Did I Ruin My Cells??

[thenunzzz]

Long story short I made a rookie mistake and completed a short circuit on 4 of my cells. I was preparing these cells for pre-charging before top balancing. They hadn’t been used since I unboxed them. I added a bus bar where it was not meant to be and sparked aggressively. I couldn’t figure a good way to get it off without zapping myself and stupidity left it overnight in the manner of the photo below:

Yes I know... very dumb, lesson learned.
Moving on, the next morning I got the bus bar off and set up another bank to cross reference the voltages to see if the cells are fried. I just picked up this Klein multimeter and honestly am not sure if I’m using it correctly. Here’s a video:

If these are indeed shot, let me know if you or someone you know has 100ah Fortune cells for sale!

 

[snoobler]

It isn't entirely clear what happened, and your readings don't make any sense with the variable voltage readings.

 

[thenunzzz]

It isn't entirely clear what happened, and your readings don't make any sense with the variable voltage readings.

here’s a reading I got with an old multimeter

 

[snoobler]

Can you easily read what you posted? I see blurry numbers and a needle.

 

[thenunzzz]

Can you easily read what you posted? I see blurry numbers and a needle.

The last picture is 6.9 volts DC with the old meter

 

[Gazoo]

I see just shy of 7 volts. Is that supposed to be a 6 volt pack?

 

[snoobler]

I suggest you break down the pack and measure cells individually.

Never, ever ever leave a known short in place. Remember that you're dealing with relatively low voltages. The risk of fatal shock is essentially zero unless you soak yourself in a highly conductive solution and press the terminals to any open wounds or mucous membranes. This is nothing like the movies where they connect a car battery to someone's nipples.

A spark might be uncomfortable, but it's not going to cause damage.

 

[thenunzzz]

I see just shy of 7 volts. Is that supposed to be a 6 volt pack?

By itself yes. I am building a 24v 200ah bank with 16 prismatic cells. I should specified.

 

[thenunzzz]

I suggest you break down the pack and measure cells individually.

Never, ever ever leave a known short in place. Remember that you're dealing with relatively low voltages. The risk of fatal shock is essentially zero unless you soak yourself in a highly conductive solution and press the terminals to any open wounds or mucous membranes. This is nothing like the movies where they connect a car battery to someone's nipples.

A spark might be uncomfortable, but it's not going to cause damage.

I’ll send some pictures with the Klein multimeter. I measured them individually earlier with the old school multimeter and they all measured 3.2v and cross referenced that with the undamaged cells to match. And looking back I figured it wouldn’t have hurt. I sure wish I hadn’t walked away from it...

 

[snoobler]

There should be some detectable outcome from the short.

The only way I can imagine that something Egon-bad didn't happen is if the busbar oxidized and stopped flowing current, and that though comes straight from the cleft of mine nethers.

 

[thenunzzz]

There should be some detectable outcome from the short.

The only way I can imagine that something Egon-bad didn't happen is if the busbar oxidized and stopped flowing current, and that though comes straight from the cleft of mine nethers.

Here’s a video of the individual test:

They all read 3.2v on two different old multimeters. I have the electrodacus on hand. Can I hook it up the 4 cells configured 4p4s and get better information?

 

[Gazoo]

I am lost because of the way that volt meter works. When you connect the leads, as you did the first time around, the voltage shouldn't drop. But you have verified the voltage with another meter and double verified with other cells.

I am confused because a dead short should cause the busbar to be red hot, literally, and I would think the cells(s) would smoke and deform.

As @snoobler indicated, there should be something visually noticeable. It looks like one of the studs in your first photo arced badly. Your saving grace could be the busbars were not tightened down flat against the terminals, and were acting as a resistor which would have lessened the flow of current. I am still surprised at all of this and the fact you are seeing decent cell readings surprises me more.

I think the next step would be to capacity test the four cells before doing anything else with them. Running a capacity test on each one would be the most ideal way.

 

[Pyrofx]

Maybe you hooked up correct
Spark was cells equalizing?

 

[thenunzzz]

I am lost because of the way that volt meter works. When you connect the leads, as you did the first time around, the voltage shouldn't drop. But you have verified the voltage with another meter and double verified with other cells.

I am confused because a dead short should cause the busbar to be red hot, literally, and I would think the cells(s) would smoke and deform.

As @snoobler indicated, there should be something visually noticeable. It looks like one of the studs in your first photo arced badly. Your saving grace could be the busbars were not tightened down flat against the terminals, and were acting as a resistor which would have lessened the flow of current. I am still surprised at all of this and the fact you are seeing decent cell readings surprises me more.

I think the next step would be to capacity test the four cells before doing anything else with them. Running a capacity test on each one would be the most ideal way.

Yea I don't know what the deal is with that volt meter, but the videos I have watched on these Klein multimeters don't do that when touching a battery. Both the old multimeters showed the same information essentially which leads me to believing the old meters data. The cells and bus bars never got hot, maybe because the busbars didn't have a solid connection being loosely fitted.

Here's the damage:

And I like the idea of the capacity test. I don't want to just write them off if there are actually not damaged.

 

[thenunzzz]

Maybe you hooked up correct
Spark was cells equalizing?

It couldn't possibly be correct connection. This is the layout below:

 

[Pyrofx]

Looks like correct for 24 to me

 

[thenunzzz]

Looks like correct for 24 to me

Yes, but look at 4 and 5. The center cells positive and negative are not supposed to be connected.

 

[Pyrofx]

And if you had inverter hooks up there would be a huge inrush

 

[thenunzzz]

And if you had inverter hooks up there would be a huge inrush

No hooks up just cells by themselves that's all

 

[Pyrofx]

That made a parallel set. If it was shorted it would get red hot