Wh and Ah and More

[upnorthandpersonal]

The shadiness lies with EVE the manufacturer themselves, retailers will put whatever spin they have to do to sell the stock they have.

That I agree with 100%.

 

[BuffaloTrace]

Well yes, but that's not the argument.

No, the issue is the opposite: not measuring 280Ah (being below that), but still getting the factory specified Wh (using said handwaving).

Right but the issues are linked. if it's impossible to get the specified AH out of a cell without also achieving the factory rated WH (obvious testing efficiencies set aside) then of course for simplicity for the end user the AH rating makes sense, and many ways to test this without having to take the efficiencies of the testing into account.
Basically if the cell tests at its factory rated AH or above, that cell will theoretically put out its factory rated power in WH or therms. But if it tests under it can still theoretically put out its rated power.....?
-Derp

 

[Quattrohead]

Therms is a much more accurate way of measuring propane. Don't matter though, it's wrong and illegal to use therms for retail sales.

But strangely enough that is what they use to measure gas consumption in the UK so what's legal in one country isn't necessarily legal in another. In other words any facts can be bent to suit the argument

 

[upnorthandpersonal]

But if it tests under it can still theoretically put out its rated power.....?

No, that's the point. Unless you use said handwaving.

 

[Tomthumb62]

That's the issue: "they are rated at 896Wh each". Where does this come from? By multiplying 3.2V nominal with 280Ah capacity. Eliminate the 3.2V and take your 900.25Wh you measured. Divide 900.25 by 3.2V - awesome, 281Ah per cell yes? But you measured 278Ah. So which one is correct? But SFK said 3.25V is nominal for Grade A, so you should divide your 900.25 by 3.25, so 276Ah - cool you're over that cause you measured 278! All perfect! Well, no, of course not. This is just handwaving around the fact that the cell is rated at 280Ah and doesn't meet this...

That's why Wh aren't used, and why cells are rated in Ah.

So I’m trying to follow the reality here. First, thank you for taking the time to explain how Wh isn’t a rock solid measurement due to hand waving.

So you’ve explained that SFK used to advertise their cells in Wh. I’m unclear if any of the other sellers mentioned in this thread (such as 18650 battery store) have also done this in the past, but now no longer do? Can you comment on the other sellers?

 

[upnorthandpersonal]

I spun off this thread somewhere in the middle and moved it to chit-chat. Now we are free

 

[upnorthandpersonal]

So I’m trying to follow the reality here. First, thank you for taking the time to explain how Wh isn’t a rock solid measurement due to hand waving.

So you’ve explained that SFK used to advertise their cells in Wh. I’m unclear if any of the other sellers mentioned in this thread (such as 18650 battery store) have also done this in the past, but now no longer do? Can you comment on the other sellers?

Cells are specified in both Wh and Ah. You need to meet both criteria. Not meeting the Ah measurement and blaming the person doing the measurement, or explaining that it does't matter because 'nominal voltage handwaving' is wrong.
Point is, measuring Ah accurately is much more straight forward than measuring Wh, so that's what most cells are mainly tested at (including in the datasheet of the manufacturers).

 

[EastFalcon]

I spun off this thread somewhere in the middle and moved it to chit-chat. Now we are free

AHH, I was like what happened to the posts!

 

[EastFalcon]

So I’m trying to follow the reality here. First, thank you for taking the time to explain how Wh isn’t a rock solid measurement due to hand waving.

So you’ve explained that SFK used to advertise their cells in Wh. I’m unclear if any of the other sellers mentioned in this thread (such as 18650 battery store) have also done this in the past, but now no longer do? Can you comment on the other sellers?

They put both on the label now, I linked to my thread.

I think the issue was with the 280K only meeting WH but not AH.

My cells form 18650 were the same way, just shy of AH but meeting WH.

So the issue of the 280K affects all vendors, now they have a 280K v3 that fixes this.

 

[upnorthandpersonal]

Yes, the issue was EVE and a bad batch of 280k - however the label did not have 277Ah on them, they had 280+Ah on them. When people tested that, and came to the lower number and made SFK aware of this, they got blasted, called shills for Docan or other vendors, blamed test methods, called it 'conventional YT mindset' etc.

 

[EastFalcon]

Well according to a spreadsheet 18650batterystore gave me I was supposed to get 295AH on a cell that tested only to 278AH. There spreadsheet did not have WH on them only AH. I just said the heck with it I have them now and its fine.

 

[upnorthandpersonal]

Well according to a spreadsheet 18650batterystore gave me I was supposed to get 295AH on a cell that tested only to 278AH. There spreadsheet did not have WH on them only AH. I just said the heck with it I have them now and its fine.

And if you're fine with that, that's ok. However would you agree that someone has the right to complain when the cell doesn't meet the specified ratings? NKON here in Europe for example will replace cells even for Grade B cells that don't perform as advertised.

 

[hwy17]

But strangely enough that is what they use to measure gas consumption in the UK so what's legal in one country isn't necessarily legal in another. In other words any facts can be bent to suit the argument

My family in the UK get their gas bill in kwh, gas customers here in California get billed in therms, and propane is sold in gallons.

All of which illustrates it's not the best measurement that's important, it's the one that is standard in the market you are trading in. Which it seems like in batteries is the Ah.

Propane is sold in gallons the same reason batteries might be sold on Ah, limitations of the testing equipment. Therm or kwh billing requires precise sampling and testing of the exact energy content, while gallons is purely volumetric, much like coulombs or Ah.

 

[Steve_S]

A GALLON YOU SAY !
A Genuine Gallon @ 4.55 Litres (Imperial Gallon)
OR An American Gallon @ 3.78 Litres ?
When a Gallon is NOT a Gallon...
Colour or Color ?

 

[hwy17]

A GALLON YOU SAY !
A Genuine Gallon @ 4.55 Litres (Imperial Gallon)
OR An American Gallon @ 3.78 Litres ?
When a Gallon is NOT a Gallon...
Colour or Color ?

British people use this one weird trick to get insane MPG's!