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Watt the fμck?

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nali:

--- Quote from: mikerj on September 30, 2022, 09:15:02 pm ---
--- Quote from: nali on September 28, 2022, 08:32:05 pm ---What about those natty little in home displays you get to tell you how much money you're saving with your smart meter? (according to the sales propoganda)

--- End quote ---

I presume the power that the smart meter requires is drawn from the unmetered side?  Anyone know typical power draw?  Guessing not huge but when there is millions of the bloody things...

--- End quote ---

Yes they do. The meter itself doesn't draw much, most of the power goes to the bolt on comms hub which facilitates the Home Area Network. Although the interface spec calls for a maximum power delivery of 6W typical power might be a 100-200mW.

coppice:

--- Quote from: mikerj on September 30, 2022, 09:15:02 pm ---I presume the power that the smart meter requires is drawn from the unmetered side?  Anyone know typical power draw?  Guessing not huge but when there is millions of the bloody things...

--- End quote ---
It is a requirement that an electricity meter is powered from the unmetered side. If you think about it, it really has to be. Otherwise the meter would creep when the entire property is turned off, and they would have a customer service nightmare. Meters also don't read the first few milliamps, so they don't creep on noise. The exact number of milliamps varies with the location. Germany estimated that it took a 600MW generating set to power all its Ferraris wheel meters. Electronic meters initially had the selling point of cutting this considerably. Early smart meters took a modest fraction of a watt, However, they have grown in complexity, and I'm not sure how much most of them currently take.

AVGresponding:

--- Quote from: james_s on September 30, 2022, 07:27:28 pm ---
--- Quote from: AVGresponding on September 30, 2022, 01:12:27 pm ---Never seen one here in 30 years in the business. Sounds like it's a 7 that's just been qualified at a different, lower, discharge current. Either that or it's a Chinese "9Ah" like those 900,000mAh power banks and 5000mAh 18650's on ebay.[/color][/size][/b]

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Or technology has improved and they're able to pack a bit more into the same size package?

Power Sonic is a reputable brand, they offer both a 7 and 9Ah battery, Digikey is a reputable seller and carries them, albeit at an inflated price. I have about half a dozen UPSs with that size and they all came with 9Ah batteries in them.

https://www.digikey.com/en/products/detail/power-sonic-corporation/PS-1290-F2/13577465

--- End quote ---

Looking at the datasheet for the product you linked, they have done exactly what I said; used a lower discharge current to exaggerate the capacity. I am familiar with the Power Sonic brand, and consider them to be one of the budget brands, they are in no way a premium brand.

There isn't really the potential for the kind of incremental technological improvement that you suggest; lead-acid batteries have a specific chemistry, and the volume of electrolyte is what determines the capacity. You can only fit so much electrolyte in a given volume. The size of the electrode plates and their shape determines the safe current capability, and in essence, the bigger they are, the more current, but also the less space there is for electrolyte.

Gel type batteries have an additional disadvantage in that the electrolyte isn't free to circulate around the electrode plates, which means that in order to extract the most capacity, lower discharge currents are needed, and this is why lower currents in general than liquid LA batteries are specified, despite often having much larger Ah capacities. Give them too much current, and they'll locally boil the electrolyte off the plates and fail open.




--- Quote from: Neper on September 30, 2022, 08:45:43 pm ---
--- Quote from: AVGresponding on September 30, 2022, 01:12:27 pm ---Never seen one here in 30 years in the business. Sounds like it's a 7 that's just been qualified at a different, lower, discharge current.
--- End quote ---

From what I understand, they use a somewhat different technology named AGM (for Absorbent Glass Mat). No lead gel as before but fibreglass mats soaked with a liquid electrolyte. Might explain the slight difference in capacity.


--- End quote ---

AGM and Gel are two names for the same thing. They use a gel electrolyte absorbed into a glass-fibre mat to keep it in contact with the lead electrodes. This means you can use them in any orientation, unlike a traditional lead-acid wet cell.

nali:

--- Quote from: coppice on October 01, 2022, 01:54:09 am ---
--- Quote from: mikerj on September 30, 2022, 09:15:02 pm ---I presume the power that the smart meter requires is drawn from the unmetered side?  Anyone know typical power draw?  Guessing not huge but when there is millions of the bloody things...

--- End quote ---
It is a requirement that an electricity meter is powered from the unmetered side. If you think about it, it really has to be. Otherwise the meter would creep when the entire property is turned off, and they would have a customer service nightmare. Meters also don't read the first few milliamps, so they don't creep on noise. The exact number of milliamps varies with the location. Germany estimated that it took a 600MW generating set to power all its Ferraris wheel meters. Electronic meters initially had the selling point of cutting this considerably. Early smart meters took a modest fraction of a watt, However, they have grown in complexity, and I'm not sure how much most of them currently take.

--- End quote ---

The metered side is also internally switched by a bistable relay. Shame the question didn't come up a few days ago as I've just finished a contract at a meter manufacturer otherwise I could've looked up the spec or just hooked up and measured a device.

Neper:

--- Quote from: AVGresponding on October 01, 2022, 07:40:59 am ---I am familiar with the Power Sonic brand, and consider them to be one of the budget brands, they are in no way a premium brand.
--- End quote ---

What about Yuasa? Panasonic don't seem to make lead gel batteries anymore. Any other brand you'd be able to recommend?

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