Battery cell capacity testing.

Just John

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I have started trying out a new tester, the ET5410 (about $185 including air freight). At 35 amps it takes about 8 hours to test a cell, but I'm going to test lower amps due to my fuse holder heating up.
It's much better than the $30 tester from ATorch. This $30 tester has a tendency to burn out quickly, so be aware of that. While it is working, this cheap tester seems to be very accurate. I just worry about it shorting, hence the fuse.

To make testing and charging easier, I've been using home made Anderson powerpole (45 amp) connectors, with a 40 amp inline automotive fuse. Until after I made my own, I didn't know of a source to buy them pre-made, here it is. The ones I made only have a fuse on the positive side. I can tell you that testing at 20 amps, no problem. Testing at 35 amps (since it has a 40 amp fuse), the fuse holder is the weak link. The wire and all crimps are not getting warm, but that fuse holder certainly is. I think I'll dial it down to 30 amps next test. Add some 10 gauge copper wire and some good ring terminals to a power supply and tester, and easily swap between them. Makes charging, capacity testing, etc really easy. If you could change the voltage high and low disconnect, THIS would be very interesting (7 anderson connectors with a web server to turn them on/off and get voltage/amps and automatic high/low voltage/amps disconnect)

I'm also going to be testing the new and improved ATorch tester, the DL24P. This one certainly looks better, much better heatsink, much higher quality in general (even decent but too short "free accessory"). I haven't had a chance to run this one yet, but certainly the improved voltage sense circuitry shows someone was listening. It's also over $50! It does include bluetooth.

I can highly recommend the Riden power supply (and battery charging feature). I have tested this and when set to 3.65 volts, it will charge up to that voltage, and automatically turn off charging when less than .1 (1/10 of an amp) is being drawn. Very reliable, rock solid and pleasant interface. Nice piece of equipment, a genuine lab grade power supply for about $160. Don't bother with the WiFi unless you are into automation like me.

Anyone else care to share how they are testing?
 

Just John

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2,381
I have started trying out a new tester, the ET5410 (about $185 including air freight). At 35 amps it takes about 8 hours to test a cell, but I'm going to test lower amps due to my fuse holder heating up.
It's much better than the $30 tester from ATorch. This $30 tester has a tendency to burn out quickly, so be aware of that. While it is working, this cheap tester seems to be very accurate. I just worry about it shorting, hence the fuse.

To make testing and charging easier, I've been using home made Anderson powerpole (45 amp) connectors, with a 40 amp inline automotive fuse. Until after I made my own, I didn't know of a source to buy them pre-made, here it is. The ones I made only have a fuse on the positive side. I can tell you that testing at 20 amps, no problem. Testing at 35 amps (since it has a 40 amp fuse), the fuse holder is the weak link. The wire and all crimps are not getting warm, but that fuse holder certainly is. I think I'll dial it down to 30 amps next test. Add some 10 gauge copper wire and some good ring terminals to a power supply and tester, and easily swap between them. Makes charging, capacity testing, etc really easy. If you could change the voltage high and low disconnect, THIS would be very interesting (7 anderson connectors with a web server to turn them on/off and get voltage/amps and automatic high/low voltage/amps disconnect)

I'm also going to be testing the new and improved ATorch tester, the DL24P. This one certainly looks better, much better heatsink, much higher quality in general (even decent but too short "free accessory"). I haven't had a chance to run this one yet, but certainly the improved voltage sense circuitry shows someone was listening. It's also over $50! It does include bluetooth.

I can highly recommend the Riden power supply (and battery charging feature). I have tested this and when set to 3.65 volts, it will charge up to that voltage, and automatically turn off charging when less than .1 (1/10 of an amp) is being drawn. Very reliable, rock solid and pleasant interface. Nice piece of equipment, a genuine lab grade power supply for about $160. Don't bother with the WiFi unless you are into automation like me.

Anyone else care to share how they are testing?
Some updates to myself (since nobody else is sharing):
The 40 amp automotive fuse holder is junk, it gets dangerously hot pulling even 30 amps continuously. I hate the thought of running ANY type of test on a large battery without a fuse. I've ordered some mini-anl fuse holders that I hope won't be too big (along with 50 amp fuses). The Anderson powerpole connectors rated for 45 amps, no problem at all. The 10 gauge stranded copper wire works quite well to handle 40 amps continuously, warm, but not dangerous. The crimp connections, don't heat up at all.

The ET5410 tester rated for 40 amps continuous current pull from the battery seems to be working well, no problems so far other than a really stupid/unintuitive interface to set it up. It does not have remote sense leads, so it is reading the battery voltage as 3.07 volts, but my meter says 3.267.


IMG_20210109_160226235_HDR.jpg

This shows it set to 40 amps (Battery I: )and a cutoff voltage of 2.5 volts (Cut Off V: ) and 96.995 amp hours drawn so far (I had to cut some other tests short due to heat, it's actually had around 260 AH drawn at 35, 30 and 25 amp hour rates on a 280 AH Eve cell, this is now 40 amps with a straight wire).
I will take the cover off and poke around to see if there are any obvious hotspots, but it seems you get what you pay for (around $185 including air freight from China). Wait until I've looked inside, but so far this seems the best and cheapest option if you want to test a large number of cells without burning up the tester (and possibly the battery cell). It has a USB interface to allow programming test sequences, I haven't tried that yet (it's just a USB to serial port). Waiting until the cell gets depleted to make sure it stops at 2.5 volts like it should (likely 2.7 actual volts).


Next my Riden 12 amp power supply:
IMG_20210109_160248489.jpg

This is in battery charge mode (the red icon with a green battery down bottom center).
3.65 is the charge voltage (V-SET center right)
Charge rate is 12.05 amps (I-SET center right)
Currently the display shows 3.56 volts measured on the cell (no remote sense, so not as accurate as I'd like)
11.99 amps going into the cell.
259.220 Amp hours have gone into the cell so far
When cell voltage is 3.65 (my Fluke says 3.654) and amps drop to .1 (1/10th of an amp) it will automatically stop charging. This works very reliably, and is an excellent way to get all cells identically (and fully) charged. Basically, up until 3.65 volts, it will increase voltage until it is putting 12 amps into the cell, I think here it was outputting 3.60 volts and 11.99 amps. It won't go over the 3.65 volts, and that is one of the ways it keeps it accurate without any remote sense leads.
Where it gives total amp hours, it cycles between several values, including the temperature (includes a 3 foot or so long temperature probe) in Fahrenheit and Celsius, total watt hours, actual output voltage, etc.
A WiFi interface is extra (I have one, don't bother)

Really first class, easy to use interface, and I can't wait to get the 18 amp version (woohoo, 50% more power). They come as a "kit", power cord and CR1220 battery not included. The buck converter board is around $75, the metal shell is about $18, and the 800 watt 69 volt switching power supply is $58. You can buy different power supplies, or use your own spare, the one they sell just fits in the case well and has a cooling fan. It will limit your output at higher voltages, since full range would require more than 1100 watts. (up to about 40 volts, the full 18 amps is available).

The ATorch DL24P still has the same problem, at cell voltage levels, a diode heats up too much and won't last long. Fortunately on this version (new color display, 180 watt, Bluetooth) the now much improved heat sink is offset enough, and the diode moved enough that I'm going to try and put a Raspberry Pi heatsink on it. That might work enough (it is in the fan airflow), then again it might not. The remote voltage sense is a welcome change, it now accurately reports the cell voltage. The Bluetooth android app isn't worth the time to load on your phone, that's a shame since it could be very useful, but it really sucks.
 
Last edited:

Just John

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So are you believing you lost 0.5.% of original capacity after just one cycle?
Not necessarily, lots of factors involved (not the least of which are shunt accuracy on the charge and discharge). I'll know more when I test the discharge capacity. This time I'll be testing it at 40 amps, I think this one I originally tested at 15 or 10 amps, trying to find a spot where the diode didn't heat up so badly on the cheap tester.
 

fafrd

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Aug 11, 2020
Messages
2,264
Not necessarily, lots of factors involved (not the least of which are shunt accuracy on the charge and discharge). I'll know more when I test the discharge capacity. This time I'll be testing it at 40 amps, I think this one I originally tested at 15 or 10 amps, trying to find a spot where the diode didn't heat up so badly on the cheap tester.
I’ve been testing my cells on one of those cheapo 150W testers at 10A discharge and getting results similar to yours, but I’m itching to connect up my 3kW inverter and see what capacity I get at sustained discharge of 70A (or 0.25C, still well below rated discharge currents of 0.5C / 140A).
 

Kerry downunder

Solar Enthusiast
Joined
Sep 28, 2020
Messages
35
I have started trying out a new tester, the ET5410 (about $185 including air freight). At 35 amps it takes about 8 hours to test a cell, but I'm going to test lower amps due to my fuse holder heating up.
It's much better than the $30 tester from ATorch. This $30 tester has a tendency to burn out quickly, so be aware of that. While it is working, this cheap tester seems to be very accurate. I just worry about it shorting, hence the fuse.

To make testing and charging easier, I've been using home made Anderson powerpole (45 amp) connectors, with a 40 amp inline automotive fuse. Until after I made my own, I didn't know of a source to buy them pre-made, here it is. The ones I made only have a fuse on the positive side. I can tell you that testing at 20 amps, no problem. Testing at 35 amps (since it has a 40 amp fuse), the fuse holder is the weak link. The wire and all crimps are not getting warm, but that fuse holder certainly is. I think I'll dial it down to 30 amps next test. Add some 10 gauge copper wire and some good ring terminals to a power supply and tester, and easily swap between them. Makes charging, capacity testing, etc really easy. If you could change the voltage high and low disconnect, THIS would be very interesting (7 anderson connectors with a web server to turn them on/off and get voltage/amps and automatic high/low voltage/amps disconnect)

I'm also going to be testing the new and improved ATorch tester, the DL24P. This one certainly looks better, much better heatsink, much higher quality in general (even decent but too short "free accessory"). I haven't had a chance to run this one yet, but certainly the improved voltage sense circuitry shows someone was listening. It's also over $50! It does include bluetooth.

I can highly recommend the Riden power supply (and battery charging feature). I have tested this and when set to 3.65 volts, it will charge up to that voltage, and automatically turn off charging when less than .1 (1/10 of an amp) is being drawn. Very reliable, rock solid and pleasant interface. Nice piece of equipment, a genuine lab grade power supply for about $160. Don't bother with the WiFi unless you are into automation like me.

Anyone else care to share how they are testing?
I have the Atorch DL24P and it worked well on the 12V 200AH battery pack, however when I tried to use it to test a 24V pack, the voltage indicater only shows 18.4...V. when connected to the Battery the voltage on the leads are the same however when I disconnect the DL24P the voltage on the leads is 28.2V. Do you have any info that can correct this?
Kerry
 

charlesrg

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Joined
Nov 3, 2020
Messages
54
I’ve been testing my cells on one of those cheapo 150W testers at 10A discharge and getting results similar to yours, but I’m itching to connect up my 3kW inverter and see what capacity I get at sustained discharge of 70A (or 0.25C, still well below rated discharge currents of 0.5C / 140A).
So you've been using the DL24 to test the batteries reliably ? I just received mine and wanted to test one cell. At 10 Amps it will take about 30 hours but it will do. I was afraid of it melting at 10 Amps.
 

Just John

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So you've been using the DL24 to test the batteries reliably ? I just received mine and wanted to test one cell. At 10 Amps it will take about 30 hours but it will do. I was afraid of it melting at 10 Amps.
They work fine at 10A, and maybe up to 15A, but a 20A they will let out magic smoke sooner or later.
 

Just John

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Notes on the DL24P tester:

The diodes (not the MOSFET) on this get VERY hot running at 20 amps, so I thought I'd show how hot, and how I measured. Please note that somewhere between 10 and 15 amps is a safe current to run this (and similar testers). First, the DL24P tester I linked above has voltage sense leads for more accurate cutoff voltages, and includes two temperature sensors, one underneath the MOSFET, and another that plugs in and can be placed where you need it. Notice in the picture below, I placed it directly underneath the diode which comes with no heatsink other than the PCB. I did try placing a Raspberry Pi heatsink on the diode, however the actual device has the heatsink side soldered to the PCB and uses the PCB as the heatsink, so I had little hope this would help. Indeed, it made no difference.

temperature.jpg
Heatsink.jpg

Now, the temperature readings at 20 amp current draw while testing a single 3.65 volt cell (also note I used high quality Arctic MX-4 heatsink compound and replaced the thermal compound on the MOSFET).
DL24P_20A_temp.jpg

Now the temperature at 15 amps current draw (measured through the PCB it must be noted):
DL24P_15A_temp.jpg

70 degrees Celsius is as high as I would run any normal semiconductor for an extended period of time. Notice after I replaced the thermal compound on the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) the temperature on that device is never a concern.

My conclusion, run these type of test devices at 15 amps or below. They won't last very long at any current above 15 amps.
 

fafrd

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Notes on the DL24P tester:

The diodes (not the MOSFET) on this get VERY hot running at 20 amps, so I thought I'd show how hot, and how I measured. Please note that somewhere between 10 and 15 amps is a safe current to run this (and similar testers). First, the DL24P tester I linked above has voltage sense leads for more accurate cutoff voltages, and includes two temperature sensors, one underneath the MOSFET, and another that plugs in and can be placed where you need it. Notice in the picture below, I placed it directly underneath the diode which comes with no heatsink other than the PCB. I did try placing a Raspberry Pi heatsink on the diode, however the actual device has the heatsink side soldered to the PCB and uses the PCB as the heatsink, so I had little hope this would help. Indeed, it made no difference.

View attachment 38942
View attachment 38944

Now, the temperature readings at 20 amp current draw while testing a single 3.65 volt cell (also note I used high quality Arctic MX-4 heatsink compound and replaced the thermal compound on the MOSFET).
View attachment 38945

Now the temperature at 15 amps current draw (measured through the PCB it must be noted):
View attachment 38946

70 degrees Celsius is as high as I would run any normal semiconductor for an extended period of time. Notice after I replaced the thermal compound on the MOSFET (Metal Oxide Semiconductor Field Effect Transistor) the temperature on that device is never a concern.

My conclusion, run these type of test devices at 15 amps or below. They won't last very long at any current above 15 amps.
Fantastic work - thanks.

I’ve been limiting my discharge to 10A and these measurements make me glad I did.

These cheapo-capacity testers seem to do a pretty good job protecting themselves from too much power, but if you ever get a series battery hooked up and measure similar temps at 150W and currents of 10-15A, that would also be very interesting...
 

Just John

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Fantastic work - thanks.

I’ve been limiting my discharge to 10A and these measurements make me glad I did.

These cheapo-capacity testers seem to do a pretty good job protecting themselves from too much power, but if you ever get a series battery hooked up and measure similar temps at 150W and currents of 10-15A, that would also be very interesting...
I can try that in the next few days. Currently just started a run on a 4 cell pack (i.e. 12 volts) using a 27 amp load (about 365 watts to start at 13.8 volts). I have been using the ET5410 since it has significantly more capacity. So far it handles the 27 amp draw on a 12v pack really well. They just sent me a second one for free, so I can soon test at much more current. It of course is easily handling 40 amps for a single cell.
 

Just John

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Fantastic work - thanks.

I’ve been limiting my discharge to 10A and these measurements make me glad I did.

These cheapo-capacity testers seem to do a pretty good job protecting themselves from too much power, but if you ever get a series battery hooked up and measure similar temps at 150W and currents of 10-15A, that would also be very interesting...

OK, did some testing on a 12 volt pack for you (8 amps is what I would feel comfortable with):

10 amps
10AMP.jpg

9 amps
9AMP.jpg

8 amps
8AMP.jpg

7 amps
7AMP.jpg
 

fafrd

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OK, did some testing on a 12 volt pack for you (8 amps is what I would feel comfortable with):

10 amps
View attachment 39326

9 amps
View attachment 39327

8 amps
View attachment 39328

7 amps
View attachment 39329
Thanks. So even running at rated Watts is a bad idea for these cheapo capacity testers. Limiting to ~75% of rated power or 8A @ 12V far safer.

Is that temp being measured still at the diode and is 72C / 162F the kind of temp that will cause a diode to die a premature death?
 

Just John

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Thanks. So even running at rated Watts is a bad idea for these cheapo capacity testers. Limiting to ~75% of rated power or 8A @ 12V far safer.

Is that temp being measured still at the diode and is 72C / 162F the kind of temp that will cause a diode to die a premature death?
I'm not sure what temperature the diode is rated at, but semiconductors in general have a vastly reduced life expectancy at 80C. I know if your CPU or GPU in your computer are running above 70C, you need better cooling. I am sure that power semiconductors are rated for higher temperature, however the FET and diode like to fail as a short. This is why I have a fuse in the circuit as well. I am positive that even the designed for high power parts like these are not designed for over 90C operations long term (which is exactly what you get at 20 amps and 3.65 volts). Yes, the temperature sensor is still taped in the same spot, and I did verify it is accurate by comparing with a cheap thermal sensor "gun".
 

Bud Martin

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I'm not sure what temperature the diode is rated at, but semiconductors in general have a vastly reduced life expectancy at 80C. I know if your CPU or GPU in your computer are running above 70C, you need better cooling. I am sure that power semiconductors are rated for higher temperature, however the FET and diode like to fail as a short. This is why I have a fuse in the circuit as well. I am positive that even the designed for high power parts like these are not designed for over 90C operations long term (which is exactly what you get at 20 amps and 3.65 volts). Yes, the temperature sensor is still taped in the same spot, and I did verify it is accurate by comparing with a cheap thermal sensor "gun".
Its the junction temperature that yoiu have to be concerned about, typical max junction tempearture is around 150c, you will have to calculate the size of the heatsink based on thermal resistance of the device spec,, etc., thermal resitance will be shown degree C per Watt.
 

Just John

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Its the junction temperature that yoiu have to be concerned about, typical max junction tempearture is around 150c, you will have to calculate the size of the heatsink based on thermal resistance of the device spec,, etc., thermal resitance will be shown degree C per Watt.
Yes. it runs too hot.
 
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