Wireless batteryless TPMS

Thread Starter

yairkaba

Joined Jan 17, 2019
6
Hello all!
I want to design a TPMS, and I've heard that the market is getting into batteryless solutions, meaning the S/Tx sensors and transmitter (and the entire circuit) inside the tires won't need batteries at all, as it is complicated to replace. The solution is done by an Energy Harvester.
My problem is understanding wich energy harvesters are the most proper to use? or, which are the most common in the industry and why?
i.e, Piezoelectric MEMS, Electromagnetic device, Active RFID tags, magnetic induction - those are all possible energy sources for the circuits.

Many thanks and hope we will have a long thread :)
 

wayneh

Joined Sep 9, 2010
17,153
Hello all!
I want to design a TPMS, and I've heard that the market is getting into batteryless solutions, meaning the S/Tx sensors and transmitter (and the entire circuit) inside the tires won't need batteries at all, as it is complicated to replace. The solution is done by an Energy Harvester.
My problem is understanding wich energy harvesters are the most proper to use? or, which are the most common in the industry and why?
i.e, Piezoelectric MEMS, Electromagnetic device, Active RFID tags, magnetic induction - those are all possible energy sources for the circuits.

Many thanks and hope we will have a long thread :)
These guys make a case for piezoelectric.
https://www.sensorsmag.com/embedded/powering-tire-pressure-sensors
 

Sensacell

Joined Jun 19, 2012
2,851
Because it did not work, or was not cost effective.

So many tech company press releases fail to live up to the test of reality.

Shareholders demand progress... Engineers show something they have been tinkering with that barely works...
Two weeks later, the company spits out a press release... The engineers quietly cringe in the back of the conference room...
 

Thread Starter

yairkaba

Joined Jan 17, 2019
6
Oops...what a bummer :)
I guess that happens in many new startups with crazy ideas...

This company makes a batteryless product for race cars, but it gets to $3000: http://www.stackltd.com/tpms.html

But from a calculation I made, it seems that it is possible to generate more than enough energy for the sensors. The data transmission is the big issue. it takes a lot of energy.
 

MrSoftware

Joined Oct 29, 2013
2,015
<....snip...> Engineers show something they have been tinkering with that barely works...Two weeks later, the company spits out a press release... The engineers quietly cringe in the back of the conference room...
LOL, you've lived this before! My favorite is when the head of marketing comes down to engineering and says "we just signed a big deal to deliver xyz to the customer by next week, you guys can do that right?"!?!?
 

wayneh

Joined Sep 9, 2010
17,153
LOL, you've lived this before! My favorite is when the head of marketing comes down to engineering and says "we just signed a big deal to deliver xyz to the customer by next week, you guys can do that right?"!?!?
My first encounter with such things came very early in my carrier. I did some lab work and wrote in my monthly report that I had observed a small decrease in ... something, I can't recall what it was, but I noted the result was not statistically significant.

As my report was summarized and included in reports by my management hierarchy, each step along the way inflated the result until the final report by our VP was that I had found a significant increase, which would have been exciting but for the fact it wasn't true. Guess who took the heat for having to tamp down the excitement.
 

Sensacell

Joined Jun 19, 2012
2,851
LOL, you've lived this before! My favorite is when the head of marketing comes down to engineering and says "we just signed a big deal to deliver xyz to the customer by next week, you guys can do that right?"!?!?
Haha - at least that means the company might make a sale.
 

cork_ie

Joined Oct 8, 2011
428
There are distinct disadvantages to having separate sensors in each tyre as they are easily damaged and have a high failure rate . They also need to be reprogrammed each time the tyres are rotated. The main advantages with discreet TPMS sensors is that they can also detect tyre temperature and warn of impending failure and monitor tyre pressure when the vehicle is at a standstill.
Many modern cars rely on the ABS sensors to provide the required information. With ABS sensor tyre pressure monitoring it is simply a matter of pumping the tyres to the required pressure and pressing a reset button. Immediately the system counts the pulses from each wheel and stores the deviation from the average, for each individual wheel. If one tyre loses pressure the number of pulses per mile will increase and the deviation for that particular wheel will have changed. This will cause the system to alert the driver.
Thus if you want to go "making" there are several other more valuable driver aids that you could explore . If you want to simply install TPMS on your vehicle I would encourage to find someway of tapping into the ABS signal without affecting them and using a microcontroller of some sort to process the information.
 

Tonyr1084

Joined Sep 24, 2015
6,069
LOL, you've lived this before! My favorite is when the head of marketing comes down to engineering and says "we just signed a big deal to deliver xyz to the customer by next week, you guys can do that right?"!?!?
Story:

A bucket of (lets call it) Poop showed up at the shipping dock. The dock workers found it and immediately complained to their lead: "We just received a bucket of poop and it STINKS!" After a very brief investigation on the part of the lead he immediately went to his direct supervisor and reported: "We just received a bucket of poop the likes of which stinks very strongly." Of course the supervisor decided to escalate the matter and reported to the shop foreman saying: "We've received a bucket of excrement and its very powerful." The foreman carried the report even higher to the shop manager and said "We've received a bucket of fertilizer the likes of which is very powerful." The manager took this report to the board of directors exclaiming "We've just acquired a container of fertilizer which is reported to be very potent." The board decided that they must have more of this stuff and promptly issued orders for much more. The moral of this story is that THIS is EXACTLY how CHIT gets started!

When I worked in the final staging inspection for trade computer systems, my job was to make sure the order was complete. I can't begin to tell you how many times planners told customers "We can have that to you in three days" when the fact was that WE weren't going to have it for two months. My favorite sign on the wall (I posted it) was "A lack of planning on your part does not justify an emergency on my part." I got yelled at for that.
 

thicc1jz

Joined Mar 15, 2019
10
I work for a shop and I see a lot of 'direct' tpms sensors leak air due to corrosion. All Honda tpms sensors have an aluminum valve stem, they are not made to last.
 

Tonyr1084

Joined Sep 24, 2015
6,069
Factory OEM TPMS from Toyota lasted 10 years before batteries went dead. After market TPMS lasted 5. Never had any leaks.

The OLD TPMS - I'd like to find a way to use them to sense air pressure on the nose of my Taco when driving on the freeway. When I come up to a truck I'd like to see how the pressure changes.
 
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