Where does a smart gas meter get is power from? - Page 1
Forum section: electronics / general

author: BlackICE
author_rank: Regular Contributor
timestamp: August 27, 2023, 05:35:18 am
content: Where does a smart gas meter get is power from? It is easy for an electric meter, but how about for a gas meter that doesn't have any wires attach to a power supply? I don't see any solar panels. Is it battery powered? Does it have a small gas flow generator?

author: AlbertL
author_rank: Regular Contributor
timestamp: August 27, 2023, 06:49:49 am
content: Mine has a battery - I know, because I got a notice from the gas company that they have to replace it.

author: Circlotron
author_rank: Super Contributor
timestamp: August 27, 2023, 07:12:42 am
content: What about my water meter? A guy comes along and waves a wand at it and gets a reading. No obvious way to open it up and put a battery in it.

author: BlackICE
author_rank: Regular Contributor
timestamp: August 27, 2023, 07:30:55 am
content: I found one solution that can work for 10+ years.https://www.electronicdesign.com/technologies/power/article/21808193/how-to-efficiently-power-your-smart-gaswater-meter

author: Shonky
author_rank: Frequent Contributor
timestamp: August 27, 2023, 08:53:11 am
content: Both gas and water can use battery. Of the order of 10 year lifetime. There are even units with remote comms these days running NB-IOT LTE modems. Others are Zigbee or similar local comms.

author: mtwieg
author_rank: Frequent Contributor
timestamp: August 28, 2023, 11:57:01 am
content: Quote from: Circlotron on August 27, 2023, 07:12:42 amOne of my electronics mentors back in university founded a company (now called Aclara) which pioneered wireless metering. They invested in special batteries which would last 10+ years (not sure what the chemistry was). IIRC the idea that being mains-powered would actually reduce their lifespan overall (battery powered means you can make a much better seal on the enclosure, and you're not subject to power surges).That was at least 30 years ago, with newer battery tech and lower power silicon I'm betting they've doubled that lifespan.

author: mspec
author_rank: Contributor
timestamp: December 05, 2023, 09:14:00 pm
content: In my experience with smart metering technology, I've learned that smart gas meters typically operate on an internal battery. This is because, unlike electric meters that can quickly draw power from the grid, gas meters usually don't have an external power source. The internal batteries in these meters are efficient and designed to last several years, minimizing the need for frequent replacements.While researching optimizing energy usage in my home, I came acrosshttps://thingsboard.io/smart-metering/. This resource provided valuable insights into the advanced capabilities of smart metering solutions. Beyond measuring consumption, these systems offer extensive data analytics and remote monitoring features. Utilizing such technology has allowed me to understand better and manage my utility usage, bringing efficiency and a higher level of control to my daily resources.

author: Smokey
author_rank: Super Contributor
timestamp: December 05, 2023, 09:31:48 pm
content: This is interesting. Is the idea here that after 10+ years that the tech will have changed enough that the whole meter will be upgraded? Replacing the battery on EVERY gas meter every 10-15 years seems like a nightmare. Especially if one of the features is how weather sealed the enclosure is.

author: Smokey
author_rank: Super Contributor
timestamp: December 05, 2023, 09:33:58 pm
content: Quote from: BlackICE on August 27, 2023, 07:30:55 am"For the purpose of this case study, the PA works off a constant voltage of 4.1 V. As seen in Figure 2, the PA requires a current burst of 0.7 A for one second every six hours to transmit data. The rest of the time, the PA is shut down. This corresponds to an average current of 32 µA."

author: coppice
author_rank: Super Contributor
timestamp: December 05, 2023, 09:42:16 pm
content: Running a water or gas meter with radio communication from a battery for 10 years is easy. 15 years is possible. Beyond that the life of the battery itself gets a bit iffy and/or expensive. Its a given that most of its initial stored energy will be lost to leakage, but the iffy part is whether its function will completely falls apart at random due to corrosion. Tadiran have a long history of making industry leading low discharge rate/long operating life batteries. Some people are claiming 20 or 25 years now, but lack a track record to support the claim.

author: nali
author_rank: Frequent Contributor
timestamp: December 05, 2023, 09:49:52 pm
content: FWIW I recently spent a while working for a smart meter mfr, and ~30uA is about right for the entire meter (including Zigbee comms). I can't remember the exact battery used but it was Li-SOCl2 and would've been a few Ah @ 3.6V

author: TimFox
author_rank: Super Contributor
timestamp: December 05, 2023, 09:53:16 pm
content: The small "smart" "guts" package of my gas meter, in the new meter installed to replace my original manual dial-read meter assembly, have been replaced once on a battery-replacement schedule.I believe the mechanical metering bits remained in the box, since no changes were made to the piping on that replacement.

author: Smokey
author_rank: Super Contributor
timestamp: December 05, 2023, 11:45:15 pm
content: Thinking about all this, I wonder if there is an attach vector here. If you could wirelessly continuously ping a meter and request readings over and over you could seriously reduce the lifespan of the battery if it's only expecting spaced out intermittent data requests.

author: tszaboo
author_rank: Super Contributor
timestamp: December 05, 2023, 11:45:26 pm
content: Quote from: nali on December 05, 2023, 09:49:52 pmTadiran, 26500 size most likely. You get decades of lifetime if the design is properly done. You need a supercap for those RF bursts.

author: coppice
author_rank: Super Contributor
timestamp: December 05, 2023, 11:57:43 pm
content: Quote from: Smokey on December 05, 2023, 11:45:15 pmUltra-low energy radio communications ALWAYS relies on things waking up in small time slots, just wide enough to deal with the expected accuracy error in the clocks at the two ends of the link. You can't continuously ping the meter, as its not listening most of the time. You can raise its consumption by making it respond at every possible opportunity, but protocols usually take at least some basic precautions against this becoming a serious problem. You don't want a system error at the interrogator meaning the batteries in millions of nodes need replacing early.

author: Dundarave
author_rank: Regular Contributor
timestamp: December 06, 2023, 03:00:00 am
content: Quote from: Smokey on December 05, 2023, 09:31:48 pmWe don’t have electronic gas meters where we are, but they do actually replace the whole meter every 10 years regardless. They send advance notice because they want you at home so when the guy comes he can relight any appliance pilot lights you might have.The point is, a 10 year sealed-in battery would be fine for things you have to swap out every 10 years anyway for safety and calibration.

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 06, 2023, 12:30:51 pm
content: They just replaced the water meter at my place last week. I guess the battery was getting low.I wouldn't be surprised if it transmits a help signal when the meter reader waves their divining device to take a reading.

author: xrunner
author_rank: Super Contributor
timestamp: December 06, 2023, 01:08:15 pm
content: Gas meter has a battery in it, I asked the meter guy who replaced my gas meter a few months ago. The old original meter (1970 vintage) had a gas leak which I smelled outside.Matter of fact, I just now checked whether the daily usage data has shown up in the system - it has. So it's transmitting it's data to ... some device somewhere. I think it can link to the next closest gas meter, and they all figger out how to get the data to the company, but I haven't researched how yet.

author: tszaboo
author_rank: Super Contributor
timestamp: December 06, 2023, 01:22:03 pm
content: The protocol is likely wireless M-BUS which is a sub GHz ISM band protocol with 1-2 KM range.

author: SeanB
author_rank: Super Contributor
timestamp: December 06, 2023, 02:13:15 pm
content: All these contain a rather large coin cell, that provides power to them. Those with remote reading have a truly massive cell in them, around D size, that has a massive capacity, and which lasts around 26 years in normal operation, with a reading being sent once every 6 hours or so. The electricity meters also have a coin cell in them, to back up both the calibration constants, and to store the registers, plus for prepaid they also run a small RTC and store the tokens used. the modern ones also come with a GSM addon module, which uses a SIM to allow remote metering, and also gives the meter a reasonably accurate clock for free, useful to detect tampering, as the 20 digit tokens you enter are both meter specific, sequential, and are time coded so they only operate for a certain time after generation, and thus you find it hard to spoof them.Took one apart that had failed, and it had a CR2477 cell inside it, still good after close to 2 decades of service, and still probably backing up the on chip RAM as well. They are also used on toll road transponders, where they easily last a decade or more in use, and where they need to provide a large current pulse during response to a interrogation pulse from the roadside transponders, so also have some nice big chunky tantalum capacitors in parallel as well.

author: Bud
author_rank: Super Contributor
timestamp: December 06, 2023, 03:38:08 pm
content: This guy did amazing job decoding water meter data transmission protocolhttps://jimlaurwilliams.org/wordpress/?p=3048

author: coppice
author_rank: Super Contributor
timestamp: December 06, 2023, 05:20:26 pm
content: Quote from: Dundarave on December 06, 2023, 03:00:00 amThis is supposed to happen in most places, since meters are usually only rated to maintain their approved accuracy for 10 years. They should be swapped for refurbished meters, that have been through calibration checks. In practice things vary.

author: coppice
author_rank: Super Contributor
timestamp: December 06, 2023, 05:23:10 pm
content: Quote from: tszaboo on December 06, 2023, 01:22:03 pmWireless M-BUS is used, but so are numerous other protocols like DLMS. Its a very fragmented market.

author: paulca
author_rank: Super Contributor
timestamp: December 08, 2023, 10:39:13 am
content: Our gas meters with card slot, are battery operated.It's a single, non-replaceable battery designed to last well over 10 years.Basically it's a calculator IC running off a battery the size of a coffee mug. The only "power hungry" thing it has to do is push the solenoid spring back to latch the value open after it shuts (out of credit).When you hold the button down to reconnect the gas, it takes it ages and ages and then finally it will pop the value open and you here the hydraulic hammer of the gas pressure stabilise.I asked how it achieves that and if the delay is it charging something up to get enough current to pop the value open, but the engineer said it was more to do with it checking for pressure on both sides before it turns the gas on and if you left an appliance on or had a leak it would not switch on.They are in rotation for replacement, mine is only 3 years old, but some have been in the field for well over 10 years now. They are starting to become a nuissance for engineering call outs to dead meters.I found this out by arranging an engineering support callback with them to enquire how I can tap the meter for data. Out of interest... inside the meter box is Zone 0. There are very strict limits on current and voltage within that space and all aperatus must be certified or approved. Any foriegn device seen within the box, could trigger a "tampering" investigation. We came to the conclusion that the best thing was to buy the actual pulse detector snap on from the company that makes the meter. It is a battery operated magnetic pulse detector which couples to teh meter and emits an RF pulse which can be captured remote to the box. The gadget is cheap. The protocol and the receiver are not so easy to find or cheap. I didn't investigate much further, but I'm sure there is a way, just not that fussed.

author: coppice
author_rank: Super Contributor
timestamp: December 08, 2023, 03:42:11 pm
content: Some gas and water meters with shut off valves have quite a small battery for something with a chunky valve. They don't expect a huge number of valve operations over 10 years, and use a supercap to slowly store up enough energy from the battery for a single shot of valve operation, avoiding excessive short term loads on the small battery.