How to replace TPM batteries

[pewter99]

I`ve had some luck with replacing the batteries in my early TPM Sensors, so I`d like to share what I`ve learned with the other members on the Forum.The sensors are designed to be "throw Away" items, and some members will consider this to be more hassle than its worth. On the other hand, I love to disassemble anything I can get my hands on, and if I can prove it can be fixed, I WIN!!!

First off, they are "Potted" with a relatively soft sealant material that can be slowly and carefully removed to expose the battery. Looking at the picture, it is always placed to the right of the valve stem. Besides it being set in sealant, there is a small strip of doublebacked tape in there also. It doesnt come out willingly!

The Battery is a common 3 volt Lithium CR2477N. The only issue here is, you can`t heat the battery with a soldering Iron, it will boil the liquid inside and ruin it. I found a place locally called "Batteries Plus" that not only supplied the batteries, they had a Tech on duty who welded the Solder straps in place for me.
When reinstalling the new battery, place it Positive side down, and the terminal furthest away from the valve stem is also positive.
I then used a standard soldering Iron to re-attach the battery straps. Once thats complete, using a Voltmeter, confirm 3 volts at the terminals. I went one step further by using my Corvette to see if the Sensor would program and be seen by the monitoring system before "re-potting".
There are probably better materials out there to repot the sensor with, but I used JB Weld. It has worked well, not been conductive enough to run the batteries down and you can be assured of a good bond. Unfortunately, the draw back when this material is used, the sensor battery can never be removed again without totally destroying the case.
Several Forum members have "Donated" their Used sensors to me as test subjects...You guys know who you are, and for that I`m grateful, Thanks!!
I`ve had a 70% success rate, and as I do more that rate should get better...But as I said earlier, I only did this as a challange and to share the knowledge with the forum.

View of the Outer Case


Started Removing Potting Material


Battery Exposed (Negative Side)


Battery Removed




Digi-Key sells this one which looks very close for $3.48, they currently have 4087 of then in stock. Only $3.12 each if you buy 10+. This is a Panasonic BR2477A/VA Lithium 24.5mm 3V 1000mAh coin cell. Digi-Key part number P030-ND, find them at http://www.digikey.com. Digi-Key does charge $5 handling charge for orders under $25.



I think I would try simple silicon sealer for potting. It's water proof, soft, cheap, and sticks to almost anything. Should be easy to get out the next time, specially if you soak that corner of the sensor in gas over night. Only problem I see with silicon sealer is the silicon is kind of springy, but if it is thin between the battery and case the battery won't move much at all. I would put a little in the bottom of the sensor, set the battery in the silicon and press it down, then solder the leads, the cover the rest with silicon. This way there should be a thin layer of silicon between the battery and case basically gluing the battery to the case so it can't move.