Arvid

Hi... regarding the sensor in the original 12 Volt battery.... This is taken from the European Lexus Club site (translated from German to English language by me...totally NOT understandable by Google Translator :-) )

Written by the member 2008LS600H.....

Now I have paid my dues. I hope at least someone else can do good for my experience.

To be sure I do have ordered a new original battery for 397 EU gross at www.original-teile.de.

When removing the old battery I wanted to find out where the wire went and find out what it was... it was possible that the sensor was wedged deep down between the plates..so it could measure the temp in a decent way....I thought..

I began to take away the silicone where the sensor dissappear at the top of the battery...and that was that...I had the sensor between my fingertips....

So it's stuck just above the hole on the battery. I have taken a picture.

On top it says: 202AT. Google had the solution: An AT thermistor. ( original in German language:
eine schnöder Thermistor) ....
AT THERMISTOR
The AT thermistor is a high-precision thermal
sensing device featuring extremely small
B-value tolerance and resistance.
When used as a temperature gauge, the AT
thermistor requires no adjustment between
the control circuit and the sensor.
This insures temperature precision of 0.3 C. (32.54 F.)
Temperature indicators and control instruments
are now available for use with the thermistor.

The data sheet is here:
http://www.wescomponents.com/datasheets/202AT.pdf

Conclusion: Find a a good starter battery ...and glue the thermistor to it...

This is where the German Lexus Club member found the Thermistor.....(picture below)


And here is where the Thermistor wires goes into the original battery in my car: (The tube is for venting the battery to the outside of the vehicle) ...(picture below)

lexus600hl

Excellent information Arvid. I thought about doing that bud didn't. Glad you did.
I just changed my battery.. so, 3 years from now, I would do this.. I could buy a $100 battery and simply use the existing thermister.
I assume there was a reason for the vent tube for that battery but after market battries of that size don't have vent outlets.

USLEX

Arvid, I have a sneaking suspicion (no electrical symptoms yet) it won't be long before I need to replace my current factory Panasonic battery. I will have to confirm but I think it was replaced in 2012.
When the original Panasonic battery died, I went to Advance Auto and they gave me the one that was called for the LS460 as their computer showed the LS600 uses the same battery. Of course there was no thermocouple contact so I took it to the Lexus dealer. Fortunately, the dealer pointed out my battery was still covered under the 4yr/50K factory warranty so they replaced it no charge. (Bought my LS600 new and expected it to last 5 years.)
That said, I am not concerned about the gas/pressure vent equalizing tube. The big question is where do I hook up that thermocouple on a new after market battery? I can't tell by the picture if there was a thermocouple contact for the aftermarket battery the guy from Germany used. Thanks for any help on this.

Arvid

Hi, the text and pictures I had in the post on the Thermistor, all that was written there in cursive text, was written by the German owner, not me...I just translated the text into english... and his: Conclusion: Find a a good starter battery ...and glue the thermistor to it...
I have never changed the battery in my car, and it's just over (by a few days) 5 years since I bought mine secondhand in Switzerland, Don't think it is the original though...since it is marked 010711
Regards
Arvid

USLEX

Thanks Arvid. I got your PM too. Since you changed your battery. When you say "secondhand", do you mean aftermarket not made by Panasonic? If so, where did you put the thermocouple and how did you "glue" it on? If you can take a pic of what you did, I would appreciate it. Again, thank you.

Arvid

I have possibly not been clear enough in my writing.... I have not changed my battery as long as I have had my car.... I just took a photo of my original Panasonic battery to show how the + (positive battery connection) looks... the other picture with the thermistor is taken by the German LS owner in his car. With "secondhand" I meant that I bought my car used from the first owner :-)
Everything in cursive (Italic) writing is just translated from the original German poster on the European (German) Lexus Club site, (original written in German language) on his experience looking to find a non-original battery (Non- Panasonic) that would fit his LS...
Arvid

lexus600hl

My suggestion is: Just pry the thermo couple away from the old battery. Buy the much cheaper replacement battery - almost any place.. I think around $125 or so range..
Two options:
just leave the thermo couple anywhere there.. connected to the car, so that you would not get the alarm light.
If you prefer, you can simply duct tape it to the side of the battery or leave it on top of the battery, tied with some zip tie..
The thermocouple is meant to inform the car computer, when the battery overheats.. which (hopefully) never happens.. Personally, I would not worry too much about it.. because most cars don't have a thermocouple temp sensor.. Remember, this is only the starting battery.. its not a big deal to ignore the temp sensing.. as long as the thermocouple is connected..

Also.., It would be interesting to see what the resistance of the thermo couple is.. is it 0 ohms under ideal conditions? Just curious.. IF it is zero ohms, I would even simply short out the sensor wire permanently and ignore the temp sensing aspect.

USLEX

Sounds good. Please try it and let us know how your suggestion works. You can be our champion in testing your suggestion. By the way, I looked up the thermistor ohm spec and it appears it is a 2K ohm. Hope that helps. Please let us know how your experiment goes.

USLEX

lexus600hl
Have you tried your suggestions yet. Please let us know. Thank you and Happy New Year.

lexus600hl

Happy New year. Perhaps you have not seen my prior posts. I had already changed the battery in 2012 or 13.. I bought a lexus battery because, at that time, I did not know that i could re-use the thermistor. I sold the 2nd ls 600hl. I still have one of them but I don't use it anymore. I gave it to an employee to use.
I had a big expense of hydro carbon valve replacement (common failure for 600).

DM1

After long research, I have found out that the factory battery is a 75Ah one. There is no sign on the original Panasonic battery about this. After measuring the battery and the size of the slot in the trunk of the car, it was clear that the new battery must be of almost the same size, in order to fit. Maximum 1cm more in lenght.

I have found a Varta Silver Dynamic (recommended for Start-Stop cars - not sure that was needed, just to be on the safe side), 80Ah, and after removing the thermo sensor from the original battery (use a cutter on the sides of the glue under the sticker), I have removed it.

IMPORTANT: The vent hose has been connected to a small pipe on the side of the battery. I have asked the battery shop to insert the pipe for me, and plug the other side of the battery (2 vent plugs on the VARTA)

I was just about to glue the sensor on the new battery, when I found small holes on the surface of the Varta, and just inserted tightly the sensor. No glue needed. Afterwards I have placed the battery in the car, I have used a bit of tape to fasten the cable of the sensor to the battery to avoid having it move.

The car starts up, will test in the coming days.

Please see enclosed a picture of the old battery and the new one with the sensor in place.

Hope it will save some time and money to others.

​​​​​​​

Bigsk8r

Good job on this. i was reading some of the other battery related threads and kind of face-palming that folks didn't realize that a battery in a confined space would have a thermistor and vent tube. After nearly 8 years I had to replace my battery last night. I wound up with one that has the same top design as yours and will see if my thermistor will squeeze into a hole too. Nice catch on that...