Sludge in Battery Electrolyte

[Captn D]

I have normal wet lead acid batteries and, as they have aged, I have noticed a black oily sludge appearing around the top of the cells above the electrolyte. Any ideas as to what this is and is it a bad sign?

 

[NB Willawaw]

Its Lead Oxide coming from the plates and it will eventually kill the battery. Its just normal as the battery gets older.

 

[VicS]

Lead oxide but if much is being carried up and deposited around the top of the cells it might indicate gassing due to overcharging. It might be sensible to check the charging voltage

 

[Captn D]

Thank you both. The battery voltage whilst on float charge from the Sterling "intelligent" charger is 13.6v. I don't think it can be adjusted. Is this too high?

 

[NB Willawaw]

No its okay. Float is is usually about 13.8V but it doesn't matter.

The battery will die whatever you do. Its just a question of how long.

I guess its terminal

 

[nimbusgb]

No its okay. Float is is usually about 13.8V but it doesn't matter.

The battery will die whatever you do. Its just a question of how long.

I guess its terminal

Positively terminal nothing to get negative about, you have just got the whole life out of it!

 

[Captn D]

Guess the next question is how much lead oxide gunge indicates the onset of termination? At the moment, there doesn't appear to be an excessive amount. The batteries seem to hold their charge and the voltages are consistent with normal discharge amp/hours. Should I hold on for another season?

 

[Plevier]

Guess the next question is how much lead oxide gunge indicates the onset of termination? At the moment, there doesn't appear to be an excessive amount. The batteries seem to hold their charge and the voltages are consistent with normal discharge amp/hours. Should I hold on for another season?

You really can't tell.
Some batteries will reach end of life with no muck round the top, others will show it early on.
It can be related to vigorous gassing but doesn't need to be - it's the boost charge voltage that matters for this not the float voltage.
It can be related to separator type and configuration.
It can be related to general manufacturing quality and hygiene.
Are these cheapos or quality?

 

[Captn D]

Are these cheapos or quality?

Varta - 6 years old.

 

[Plevier]

Good batteries, but ordinary car/truck type presumably.
Some deterioration and active material loss after 6 years is to be expected especially with a multi rate charger that probably goes up to significantly above gassing voltage.
If you tested them you would probably find significant capacity loss but no reason to expect sudden total failure imminently. Don't set off on a round the world with them though!

 

[NB Willawaw]

It's impossible to predict. If you don't stray too far from civilization, budget for a new one and replace when you have to.

Guess the next question is how much lead oxide gunge indicates the onset of termination? At the moment, there doesn't appear to be an excessive amount. The batteries seem to hold their charge and the voltages are consistent with normal discharge amp/hours. Should I hold on for another season?