Battery-free TPMS

[ScottG]

The latest vehicles use a TPMS system without any little batteries in the sensors - it relies on the centrifugal action for energy.

Do any of the aftermarket TPMS systems for trailers use this technology yet?

I need to have my trailers tires balanced and better valve stems installed and it would be great time to have a good TPMS system added.

Thanks,
Scott

[wa8yxm]

Dtank wrote:

GordonThree wrote:


There's no sensor inside the wheel. Computer uses voodoo....... My guess

Same voodoo a Thermos uses.

Keeps hot things hot, cold things cold. - How do it know ??

Voodoo, of course !!...:S

.

The ABS Sensors sense how fast the wheels are turning, essencally tacs'.. If all wheels are PROPERLLY inflated then tehy all have the same radius and (And diamater) and all turn at the same speed.

If one is low the tire gets effectively "Smaller" and turns faster.

The computer sees this and reports. No voodo involved, simple mathmatics and physics Only "Voodo" to those who deny science.

[fj12ryder]

Keeps hot things hot, cold things cold. Does that mean I can put in a cup of coffee and a popsicle?

[Dtank]

GordonThree wrote:


There's no sensor inside the wheel. Computer uses voodoo....... My guess

Same voodoo a Thermos uses.

Keeps hot things hot, cold things cold. - How do it know ??

Voodoo, of course !!...:S

.

[Cydog15]

Pressurepro is the only US made system I would consider.

[road-runner]

I saw a couple of posts saying that the indirect TPMS is no longer used. It is being used in some or all current Audi and Honda models.

[fj12ryder]

And personal jet packs are probably in the future too, but sometimes simple works very well. A small battery that last a couple years versus the rather convoluted query/response type necessary for the SAW system to work. KISS.

[RCMAN46]

Remember this when you were a child?




If there were innovators that were not willing to think outside of the box as many on this forum seem not willing to do we would not have the Apple watch and cell phones.

A batteryless TPMS sensor or one that can be recharged due to wheel motion is probably in the future.

Think about it. The force on a valve stem while the wheel is in motion is not constant. There is still gravity acting on the valve stem which explains why rubber valve stems do not work well with external TPMS sensors.

[ktmrfs]

did some research and yes, some SAW device sensors are coming to market. they don't need a battery, but the sensor must be located quite close to the transmitter, within a few feet or less. so, they mount a transmitter near each tire to interogate the wheel. for aftermarket that means installing sensors in the wheels and then installing transmitters near each wheel and that transmitter then either wired or wireless to the display.

most talk about using CANbus, probably aimed at OEM mfg applications.

the do appear to offer faster response times and faster update rates.

[theoldwizard1]

Harvey51 wrote:
Hmm, why not a sensor mounted in the rim, powered by electromagnetic induction as new phones can be charged?

Induction requires very close proximity or high power.

[theoldwizard1]

GordonThree wrote:
There's no sensor inside the wheel. Computer uses voodoo or maybe math, ambient temperature and wheel speed to calculate air pressure. My guess

Other manufacturers tried this long time ago and found it to be not accurate enough. It also does not handle the case of all tires equally under or over inflation.

[fj12ryder]

Boon Docker wrote:

ktmrfs wrote:
virtually ALL TPMS systems rely on tire rotation to wake up the system to conserve battery life. the ones inside the tire have a battery. I seriously doubt there are any that do not use a battery.
Even the external systems sense roation to wake up the system.

centrifical rotation by itself is not a way to generate power.

Yes there are batteryless TPMS sensors on the market that use "SAW" technology.

Maybe I'm misunderstanding how these work, but it looks like the passive sensor "replies" to a "query" from an antenna. Without input from the antenna, there would be no action by the sensor. You may not need a battery in the sensor but there would have to be an antenna constantly querying the sensor. Or am I "unclear on the concept". 🙂

[Dutch_12078]

ktmrfs wrote:
virtually ALL TPMS systems rely on tire rotation to wake up the system to conserve battery life. the ones inside the tire have a battery. I seriously doubt there are any that do not use a battery.
Even the external systems sense roation to wake up the system.

centrifical rotation by itself is not a way to generate power.

TST's sensors turn on when installed and only shut off when removed. The monitor will shut down when running on the internal battery, but just a tap will wake it up so it can update with the current readings before rolling out.

[Harvey51]

Hmm, why not a sensor mounted in the rim, powered by electromagnetic induction as new phones can be charged? I hear it is a pain moving sensors back and forth to winter and summer tires, costing more than the cost of the product itself over a few years. SIL says he has sensors in both sets of tires and after changes the sensors often fail to be recognized by the truck.

[Boon_Docker]

ktmrfs wrote:
virtually ALL TPMS systems rely on tire rotation to wake up the system to conserve battery life. the ones inside the tire have a battery. I seriously doubt there are any that do not use a battery.
Even the external systems sense roation to wake up the system.

centrifical rotation by itself is not a way to generate power.

Yes there are batteryless TPMS sensors on the market that use "SAW" technology.