Let me begin by saying this purely an academic project, I'm not responsible if you put these in your wheels and your car explodes.

I recently purchased some used TPMS sensors to see what would be necessary to replace the batteries, repair and/or replace the potting compound, and possibly even repair cracks on the housing. The thought of paying in excess of $60 to replace the entire sensor because the batteries are expired (should cost less than $5) leaves a really bad taste in my mouth.

I've done tons of research on this subject so far. I would like to let everyone know what I've found thus far, if anyone has similar interest. I am also requesting a bit of help (see below), if anyone has the means provide it.

OEM TPMS sensor assembly information: The following will only detail the sensor assembly.
Beru PN: 6 790 054-04
BMW PN: 36106790054

First of all, with the valve retainer hole on the bottom of the TPMS housing, this battery can be found on the left hand side, underneath the cured (probably silicone based) potting compound. The outer diameter of the battery has a pink (probably rubber) insulator. It is mechanically clamped on each battery terminal (+/-) to the embedded radio board which is under the potting compound on the right hand side underneath the potting compound.

Battery Details: The following are details of the embedded battery. This is the most important thing to know about, before replacing the battery as a home built project.

TPMS Sensor Power Battery Manufacturer: Maxell
TPMS Sensor Power Battery PN: CR2450HR (TR)
CR2450: A standard, for more information see the Wikipedia article.
'HR' designation: This battery designation is specifically designed for TPMS systems. Designed specifically for reliability with high acceration resistance (Gs) and heat resistance (see the spec sheet).
'TR' designation: This battery designation means that it has a terminal mechanically attached to the positive and a terminal mechanically attached to the the negative electrode. This is for convenience of not having to solder the battery.

The plan:

The plan is to replace this battery, I was planning on cutting the terminals and soldering them directly to the battery, ensuring no more resistance than stock. According to some other literature I read, as long as I heat the area minimally for less than 5 seconds, with a solder pool that is not excessive, it should be a satisfactory solder and should not damage the battery itself. At that time, I'll apply a suitable potting compound. After curing I'll take them to a nearby tire and wheel store for testing.


The (current) issue (Can you help?):

Maxell is the only manufacturer that I know of that builds batteries to these specifications. The other coin type batteries that I have found are not designed for industrial applications, and may exhibit early failure, which may produce subpar results. They have a much smaller temperature range, and their spec sheets do not detail their acceleration resistance.

I would like to find a replacement for these batteries that is either the same, or with similar specs (3V, long mAh life, etc.., high temperature range, high acceleration range) or a retail outlet that I could purchase these in small quantities, with or without terminals (TR). I've searched high and low to find an alternative and haven't found anything yet. Any ideas?

TLDR;: I would like to find a TPMS battery replacement, and cannot find a place to buy one in small quantities.

 

there are 2 other componets besides the batterys, the pressure transducer and the transmitter

i surmise that the useful life of those 2 items is only slightly more than the useful life of the batterys

i did find a japanese company that will sell the batterys in lots of 1,000 pieces, no luck with single batteries ... not surprising as maxwell considers them "industrial grade"

scott

 

You're technically correct and I'll improve the wording. Thanks

About transmitter/transducer life, I would love to test the life of it. I'd be surprised if I couldn't make them last two battery lives, though I do expect the transducer to go first.

 

i bought my second tpms set for my winter wheels from alex @ tirerack

the sensors were $42/ea and the stems were $8/ea, german made, i think they were beru brand

the sensor had 3 batteries in it

searching for "maxwell CR2450" batteries, the best price i found was $4.95 ea, note that was NOT the HR heavy duty nor did they have the tabs, just the standard consumer version

searching for generic cr2450 batteries, i found them for $1.05 ea

i did find "Battery FX3U-32BL CR2450HR-flex Mitsubishi Series PLC batteries", a version that comes with a wire pigtail for 12.33 UK pounds ea or $19.42 ea plus frt and import duty (?) or $58,46 per wheel sensor

hmmmm .... a losing proposition vs $42 ea from Alex

call Alex @ tirerack and order new ones

scott