Why is one cell charging and the other lowering at the same time?

[Stewfish]

Why is this happening. Everything looked good this week after I replaced some failing cells in our two 48v batteries. At times cells 24 and 25 yo yo taking cell 24 lower and 25 higher and for half of the day they have stayed at the more narrow differentiation. Batrium seems to be bleeding off voltage on 25 (denoted by the red cube) as if its going to run away with the amos from cell 24. See pics I have seen the larger differentiation/yo yo happen half a dozen times for a second or two at the most. I'm glad I caught it on camera to show you

I noticed today while charging at 54.1v which is well below the 58v possible to be safe for any less resistive cells, that the cell number 25 started to take off while at the same time cell number 24 started to lower it's as if somehow at the same time one cell got more resistance while the other got less resistance compared to every other cell. These were unused cells that were replaced along with six other cells to replace cells that were going bad.

I'm getting a little frustrated with these cells after buying 40 of them I feel like a year later I have junk that won't last another year.

I'll update on who makes the cells and their customer service when I see wether they replace the bad cells, now I may need another one or two cells depending on what happens with these.

 

[Supervstech]

Very odd.
I would test voltages and confirm balance lead placement.
You could have a bad cell that is self discharging… but it’s odd.

 

[Stewfish]

Very odd.
I would test voltages and confirm balance lead placement.
You could have a bad cell that is self discharging… but it’s odd.

This is Batrium software/hardware - The voltages are shown for those two cells. They are conveniently the high and low numbers on the left.
2.83 and 3.78

The scale on the left shows real time voltage with no real delay for all cells. You can hover over things also. It's live and turning on something is seen right away

Vs watch power is very slow to update

 

[Supervstech]

Yes… voltage is shown, but I would get a meter, and confirm it. Wouldn’t be the first time I found a bad sense lead.

 

[sunshine_eggo]

Did you confirm those voltages with a multimeter directly on the cells?

(2.83 + 3.78) / 2 = 3.305 - pretty close to the others?

I'm w/@Supervstech - balance lead issue.

 

[Stewfish]

Not close on the lifepo charge curve.

Oh, I just saw your averaging

 

[Stewfish]

I'll check but it would be sporadically new today.

 

[sunshine_eggo]

I'll check but it would be sporadically new today.

The best way to fail to solve a problem is to believe it can't happen.

You have absolutely batty-nut-shit readings... Why not check voltage?

You've indicated it's erratic - that screams connection problems.

 

[Stewfish]

Did you confirm those voltages with a multimeter directly on the cells?

(2.83 + 3.78) / 2 = 3.305 - pretty close to the others?

I'm w/@Supervstech - balance lead issue.

Its 3.317 across both and 3.32 on others nearby. I guess I'll power down the batrium and build two new leads

 

[Stewfish]

The best way to fail to solve a problem is to believe it can't happen.

You have absolutely batty-nut-shit readings... Why not check voltage?

You've indicated it's erratic - that screams connection problems.

So what would cause it?

 

[sunshine_eggo]

So what would cause it?

Corrosion
thermal cycles
broken strands
weak crimp
loose connection
The flying spaghetti monster did not look favorably upon you
For an instant, every atom in the universe existed to cause you trouble
?

I'd check everything from the cell terminal to the Batrium.

 

[kromc5]

I had one m8 that was defective and read the wrong voltage. I would do another device sync make sure it passes and verify with the meter that both are correct. How do all the cells look in telemetry cell info?

 

[Stewfish]

Yep lead 24 was bad. Thanks guys!

Very wierd

 

[sunshine_eggo]

Yep lead 4 was bad. Thanks guys!

Very wierd

Cause?

 

[Stewfish]

I spent a minute or two ohming out the wire parts with the alarm/sound function. When I did wiggle lead 24 I lost all readings. So it was a grimlin fault/ broken wire somewhere in the lead.

I used heat shrink connectors w a special heat shrink crimper so the wires wouldn't be the only support to the terminals. they all hav those terminal ferrels with the specialty crimper. tinned ring terminals w another specialty ratcheting crimper for those. Specialty 500 ft spool of tinned wire that was suggested.

We are in the desert thus minimal moisture, and no corrosion seen


Go figure

 

[Stewfish]

The fuse was good.

I didnt want to mess with it much so I just made a new lead. All my tool and parts are right next to the battery cabinet so it took 5 minutes to fix all new

 

[Stewfish]

Batrium does tell you to use small guage wire to act like a fuse (I think it was 24g). Anyway it must have done its job.

But I wonder if it was a fuse type /thermal issue and what would cause it. Maybe the batrium was bleeding off too many amps on #24 to lower the voltage as not to run up during charging.