Dead Cell

[FatCatRC]

How does a battery just lose a cell and the pack still work? My 6s battery wouldn't charge so i checked the cells and #5 was dead flat no volts at all. It reads at 16v aprox from the xt60 connector. I can plug it in my car and she still turns on an runs. It charged yesterday and worked fine. How did it just lose a cell overnight? And not just lose it but have it go completely dead flat. The battery has no damage to it at all and has never seen a jump.

 

[SrC]

The nature of lipos. Cells fail without warning. You essentially have a 5S pack now. In theory, that one cell is not completely dead, because it still is not fully "OPEN". Fully open and that pack will give you nothing. Is the pack puffed. Is that one cell puffed out. How many cycles have you run it??? Try to balance that one cell alone out of series. If there is any hope for it. Probably bricked. What is the IR's across all cells???? If the IR's are poor, then that pack was on its way out anyway.

 

[rflx]

Edit: oops, didn't read correctly. Can you read out the internal resistance of the cell?

 

[FatCatRC]

The nature of lipos. Cells fail without warning. You essentially have a 5S pack now. In theory, that one cell is not completely dead, because it still is not fully "OPEN". Fully open and that pack will give you nothing. Is the pack puffed. Is that one cell puffed out. How many cycles have you run it??? Try to balance that one cell alone out of series. If there is any hope for it. Probably bricked. What is the IR's across all cells???? If the IR's are poor, then that pack was on its way out anyway.

The pack is very new, it has 5 runs on it max was always balanced charged and stored proper. Was never used for jumps and has no damage at all to it. No puffed cells no damage to the balance leads and it charged fully and ran np yesterday but died over night.

What is the overall voltage of the lipo? It sounds like it might just be the balancer cable.

overall volts is 16.27 volts on my hobbywing program box tester and 16.47 on my volt meter. The hobbywing box says cell 5 is 0v.

Edit: oops, didn't read correctly. Can you read out the internal resistance of the cell?

How do I do that?

Edit: oops, didn't read correctly. Can you read out the internal resistance of the cell?

I don't have a resistor is there another way to text the resistance?

 

[nino]

Your charger could have that function.
That's weird. It should be shorted out forthe battery to work. Maybe the cell is OK but one of the balance leads is disconnected?

 

[Yas]

If your pack isn't old and you've not tugged on the balance leads, my guess is the balance port plugs aren't fully home and aren't making contact properly

I spent an hour this week myself changing balance pins and still wondering why my 6s lipo was only reading 5 cells... didn't think to check both of my balance port plugs. One of them was half out ?

 

[FatCatRC]

Your charger could have that function.
That's weird. It should be shorted out forthe battery to work. Maybe the cell is OK but one of the balance leads is disconnected?

But why would it read 16.47 volts at the main xt60 connector? This is whats throwing me off too, like how is it just bypassing that cell and showing 16.47 volts you would figure the whole pack wouldn't work no?

If your pack isn't old and you've not tugged on the balance leads, my guess is the balance port plugs aren't fully home and aren't making contact properly

I spent an hour this week myself changing balance pins and still wondering why my 6s lipo was only reading 5 cells... didn't think to check both of my balance port plugs. One of them was half out ?

I checked every cell with a volt meter and it's the first black pin that is not showing voltage. I want to pull it apart really bad to see if it's just a lose connection but I want to wait to see what the store i bought it from says first. See if I can just straight up warrenty and not even mess with it.

 

[Yas]

But why would it read 16.47 volts at the main xt60 connector? This is whats throwing me off too, like how is it just bypassing that cell and showing 16.47 volts you would figure the whole pack wouldn't work no?

I checked every cell with a volt meter and it's the first black pin that is not showing voltage. I want to pull it apart really bad to see if it's just a lose connection but I want to wait to see what the store i bought it from says first. See if I can just straight up warrenty and not even mess with it.

Ah crap, you're right. It must be a solder joint. I would definitely wait for what your retailer would say first. Hope it gets sorted ?

 

[SrC]

Your charger could have that function.
That's weird. It should be shorted out forthe battery to work. Maybe the cell is OK but one of the balance leads is disconnected?

I was thinking the same thing.

 

[FatCatRC]

I was thinking the same thing.

My charger atm does not have that function, But I think my new one in the mail does. The ebay guy has emailed me back asking for pictures of the voltages. hopefully he give me a new one if not I'm tearing this one apart and going exploring. I'm a little nervous with the 6s though I have fixed 3s and 2s batteries before but never a 22v beast. Worst thing that could happen I guess is my cats get a good firework show and I learn how to weld real fast lmao!

 

[FatCatRC]

New battery on the way!

 

[rflx]

New battery on the way!

So no conclusion to the mystery?

 

[Rcproponent]

So no conclusion to the mystery?

Yep, new battery on the way... ??

 

[FatCatRC]

So no conclusion to the mystery?

Pulling it apart now I will update with results

 

[SrC]

Probably a bad solder joint at the cells balance lead somewhere. Poor QC happens like this.

 

[FatCatRC]

I'm so confused!!! I set my multi meter to auto, and I tested all cells. All give me voltage except on cell, the one cell makes my multi meter go into ohm mode or will buzz like it does for a closed circuit.

 

[SrC]

Check that one cells Internal resistance in OHM setting. What does it read?

 

[FatCatRC]

159.0 ohms

159.0 ohms

rest read 0
I don't get it. Did that cell essentially turn into a brick?

 

[FatCatRC]

Check that one cells Internal resistance in OHM setting. What does it read?

The "dead" cell reads 159.0 ohms and the others read 0. Any thoughts?

 

[SrC]

159 ohms is a bricked cell for sure. In general all cells should be of the same or close in IR's. As cells get older the IR goes up gradually. Its good way to guage the life expectancy of that pack as its used over time. But one cell way out of sync with the rest is a sure sign of a failing cell. IR's are best tested and most accurate when the cells are fully charged and all are balanced at 4.2v/cell.