What is going on here? Just got ZKE-40

[Alkaline]

Recently,

I am thinking relying on AH is not enough to determine cell quality, so I finally ponied up the cash and bought a ZKE-40 tester and tested 1 of my Luyuan 280K cells, matched & batched genuine.

As you can see it falls a bit short on the AH, but at the same time exceed the WH of the cell (the 280k is a 896WH cell).

So I have been asking around and it seems the grade B cells are the exact opposite, they pass *(the good grade b...) the AH but they fail the WH test?

Is my tester defective or anyone else that has this with Luyuan Cells what are you getting?

I will be testing 2 year old xuba cells next just to compare but those are 280N cells.

 

[Bud Martin]

May be it is not well calibrated.
Can you do more test on a bunch of batteries you have?

 

[Alkaline]

I'm going to test 2 year old xuba 280 cells. Anyone else have a ZKE40 to compare?

 

[sunshine_eggo]

Cells should meet both ratings. Relying on Wh introduces additional error into the measurement and is inherently less reliable.

Ah needs current and time.
Wh needs current, voltage and time.

Each variable has an accuracy/error associated with it.

If a cell meets Ah but fails Wh by a small amount, cell is probably good.
If a cell fails Ah but meets Wh, I would regard the test as suspicious UNLESS I verified the IR is notably lower than spec.

Wh becomes completely unnecessary if you're confirming that the cell meets internal resistance specs. High IR will cause Wh to be low. If Ah good and IR good, cell good.

IMHO, if you're not working with laboratory grade calibrated equipment that cost several times more than the battery/cells you're testing OR you calibrate/correlate the equipment to known standards in the measurement range, you're going to be lucky if your test results are within ±3%. of reality.

 

[Alkaline]

Both my amazon fan tester and the ZKE are saying almost exactly the same https://www.amazon.com/dp/B0B5CNRMTK?psc=1

I don't think its my tester, I'm hoping more people will post.

I measured exactly like Andy from off grid garage, buss bar clamped to the terminal. Charged to 3.65 until .5 amp. Wait 1hr and then do discharge.

 

[Bud Martin]

Both my amazon fan tester and the ZKE are saying almost exactly the same https://www.amazon.com/dp/B0B5CNRMTK?psc=1

I don't think its my tester, I'm hoping more people will post.

I measured exactly like Andy from off grid garage, buss bar clamped to the terminal. Charged to 3.65 until .5 amp. Wait 1hr and then do discharge.

The fan tester does not have Voltage sensing wires for measuring the Voltage at the battery terminals for accurate Wattage calculation, it is measuring the Voltage on the load.

 

[Alkaline]

No it does this one has v-sense: I made sure of it

https://m.media-amazon.com/images/I/81UzVdben4L._SL1500_.jpg

it has 4 total outputs 2 for the main wires and 2 for v-sense wires.

 

[Bud Martin]

OK, that is the better one.

 

[Just John]

Both my amazon fan tester and the ZKE are saying almost exactly the same https://www.amazon.com/dp/B0B5CNRMTK?psc=1

I don't think its my tester, I'm hoping more people will post.

I measured exactly like Andy from off grid garage, buss bar clamped to the terminal. Charged to 3.65 until .5 amp. Wait 1hr and then do discharge.

I compared results of multiple testers (including the ZKE-40, and an identical tester like yours from Amazon, and even cheaper versions without voltage sense leads) with TWO calibrated loads.
Even the cheap testers are much more accurate than you would think given the price. Hard to be 100% definitive since temperature fluctuations can affect results, but all measured within a single amp hour range. The ZKE-40 is very accurate when compared to real calibrated loads.

 

[Alkaline]

So I just finished testing my Basen EVE 280 Cell. I bought these in November 2020, I would say I have about 15-20 cycles on this pack in a 8s using overkill solar 120A 8s BMS configuration.

Alex Chen Assured me these are grade A perfect cells, like a nub I believed him because also I watched lithiumsolar DIY bank and he said he was getting 280AH, plus many people on the forums were saying basen is great at that time.

Well 265 is what I have and this was the strongest cell in my pack, I suspect other cells will be worse, my screw up is that I did not test these cells when I got them so I don't have a baseline...But even if they were 280 (which I don't think they were) Its pretty bad loosing 15 Ah after just 15 cycles...

Next I'm going to test my Xuba EVE 280 cells.

 

[John Frum]

Alex Chen Assured me these are grade A perfect cells,

Who is Alex Chen?

 

[Alkaline]

he used to be the sales guy for Basen.

 

[John Frum]

Did you validate the voltage and amperage against your reference(s)?

 

[John Frum]

Why not show us the charge and discharge curve?

 

[John Frum]

What was the ambient temperature and cell temperature during the test?

 

[BradCagle]

I know these ZKE testers are getting popular. But I don't trust them yet. This is not the first time I've see them pass Wh, but under on Ah

 

[John Frum]

Have you tried doing a discharge test with your PSU stunt doubling for a battery?

 

[Alkaline]

Why not show us the charge and discharge curve?

I showed the discharge curve? I charged and starting voltage look at the chart they were charged to 3.65 and then discharged.

 

[Alkaline]

I know these ZKE testers are getting popular. But I don't trust them yet. This is not the first time I've see them pass Wh, but under on Ah

Well thats why I made this thread to see if my charger is busted. But I tested 3-4 of my Luyuan cells and those grade A cells all behave this way 277-279 ish but all have over 900 WH.

I think the grade A cells have more WH for the same AH. Also the average voltage for the Luyuan matched & batched genuine cells is higher than grade than the Xuba or Basen.

JustJohn has the same tester I do and also luyuan cells I'll ask him to upload htis results, he has matched & batched from Luyuan as well.

 

[Alkaline]

Did you validate the voltage and amperage against your reference(s)?

how exactly do you do this? I just took my tester out attached the v-sense cables to the screw and used 2 buss bars on each terminal with the clamp.