Corrosion hole in lishen casing

[joeblack5]

New lishen 272Ah cells 20% charged in 16 cell series on double cardboard in basement..no connection to anything else.

Bad luck caused the dishwasher to release some gray water in the basement.
A little soaked up in the cardboard.

Did not think much about it. Two days later I noticed a bubble at the bottom of two cells.

In some of the aluminum cases it seems to be a thru hole. No liquid is coming out.
Yet..

Likely caustic dishwasher water and the galvanic potential of the aluminum casing after the liquid slowly migrated thru the blue plastic.

Johan

 

[kuranaga]

hydroxides eat aluminum very quickly - within minutes. Put a piece of aluminum foil into caustic soda solution and you will see.

 

[joeblack5]

I have a feeling that the voltage differential between the casings gave it some help

 

[kuranaga]

could be but the casings would need to be immersed to some extent. just some wet at the bottom unlikely

 

[Will Prowse]

Wow that's awful!!

 

[joeblack5]

With kuranaga's comments in mind, I did some more test with aluminum foil in the same liquid that these batteries were exposed to...left it in / on there for two weeks ...and nothing happened. Aluminum foil became less shiny and dirty looking.. no holes ..still foil.

So I do not think that the liquid itself was very aggressive to aluminum.

The aluminum was eaten away under the blue foil close to the folds at the bottom and that the batteries were not immersed but were standing on soaked cardboard.

Since the aluminum cases have some I think that the aluminum was eaten because some current was flowing from batteries housing to the next battery housing.

The soaked cardboard must have been the conduction route.

Now I would be interested in knowing if this electrolytic attack also occurs from the inside when the there is current flowing via the housing.

Overall I feel this is very concerning in all application where the batteries are exposed to humidity and condensing applications where liquid could potentially develop at the bottom of the batteries.

Interesting info at fractory.com ...aluminum corrosion...

Johan

 

[HRTKD]

Based on just the pictures alone, it looks like surface corrosion, not a through hole into the battery. The aluminum case isn't very thick, but I would try to remove the corrosion, apply a corrosion inhibitor and keep an eye on it.

 

[joeblack5]

Unfortunately from three of the six cells the cases are corroded thru. The pouches are visible. Sorry if my fotgraphy is not up to that detail..
Of course I will try to save these cells but with high internal pressures and the damage at the corners rupture would be possible

My warning to others is just that if you have condensing going on or use these in an unconditioned space that you should keep an eye on this.

Johan

 

[HRTKD]

Well, I guess a patch of duct tape isn't going to cut it then.

The EVE datasheet says storage humidity is 95% or less. That seems awfully high to me. I live in a very low humidity area. 95% humidity inside my RV would require a multi day rain I suspect.