Wh and Ah and More

[upnorthandpersonal]

Please tell us about SFK's "shadyness"

This was when the LF280k cells didn't pull 280Ah. Back before it became well known that EVE had issues with the 280k not pulling full capacity. So people measured SFK cells, and didn't reach 280Ah even if the test report said they would (which EVE probably messed up). Instead, users were at fault for 'wrong test equipment' and 'conventional YT mindset'. And they came up with the 'you must take the measured Ah and multiply with 3.2V and you get the correct Wh on the label' - which is nonsense. A main reason to measure Ah instead of Wh is because you can take voltage (and any losses related to that) out of the equation (which I've demonstrated and is on a video on my channel). If they then make claims such as "Ah without nominal voltage means nothing, otherwise we have an infinite Ah battery for you at 0V" (see screenshot above) you've completely lost all my respect and confidence.

 

[Will Prowse]

I'm sure @Will Prowse has his ideas on that statement.

Yeah please expand on this, what did they say? Funny they said I'm a good guy when I don't know them. Do they even know how this forum works? @Alkaline

 

[Alkaline]

Yeah please expand on this, what did they say? Funny they said I'm a good guy when I don't know them. Do they even know how this forum works? @Alkaline

Check Pm I sent contact phones for both, this way instead of hearsay you can speak to them direct.

 

[Will Prowse]

Check Pm I sent contact phones for both, this way instead of hearsay you can speak to them direct.

Everyone I just talked to said they have no clue what you are talking about.

 

[Tomthumb62]

Tomthumb,

You said I have been here for a while, well haven't you? Both 18650, and SFK had there account removed when the vendor section was removed along with various other alibaba sellers account so how exactly are you expecting any response form either company. No company is going to want to engage in a place where they have been removed I have spoke to both Chris from 18650 and Tommy from SFK they both said (paraphrasing) Will Prowse is a good guy but the forums basically are run by third party sellers.

I remember reading those threads and I can tell you they both were accusing docan and a number of other alibaba companies of the same thing: selling grade B cells as A. Back then there wasn't the QR codes with a B so it was harder to tell, but test report existed then to but trying to distinguish between the 2 grades was very difficult. Basically the vendor forum was a big mess so its understandable why its gone.

As for the thread you point to its ramblings you have SFK haters vs SKF supporters (and you can add me to this because I have rept 280s from them, but I try to be unbiased, emphasis on the TRY). There is nothing everyone isn't already aware of and has made there opinion of.

18650, SFK, Ezealco and Now Battery Hookup all sell grade A cells with test reports, you can not go wrong from any vendor and there prices are within a few dollars of each other. Depending on the amount of cells you need you can select the vendor that suits you best. No one is buying 4 cells form SFK as there prices are too high, but clearly if you need a lot of cells they have the best price/cell. For me Ezealco would be the best if you need 16 cells as I can drive to houston and pick up them (even thought I have to pay sales tax). I think you and timselectric are trying to create unneeded BS drama among these vendors when you should be focusing on the fight between vendors that have test reports and the ones without.

Alkaline - Thanks so much for that concise perspective of the topic. You obviously know more than I do. I certainly did add to unnecessary drama with my "off the rails" comments (oops that was a different thread) my adding to confusion to the topic. If we all were in person and could banter quickly back and forth, one of you probably would have shut me down right quick basically telling me I don't know what I'm talking about. Well, I do know what I'm talking about, but only the part that I know about, lol! I don't know the whole story and people like you know more of it.

I'm sorry to this forum for not keeping my mouth shut, but I'm glad it resulted in what you just wrote to me here. I want to buy cells at some point (might be a year out or more) and starting to learn the landscape and history is helpful. Perhaps I should have just read hundreds of more posts/comments before chiming in here.

As for this forum being run by third party sellers, maybe that was the deal in the past (when 18650 and SFK were part of it), but I don't get the sense it's that way now. I think Will made a good call on cutting out the vendor section. I wasn't here during that fiasco but have read about it a few times. And I guess there was a group buy that lots of people got burned on.

Now the main vendors on the forum I am aware of (and aren't cell-specific) are Current Connected and Signature Solar. There is obviously a lot of grunting about SS and I hear pretty much nothing but good for CC. I think it is a boon that both companies participate here. CC in particular adds a lot of value to this forum, IMO and I do hope that is turning into more sales for them. Their business model isn't suited so much for my needs (the cost of shipping kills it for me usually) as I don't need the higher level of customer service they offer. But if I wasn't so cheap (my solar is currently confined to our leisure camp trailer), I would just buy everything (not cells obviously as I don't think they sell them) from them and rest assured I would much more likely to be taken care of over another company that sells cheaper but struggles to follow through on support. I have mostly bought (not cells they don't sell them) from invertersRus.com as they have b-stock Victron which saves a few ponies and their customer service (plus free shipping) has been excellent. I once ordered a set of battery cables from CC and shipping was $19...I told them about this and I think they have lowered the price on small items like that, good to know they listen to their customers...they do seem to care a lot.

 

[Will Prowse]

I also told both companies how I run this forum and told them I run it 100% and if someone has a problem, come to me.

Vendors can post just fine here, but direct promotion isn't. What we had in the past was Michael b caros and endless salesman accounts pushing their products on members. Not cool.

 

[Will Prowse]

Alkaline - Thanks so much for that concise perspective of the topic. You obviously know more than I do. I certainly did add to unnecessary drama with my "off the rails" comments (oops that was a different thread) my adding to confusion to the topic. If we all were in person and could banter quickly back and forth, one of you probably would have shut me down right quick basically telling me I don't know what I'm talking about. Well, I do know what I'm talking about, but only the part that I know about, lol! I don't know the whole story and people like you know more of it.

I'm sorry to this forum for not keeping my mouth shut, but I'm glad it resulted in what you just wrote to me here. I want to buy cells at some point (might be a year out or more) and starting to learn the landscape and history is helpful. Perhaps I should have just read hundreds of more posts/comments before chiming in here.

As for this forum being run by third party sellers, maybe that was the deal in the past (when 18650 and SFK were part of it), but I don't get the sense it's that way now. I think Will made a good call on cutting out the vendor section. I wasn't here during that fiasco but have read about it a few times. And I guess there was a group buy that lots of people got burned on.

Now the main vendors on the forum I am aware of (and aren't cell-specific) are Current Connected and Signature Solar. There is obviously a lot of grunting about SS and I hear pretty much nothing but good for CC. I think it is a boon that both companies participate here. CC in particular adds a lot of value to this forum, IMO and I do hope that is turning into more sales for them. Their business model isn't suited so much for my needs (the cost of shipping kills it for me usually) as I don't need the higher level of customer service they offer. But if I wasn't so cheap (my solar is currently confined to our leisure camp trailer), I would just buy everything (not cells obviously as I don't think they sell them) from them and rest assured I would much more likely to be taken care of over another company that sells cheaper but struggles to follow through on support. I have mostly bought (not cells they don't sell them) from invertersRus.com as they have b-stock Victron which saves a few ponies and their customer service (plus free shipping) has been excellent. I once ordered a set of battery cables from CC and shipping was $19...I told them about this and I think they have lowered the price on small items like that, good to know they listen to their customers...they do seem to care a lot.

Anyone can make an account here today. If there is any corporate affiliation of a member, needs to be stated in the subtitle of a profile.

 

[Steve_S]

Further on Will's post, we have also had Manufacturers/Developers, Vendors/Suppliers who have come on here, and interacted with the membership in both supporting them and even in gaining their help & feedback to improve products & offerings.

There are other boards out there, I've gone & looked but never joined because simply, this is the best.

 

[sparrowhawk]

Further on Will's post, we have also had Manufacturers/Developers, Vendors/Suppliers who have come on here, and interacted with the membership in both supporting them and even in gaining their help & feedback to improve products & offerings.

There are other boards out there, I've gone & looked but never joined because simply, this is the best.

And simply irresistible!

 

[Sam Cho TX]

And they came up with the 'you must take the measured Ah and multiply with 3.2V and you get the correct Wh on the label' - which is nonsense. A main reason to measure Ah instead of Wh is because you can take voltage (and any losses related to that) out of the equation (which I've demonstrated and is on a video on my channel). If they then make claims such as "Ah without nominal voltage means nothing, otherwise we have an infinite Ah battery for you at 0V" (see screenshot above) you've completely lost all my respect and confidence.

I am very confused on this, and I will agree that SFK is the only company constantly says WH everyone else uses AH and so do many review videos. I called them today and they were upset with me on the phone saying I'm causing problems for them from Diy Solar Forum. Not my intentions but it is what it is I want to find out.

So I started asking questions on Quora and even chat Gpt:

ChatGPT

A conversational AI system that listens, learns, and challenges

chat.openai.com

Many Electrical Engineers and Professors answered my questions:

Battery capacity question: When testing capacity, can you take watt-hour measured and divide by nominal voltage (in my case 3.2v for LFP)...

Dieter Ernst's answer: Taking the energy measured in Wh, and dividing it by nominal voltage, will indeed give you charge capacity in Ah. Ampere hours, but also watt hours need either a shunt or a current clamp to measure the current. Characterizing a battery by its energy content (Wh) is way be...

www.quora.com

What is the proper way of measuring battery capacity watt-hour capacity or amp-hour? I need some experts (Ph.D types).

Stephen Dudley's answer: Either or both… Personally I find watt hours more useful (I deal in offgrid solar), as watthours generated/used remains the same regardless of voltage, where amp hours you need to know the voltage as well (which on the battery size could be 12v nominal, 24v, or more comm...

www.quora.com

Everyone has said the same thing, Watt Hour is the better measurement and you an convert watt hour to amp-hour by dividing by 3.2 or nominal voltage.

Can you point me to literature that would disagree because this seems to be going back and forth and I'm also not figuring out if WH is better than why is everyone always talking about AH.


Seems to me WH should be better because it takes voltage and everything else into perspective.

 

[Sam Cho TX]

Playing devils advocate I tried to force chat GPT to make Ah the better measurement and it kept saying both have there place, but unlike WH it did not get to the Ah is better than Wh if you had to pick one despite my push to make Ah the better way.

ChatGPT

A conversational AI system that listens, learns, and challenges

chat.openai.com

yes I know its Chat GPT but its fun ?

 

[42OhmsPA]

I am very confused on this, and I will agree that SFK is the only company constantly says WH everyone else uses AH and so do many review videos. I called them today and they were upset with me on the phone saying I'm causing problems for them from Diy Solar Forum. Not my intentions but it is what it is I want to find out.

Better watch out or they will be airing your dirty laundry on the interwebs.

Where are they constantly using WH?

So I started asking questions on Quora and even chat Gpt:

ChatGPT

A conversational AI system that listens, learns, and challenges

chat.openai.com

Many Electrical Engineers and Professors answered my questions:

Battery capacity question: When testing capacity, can you take watt-hour measured and divide by nominal voltage (in my case 3.2v for LFP)...

Answer (1 of 4): Taking the energy measured in Wh, and dividing it by nominal voltage, will indeed give you charge capacity in Ah. Ampere hours, but also watt hours need either a shunt or a current clamp to measure the current. Characterizing a battery by its energy content (Wh) is way better t...

www.quora.com

What is the proper way of measuring battery capacity watt-hour capacity or amp-hour? I need some experts (Ph.D types).

Stephen Dudley's answer: Either or both… Personally I find watt hours more useful (I deal in offgrid solar), as watthours generated/used remains the same regardless of voltage, where amp hours you need to know the voltage as well (which on the battery size could be 12v nominal, 24v, or more comm...

www.quora.com

Everyone has said the same thing, Watt Hour is the better measurement and you an convert watt hour to amp-hour by dividing by 3.2 or nominal voltage.

Can you point me to literature that would disagree because this seems to be going back and forth and I'm also not figuring out if WH is better than why is everyone always talking about AH.


Seems to me WH should be better because it takes voltage and everything else into perspective.

Watts = power

 

[EastFalcon]

I am very confused on this, and I will agree that SFK is the only company constantly says WH everyone else uses AH and so do many review videos. I called them today and they were upset with me on the phone saying I'm causing problems for them from Diy Solar Forum. Not my intentions but it is what it is I want to find out.

So I started asking questions on Quora and even chat Gpt:

ChatGPT

A conversational AI system that listens, learns, and challenges

chat.openai.com

Many Electrical Engineers and Professors answered my questions:

Battery capacity question: When testing capacity, can you take watt-hour measured and divide by nominal voltage (in my case 3.2v for LFP)...

Dieter Ernst's answer: Taking the energy measured in Wh, and dividing it by nominal voltage, will indeed give you charge capacity in Ah. Ampere hours, but also watt hours need either a shunt or a current clamp to measure the current. Characterizing a battery by its energy content (Wh) is way be...

www.quora.com

What is the proper way of measuring battery capacity watt-hour capacity or amp-hour? I need some experts (Ph.D types).

Stephen Dudley's answer: Either or both… Personally I find watt hours more useful (I deal in offgrid solar), as watthours generated/used remains the same regardless of voltage, where amp hours you need to know the voltage as well (which on the battery size could be 12v nominal, 24v, or more comm...

www.quora.com

Everyone has said the same thing, Watt Hour is the better measurement and you an convert watt hour to amp-hour by dividing by 3.2 or nominal voltage.

Can you point me to literature that would disagree because this seems to be going back and forth and I'm also not figuring out if WH is better than why is everyone always talking about AH.


Seems to me WH should be better because it takes voltage and everything else into perspective.

This is quite interesting, I think this should be moved to the main forums, I have always thought the way to go was AH as well!

Chat GPT is insane you can write whole term papers with it, using it to check for battery questions is genius

 

[Steve_S]

Below is an EVE 280 QR Code.
Note is shows 896Wh (280AH * 3.2V = 896Wh)

 

[Sam Cho TX]

Ok so I'm trying to understand how is using Wh being shady? According to upnorthandpersaul Wh is wrong and Ah should be used also 9/10 videos of capacity test I have seen are all using Ah.

About 1 year ago I had 4x 280K cells form SFK and I built a battery it tested to 278.1 AH and 3601 WH with the 150 AMP bms (same as jbd). So is this a pass or fail on capacity? 3601/4 = 900.25 Wh/cell if they are are rated to 896 Wh each. 900.25/3.2 would be 281.3 Ah.

 

[Steve_S]

Possible answer.
When EVE and other manufacturers state the Wh capacity, this is done at Nominal Voltage of 3.200 Volts per cell.
When testing a battery pack, you are pulling from 100% to 0% +/-. Not Nominal which is 50%.

 

[Brucey]

Better watch out or they will be airing your dirty laundry on the interwebs.

Where are they constantly using WH?

Watts = power

Continuous discharge of only 500W? Is that a typo? That's less than 0.5C?

 

[BuffaloTrace]

Continuous discharge of only 500W? Is that a typo? That's less than 0.5C?

How many watts is 0.5C for a 280ah Eve cell?

 

[42OhmsPA]

Continuous discharge of only 500W? Is that a typo? That's less than 0.5C?

It threw me off as well. I suspected they use watts so they can have a bigger number for advertising or it's a typo, but other cells were similar.

How many watts is 0.5C for a 280ah Eve cell?

Let's see if I screw this up.
280 x 0.5 = 140 x 3.2? = 448 watts.
Hmmm 500 / 140 = 3.571... What voltage are they using to derive 500 watts...?

 

[upnorthandpersonal]

Ok so I'm trying to understand how is using Wh being shady? According to upnorthandpersaul Wh is wrong and Ah should be used also 9/10 videos of capacity test I have seen are all using Ah.

Couple of reasons:

- For one, measuring Wh means tracking two variables (voltage and current) versus only one (current) over time. Energy is the area under the curve of these measurements over time. However, if you have losses anywhere in your set-up (like connections, wires, etc.) you won't measure those at your instrument due to these losses. AmpHours eliminate these losses altogether, and is the reason why this is chosen for battery testing - have a look at this extreme set-up I did:

- Secondly: a cell that is specified at 280Ah (in addition to whatever other means) means that it should deliver a constant 280A for one Hour. Or, at 0.2C, 56A for 5 hours. This is a very straight forward test, again, because losses don't matter (the current is the same everywhere in the circuit - see video again). If you measure anything less than that, it means it doesn't match the manufacturer specification and everything after that is handwaving.

- Handwaving: suppose you only measure 277Ah, but someone tells you that you measured this wrong, you should have measured Wh (which you reliably can't do with available consumer equipment) so they tell you that you should multiply this 277Ah with the nominal voltage of 3.25V. This gives you 900Wh, which is on the label as well, so all good! Or something along those lines. But, I hear you say, nominal voltage is 3.2V, not 3.25V? Their quote:
"Grade A cells provide the same watt-hours for less capacity e.g. 900WH at only 276AH vs Grade B cells that provide 900WH at 280 AH capacity.The watt-hour remains the same for both but grade A cells have average voltage of 3.25 vs 3.20 volts for grade B." - note that this was after they said that "We have tested our cells they all test above 281 AH we tested 3 cells and the highest tested to 285 AH." You can find these comments under [1].

By the way, have a look at their current site and the label on the batteries:

SunFunKits.com - Certified Automotive Grade A Genuine EVE Lithium LF280K Lithium Iron Phosphate Battery 280AH 4 pack - Sun fun kits

SunFunKits.com - Certified Automotive Grade A Genuine EVE Lithium LF280K Lithium Iron Phosphate Battery 280AH 4 pack - Sun fun kits

www.sunfunkits.com

No more mention of WattHours, all in AmpHours.

I called them today and they were upset with me on the phone saying I'm causing problems for them from Diy Solar Forum. Not my intentions but it is what it is I want to find out.

If any of my customers (or students) question what I said or am not clear about, and post these things in a forum where there are different views and they get it wrong - I would go into discussion with them, backing it up with science and data. Getting upset because of a discussion in my opinion means you've been wrong, don't want to admit it, and bury what was once said. If I then get proven wrong for whatever reason, I adjust to that accordingly. I wouldn't get upset about any of those things. Either I'm right, or I'm wrong. If I'm right, I back that up with data and science (like I have been doing on this matter for a long time). If I'm wrong, proven with evidence, I will happily take it but never would I get upset about it.


[1] www.youtube.com/watch?v=rsO4ctUlCGY&lc=Ugywf-koQpjFph1p0Yp4AaABAg.9eIOjB47rBQ9eMZFiCxrMP