Discharge tester board queries

Rad

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Aug 18, 2017
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Hi Powerwallers

I am considering using these ZB2L3boards for my cell discharge testing. I am struggling to find answers to questions I have:

1) Is this aproper constant current discharge circuit or does it just rely on a resistor connected to the cell under test?

2) What cut of voltage does it use?

3) Is the cut off voltage reliable / accurate?

4) Can anyone link me a circuit diagram for them?

Thanks and apologies if this has been covered elsewhere.


image_cuvfkl.jpg
 

Geek

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Aug 15, 2017
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1) Is this a proper constant current discharge circuit or does it just rely on a resistor connected to the cell under test?

It is not a constant current tester. It does just use a resistor.

2) What cut of voltage does it use?

It can be set to whatever you like.

3) Is the cut off voltage reliable / accurate?

I have never checked how accurate. I guess so capacity test seem to be reasonably consistent 5-10% error.

4) Can anyone link me a circuit diagram for them?

Thispage has one.
 
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Rad

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Geek said:
1) Is this a proper constant current discharge circuit or does it just rely on a resistor connected to the cell under test?

It is not a constant current tester. It does just use a resistor.

2) What cut of voltage does it use?

It can be set to whatever you like.

3) Is the cut off voltage reliable / accurate?

I have never checked how accurate. I guess so capacity test seem to be reasonably consistent 5-10% error.

4) Can anyone link me a circuit diagram for them?

Thispage has one.

Thanks for the great help Geek. Would it calculate capacity by accumulating a series of measurements at regular intervals?
 

Rad

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Thank you Thanar. It looks well made, quite pricey though.
 

ozz93666

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The device in post 1 is excellent ... I use it .

When you connect the cell it gives voltage with zero current , press the button and it starts to discharge at the rate you have set by a resistor , I use a coil of single strand telephone wire , length cut to give the right resistance ...

After start you get voltage of cell at your discharge rate ...from this voltage drop you can find the internal resistance of the cell instantly, (make up a chart) ... to get accurate int resistance you need a very firm terminal contact , not possible with opus ( they admit this in their manual)

If zero current voltage is 4.10 and when you start discharge it drops to 3.90 ...and your discharge rate is 1A , you can see the drop is 0.2V

V=I R ..... 0.2 = 1 x R .... R (internal resistance of cell) = 200m ohms
 

Rad

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ozz93666 said:
The device in post 1 is excellent ... I use it .

When you connect the cell it gives voltage with zero current , press the button and it starts to discharge at the rate you have set by a resistor , I use a coil of single strand telephone wire , length cut to give the right resistance ...

After start you get voltage of cell at your discharge rate ...from this voltage drop you can find the internal resistance of the cell instantly, (make up a chart) ... to get accurate int resistance you need a very firm terminal contact , not possible with opus ( they admit this in their manual)

If zero current voltage is 4.10 and when you start discharge it drops to 3.90 ...and your discharge rate is 1A , you can see the drop is 0.2V

V=I R ..... 0.2 = 1 x R .... R (internal resistance of cell) = 200m ohms

Thanks for the helpful anddetailed information ozz93666. Checking the internal resistance by noting the voltage drop and looking it up on a reference tableis an excellent additional check. What length and diameterwire are you using as your load resistor?I just tried to measure a 25cm length of 0.6mm diameter wire rescuedfrom solid cat5/6 cable. My meter resolvesto 0.01ohm but gave very inconsistent readings. Even shorting out the meter terminals with a thick bridge wiresometimes gave a higherreadings than the 25cm test wire. I am guessing I would like to test my cellsin the range of 1 to 2amps.

image_pwbjxa.jpg

image_afpril.jpg
 

ozz93666

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Rad said:
ozz93666 said:
The device in post 1 is excellent ... I use it .

When you connect the cell it gives voltage with zero current , press the button and it starts to discharge at the rate you have set by a resistor , I use a coil of single strand telephone wire , length cut to give the right resistance ...

Thanks ....What length and diameterwire are you using as your load resistor?I just tried to measure a 25cm length of 0.6mm diameter wire rescuedfrom solid cat5/6 cable.[/diy]

You'll need quiet a length of wire ... I had some two strand telephone wire used for connecting outlets around the house , fairly thin and it was magnetic !! very unusual to use copper plated iron wire for electrical work , but phone lines don't carry much current , so I guess they used iron since it wascheaper , and just what we need since it will be high resistance ... I srippedoff theouter plastic , leaving the 2 wires each with aplastic covering , I wound about 10 meters of this into a compact bundle , trimmed some off till I got the resistance I needed by trial and error.... copper wire is not very suitable it would have to be thin enamelled and quiet long , a coil ina transformer perhaps .... most people will buy standard resistors , high wattage , i just had the wire lying around so i used it .

A critical part is the connection and disconnection of the cells to the device , I've tried 3 different styles and none are very satisfactory ...
The style with curly springs on one end are no good for a firmconnection

This is the best type IMO



It gives a firm connection but a real hassle to load and unload cells , I've decided to make my own custom made thing , with two 12v solenoids that when powered, push contact on the ends of the cell...

I've even bought one of these , 7 euro .. supposedly designed for the job ...it's useless ...... Iget everything from eBay ..

 

Rad

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Aug 18, 2017
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ozz93666 said:
Rad said:
ozz93666 said:
The device in post 1 is excellent ... I use it .

When you connect the cell it gives voltage with zero current , press the button and it starts to discharge at the rate you have set by a resistor , I use a coil of single strand telephone wire , length cut to give the right resistance ...

Thanks ....What length and diameterwire are you using as your load resistor?I just tried to measure a 25cm length of 0.6mm diameter wire rescuedfrom solid cat5/6 cable.[/diy]

You'll need quiet a length of wire ... I had some two strand telephone wire used for connecting outlets around the house , fairly thin and it was magnetic !! very unusual to use copper plated iron wire for electrical work , but phone lines don't carry much current , so I guess they used iron since it wascheaper , and just what we need since it will be high resistance ... I srippedoff theouter plastic , leaving the 2 wires each with aplastic covering , I wound about 10 meters of this into a compact bundle , trimmed some off till I got the resistance I needed by trial and error.... copper wire is not very suitable it would have to be thin enamelled and quiet long , a coil ina transformer perhaps .... most people will buy standard resistors , high wattage , i just had the wire lying around so i used it .

A critical part is the connection and disconnection of the cells to the device , I've tried 3 different styles and none are very satisfactory ...
The style with curly springs on one end are no good for a firmconnection

This is the best type IMO



It gives a firm connection but a real hassle to load and unload cells , I've decided to make my own custom made thing , with two 12v solenoids that when powered, push contact on the ends of the cell...

I've even bought one of these , 7 euro .. supposedly designed for the job ...it's useless ...... Iget everything from eBay ..
Wow you have put in a lot of effort, very nice to be able to 'tune' the resistor to exactly what you want. I think I will buy some 2.2ohm 10watt resistors. Yes I have noticed a big variationbetween the different types of holders too, just slightsqueezing on the end of the plastic housing can make a difference.Good luck with the 'powered' holder!

I will order the ZB2L3 boards but have just noticed there are different versions of them. So the manufacturer must have upgraded the firmware as the boards look identical. This one is version 2.38. The product description claims there is an 'upgraded function' whatever that may be.

https://www.aliexpress.com/item/ZB2...9.html?spm=a2g0s.13010208.99999999.262.bREq3E


image_ydsont.jpg
 

BlueSwordM

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I would recommend this:
https://www.banggood.com/Original-Z...s=search&stayold=1&ID=522661&cur_warehouse=CN

Extremely nice, and has 4 pin voltage monitoring, meaning voltage reading is very accurate.

Also very useful to test parallel packs and internal resistance of the cells.

I use these holders, and then mod them with spring bypasses:

Makes it very easy to push high current over the stock springs, which are trash above 1A.

I can easily pull 5A from them without any problems. I could probably pull even more current from them, but my 18AWG wire would probably heat up at that points.
 

Rad

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Messages
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BlueSwordM said:
I would recommend this:
https://www.banggood.com/Original-Z...s=search&stayold=1&ID=522661&cur_warehouse=CN

Extremely nice, and has 4 pin voltage monitoring, meaning voltage reading is very accurate.

Also very useful to test parallel packs and internal resistance of the cells.

I use these holders, and then mod them with spring bypasses:

image_veqaus.jpg


Makes it very easy to push high current over the stock springs, which are trash above 1A.

image_rdbrve.jpg


I can easily pull 5A from them without any problems. I could probably pull even more current from them, but my 18AWG wire would probably heat up at that points.

Thanks BlueSword. Those units look really good but I am wanting to build a discharger with about a 20 (individual)cell capacity. The better quality ones would be very expensive if I had to use so many.I ordered the ZB2L3 boards yesterday so I will just have to work with them. Maybe I could mod them to 4 wire operation to improve the voltage measurement, when I eventually have a board in my hand I will be able to check the track layout. I see your mods to your holders, in my experience I have alsofound the contact point between the tip of the spring and the contact area on the battery to be abigproblem. By its nature there is usually only one tiny point of contact and that encourages electrochemical reactions and subsequent connection issues.
 

BlueSwordM

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I couldn't do these mods the usual way since my flat tip was dying, and had to do the job quickly.

Usually, what I do is fill the tip point of the spring with solder, and that makes a large surface contact with the cell.

However, I found it annoying, so I ordered phosphor bronze springs, which are a lot better than even excellent steel springs:
https://www.fasttech.com/products/0...rydriver-contact-support-spring-for-flashligh

Testing:
http://budgetlightforum.com/node/35228
The shit springs in the holders experience a very large voltage drop, about 2.5x as much as the worst springs you see in the test. Meaning above 1A, they experience a 0.15V drop, and as they heat up, the resistance goes up again.

I'm currently engineering a solution to make very high efficiency battery holders, and easy connections.

Should be awesome!
 

higher_wire

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Aug 30, 2017
Messages
61
I have a dozen of those boards run off of a 5v phone charger as part of my charge/discharge station. They include two resistors each, but I only use one for 500 mA discharge. I can't comment on accuracy, but I haven't had any issues with them.
 
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Rad

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Messages
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BlueSwordM said:
....

Testing:
http://budgetlightforum.com/node/35228
The shit springs in the holders experience a very large voltage drop, about 2.5x as much as the worst springs you see in the test. Meaning above 1A, they experience a 0.15V drop, and as they heat up, the resistance goes up again....

Interesting spring test!
 

BlueSwordM

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Also, the reason the generic 18650 battery holder experience such large voltage drops is because of not only the springs, but also because they use extremely thin for the connections, and not entirely made of copper, but has aluminium in it.

This is why their resistance is so high even compared to the bare springs. Replace the wires, and from testing, the voltage drops goes from 0,15V at 1A, to 0,085V at 1A. That is still significant though, and as they heat up, it gets worse, and I'm not buying any of these holders again.

BTW, I received my phosphor bronze springs. I just now have to wait for my brass buttons for the positive electrode, and the prototyping will begin!

Phosphor bronze springs for the negative electrode:
https://www.fasttech.com/products/0...rydriver-contact-support-spring-for-flashligh

Brass buttons for the positive electrode:
https://www.aliexpress.com/item/50p...-Flat-Metal-Spacer-Beads-Fit/32799436603.html
 

reg_zz

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New to using a ZB2L3 battery capacity tester. I am unsure of the required power source for the tester? I have tried a USB port from a laptop but keep getting error @ #2. Does this mean inadequate power or is battery been tested not good( even as Volt Meter says 4.01 amp. Do I need a certain voltage for input power?
 

floydR

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Messages
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New to using a ZB2L3 battery capacity tester. I am unsure of the required power source for the tester? I have tried a USB port from a laptop but keep getting error @ #2. Does this mean inadequate power or is battery been tested not good( even as Volt Meter says 4.01 amp. Do I need a certain voltage for input power?
Do you have a wall wart usb charger maybe try with that to power the ZB2L3? The Laptop usb might not be strong enough doubtful but you never know.
Power supply voltage: DC4.5-6V (micro USB connector)//Operating Current: less than 70mA //D
 

floydR

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Only way to find out is to try it. doesn't matter the brand just the volts the amps should be fine you need less than 70mA
later floyd
 

reg_zz

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I ahve tested the voltage of a number of 18650 and have tried a number that show a voltage of 3.9-4.1 volts. The result is when I connect them I get the number 6 or 7 then i enter 'okay'. The result is error #2; " voltage of cell below set cut off" ?
 
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