Gas Meter Still Increasing Whilst Gas Isolated (Siemens/Landis+Gyr E6S)

Phones4Chris

Gerry1 said:

Phones4Chris said:

Grizzlebeard said:

Re low battery warning.

Would prob add to cost and complexity.

(Following thoughts are off the top of my head. I retired from electronics ~30 years ago before this gee-whizz tech had been developed. My brain-battery is also running on empty so I willingly concede to anyone who corrects me with better knowledge)

I assume they use Lithium or similar primary cells which maintain a fairly constant terminal voltage (@ low load) until it drops quite suddenly at end of life.

Actual end of life point is quite hard to predict because of manufacturing tolerances.

dv/dt detection on it's own miight be to late, so a low discharge backup standby might be required for the SOS call.

Or they could use Coulomb counting to squeeze a decent amount of E-juice out without false go/no-go detection.

Predicting end of battery life too soon is very expensive because it means sending out Engineers to change a lot of meters unnecessarily. Cheaper to allow the tank to run till it's totally empty and shug shoulders at consumer inconvenience....

(Edit--

P.S. for all I know the latest generation of meters might already be doing all this so it's "only" the millions of legacy meters that are still a problem.)

Just been catching up on this thread so thought I'd chuck in my tuppence on this display issue.
To do what Gerry has suggested would IMHO add to cost and complexity.
It looks to be simply an 8 digit LCD type display, so to show a message as Gerry suggested it would need a more complex display, that's leaving aside the additional code in the firmware. It would be simple enough though to make it display 8A77ER4 - except I can't type the digits as they would actually display, but I'm sure you get the idea!
This would involve a simple change to the on-board firmware to make it display that rather than a lower case b.
I would have thought that could be done on existing hardware (but I'm not thinking retrofit, just ongoing production with existing hardware).

Even so, the point about being able to detect that state of a Lithium battery before problems start occurring are very valid, it's not going to solve the reading error problem as it's not going to be reliable even though it's a clearer warning, the meter would still need to be changed promptly. 
Engaging brain, I though perhaps a backup Lithium battery could be a solution with some modified electronics. Ok this would involve a hardware change and an additional battery.
But the cost of this would be so minimal, for the sake of improved confidence in reliability and reduced cost to the industry of dealing with complaints and issues when these current meters fail because of battery problems, I would have thought it worth it.
The circuit design would be such that when the primary battery has run out of life, the display switches to give the warning (perhaps alternating with a reading) and the Backup battery is switched in allowing a (small) period of time for the meter to be replaced. Quality Lithium batteries that are not being discharged (ie only a small self-discharge) will last longer than 10 years, so I feel this a workable solution for short term backup.
Thoughts? @Grizzlebeard @Gerry1

@PhonesforChris It seems to be quite an ancient meter that's poorly designed so it's unlikely to be updated significantly.  But there's no reason why meter readers couldn't affix a sticker warning the consumer to call their supplier immediately if 'b' is displayed.

With new meters it would be trivial to design in a 'more bars the better' battery status icon and a Plain English warning message.  My £40 DAB+ radio has both of those features (and a full colour screen as well) and all at a fraction of the cost of a so-called smart meter.  No need for the complexity and unreliability of two batteries, just set a Low Battery flag when smart readings are sent.

And before the shills start complaining, I'm fully aware that the OP's meter isn't smart but I'm talking general design principles.

As these older Digital Meters are possibly no longer in production, and very likely not to ever be installed as replacement meters by energy companies, it was more of an academic type of discussion/suggestion. The idea of stickers on such older meters is a good one, maybe Cadent could mail them out and tell people to stick them on their meter as meter readers are a rarity, and I doubt suppliers are sufficiently clued up to know who had them (even though it would be possible to find out, they are no doubt snowed under with plenty of other customer issues).

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!
And two batteries are not increasing Unreliability, they are providing an element of Redundancy removing a Single Point Failure, therefore increasing Reliability. More complex displays are not needed and they would decrease reliability because of their increased complexity.

Gerry1

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

BobT36

Gerry1 said:

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

lol at "too complex" for something that simple, in this day and age...
It's only "too complex" because it wouldn't save the meter manufacturers and energy companies any money. Quite the opposite, in-fact if over-reading is more common than under.

Gerry1

BobT36 said:

Gerry1 said:

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

lol at "too complex" for something that simple, in this day and age...
It's only "too complex" because it wouldn't save the meter manufacturers and energy companies any money. Quite the opposite, in-fact if over-reading is more common than under.

Over-reading doesn't seem to be spotted (except by The Mysterious Third Party if you switch suppliers) but I bet a meter reading that had jumped backwards would immediately be ruled invalid.

Phones4Chris

Gerry1 said:

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

@Gerry1 You said you're not a battery expert. Please go away and look at the discharge characteristics of Lithium Batteries compared to Alkaline, NiCd & NiMH, therein lies the difficulty, you have certainly missed the point. By the time the 'b' appears it's really too late.
Consumers deserve something a lot better than is being currently offered with smart/electronic gas meters, they are abysmal. If they were anywhere near as good as the maligned electricity smart meter, it would be a different kettle of fish.
I'd also suggest that doing a course on Design Reliability would be a good idea.

FreeBear

Phones4Chris said:

Gerry1 said:

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

@Gerry1 You said you're not a battery expert. Please go away and look at the discharge characteristics of Lithium Batteries compared to Alkaline, NiCd & NiMH, therein lies the difficulty, you have certainly missed the point. By the time the 'b' appears it's really too late.

Lithium Thionyl Chloride batteries have a very stable and flat discharge curve for most of their operating life. Voltage drops of very quickly at the end. Depending on load profile, this could be as little as 3% remaining charge, or as much as 15%. A typical gas meter will have a battery designed for a 10 or even 20 year life. So you have a window of 4-8 months to signal low battery (and yes, smart meters can send a signal).

Form - https://tadiranbatteries.de/wp-content/uploads/2021/05/Technical-Brochure-LTC-Batteries.pdf

Phones4Chris

FreeBear said:

Phones4Chris said:

Gerry1 said:

Phones4Chris said:

Also, I think you've missed the point about the difficulty of doing what you've suggested with Lithium batteries whether it's a Smart or older Digital meter. Never Mind. And of course your DAB+ radio does not use Lithium batteries!

@Phones4Chris Nope, it has a 1900mAh Lithium battery.  I'm not a battery expert and the radio battery is obviously rechargeable rather than primary.  However, given that a battery delivering a voltage above the minimum is critical to the correct operation of a gas smart meter and to prevent it malfunctioning, it clearly requires a monitoring and telemetry function to be built in.

Given all the anti-tampering and the other highly complex functionality, the extra cost would be trivial when compared to all the predictable problems caused by under or overcharging.

@Gerry1 You said you're not a battery expert. Please go away and look at the discharge characteristics of Lithium Batteries compared to Alkaline, NiCd & NiMH, therein lies the difficulty, you have certainly missed the point. By the time the 'b' appears it's really too late.

Lithium Thionyl Chloride batteries have a very stable and flat discharge curve for most of their operating life. Voltage drops of very quickly at the end. Depending on load profile, this could be as little as 3% remaining charge, or as much as 15%. A typical gas meter will have a battery designed for a 10 or even 20 year life. So you have a window of 4-8 months to signal low battery (and yes, smart meters can send a signal).

Form - https://tadiranbatteries.de/wp-content/uploads/2021/05/Technical-Brochure-LTC-Batteries.pdf

Not sure how you derive your 4-8months, especially as others connected with the industry have frequently stated a 10 year life for these meters, not 20! And judging by the number of reports we see round here, if they do send signals, as another poster remarked, do the suppliers take any notice? We guess not, again judging by consumers' reports. Even when the consumer has noticed either the 'b' or complete lack of display, suppliers aren't rushing out to replace the meter. I don't recall seeing any reports of meters in that state still sending data and people frequently complaining about estimated bills as a consequence, often higher that their expected usage.
I still say the current design is abysmal, consumers deserve better, end of life reliability of these things isn't acceptable.

FreeBear

Phones4Chris said: Not sure how you derive your 4-8months, especially as others connected with the industry have frequently stated a 10 year life for these meters, not 20!

3% of ten years is ~4 months - The 3% is from the curve shown in fig 2.5 above.

Landis+Gyr claim 15 year battery life for the G470 - Whilst not the model the OP has, plenty of other people have one fitted.

Qyburn

FreeBear said:

3% of ten years is ~4 months - The 3% is from the curve shown in fig 2.5 above.

You're assuming (a) that the threshold for detecting end of life low battery is right at the start of the last 3% of capacity and (b) that the meter will continue to work until voltage drops to zero. What would it be if the threshold was say 3.0V and the meter stopped working at say 2.5V. Or using real thresholds of course if you happen to know them.

Phones4Chris

Qyburn said:

FreeBear said:

3% of ten years is ~4 months - The 3% is from the curve shown in fig 2.5 above.

You're assuming (a) that the threshold for detecting end of life low battery is right at the start of the last 3% of capacity and (b) that the meter will continue to work until voltage drops to zero. What would it be if the threshold was say 3.0V and the meter stopped working at say 2.5V. Or using real thresholds of course if you happen to know them.

I tend to agree, and how accurate would such detection be, especially with the poor quality circuit boards we tend to hear about. I still think dv/dt is far too steep to be of much practical use with single lithium cells. The theory is fairly simple, you should avoid single point failures in critical circuits, a bit of simple redundancy can improve Reliability.