Li-Ion Capacity Test DIY constant current load
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Kind regards from Slovenia
Date: 2020-09-05
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Comments and reviews: 9
1959Berre
Resistance is not entirely constant during discharge. Internal resistance is in series with the load resistance. Internal resistance is related to both temperature and state of charge (STOC. You can easily compare the capacity of batteries without a constant current source. Just charge the battery to its maximum voltage and discharge it over a fixed resistor (4ohm. The time it takes to reach the minimum voltage of, let's say 2. 5 VDC, is relative to the battery's capacity. Obviously, a battery with the highest charge will last longer under equal conditions of which temperature is important.
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Resistance is not entirely constant during discharge. Internal resistance is in series with the load resistance. Internal resistance is related to both temperature and state of charge (STOC. You can easily compare the capacity of batteries without a constant current source. Just charge the battery to its maximum voltage and discharge it over a fixed resistor (4ohm. The time it takes to reach the minimum voltage of, let's say 2. 5 VDC, is relative to the battery's capacity. Obviously, a battery with the highest charge will last longer under equal conditions of which temperature is important.
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education
By the way. Im curious,
is your testing internationally accepted as a standard way of testing? Are there any rules on manufacturing on the maximum allowed battery storage capacity to be circulated in the market?
Last but not least, should your testing bench is acceptable as a standard, wouldnt other batteries would fall under lower capacity than stated? For example taking the battery you tested in the video in com parison with other batteries in phones and electronics? Aspect ratio of battery volume vs capacity.
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By the way. Im curious,
is your testing internationally accepted as a standard way of testing? Are there any rules on manufacturing on the maximum allowed battery storage capacity to be circulated in the market?
Last but not least, should your testing bench is acceptable as a standard, wouldnt other batteries would fall under lower capacity than stated? For example taking the battery you tested in the video in com parison with other batteries in phones and electronics? Aspect ratio of battery volume vs capacity.
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enrique
I'm not completely sure but it seems to me that the explanation of the circuit is wrong. The output of the op amp should not oscillate but this is an unwanted effect that is solved by placing a capacitor to ground. I hope I am not wrong. I think by now you discovered that it was wrong but this video is still on YouTube with incorrect information. The rest of the video is great. Regards!
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I'm not completely sure but it seems to me that the explanation of the circuit is wrong. The output of the op amp should not oscillate but this is an unwanted effect that is solved by placing a capacitor to ground. I hope I am not wrong. I think by now you discovered that it was wrong but this video is still on YouTube with incorrect information. The rest of the video is great. Regards!
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hojnikb
A better way about this would be buying an lipo charger/balancer. Imax B6 can be had for 15-20 and using cheali-firmware it can do capacity check with a single click.
You can also set constant current or constant current and variable current with fixed voltage, when it drops to cutoff like 3V. So you can get a decent idea what the ideal capacity is.
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A better way about this would be buying an lipo charger/balancer. Imax B6 can be had for 15-20 and using cheali-firmware it can do capacity check with a single click.
You can also set constant current or constant current and variable current with fixed voltage, when it drops to cutoff like 3V. So you can get a decent idea what the ideal capacity is.
reply
Steve
To be honest I am surprised they are above 600 mAH. An easy way to see if they are the real deal before purchase is by asking the seller how many grams a single battery weighs. They are usually well below 25-30 grams which is a dead giveaway that they are purposely mislabeled. A real 18650 battery weighs around the 35-40 gram mark
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To be honest I am surprised they are above 600 mAH. An easy way to see if they are the real deal before purchase is by asking the seller how many grams a single battery weighs. They are usually well below 25-30 grams which is a dead giveaway that they are purposely mislabeled. A real 18650 battery weighs around the 35-40 gram mark
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Allin7days
When it comes to 18650 Li-Ion battery, the valid ranges are from 2, 000 to 3, 500 mAh depends on its drain characteristics.
Avoid the batteries claiming anything below or above this range.
Btw, higher the drain current(>30A, the smaller the capacity (close to 2, 000 mAh, and of course, lower the drain current(
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When it comes to 18650 Li-Ion battery, the valid ranges are from 2, 000 to 3, 500 mAh depends on its drain characteristics.
Avoid the batteries claiming anything below or above this range.
Btw, higher the drain current(>30A, the smaller the capacity (close to 2, 000 mAh, and of course, lower the drain current(
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ash0787
What can we add to this to make it better? it doesn't seem very practical in this form with the requirement of using external measuring stuff, how can we add something which is going to show when the circuit is operating properly and also when the battery is drained? comparator linked to an LED?
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What can we add to this to make it better? it doesn't seem very practical in this form with the requirement of using external measuring stuff, how can we add something which is going to show when the circuit is operating properly and also when the battery is drained? comparator linked to an LED?
reply
Gianluca458
I used an IRFZ44N instead of IRLZ44N, my circuit not works. Why? Please can you help me?
---UPDATE---
I solve the problem. It was the mosfet that have some problems. I changed it with an IRF3205 and it seems to work perfectly. Now i can test my batteries! Thanks!
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I used an IRFZ44N instead of IRLZ44N, my circuit not works. Why? Please can you help me?
---UPDATE---
I solve the problem. It was the mosfet that have some problems. I changed it with an IRF3205 and it seems to work perfectly. Now i can test my batteries! Thanks!
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mst274
Great video! Could you modify this circuit to use the current for charging an empty battery? Basically, run a battery discharge test while charging an empty battery. Might be a great idea for future video!
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Great video! Could you modify this circuit to use the current for charging an empty battery? Basically, run a battery discharge test while charging an empty battery. Might be a great idea for future video!
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