Has anyone used that Chinese Capacity Tester Will used on his video?

[TommyHolly]

Hello,
I’m wondering if my new Capacity Tester is bad or the first battery I tried testing is bad? It’s the exact capacity tester in Will’s video:

I tried my first capacity test using that cheap $40 capacity tester that Will had on his channel. For some reason I can’t get it to work, but it might be because of the battery?? Maybe I discovered my first bad battery?

- I top balanced the battery at 3.65v until the charger showed 0 amps going in.
- When I hooked up the cell to the tester, it showed 3.52v
- I watched the video again and set up the capacity tester so it shuts off at 2.60v as a Low Cutoff Voltage like he recommended.
- Then I adjusted down the current to 20A, which on my battery is 2C, just like in the video.

**Almost immediately, the Low Voltage alarm went off and the test stopped immediately. The screen flashed “2.60!” I couldn’t resume the test because the battery would instantly drop down under 2.6v during the test??

I grabbed a multimeter and it was actually displaying 3.17v directly on the cell. So maybe the capacity tester is bad??

I was forced to turn down the current to 15A and the voltage on the Capacity Tester says 2.7v which is dangerously low and close to shutting off the test again. The multimeter directly on the cell showed 3.102v. So maybe I have to turn it down all the way to 1C 10A???

Im thinking either the cheap capacity tester is bad or the battery cell is bad. What do you guys think?

 

[TommyHolly]

To make sure my yellow voltmeter isn’t bad, I used a second red Uni-T voltmeter which matched the results of the yellow one.

 

[anadiner]

Oh man, gotta hate when testing new item the 1st time on a faulty product. U know theres no way to answer this question except trial and error.

If I dont know if its the bulb or lamp, I put the bulb in a lamp I know works. Or a working bulb in the lamp to see if it comes on.

So, you're for sure headed in right direction.

 

[TommyHolly]

Oh man, gotta hate when testing new item the 1st time on a faulty product. U know theres no way to answer this question except trial and error.

If I dont know if its the bulb or lamp, I put the bulb in a lamp I know works. Or a working bulb in the lamp to see if it comes on.

So, you're for sure headed in right direction.

The battery is 6 years old and was the worst battery I tested during my Resting Voltage Internal Resistance Tests... It's very likely I have some bad Lithium Batteries in my 48-cell system. After top balancing, this particular one went from 3.64v down to 3.56v with no load in 7 days. (The rest only dropped a maximum of 0.02v in that same time.) So it's quite possible that this battery is bad. The only thing which makes me question that, is the Chinese Capacitor Tester shows a different voltage than my multimeters??? Will did say to buy 3 Capacity Testers... I should have done that.

 

[Texas-Mark]

Did you try measuring the voltage at the terminals of the capacity tester to rule out a bad tester lead (i.e. with a lot of resistance that manifests when under load)?

 

[Short_Shot]

I have the newer model with a color screen that's otherwise mostly the same.

My first one didn't work at all. Returned for a new one. Second works perfectly.

The first one didn't detect any voltage at all.

 

[noenegdod]

I have 2 of them. I was testing 16 280 AH cells. I would set them to draw 11.8 amps and tests were always done in just under 24 hours. The timer on one would be 5 minutes faster and the other would be 10 minutes slow so the displayed AH was always off. I would just do the math myself for documentation purposes.

 

[koobs]

From the pictures, you're seeing a voltage drop across the leads due to the load.
This is why the newer tester model has 2 separate leads for voltage sensing.
Oversize all your cables. Make sure there's solid connection between the battery and cables, and the tester unit.
When draining a large current from a small battery, you'll likely see significant voltage drop anyhow, but it shouldn't be as big as you're seeing unless the battery is bad.
Change the leads from the default factory supplied ones, as they can be really shitty with high resistance.
With new leads and solid connection points, if there's still a drop then buy the newer testing unit.

 

[TommyHolly]

Did you try measuring the voltage at the terminals of the capacity tester to rule out a bad tester lead (i.e. with a lot of resistance that manifests when under load)?

No I didn't? The leads are connected to the battery. Would I have a different reading a few inches down at the terminals of the Capacity Tester?
*Note: A few hours later after lowering down the current to 15A to 9A, I'm around 85Ah and the test isn't finished yet,

 

[TommyHolly]

From the pictures, you're seeing a voltage drop across the leads due to the load.
This is why the newer tester model has 2 separate leads for voltage sensing.
Oversize all your cables. Make sure there's solid connection between the battery and cables, and the tester unit.
When draining a large current from a small battery, you'll likely see significant voltage drop anyhow, but it shouldn't be as big as you're seeing unless the battery is bad.
Change the leads from the default factory supplied ones, as they can be really shitty with high resistance.
With new leads and solid connection points, if there's still a drop then buy the newer testing unit.

The default factory leads supplied are about 14 AWG. The same or larger than the average speaker wire. I really don't know but will it create that much of a difference in voltage reading? I guess I can buy 6 AWG or something really thick but would it make a difference?

The current I'm draining was around 15A at first. Each time I hear the alarm reach the low voltage cutoff, I turn down the current slightly. After hearing the alarm 6 times now in the last 7 hours, I'm at 5.5A load and a total of 86Ah...

Sadly, I won't be able to change the leads. I'm in the jungle of Central America surrounded by crocodiles and howler monkeys and there isn't any stores that sell anything better. I can order things from the USA, but it takes 20-30 days at least.

 

[TommyHolly]

From the pictures, you're seeing a voltage drop across the leads due to the load.
This is why the newer tester model has 2 separate leads for voltage sensing.
Oversize all your cables. Make sure there's solid connection between the battery and cables, and the tester unit.
When draining a large current from a small battery, you'll likely see significant voltage drop anyhow, but it shouldn't be as big as you're seeing unless the battery is bad.
Change the leads from the default factory supplied ones, as they can be really shitty with high resistance.
With new leads and solid connection points, if there's still a drop then buy the newer testing unit.

By the way, what newer tester model?? Are you referring to the one on Amazon that costs $99? and is 180w? I purchased the $49 version that is 150w.

 

[koobs]

The Chinese provided leads are often of poor quality; ie not pure copper, but instead CCA, and have very thick insulation and little conductor material. The thickness of the conductor + coating is misleading due to the large coating.

The newer model has buttons instead of the turn knobs, and voltage sensor leads too.

Very quick search on aliexpress:

33.48US $ 20% OFF|Dl24 150w 20a Dc Power Usb Tester Electronic Load Lithium Battery Capacity Monitor Discharge Meter Supply Checker With App - Battery Testers - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[TommyHolly]

The Chinese provided leads are often of poor quality; ie not pure copper, but instead CCA, and have very thick insulation and little conductor material. The thickness of the conductor + coating is misleading due to the large coating.

The newer model has buttons instead of the turn knobs, and voltage sensor leads too.
View attachment 61055
Very quick search on aliexpress:

33.48US $ 20% OFF|Dl24 150w 20a Dc Power Usb Tester Electronic Load Lithium Battery Capacity Monitor Discharge Meter Supply Checker With App - Battery Testers - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I saw this exact same model on Amazon for $99… I guess I should order it?

 

[TommyHolly]

Something I noticed with the 150w, $49 version I purchased off Amazon.

When I initially turned it up to 20A, the low voltage alarm immediately kicked on. Each time I would lower the current slightly and the alarm would eventually kick on. I went from 20A, 15A, 11A, 8A, 5A, 3A, 1.5A… and finally I gave up after reaching about 90Ah. (Far short of the 100Ah the cel is rated at(

I’m wondering if others had to gradually lower the current as well? Or do you stop the test immediately after the first time the low voltage alarm shuts the test off?

 

[koobs]

If you can afford it, i'd go the 180w version for $10 more.
Also depends on how soon you need it. Coming from Aliexpress means China, which means likely at least a month to get to you.

That voltage drop could be due to high cell internal resistance (old and used cell), or poor wiring. Hard to tell.

 

[drifty325i]

Just ordered the 180w one, thanks guys

 

[Texas-Mark]

No I didn't? The leads are connected to the battery. Would I have a different reading a few inches down at the terminals of the Capacity Tester?

As someone else also mentioned, the leads may have a lot of resistance when under load causing a voltage drop. They may also be fine, but by measuring where they connect to the board, you can rule out that possibility. If you measure there and it's the same (or very close) reading as what the board is reporting, you know the leads are the problem.

 

[740GLE]

That or the alligator clips, put proper ring terminals on. If the load tester thinks the cell voltage is 2.6, but you’ve proven otherwise, it’s not the cell that you should be worried about.

 

[Texas-Mark]

That or the alligator clips, put proper ring terminals on.

Good point. Small alligator clips are fine if you are just measuring voltage, but as soon as you start pulling any current, all you have is the teeth contact area to pass all of the current. Reminds me of having a nice set of heavy duty jumper cables, but then not being able to get a good jump because you can only get two teeth to grab onto the battery terminal.

 

[740GLE]

Also in the video you can see the rest leads were changed out and larger allagator clips were used. But, during single cell testing the voltage did drop to 2.77, so imagine if you had crappier connections the test rig would just read lower voltages.