Would you return these batteries?

[dure16]

I bought a couple no-name 2S batteries from Amazon and they balance fine, but the resistance levels are higher than I usually see on new batteries.

What resistance levels do you expect from a new battery?

Battery 1:
6.1 mΩ
9.7 mΩ
Battery 2:
4.5 mΩ
7.2 mΩ

 

[joshludden]

I bought a couple no-name 2S batteries from Amazon and they balance fine, but the resistance levels are higher than I usually see on new batteries.

What resistance levels do you expect from a new battery?

Battery 1:
6.1 mΩ
9.7 mΩ
Battery 2:
4.5 mΩ
7.2 mΩ

Seems high to me

 

[dure16]

I just checked again and they're different (mid-charge). Is it normal for the to change throughout the changing process?

Battery 1
7.7
6.7

Battery 2
14
9.6

 

[joshludden]

I just checked again and they're different (mid-charge). Is it normal for the to change throughout the changing process?

Battery 1
7.7
6.7

Battery 2
14
9.6

Mine will fluctuate some but still nothing nearly that high. I think they usually measured around low 4's or higher 3's if I remember correctly

 

[jkflow]

They will fluctuate and should be lowest when at full charge. Only look at the IR at one level (your pick) but be consistent yourself.
As long as the values are relatively identical across the packs you should be ok, it's a lower C rated lipo just based on what I'm seeing, and you are giving no details.

 

[dure16]

They will fluctuate and should be lowest when at full charge. Only look at the IR at one level (your pick) but be consistent yourself.
As long as the values are relatively identical across the packs you should be ok, it's a lower C rated lipo just based on what I'm seeing, and you are giving no details.

Thanks. 50C.

 

[jkflow]

Definitely not stellar performers, but that's what you get with no names.
I wouldn't use anything above 10mOhm (full charge) in an RC car unless it's a toy grade.
That is just me. Not a hard stop either, just a guide.

 

[Diem Turner]

Temperature will make a huge difference in the IR of your batteries. The warmer, the higher the IR. Most people measure them at 70-72°F.

 

[Jerold]

First it sounds like a bargain brand and you get what you pay for. If you normally buy named brand batteries, it might be time to reevaluate your expectations of quality for this particular brand.

As @Diem Turner mentioned IR is not a linear number. Nor is it normally a specified parameter from the manufacture and it will also change with time and use. So there is no way to tell if the numbers you are seeing are "normal" for that battery. If it concerns you, I would start recording the IR before and after charging the battery. The number don't matter as much as consistency. Do it under the same conditions (as much as possible) to reduce the influences from outside factors like heat.

If the numbers are inconsistent, your charger may not be very good at calculating IR or it might be an indication that the batteries need to go away.

Is it safe? There are no guarantees with any LiPos to be safe. Even the good ones burn up.

 

[Diem Turner]

First it sounds like a bargain brand and you get what you pay for. If you normally buy named brand batteries, it might be time to reevaluate your expectations of quality for this particular brand.

As @Diem Turner mentioned IR is not a linear number. Nor is it normally a specified parameter from the manufacture and it will also change with time and use. So there is no way to tell if the numbers you are seeing are "normal" for that battery. If it concerns you, I would start recording the IR before and after charging the battery. The number don't matter as much as consistency. Do it under the same conditions (as much as possible) to reduce the influences from outside factors like heat.

If the numbers are inconsistent, your charger may not be very good at calculating IR or it might be an indication that the batteries need to go away.

Is it safe? There are no guarantees with any LiPos to be safe. Even the good ones burn up.

+1
Absolutely. Consistency in measuring conditions is paramount if the numbers you are measuring are to be meaningful in any way. It is necessary for a load to be applied while measuring, so don't just hook the battery up and measure the IR. If you have a dedicated lipo tester like the one you can get from SMC, those will apply a load internally during the lipo check.

The method I found over and over again when researching the topic of IR was the following: Start with a battery at 60% charge that has been sitting at 70-72°F (Ideally you always want the temp to be the exact same every time for repeatability) for several hours to ensure that the temperature is homogenous throughout the pack. Hook it up to the charger and begin charging at a 1.5C rate (i.e. 5000mAh battery at 7.5A and so forth). Wait a few seconds and then check IR. Repeat the exact same procedure every time you measure IR and, if you're journaling your data, notate variables such as temperature as well as it does make a difference.

 

[LibertyMKiii]

Everyone has different experiences with this stuff and maybe the equipment is providing different readings as part of the issue.... The cell checker I am using is very cheap.

A pair of CNHL G+ 70c 3s packs each had a cell that was reading relatively high. One was around 7 and the other pack had one at 9.

I still see great performance out of these 2 battery packs. (like world record speed run performance)
LiPos seem to be near the end of life when they reach the 15-19milli-ohm range from my experiences.

 

[jkflow]

In general, please provide more details.
Capacity is the biggest factor for IR, brand and C rating only matter if they are bad and it's good to know to avoid them.

A simple 'is this a good value' is somewhat meaningless. It's a stellar value for a 500mAh pack and complete garbage for a 10000mAh pack.

The biggest thing is that all cells should be around the same value, as the highest value will be your lowest performer and drag down the pack.
For the above 5000mAh range all cells should be below 5mOhm ea. Mine are typically in the 1.5 to 3 range.
Below 10mOhm is ok as well, but never seen one.

 

[SrC]

I bought a couple no-name 2S batteries from Amazon and they balance fine, but the resistance levels are higher than I usually see on new batteries.

What resistance levels do you expect from a new battery?

Battery 1:
6.1 mΩ
9.7 mΩ
Battery 2:
4.5 mΩ
7.2 mΩ

Seems too high and all over the place. 3 or 4 miliohms is about right and they should all be within a point or 2. What I've seen with better brands and lipos that have given good longevity.
IR's are always best tested when the lipo cells are Fully Charged.
I would send them back if when full charged and their IR's still look whacked out.
Even cheapo lipos should not be like that. But do check them when fully charged. and balanced.
What was the resting voltages of all the cells out the box? This matters also.
Cheaper lipos use poorly matched LOW grade ( cheap) cells.
And also sometimes the cells are New OLD stock. Sitting around for way too long without use. Cells lose voltage just sitting with time as the enemy, And this affects IR"s over time.

 

[Sirkensirlot]

Everyone has different experiences with this stuff and maybe the equipment is providing different readings as part of the issue.... The cell checker I am using is very cheap.

A pair of CNHL G+ 70c 3s packs each had a cell that was reading relatively high. One was around 7 and the other pack had one at 9.

I still see great performance out of these 2 battery packs. (like world record speed run performance)
LiPos seem to be near the end of life when they reach the 15-19milli-ohm range from my experiences.

I have posted this before but I have 3 lipo cell checkers. ISDT / Battery Doctor & Outlander . None are accurate

 

[Diem Turner]

I have posted this before but I have 3 lipo cell checkers. ISDT / Battery Doctor & Outlander . None are accurate

If you want something accurate, the ESR meter from SMC should fit the bill but it does cost $150. It also provides C-ratings for each cell though. So if you have the coin and really want to check your batteries, this is the way to go.

 

[LibertyMKiii]

I have posted this before but I have 3 lipo cell checkers. ISDT / Battery Doctor & Outlander . None are accurate

I cannot seem to even get accurate cell voltage between the 2 cell checkers I have and my charger. It seems impossible to know which is correct. Hopefully, when I charge my batteries they are actually fully charged?!

 

[jkflow]

A word of advice, at best our cell checkers are yard sticks. Stay with the one (and only one) you like the best, you can't compare between different brands.
If you want the cream of the crop, you need to get the one Mark II listed above, and it will run ~ $150. Just a little overkill for bashing

 

[SrC]

I have posted this before but I have 3 lipo cell checkers. ISDT / Battery Doctor & Outlander . None are accurate

I tend to take the averages overall. Yes they are not all identical reads. But within a few Points are good enough. And again like I said above, IR reads are most accurate when the Lipo cells are fully charged. How the Lipo Mfrs. read them.

 

[SrC]

A word of advice, at best our cell checkers are yard sticks. Stay with the one (and only one) you like the best, you can't compare between different brands.
If you want the cream of the crop, you need to get the one Mark II listed above, and it will run ~ $150. Just a little overkill for bashing

Agree. The more lipo checkers you have, the more different reads you will get. The more you will scratch your head. Just confuse something that is really simple.
But I find that one must place a certain amount faith in the voltage reads of the charger. Because this is what's in control of those cells.
IR's the same. I have found IR's can be a variable every time you check those same cells back to back. Whether checked at the charger or the cell checker.


Edit.
IR reads mean nothing to me unless the cells are at 4.2v. How I fly.