An other quick battery question

[dor]

A few weeks ago I replaced my 4 leisure batteries with new 110Ahr open cell standard leisue batteries.

 

I expected a siginificant improvement, but they seemed to run down very quickly, as well as charge up quickly. All the signs of sulphated batteries but these were new. I've just checked them after a couple of hours charging. Left for half an hour, then disconnected and voltage checked individually. I had 12.76, 12.77, 11.36 & 12.74. So, simple enough, one dodgy battery pulling the others down. So I've brought it back with me intending to take it back to the supplier this afternoon. Just checked the voltage on it again and it is reading 12.52, which is about what I would expect after a good stabilisation period as they probably weren't fully charged. So how come it read 11.37, then a hour or so later read 12.52? Any ideas?

[KenK]

A few weeks ago I replaced my 4 leisure batteries with new 110Ahr open cell standard leisue batteries.

 

I expected a siginificant improvement, but they seemed to run down very quickly, as well as charge up quickly. All the signs of sulphated batteries but these were new. I've just checked them after a couple of hours charging. Left for half an hour, then disconnected and voltage checked individually. I had 12.76, 12.77, 11.36 & 12.74. So, simple enough, one dodgy battery pulling the others down. So I've brought it back with me intending to take it back to the supplier this afternoon. Just checked the voltage on it again and it is reading 12.52, which is about what I would expect after a good stabilisation period as they probably weren't fully charged. So how come it read 11.37, then a hour or so later read 12.52? Any ideas?

 

I'm no expert but possibly the movement remade a poor internal connection. I had one a couple of years ago which appeared to charge perfectly, excellent voltage and hydrometer readings but it wouldn't give a decent output. I'd take it back and get them to change it.

 

Ken

[Nickhlx]

I'm no expert but possibly the movement remade a poor internal connection. I had one a couple of years ago which appeared to charge perfectly, excellent voltage and hydrometer readings but it wouldn't give a decent output. I'd take it back and get them to change it.

 

Ken

 

 

There was a very similar thread on here a couple of weeks ago and the bottom line is that the batteries were dead....

 

Nick

[smileypete]

A few weeks ago I replaced my 4 leisure batteries with new 110Ahr open cell standard leisue batteries.

 

I expected a siginificant improvement, but they seemed to run down very quickly, as well as charge up quickly. All the signs of sulphated batteries but these were new. I've just checked them after a couple of hours charging. Left for half an hour, then disconnected and voltage checked individually. I had 12.76, 12.77, 11.36 & 12.74. So, simple enough, one dodgy battery pulling the others down. So I've brought it back with me intending to take it back to the supplier this afternoon. Just checked the voltage on it again and it is reading 12.52, which is about what I would expect after a good stabilisation period as they probably weren't fully charged. So how come it read 11.37, then a hour or so later read 12.52? Any ideas?

Try checking the SG on each cell.

 

cheers,

Pete.

Edited November 6, 2009 by smileypete

[nb Innisfree]

Moving around dislodged an air lock?

[Ermenilda]

interesting... conflicting... surely this would have been a perfect post for here

[WotEver]

interesting... conflicting... surely this would have been a perfect post for here

No it wouldn't. It's completely irrelevant to that thread.

[dor]

OK - result. Took the battery back to the supplier who identified one completely dead cell and replaced the battery with a new one. No explanation for why the voltage increased though.

[WotEver]

OK - result. Took the battery back to the supplier who identified one completely dead cell and replaced the battery with a new one. No explanation for why the voltage increased though.

My guess is Ken was right - intermittent bad connection within the battery. If the cell was completely (and permanently) dead then you'd never have seen more than around 10.5V - the fact that you saw 11.36 and then 12.52 demonstrates a dodgy connection rather than a completely dead cell.

 

Tony

[smileypete]

OK - result. Took the battery back to the supplier who identified one completely dead cell and replaced the battery with a new one. No explanation for why the voltage increased though.

BTW what make and type was the battery?

 

cheers,

Pete.

[Arnot]

A few weeks ago I replaced my 4 leisure batteries with new 110Ahr open cell standard leisue batteries.

 

I expected a siginificant improvement, but they seemed to run down very quickly, as well as charge up quickly. All the signs of sulphated batteries but these were new. I've just checked them after a couple of hours charging. Left for half an hour, then disconnected and voltage checked individually. I had 12.76, 12.77, 11.36 & 12.74. So, simple enough, one dodgy battery pulling the others down. So I've brought it back with me intending to take it back to the supplier this afternoon. Just checked the voltage on it again and it is reading 12.52, which is about what I would expect after a good stabilisation period as they probably weren't fully charged. So how come it read 11.37, then a hour or so later read 12.52? Any ideas?

There are a couple of possible reasons.

 

One is that there was a broken intercell connector inside the battery, this could create all sorts of problems by becoming open circuit or even emulating a seventh cell in the battery.

 

The other (and more likely) is that there was a faulty cell that under load conditions had swapped polarity and thus subtracted from the series voltage sum (or under recovery anywhere in between). After being left fallow for a while it could have recovered and once more added to it.

 

This is a phoenomenon I have noticed before but ususally in starting batteries that tend to have to produce higher discharge rates.

 

Regards

 

Arnot

[Gibbo]

A likely possibility is a damaged separator between plates allowing the plates a partial short (thus lowering the voltage of that one cell. As the battery (or perhaps just that one cell) discharged this part could turn to lead sulfate (not a particularly good conductor) thus partially insulating itself again allowing the voltage to rise back up.