-made battery with the thermistor pre-attached to the battery case (under an adhesive label) with a harness and plug attached to the thermistor as part of a special battery...


This is an abbreviated and simple explanation of how this thermal sensor (a.k.a. thermistor) device works. The resistance of this thermistor is fed to a circuit in the vehicle and the temperature of the 12 volt battery's case (or nearby air temperature) can trigger an event - which might throw a code, display a massage or even shut-down a mechanical activity (e.g. DC motor or ICE) or an individual component - if the thermal sensor reads a temperature deemed outside the design parameters for the part or thing the sensor is used to protect.

A thermistor is a thermal sensor for which its resistance is used in a circuit designed to measure the temperature of air, liquid, or a surface material. The thermistor itself is not necessarily embedded or submerged in/on or within a material substance (e.g. molded into a plastic battery case). A thermistor is often clamped by some means to the outside of a pipe carrying a liquid or affixed with strong adhesive tape or glue to the case of an electric motor for example - - or to a battery's case!

bclexus

OEM Part Numbers: 19204230, 25687483, 8862532170 - $20.00 - Available from many sources, including Amazon.

spineman

Yep, them Japs put the part number right on it! How ingenious! I don't think that is my issue though. It was working fine until I got the new battery (or so I think). That sensor was never touched until I pulled it out the other day. It is mounted to the battery frame/holder. I have the updated ECU on the way from ebay and I found that same exact Bluetooth battery monitor on Aliexpress for $10

spineman

Yep, them Japs put the part number right on it! How ingenious! I don't think that is my issue though. It was working fine until I got the new battery (or so I think). That sensor was never touched until I pulled it out the other day. It is mounted to the battery frame/holder. I have the updated ECU on the way from ebay and I found that same exact Bluetooth battery monitor on Aliexpress for $10.

@gripau1 disconnecting the sensor and then driving for a day did not set off any CELs