Battery hitting lvsd early

[Caleb90]

I have one 3s battery that has been tripping the low voltage shutdown early. When i go to charge it, it shows around 3.8v per cell. While the other shows 3.5v per cell. Also the run time is much shorter. There isnt any puffing and both ir rates are 10.6. is this a sign of battery needing to be retired?

 

[FJC_GUY]

What rig are you running it in?

In my Vorteks the LVC will kick in under heavy throttle around 3.8v per cell. On my Crawler it will run down to 3.5 no issue.

 

[Chubaka]

Curious as to what esc your using. My old VXL3s used to do it. My current Castle Copperhead 10 does it randomly also.

 

[Caleb90]

Arrma big rock. Stock esc. Never used to do it now it does.

 

[WickedFog]

Those IR's are pretty high. That would definitely lower the voltage output under load, causing the LVC to trip sooner.

 

[Greywolf74]

Are they both the same brand battery? Do they both have the same number of cycles on them? Different brand LiPos could perform differently from one another even if they have the same IRs. 10mOhm is generally where I start using the packs for lighter duty loads though.

Even if they are the same brand with the same IRs, If one pack has more cycles on it then that could cause it to have less mAh than a pack with less cycles.

Also the BLX100 ESC which I believe is what the Big rock comes with, has very little programmability. Now I dont know if theyre anything like the Spektrum 160A ESCs but the LVC on those ESCs can only be set to "Auto - High", "Auto-Medium", or "Auto-Low". One thing I noticed when using that ESC is that the LVC never seemed to kick in at the same level. it was always a bit different. That may be comparing Apples and Oranges though as IDK if Spektrum even makes the BLX ESCs.

 

[tntpoof]

ir is the major issue in charging and in use.try to bring ir down unlikely you can do this from reading many of your previous posts. retire pack .

 

[FJC_GUY]

Are they both the same brand battery? Do they both have the same number of cycles on them? Different brand LiPos could perform differently from one another even if they have the same IRs. 10mOhm is generally where I start using the packs for lighter duty loads though.

Even if they are the same brand with the same IRs, If one pack has more cycles on it then that could cause it to have less mAh than a pack with less cycles.

Also the BLX100 ESC which I believe is what the Big rock comes with, has very little programmability. Now I dont know if theyre anything like the Spektrum 160A ESCs but the LVC on those ESCs can only be set to "Auto - High", "Auto-Medium", or "Auto-Low". One thing I noticed when using that ESC is that the LVC never seemed to kick in at the same level. it was always a bit different. That may be comparing Apples and Oranges though as IDK if Spektrum even makes the BLX ESCs.

In my crawlers, I have no issue running a battery with a bit higher IR as long as it's even across cells. I'm not so worried about "punch" with those though as they seldom see more than 3/4 throttle.

The Vorteks once they are seeing above about 8 for IR they will start sagging and trip LVC under heavy load. Then they become crawler only.

 

[Caleb90]

Both the same brand, same ratings ,both bought at the same time. Used about the same. One maybe more than the other depending how i charged them and what trucks i was running. Here are the cell numbers off the hota.

Just looked and i bought them feb 2nd 2022

 

[WickedFog]

When you check the IR's, wait til the charge ends, and let the battery sit there for a couple minutes before you read the IR. You will get a more consistant reading that way. The IR will fluctuate during the charge cycle, so being consistant when you get the values will give you better comparisons as the pack ages.

 

[Bogda89]

Ir is useful but you can't really tell if the battery is good.

I had one protek battery that showed good ir on both cells, I don't remember the number it was over 4 years ago. But one cell was so bad that had less than 1000 mAh capacity, and lvc would cut very early

 

[Caleb90]

After full charge

 

[Greywolf74]

After full charge

View attachment 157395

View attachment 157396

The second picture there shows more irregular wear between the cells. its not wide enough gap to hurt anything yet but cell two is definitely developing resistance faster than the other cells. The first pic the IRs are much closer together although higher overall. Both batteries are still usable but not equal

 

[Caleb90]

I will run them again, this time i will mark the one that cuts off short with a marker. To see if its the same one every time

 

[Greywolf74]

I will run them again, this time i will mark the one that cuts off short with a marker. To see if its the same one every time

Ill be interested to know which one cuts off first. Are you timing the runs or are you using a data logger?

 

[WickedFog]

Ill be interested to know which one cuts off first. Are you timing the runs or are you using a data logger?

Lol, nobody but you are that big of a geek to have a data logger.

 

[Caleb90]

Ill be interested to know which one cuts off first. Are you timing the runs or are you using a data logger?

Haha, no neither. It just that obvious when its cutting off that much sooner

 

[Greywolf74]

Lol, nobody but you are that big of a geek to have a data logger.

well, I guess I need to go get my slightly larger glasses.

 

[bill_delong]

Those IR's are pretty high. That would definitely lower the voltage output under load, causing the LVC to trip sooner.

+1

I tend to retire my packs when any individual cell goes past 7mΩ as my personal preference, more info here:
https://www.rcgroups.com/forums/sho...-charger-is-the-best&perpage=100#post43510433

 

[Greywolf74]

+1

I tend to retire my packs when any individual cell goes past 7mΩ as my personal preference, more info here:
https://www.rcgroups.com/forums/sho...-charger-is-the-best&perpage=100#post43510433

I'm curious, is that for racing or just in general? My personal bashing guideline (I dont race) has become relegating a pack to light duty use at about 10mOhm and then retiring it completely somewhere around 16-18mOhm.