Anyone used this discharger?

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Cyclomania

10 kW
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May 22, 2022
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So this discharger is on sale and I think it looks interesting. But I am not quite sure what it does. What do people use these for?

Could I for example discharge my downtube ebike battery with this one if I do not want to use my battery for a while and just want to store it but at the same time do not want go out biking it empty?
Or what can this machine be used for? thanks
 
Cyclomania said:
Could I for example discharge my downtube ebike battery with this one if I do not want to use my battery for a while and just want to store it but at the same time do not want go out biking it empty?
Click to expand...
Yes, you could use it for this purpose. You could set the minimum discharge voltage, and it would stop discharging when it reaches said voltage.

I use them for testing battery capacity as well. If a battery pack advertises 10 amp hours, you could fully charge it, then set it to discharge at 1A until its rated cutoff voltage, and see if you got 10 amp hours out of it.
 
Very useful for battery tinkers. I test my batteries with it and also use it to set them at 30$ charge for storage.

If you buy one, don't make any setting changes with a battery connected. Sometimes, if you set the current and make a mistake and set it too high, it will blow up the tester. Make your changes, verify it's correct. Then connect the battery and start the test,
 
The results of steady state testing are never as useful as real world intermittent load testing on a real bike. So if you really want to know, you'll test the battery with the load you intend to use it for.
 
Chalo said:
The results of steady state testing are never as useful as real world intermittent load testing on a real bike. So if you really want to know, you'll test the battery with the load you intend to use it for.
Click to expand...
That's entirely correct, but they're still useful for bench testing against expected results. For example, if you get yourself a prismatic cell, you could look up the spec sheet and see that it's rated for 20ah @ 10amp discharge. You could then fully charge your new cell, set the tester to discharge at 10 amps, and see if you actually get 20ah. If you get less, you got an aged cell and you should maybe not use it in your pack.
 
Chalo said:
The results of steady state testing are never as useful as real world intermittent load testing on a real bike.
Click to expand...
Actually they are more useful. "Real world" testing is never uniform and repeatable. Wind, human differences, etc. even with the same route are never the same. The Atorch tester gives the same exact repeatable load time after time. I benchmark all my batteries once a year with it. Tells me quickly if I have a problem. It can even test one cell which you can't do in "real world". Works well on large (100+ah) LiFePO4 also.
 
Diggs said:
Actually they are more useful. "Real world" testing is never uniform and repeatable. Wind, human differences, etc. even with the same route are never the same. The Atorch tester gives the same exact repeatable load time after time. I benchmark all my batteries once a year with it. Tells me quickly if I have a problem. It can even test one cell which you can't do in "real world". Works well on large (100+ah) LiFePO4 also.
Click to expand...
I just received the Atorch DL-24P 180W unit. Can you give a rundown on your procedure to benchmark a battery?
 
Are you testing an ebike battery pack or individual cells?

The selections on the Atorch controlled by the buttons are a bit confusing but after you work with it a few times it becomes second nature and you can rapidly click through them. Be sure the battery you are testing is fully charged and properly connected. Set the discharge rate (I usually use CC=Constant Current. 1 amp to keep things equal across all my testing except for big LiFePO4). I usually set a low voltage cutoff appropriate for the pack I'm testing in case the BMS doesn't auto-cut. Hit the start button and let run. It will show totals when the BMS disconnects or you hit your low volt cut. You really should watch a few YouTube videos that provide much better detail.
 
Diggs said:
Are you testing an ebike battery pack or individual cells?

The selections on the Atorch controlled by the buttons are a bit confusing but after you work with it a few times it becomes second nature and you can rapidly click through them. Be sure the battery you are testing is fully charged and properly connected. Set the discharge rate (I usually use CC=Constant Current. 1 amp to keep things equal across all my testing except for big LiFePO4). I usually set a low voltage cutoff appropriate for the pack I'm testing in case the BMS doesn't auto-cut. Hit the start button and let run. It will show totals when the BMS disconnects or you hit your low volt cut. You really should watch a few YouTube videos that provide much better detail.
Click to expand...
Both. I have 2 ebikes with 48 V lithium batteries, a scooter temporarily running on 2 of these LiFePo4 (wired as 22 S) A123 LFP 36V 20Ah 720Wh High Current Battery Modules with 96 Cells | Greentec Auto

I will be getting a bunch these LiFePo4 cells to build 22S packs to replace the temporary A123 packs on my scooter.

Gotion 32135 15Ah 3.2V LFP Lithium-ion cell IFR32135-15Ah

>50K in stock, IFR32135-15Ah LiFePo4 cells, fast shipping by air or sea. We hold full Product Specification, MSDS, UN38.3, BIS, CB IEC62133, UL1642 test reports.
www.ancoo-battery.com

I did watch some videos (did see the first plus some others, not the second you posted). They are helpful, but it's good to get your input. Thanks!
 
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Zambam said:
What should I set the cutoff V to for this 48 V 7Ah battery with Samsung cells?

I had it set on 3V per cell (39V) and got 6 Ah capacity. What cutoff voltage is the 7 Ah spec based on?
Click to expand...
The 7AH is based on a cutoff voltage of 2.5V/cell at Samsung's test labs, probably at 1A discharge. That's 33.5V, Your BMS shuts off at 39-40V anyway.

I usually get about 90% on a brand new cells when I put them in a battery. Older batterys drop a little more.

Some cells appear to have appreciable capacity left at 3V/cell. Others have none,






.



.
 
docw009 said:
The 7AH is based on a cutoff voltage of 2.5V/cell at Samsung's test labs, probably at 1A discharge. That's 33.5V, Your BMS shuts off at 39-40V anyway.
Click to expand...

Why 1 A discharge and not higher?

Is 33.5 V a typo?
 
The higher the discharge rate the lower ah you will get. You need to pick a rate you can use across as many devices as possible even down to individual cells. 1 amp is also common to many other testers which helps to discuss apples-to-apples so to speak.
 
Zambam said:
Why 1 A discharge and not higher?

Is 33.5 V a typo?
Click to expand...

No, it's a math error. A 13S pack at 2.5V per cell is 32.5 volts, If you know your cells, you can look at discharge curves for them. They often provide tests at 10A, 5A, all levels,

You may have seen by now that some batteries sag so bad below 30-40% charge that they shut off with any kind of current surge. Low cost cells. The good one get down that low and just keep going.
 
To clarify. The BMS LVC works at cell level. You can't go much lower then 2.9-3.0V/cell. First cell group that gets there will trip the BMS. Bike Controller LVC works at battery level, 40-41 volts,

Atroch works at battery level, but it can't drain the battery if the BMS has tripped LVC.
 
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