Ridiculously high IR numbers from my Charger

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Zebretta
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Ridiculously high IR numbers from my Charger

Hello again,

I have a SkyRC, MC3000 charger and almost all the IR numbers I’m getting are ridiculously high compared to the numbers I get from the same batteries on another charger.

For example, 505mAh on the MC3000 and 70 on my IQ338XL

In fact, almost all the batteries I test on the MC3000 show these sky high Internal Resistances.

I don’t believe these high IR’s because the batteries charge and have near original capacities most of them.

Is this a known problem with the MC3000 or does it need calibration maybe?

Zebretta
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Found this thread…….

IR Charger Comparisons

klrman
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I find they are fairly high on my MC3000 too for my 18650's but not nearly as high as  yours.  Have you tried jiggling them in the charger and wiping both terminals of the batteries and charger?   Usually helps me.  I got fed up with all my different charger IR readings so I ordered one of these last week.

 

https://www.ebay.ca/itm/Battery-Resistance-Voltmeter-Internal-Impedance-Meter-LCD-Rechargeable-SM8124A/273104104104?hash=item3f9645eaa8:g:BEIAAOSwWmNapAyf

SIGShooter
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I don’t even bother taking IR readings on my chargers. I can get wildly varying numbers for the same battery in the same slot just by wiggling it or moving it to another slot.

klrman
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Same here, not worth relying on charger IR readings.

Zebretta
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klrman wrote:

I find they are fairly high on my MC3000 too for my 18650’s but not nearly as high as  yours.  Have you tried jiggling them in the charger and wiping both terminals of the batteries and charger?   Usually helps me.  I got fed up with all my different charger IR readings so I ordered one of these last week.


 


https://www.ebay.ca/itm/Battery-Resistance-Voltmeter-Internal-Impedance-Meter-LCD-Rechargeable-SM8124A/273104104104?hash=item3f9645eaa8:g:BEIAAOSwWmNapAyf

That looks promising, but the sellers feedback rating is not so good. A reflection of his service or the product?
btw….SkyRC specifically notes in the User Guide that the MC3000 is particularly accurate with IR readings…..go figure

Zebretta
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SIGShooter wrote:
I don’t even bother taking IR readings on my chargers. I can get wildly varying numbers for the same battery in the same slot just by wiggling it or moving it to another slot.

The only problem is……
Doesn’t that affect the capacity?

Here’s why I ask….
I have two chargers. An MC3000 and a IQ338LX

*One specific AA NiMh battery *
In the IQ338LX: IR 427 Capacity 1543
In the MC3000: IR 64 Capacity 1977

Same battery….drastically different results

I’m going to check the resistance between the battery contacts and rails to see if I can find the source of this high resistance. I’m thinking of removing all the rails & contacts and Copper plating them all.

On my particular MC3000, the rails were really hard to move. I had to be very careful putting batteries in and each time I had to carefully pull the moving contact back manually just to get the batteries inserted. So I added a small amount of Noalox onto each rail. Since then they glide effortlessly. I LOVE that part.

But I was wondering if that could have affected the resistance.

My conclusion was that if anything, Noalox would have REDUCED the resistance because it is a conductive viscous paste specifically designed to improve electrical contact and prevent surface oxidation that is known to increase resistance. Are there any EE’s here that might have the educated answer to that?

WalkIntoTheLight
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klrman wrote:

Same here, not worth relying on charger IR readings.

Yes, the IR reading are worthless as absolute values. But, I still find them useful as comparison values. I know that higher IR numbers generally mean the cell is lower-drain, even if I don’t trust the actual number to be accurate.

SIGShooter
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Zebretta wrote:
SIGShooter wrote:
I don’t even bother taking IR readings on my chargers. I can get wildly varying numbers for the same battery in the same slot just by wiggling it or moving it to another slot.

The only problem is……
Doesn’t that affect the capacity?

Here’s why I ask….
I have two chargers. An MC3000 and a IQ338LX

*One specific AA NiMh battery *
In the IQ338LX: IR 427 Capacity 1543
In the MC3000: IR 64 Capacity 1977

Same battery….drastically different results

I’m going to check the resistance between the battery contacts and rails to see if I can find the source of this high resistance. I’m thinking of removing all the rails & contacts and Copper plating them all.

On my particular MC3000, the rails were really hard to move. I had to be very careful putting batteries in and each time I had to carefully pull the moving contact back manually just to get the batteries inserted. So I added a small amount of Noalox onto each rail. Since then they glide effortlessly. I LOVE that part.

But I was wondering if that could have affected the resistance.

My conclusion was that if anything, Noalox would have REDUCED the resistance because it is a conductive viscous paste specifically designed to improve electrical contact and prevent surface oxidation that is known to increase resistance. Are there any EE’s here that might have the educated answer to that?


IR does indicate battery health, etc as I understand things. But I don’t trust the readings from my chargers so for me that feature is useless. Even if you can remove all the resistance you can on a single reading will you be able to do that each and every time you measure IR for your batteries, or at least consistently enough so that different readings are comparable? I used to measure IR using a power resister and a DMM and I wonder if that’s more accurate and repeatable?

Are your readings based on discharge or charging? Charging numbers especially between different chargers aren’t very accurate since some of the amps go into heat. And I get different discharge numbers for the same battery on different chargers so I take those with a grain of salt. I only use the discharge numbers to see if a battery is bad based on comparing numbers from previous discharge tests on the same charger.

I’m a retired programmer and not an electrician so take my comments with a large grain of salt Silly

klrman
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Zebretta wrote:
klrman wrote:

I find they are fairly high on my MC3000 too for my 18650's but not nearly as high as  yours.  Have you tried jiggling them in the charger and wiping both terminals of the batteries and charger?   Usually helps me.  I got fed up with all my different charger IR readings so I ordered one of these last week.

 

https://www.ebay.ca/itm/Battery-Resistance-Voltmeter-Internal-Impedance-Meter-LCD-Rechargeable-SM8124A/273104104104?hash=item3f9645eaa8:g:BEIAAOSwWmNapAyf

That looks promising, but the sellers feedback rating is not so good. A reflection of his service or the product? btw....SkyRC specifically notes in the User Guide that the MC3000 is particularly accurate with IR readings.....go figure

 

Post #6 of this thread helped me decide to get it.   http://budgetlightforum.com/node/61023

I ordered from them  10 days ago and tracking says I will get it in two days so not bad.

Looks like the problem with all chargers is that they really can't exert enough concentrated pressure on the terminals to give any sort of accurate readings half the time, so with this little device at least the readings will be reliable.

Wireworld
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I have this meter and whilst i cannot tell if it is accurate it does give very consistent results. Usually they are somewhat lower than my chargers but that makes sense given the likely resistance of the charger rails

AA Cycler
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Zebretta wrote:
For example, 505mAh on the MC3000 and 70 on my IQ338XL

You meant 505mOhm, didn’t you?

From my experience MC3000 is pretty accurate in measuring the IR of NiMH cells. The OPUS chargers come next (own experience) and I read Zanflare C4 is good as well (but shows high mAh)

I used to use AccuPower IQ338XL for a while. I don’t know what it shows as IR values for NiMH cells, but it’s definitely not milliohms :-). It’s more like a scale from 0 to 127 representing 0 to 1000 mOhm. This way 70 would mean 70/127*1000 = 551mOhm which is close to the MC3000 value.

Zebretta wrote:

I have two chargers. An MC3000 and a IQ338LX

*One specific AA NiMh battery *
In the IQ338LX: IR 427 Capacity 1543
In the MC3000: IR 64 Capacity 1977

Same battery….drastically different results

I thing you swapped the values by mistake. I think you meant

In the IQ338LX: IR 64 Capacity 1977
In the MC3000: IR 427 Capacity 1543

Once again, 64/127*1000 = 504 mOhm which is close to 427 from MC3000.

Anyway, I just wanted to say it is OK to trust the IR readings of MC3000.

Cheers,
AA Cycler

Cycle count tests of AA batteries - http://aacycler.com

klrman
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AA Cycler wrote:
Zebretta wrote:
For example, 505mAh on the MC3000 and 70 on my IQ338XL
You meant 505mOhm, didn't you? From my experience MC3000 is "pretty accurate":http://aacycler.com/post/internal-resistance-meters/ in measuring the IR of NiMH cells. The OPUS chargers come next (own experience) and I read Zanflare C4 is good as well (but shows high mAh) I used to use AccuPower IQ338XL for a while. I don't know what it shows as IR values for NiMH cells, but it's definitely not milliohms :-). It's more like a scale from 0 to 127 representing 0 to 1000 mOhm. This way 70 would mean 70/127*1000 = 551mOhm which is close to the MC3000 value.
Zebretta wrote:
I have two chargers. An MC3000 and a IQ338LX *One specific AA NiMh battery * In the IQ338LX: IR 427 Capacity 1543 In the MC3000: IR 64 Capacity 1977 Same battery....drastically different results
I thing you swapped the values by mistake. I think you meant In the IQ338LX: IR 64 Capacity 1977 In the MC3000: IR 427 Capacity 1543 Once again, 64/127*1000 = 504 mOhm which is close to 427 from MC3000. Anyway, I just wanted to say it is OK to trust the IR readings of MC3000. Cheers, AA Cycler

 

Problem with my MC3000 is every time I rotate the battery a little, IR readings can go up  or down significantly.

moderator007
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Li-ions will also read different IR if the internal temp is different.
Reading right off the charger the cell should read lower than a hour later at rest.

klrman
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Your saying when the cell is rested and cooled down, IR actually goes up?

moderator007
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Yes it should. Li-ions flow more current and have less IR when they are warm. Charging them at a standard current raises internal temp or using them at high currents raises temps also.
I have personally seen higher capacity numbers just after charging a battery and lower IR versus testing the capacity and IR after a rest.
You can read about the behavior here.

klrman
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Was not aware that's how it works, thanks for the info moderator.  Learned something new today 

Zebretta
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AA Cycler wrote:
Zebretta wrote:
For example, 505mAh on the MC3000 and 70 on my IQ338XL

You meant 505mOhm, didn’t you?

From my experience MC3000 is pretty accurate in measuring the IR of NiMH cells. The OPUS chargers come next (own experience) and I read Zanflare C4 is good as well (but shows high mAh)

I used to use AccuPower IQ338XL for a while. I don’t know what it shows as IR values for NiMH cells, but it’s definitely not milliohms :-). It’s more like a scale from 0 to 127 representing 0 to 1000 mOhm. This way 70 would mean 70/127*1000 = 551mOhm which is close to the MC3000 value.

Zebretta wrote:

I have two chargers. An MC3000 and a IQ338LX

*One specific AA NiMh battery *
In the IQ338LX: IR 427 Capacity 1543
In the MC3000: IR 64 Capacity 1977

Same battery….drastically different results

I thing you swapped the values by mistake. I think you meant

In the IQ338LX: IR 64 Capacity 1977
In the MC3000: IR 427 Capacity 1543

Once again, 64/127*1000 = 504 mOhm which is close to 427 from MC3000.

Anyway, I just wanted to say it is OK to trust the IR readings of MC3000.

Cheers,
AA Cycler

Yes…mOhm….thanks

Zebretta
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klrman wrote:

Problem with my MC3000 is every time I rotate the battery a little, IR readings can go up  or down significantly.

I’m going to try a bit of Noalox on the contact points and check the before and after IR on the same battery.