How to calculate battery internal resistance manually or by using a meter
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- čas přidán 10. 07. 2024
- In this video I'll show you how to calculate battery internal resistance manually or by using a meter. A meter like the Accucel 6 should be accurate enough. The advantage is you can test many cells quickly. Testing internal resistance manually is accurate but it does take some time so it is pretty impractical if you have a lot of these to test.
When testing internal resistance you have to have a good connection to the battery. He has gotten used to his setup so it works well. So make sure you do the same. A bad connection can add a lot of resistance to the reading. The spring slide in a lot of chargers are not good enough. So push the slide connection against the battery when testing resistance
I purchased an ADEASKA VC4 Plus battery charger. Comes with 4 slots to charge /discharge and includes battery resistance. Up to 10 amps charge with all the information displayed. Works really well and is a good option as it is not an expensive unit. I ordered it from a Vape shop of all things to get the best price!
out of all the internal resistance videos on youtube the way you teach it is without doubt the easiest to understand and you got the correct results on the the other channels they done it the complicated way that in fact they done it that complicated that some of them couldnt get the correct answer lol there are two different types of teachers those who can get the information over to the student with ease and there are teachers who go into too much detail that the student has got lost that why your are excellent at getting information over thankyou
he incorrectly put his voltmeter on the end of the wires, they should be placed at the ends of the cell.
Great video explaining the difference of battery .
Very useful hints! Thank you!
Best explanation I have watched, Thanks
Very well explained and informative especially interested in your observations between Hi current and low current cells. An observation although I might be mistaken - regarding the wiring in the manual calculation it would have been more accurate had you measured the under load cell voltage directly (across the battery terminals) rather than as I believe you did across the load resistor (thus introducing the added lead resistance error).
I use a cradle system with 6 modules of 13 batteries each. - 78 cells. With a voltage/ir gauge up to 100vdc I can check each module to very quickly to determine if i need to check every cell in that module. My capacity checker would take almost 3 hrs per cell: 78x3=234 hrs!😄 Thank you for explaining why I'm so happy I bought a high voltage IR tester!
Very useful information - thank you!
I'm going to get a Turnigy charger/tester. I wish you had an affiliate link so that you could profit. You make the best videos on this topic.
A lithium cell's internal resistance also relates to STOC (state of charge). Besides, it relates to temperature also. High and low internal resistance is dependant on type of chemistry and the application for which the battery is developed. A high internal resistance means a lower constant current output. High current output batteries, over 8 amp are designed with low internal resistance. Do not compare batteries between different brands, it has no meaning and you should not conclude it is good or bad.
👍
Thanks for this. I believe there is no need to measure the current to calculate the internal resistance. From Wikipedia, I notice that it is IR = ((Vo / Vl) - 1) x Rl where Vo is the no load battery voltage, Vl is the battery voltage at load and Rl is the load resistance. Using this the IR comes to 77.9 milliohm which closely matches what you got. Helpful for those who don't have a clamp meter like me :)
When comparing the IRs of different cells, we should ensure to use the same load resistance, since IR varies with discharge current.
This formula in wikipedia, I use it, simple, thanks
@@sansjunkow to choose the Rl resistor for this circuit calculation
I mean if I want to calculate internal resistance of different voltage battery what value of resistor i have to connect in Rl?
@@prakashdutt1520 I used a load resistor of 1 ohm (rated to 50W). You can use any low value resistor. But just make sure you use the same value when comparing different cells.
Very informative. Thank you
Hey there! Can't tell you how much I appreciate these videos. Thank you so much 🤘My question is when you apply the load, are you applying a load to which the battery is rated for? I'm assuming applying a weaker or stronger load would change the internal resistance respectively correct? Thank you for your time 🤘
You don't need 2 multimeters to check the R(int) If you know the resistanse of your load. Ri = (V0 - V1) / (V1/Rr) = ((V0 - V1) * Rr) / V1 Or ((4.15 v - 3.6 v) * 0.5 Om)/3.6 v = 0.076 Om or 76 mOm
You are correct .. I am using this with one multimeter to measure resistor ohm, and the volt drop. Thanks
Greetings from Saudi Arabia.
Brilliant video. A lot of very good and useful information here👍👌
Thank you! Now I looking for new version of this charger :).
I just got one off of eBay for 50.00 but be careful because there is a knock off that looks just like it and is spelled just about like it. Make sure it is spelled “Turnigy”
Awesome video. Thanks
This is Great! We can make a simple board circuit with chalk resistor then a battery terminal and volt/amp digital meter display 😊
Great instructor
Great vídeo. Hello from Brazil
i thought i was having trouble with my adding lol its ok now thankyou so much from northern ireland
Thank you!
I know this is nearly 4 years old but the info you deliver in this video is timeless and should remain relevant, even as advances in battery tech leads to higher capacity batteries, etc. It should also remain applicable even if the time ever comes, which is ultimately inevitable, that lithium-ion has to at least share the spotlight, as alternative battery tech see gains/advancements that shrink the gap we see currently, accounting for lithium's current dominance in just about every battery in use today. In consumer electronics, etc anyway... specialized/niche applications notwithstanding.
Anyway, you've gained +1 subscribers just now, as if any of your other videos are even half is informative as this one was. They'll be well worth viewing. And make subscribing to your channel a no-brainer for someone like myself.
Great explanation now I can measure all my 18650’s and get rid of the garbage 👍
the manual method works with any load? how about half amp load? since my cells were salvage cells i will not expect those were still at top condition. 1 amp or half an amp were still good cells for my packs. also is it necessary to fully charge the cells first? currently they were somewhere at 3.9v each before i stored them
Hey thanks for the video! Question: When we are testing used cells, to use in a new DIY battery pack, do we need to match the resistance of the cells as well as the capacity?
In parallel it’s not that important. In series unmatched cells with different resistance will go out of balance much faster.
I built a 12s pack I use for my lawnmower and for backup power for my refrigerator. It discharges over 12 hours with the fridge. All the banks hit 3.0v about the same time. And after a slow charge the pack is still balanced.
The lawnmower discharges it in 30 minutes. One bank will be at 3.0v (low resistance cells) another bank will be at 3.6v (high resistance cells) so when I charge them back up it will be out of balance by 0.1V-0.2v.
Thanks From Bangladesh
I have the Turnigy Accucell 6 50W version and it does have the resistance function.
thanks very much
Hi. can i check bigger batteries like 12v 100ah?
The opus c3100 which you have shown, can test internal resistance also. Use quick test and wait 10sec.
Very nice video, great explanation of what and how you where doing.
Brilliant review 👍
1. Where can I buy a Turnigy Accucell 6 from?
2. Is this good for all types of rechargeable batteries?
That seems like a huge difference in extra impedance just using those extra cables (at the end). Is the aligator clip soldering coming loose or something? Would be interesting to check just the resistance measurement of just those extra leads themselves. I bought a 20-pack of aligator leads cheap from somewhere and they were junk - some of them were multiple ohms resistance each just for a 30cm cable. I found under the rubber boots half the strands weren't even soldered. Bought a better quality set with copper clips and they don't even register any resistance on my multimeter. (only measures down to 100th's of an ohm).
HI THE SECRET IS TO BUY THE CLIPS YOU NEED AND SOLDER YOUR OWN LEADS IN I USE THEN FOR MY TEST LEADS IN THE PLANT REPAIR INDUSTRY THAT WAY YOU KNOW WHAT YOU HAVE AND WILL LAST A VERY VERY LONG TIME AND USE VERY FINE 2,5MM FLEXABLE CABLE WHICH IS HARD TO FIND,,HOPE THIS HELPS
You should be able to assume a reasonable "default" resistance for those two wires and clips (call it Rw (Resistance of Wires)) and factor that into your calculations to come up with something closer to the "real" 50mohm reading. For example, given the gauge wire you seem to be using, we might assume, as a first iteration, that each wire with the clips you are using adds a resistance of 0.1 ohm.
AC current sensors in parallel ?, does it work ?
The Accucell 6 is not accurate at measuring IR, I have one and I also have a dedicated IR meter, the Accucell 6 gives a much higher reading than the dedicated IR meter on every measurement, examples below-
aaa 1 amazon basics
dlyfull 35
turnigy 114
aaa 2 amazon basics
dlyfull 27
turnigy 120
aaa 3 amazon basics
dlyfull 37
turnigy 126
aaa 4 eneloop
dlyfull 16
turnigy 95
aaa 4 amzazon basics
dlyfull 28
turnigy 120
aaa 5 eneloop
dlyfull 40
turnigy 145
aaa 6 eneloop
dlyfull 17
turnigy 97
aaa new/unused eneloop
dlyfull 15
turnigy 95
The test leads being used on the Accucell 6 have 0.003 mΩ of resistance so that
does not account for the high reading.
And the specifications for a new aaa eneloop says it should be around 20 mΩ
which puts the dlyfull in the right area and the Accucell 6 way high.
How many cells can you charge at on time with this Turnigy ? Does each cell have to be fully charged to check the internal resistance ?
It has some info about how many it can charge printed directly on the charger - bottom left corner, easily visible in the video.
you're measuring DC resistance, better measuring impidance (to get the whole picture) - in order to do that you'll need a RC3563 and of course under different load you'll get different result... therefore it's better testing the cell for example under 10A load especially if you're going to use it in power tools
This cell is FEK!!! T-shirt Ⓒ comming soon
Good stuff.
I have a vc-4 charger ,it shows Mr value while charging,is this the internal resistance? Thanks for video!
Does anyone know if the Imax B6 charger which looks similar to this Turnigy has the IR measurement function?
I have 2 B6 AC and Battery version, and no it does not have the function (not that I have found anyway), however I think you can get a custom firmware for the B6 to add the function.
Could it mesure for 5p .. 5 battery prallel?
Could you advise where to buy the Turnigy Accucell-6 which has the IR function? I found it just by Hobbyking but not available right now.
What is the largest size battery you can test with that? Can you test car battery?
You should let folks know what maximum resistance you consider valid when testing cells like these. Another youtube tutorial uses a 1ohm resistor. So...exactly how high resistance can you use and still obtain meaningful/useful battery internal resistance value? (e.g. 2 ohms? 10 ohms? 100 ohms?)
4 Ohm to 10 Ohm, 5 Watt (the square, white, high-power resistors)
It doesn't matter (the resistor) 1 OHM is easy math though, as you have to do math to get to internal resistance. Measure open voltage (no load), V0, Add resistor R0, Measure VL. IL = V0/R0 in Amps.
Voltage Drop VD = V0-VL. R of Battery is RB. RB = VD/IL.
@@beaker2000 correction: IL = VL/R0, not V0/R0. I think you confused yourself by your poor naming choice. It would be more logical to name the resistance of the load "RL" instead of R0, and then you'd have the more obvious IL = VL/RL.
hi for my 36v 10s skateboard battery want add balance leads can i use a 14s jst connector and just connect as 10s as dont have 10s leads at moment
You can. I use 8S connector for my 7S battery pack. Or you can just cut it out.
is there a way to test a bms as have one off a hoverboard or just connect up and use it and see what happens
I'd say just connect it and see if smog is gonna come out. :D
actually i have 2x 5s bms s so can i link them together so can balance as 5s2p so will series link them to give 36 to 41v .will they charge as a whole ok with bms or do i charge seperatly?
Good question. I've never done that before. (partly because I already have balance chargers and I'm anti BMS! :D) But if you think about it, 5S has 6 cables. When you link them together, they have 12 cables and it's now 10S. A 10S BMS should only have 11 cables. At least that's my theory. If you want to charge them separately, make sure you use 2 different power sources or your chargers will short out.
Hello Sir, please I need a link to aliexpress to purchase the internal resistance Tester. I want to test my 18650cells.
Thanks
Hi, did i missed something? At first you metered with the terminals of the turnigy charger right to the cell, but at the end of video you did it through extra wires so, were the first results wrong?
How about when you have cells in parallel?
I have a 3s 50p pack and I have 2 mohm internal resistance for each parallel connection
Cells are from power tools
Cells in parallel is fine for the most part. You can treat it as a giant oversized cell. But if one of them is bad, you wouldn't know.
@@vuaeco it seems that when many cells are in parallel the internal resistance goes very low wich is very good
Of course resistance in parallel get lower, just like any resistor in parallel
@vuaeco Unfortunately you ignored several factors in this:
* precision and accuracy of your tools (centech: 1%+- 1 count, fluke 337: 2% +- 3 counts = +-.05V and +- 0.4A
* impact of the drain load on no-load battery voltage (need a more or less instant reading after making the connection! It was 3.61 V and 6.9A when you first connected, 3.59V and 6.7A when you disconnected.
Ignoring the other factors, just the range while measuring is 78mOhm (3.61/6.9) to 84 (3.59/6.7). And the uncertainty range extends that to 3.54-3.66V and 6.3 to 7.1A .
I'll assume that subtracting voltages eliminates all but the count variance there: 4.14-4.16 and 3.58 to 3.62 -> so dV = 0.52 to 0.58, A = 6.3 to 7.1 -> mOhm = 73 to 92.
* NOTE: The Turnigy has NO spec for accuracy. I wouldn't trust its numbers on any absolute scale.
Further observation: I have an iMax Mini balancer, with IR measurement. In my experience, if I disconnect/reconnect and re-measure IR several times, I get quite a bit of variation using the exact same battery and leads a few seconds apart. I've learned not to trust these as IR meters. :(
(I've just obtained a Fluke 8808A bench meter that's far more accurate. I'm hopeful I will get repeatable results with that. We'll see!)
10:48 voltage drop measure
For more accurate, for lithium 1-cell, I put resistance 500 ohm across to avoid fake voltage.
150m-ohm is too high. You should question if the turnigy csn accurately measure internal resistance. I suspect a good li-ion battery should have a resistance less than 20mohm, some even less than 10.
If I'm correct, the owner of this channel is a Vietnamese or Hongkongese guy. ^_^
Nope you’re wrong. He is an englishman
What’s your points?
Doesn't that t8 charger show by default the internal resistance if you scroll down or up?
I have a isdt q6 plus and it shows for each cell the internal resistance
It didn't show up on mine last time I checked. But I'll double check again to make sure.
Can this meter test internal resistance of 1.2v nicad / ni-mh cells?
I could read it with multimeter also?
How?
You should of placed you voltmeter at the cell, not at the end of the wires. (The best way is kelvin connection with 4 contacts).
Dear friend, when i measure a battery (18650 for exatly) with multimeter in continuity mode, this sounds but no resistance is showed and the screwdriver blinking what is happend?
Thank you so much for everything help
You dont need the ammeter. V = IR can be used to calculate current with the known resistor value. 3.61 = I*0.5, solve for I = 7.07A
That's true. But it's more accurate with an ammeter. The known resistor value is not fixed. It's changed with different temperature. After you test it with one cell, the resistor gets quite hot and that will change its resistance value. So using a fixed value printed on it isn't accurate any more. But I guess 7.1A vs. 6.7A is acceptable.
vuaeco good reply and testing method
found a closer calculation and doesnt need a ammeter :
Rin = Rload * (Voc - Vloaded )/Vloaded
got 77.92 mili ohms
Excellent .. I am using this formula to get easily and accurate internal resistance. Thank you for your help.
Greetings from Saudi Arabia.
Are you a Physics Teacher?
At the end of the video, the internal resistance 50 and 82 (calculated manually), who is wrong?
The first calculation (82) also takes into account the wire resistance, so you should be careful to use the same wires and compare cells resistance of the same type(rated amperage) to actually tell if a cell is good or bad.
@@suprarealistul I think the problem was that he measured the voltage across the resistor instead of across the battery terminals.
I bought 6 LG hg2 cells to make a 6ah m12 battery ad they're fake. I got a avg. of 86mOhms. And the white top s shiny. Damn it
It happened to me before too. LG HG2 are notoriously bad for fakes.
82 and 50 m ohm is tha very huge difrence dear sir... tha cabal has take minimaly rasistanc.
i didn't know buk lau likes batteries
Now you do. :D
@@vuaeco jokes aside tho, why not just use a tester and apply a load? testers have a resistor inside that you can check internal resistence with
Can anyone test this out and give feedback? Locate androidcircuitsolver on google
Du ma
Showing off your language skill?
@@vuaeco Du ma
No offense but your accent is crazy it is like a mix of Chinese and Alabama.
I hear that everyday. But I ain't Chinese.
To see if the battery is good or not, you should have told us what the correct Internal Resistance should have been to compare it with the measured and calculated Internal Resistance.
I came to the praised tree with the bag, but the tree is at the level of a shrub. He knows a little more than an amateur.